Biology for CAPE® Unit 2 Biology for CAPE® Richard Stuart Lorna Fosbery LaPlace McPherson Unit 2 3 Great Clarendon Oxford It University furthers and the Oxford © Press by is a Richard Press in Fosbery, illustrations © OX2 6DP, department objective publishing University Original Oxford, University’s education Text Street, of of UK Stuart and University Oxford in LaPlace Oxford the Kingdom excellence worldwide. the United is certain and University a of Oxford. research, scholarship, registered other Lorna Press in trade mark of countries McPherson 2012 2014 ® CAPE The a registered moral First This All is published edition rights stored in means, Press, or sent British Data by part prior of have Ltd this by in law, by any rights the be in (CXC ) 2014 reproduced, form of licence outside Department, Press may in writing reprographics reproduction Council 2012 University publication permission Rights in Examinations asserted transmitted, permitted the Caribbean been Oxford or appropriate to the Thornes system, expressly address must No of authors Nelson the the mark published concerning be impose the retrieval as Enquiries You by reserved. a with should of rst without agreed the rights trade or Oxford or by any University under terms organization. scope Oxford of the above University Press, at above. not this circulate same Library this work condition Cataloguing on in in any any other form and you must acquirer Publication Data available 978-1-4085-1649-2 10 9 8 7 Printed 6 5 in 4 3 Great Britain by Ashford Colour Press Ltd., Gosport Acknowledgements Cover photograph: Mark Lyndersay, Lyndersay Digital, Trinidad. 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permission iStock; Reproduced Examinations; danny of 4.3.1 permissions Burgess/Science Niesen/Shutterstock; Syred/Science Chris Jeremy Miller/Science Pete Text Institution/Visuals Dr. materials Library; work. contained in any third party website referenced in this Contents Introduction Module 1. 1 1 v Bioenergetics Energy and carbon in ATP 1.3 Leaf Biodiversity 50 4.3 Species diversity 52 4.4 Maintaining biodiversity 1 54 4.5 Maintaining biodiversity 2 56 4.6 Sampling ecosystems 1 58 4.7 Sampling ecosystems 2 60 4.8 Practice 2 living systems 1.2 4.2 2 4 structure 6 1.4 Introduction to photosynthesis 1.5 The light-dependent 1.6 The light-independent 1.7 Investigating 1.8 Limiting factors 1.9 Practice stage stage 8 exam-style questions: Ecosystems 62 10 12 Module 2 Biosystems maintenance Energy 2. 1 2.2 2.3 2.4 photosynthesis 16 exam-style questions: and photosynthesis Introduction to respiration Glycolysis The The Introduction to transport 64 1.2 The 66 1.3 Xylem: 1.4 Transpiration 1.5 Measuring transpiration 2. 1 Phloem 74 2.2 Translocation 76 2.3 Assessing the uptake of water and ions 18 structure and function 20 70 reaction and rates 26 Oxidative phosphorylation evidence for 28 Investigating respiration Anaerobic respiration in mammals Anaerobic respiration 2.9 Respiration: 2. 10 Practice in yeast summary 36 and 38 3. 1 Energy nutrient flow 3.2 Ecological pyramids 42 3.3 Ecological efciency 44 3.4 The 4. 1 Ecosystems nitrogen cycle are dynamic 40 46 48 exam-style questions: uptake water in the 34 exam-style questions: Respiration Practice The 32 2.8 78 30 2.4 2.7 72 Krebs phloem transport 2.6 68 24 cycle 2.5 1. 1 22 mitochondrion link 64 14 and and transport of minerals; transport phloem 80 3. 1 Blood 82 3.2 Blood vessels 84 3.3 The 86 3.4 Pulse 3.5 Control of the 3.6 The 3.7 Haemoglobin heart and blood cardiac of oxygen pressure heart cycle 88 90 92 and the transport 94 iii Contents 3.8 Haemoglobin of 3.9 and the transport carbon dioxide Practice The 96 exam-style questions: mammalian 4.2 4.3 Health 1.6 Summary questions 2. 1 Defence circulatory system 4. 1 1.5 Homeostasis Hormones in Regulation of mammals infectious diseases 142 2.2 Non-specic defences 144 2.3 Lymphocytes 146 2.4 The 148 blood 2.5 Antibodies 150 2.6 Types of 152 2.7 Monoclonal 2.8 Practice 102 immune response glucose 4.4 Plant 106 4.5 Practice hormones immunity antibodies Excretion 5.2 The exam-style questions: 108 Health 5. 1 and disease, and 110 kidney nephron immunology 156 3. 1 Diet 158 3.2 Fats 3.3 Investigating the 112 and disease excretory functions of the kidney 114 Osmoregulation 116 in the diet 160 effects of exercise 5.5 Practice The 162 exam-style questions: kidney, excretion 6. 1 Structure of 6.2 The 6.3 Synapses 6.4 Practice nerve 3.4 Exercise and health 164 3.5 Practice exam-style questions: and osmoregulation neurones impulse 118 Social and preventative medicine 166 4. 1 Drugs 168 4.2 The 120 122 biological effects of 124 alcohol The Module nervous 3 170 exam-style questions: system 4.3 The social effects of 4.4 The effects of 4.5 Chronic alcohol 172 126 smoking 174 smoking-related Applications of diseases biology 176 128 4.6 1. 1 Health 128 1.2 Dengue fever 130 1.3 HIV/AIDS 1.4 Diabetes iv 154 exam-style questions: Homeostasis 5.4 140 100 104 The against 136 98 concentration 5.3 statistics and 132 cancer 134 Practice exam-style questions: Substance abuse 178 Glossary 180 Index 186 Introduction This Study Guide has been developed exclusively with the Caribbean ® Examinations candidates, Council both in ) (CXC and out of to be used school, as an additional following the resource Caribbean by Advanced ® Proficiency Examination It prepared ) (CAPE programme. ® has been teaching and by a team examination. with The expertise contents are in the CAPE designed to syllabus, support learning ® by providing the features and for guidance Inside this practice On good Y our T est in problem to syllabus. course is an type Do and in CD electronic to and Biology CAPE master the refer key to your examination that includes activities to and concepts syllabus format! the answers assist you to in techniques: provide to sample with show your are the could skill level short answers be and improved. and questions. designed questions study candidate answers understanding, specifically inside examination-style example where examination examination sections to remember interactive build activities best you requirements examiner will your for questions, answering Y ourself achieve easier activities an activities you it questions multiple-choice refer This the the essay from confidence you make examination Marks and feedback These help Guide exam-style answer of of on Study developing to requirements full tools included and guide so to provide helpful that experience feedback you can will revise areas. unique combination examination practice of will focused provide syllabus you with content and invaluable interactive support to help you ® reach We your have the full potential included lots in of Biology. CAPE hints, explanations and suggestions in each of sections. ® As you you work took during textbooks, This are is this make In on .edu checked When each the for you help Y ou are you of will those to a Y ou in Use we to course, doing this up-to -date Modules the have T ry the topic, will 1 given find you good, in read you through should information and information Entries many and 3. the 3 which you find suggestions accurate Wikipedia for of Paper summary many to of each each from cover to of add the topics to notes that you Those always web. your searches websites. should any read be can that end double questions these topic. chapter are start This by is at the asking to end prompt exam-style of for you questions to to 2. Caribbean examples come within the that relevant end These countries answer notice terms At prepare find 1 relevant reliable. finish glossary. Modules all places Biology While accuracy. section. the and important internet. .ac definitions use guide CAPE lessons. changing. some or your your especially constantly notes. in through the from the in the sections Caribbean Caribbean basin and in relating its widest bordering to sense – the ® Caribbean can expect contexts Sea, not just questions and you in the countries your should use that examination regional and take that local CXC will be examinations. set examples in in Y ou Caribbean your answers. v 1 Bioenergetics 1. 1 Energy and Learning outcomes carbon Sources of Organisms On completion should list be able the of this section, of living energy require a and source systems carbon of energy and a source of carbon. you to: sources in Organisms gain transferred from their energy reactions either from involving light or elements, they use simple the energy inorganic energy for compounds or complex organic compounds. organisms Phototrophs state that living energy ows systems and is are organisms that gain their energy by absorbing light. through not recycled Chemotrophs gain their energy not from light but from chemical reactions. outline the transfer in methods of energy The organisms simplest Autotrophs list the types of understand how to eat trees in algae seagrass in as can convert use it is into carbon dioxide. complex the their eln starch, carbon forests amino as on acids and organic carbon-based Dominica, proteins. complex sugar cane compounds on the coral reefs waters around throughout St Kitts, the mangrove in elds Caribbean, trees in on Belize, their source of phototrophs use energy. terms. use simple obtain compounds to make compounds. Most energy reactions in biological to drive which the they some seaweeds use organic compounds. the to obtain to such algae, light as but this absorb comes light blue-greens, absorb energy These ocean floor are which light reaches. biological to energy you directly from the or Sun. light and energy some for protoctists such photosynthesis . and xes carbon to make This energy-rich organisms are photoautotrophs vent communities These that flourish communities rely at on depths bacteria far below that the energy from simple chemical reactions using highly reduced molecules and use the energy released to x carbon. They use need. compounds Photosynthesis is the energy that is of used compounds of and iron. This type of nutrition is found of nitrogen. These organisms are elsewhere, chemoautotrophs to Heterotrophs synthesis sulphur absorption utilising the food, turn make compounds, light other harnesses harness drive in complex compounds and they prokaryotes and process that that your anabolic On energy from which molecules. Heterotrophs organic energy plants, use as light from complex Plants, organic your inorganic indirectly of and use Y ou organisms foc us Autotrophs that dioxide glucose, food. they sunlight as obtain or these such when Barbados, should carbon carbon Heterotrophs Whether You of nutrition. compounds, S tudy form absorb feed in a variety of different ways, for example by grazing simple plants, preying on animals, parasitising other organisms and eating dead carbohydrates. and Respiration is the transfer decaying compounds complex to ATP organic and heat. digest digest their absorbing Energy to Did you know? be A TP , organisms however, rely respire. Viruses, host on Viruses as they cells the are do the not to be respiration out any in parasitism in table way of Energy Much respiration (or or lter to get their food; a gut secreting or inside cells; enzymes onto bacteria their and food fungi and products. inside available is inside by the which for organisms, work. universal energy in All which energy, energy in can cur rency carbon-based be stored whatever inside cells compounds or form, is transferred is (see released page released 4). as The is on page 3 summarises the different forms of nutrition. transfer energy make is in photosynthesis transferred use of this by heat and heating – it just respiration the is not organism. leaves and very Most heats efcient. organisms their surroundings. anything and mammals are endotherms in that they can themselves. use 2 suck of Birds else) for chew, reproduced. ultimate have internally externally available which cannot carrying bite, respiration The their is food food the made process All They of most energy from organisms. it to help maintain a constant body temperature. retain the heat and Module Source of energy Source of carbon S tudy carbon dioxide complex 1 foc us Photosynthesis and respiration are carbon (autotrophic) compounds (heterotrophic) light photoautotrophic photoheterotrophic (phototrophic) photosynthetic purple not opposites of one another. Look for reasons for this as you read this bacteria, chemical reactions bacteria Summary question 4 on page 37 in Section 2.9. some protoctists algae, non-sulphur chapter and the next. Then answer including plants chemoautotrophic chemoheterotrophic nitrifying many (chemotrophic) (see bacteria page 47) bacteria, protoctists, many all fungi and all animals Eventually, this the is the however , fate of atmosphere all this energy energy and is that radiated also leaves enters into and living space as heats the systems. infrared It surroundings is transferred and to radiation. Figure 1.1.1 These deep-sea giant Sun tubeworms, Riftia pachyptila, live in vent communities. Chemoautotrophic bacteria plants and provide the energy for these communities. other photoautotrophs herbivores decomposers Did you know? chemoheterotrophs The deepest found in vent 2010 in communities were the Cayman Trench carnivores between Jamaica heat transferred e Figure 1.1.2 and to and Cuba. the then Energy flows, it is not recycled Link Energy is used in organisms for: Energy active is the ability to do work and is transport measured movement biosynthesis First – the production of biological Law raising growth energy maintenance levels of compounds so they take part in is body transfer. temperature in the neither created – nor reactions reproduction of Remember of Thermodynamics destroyed. and joules. molecules energy in endotherms. transfers Life Note is all all about the mentioned Summary question energy energy here and answer 3. Summary q uestions 1 Explain 2 Dene why the energy ows terms: and is not recycled. autotroph, photoautotroph, chemoautotroph, heterotroph, carbon fixation, S tudy foc us photosynthesis, respiration Energy ows, 3 Draw an energy ow diagram for a farm where crops are grown to feed it does not cycle. to Never write about ‘energy cycling’ or livestock. ‘energy 4 Explain what will happen to life on Earth when the Sun dies. is examples recycled’. of See page 40 for energy ow. 3 1.2 ATP A TP Learning outcomes as On completion should be able of this section, it is one is the shows you state that ATP energy is the currency most The base With a important used molecular nucleotide. to: the molecule the adenosine. of by all structure adenine phosphate molecules organisms of A TP , and for which sugar added you learn energy is ribose this will a about transfers. in Biology Figure 1.2.1 phosphorylated together becomes a form the nucleoside nucleotide. universal within cells in NH all 2 organisms C N adenine describe the structure of ATP as N a C CH phosphorylated nucleotide HC C N N explain how ATP outline how reactions is produced oxidation/reduction are involved OCH O 2 in ATP H H production list the roles of ATP in cells. HO OH ribose S tudy foc us adenosine You should be able to make a adenosine diagram of ATP using shapes monophosphate simple diphosphate to Figure 1.2.1 represent each the adenine, phosphate group. ribose See and adenosine Summary A TP question Molecular structure of ATP triphosphate is the energy transfer molecule within cells. It is highly suited to this 1. role of as it is small production are unstable to and sites and soluble of break use. so diffuses The easily. bonds Many through between proteins a cell the within easily from phosphate cells sites groups recognise the Link adenine and unstable, Remember what you learnt in Unit active sites. ATP ts into of sites Module also that those such many in Unit anabolic that as of 1 make enzymes. 1. larger protein from See There shown are molecules, amino glucose or acids, nucleic very for is easily. an very in releases the molecule, energy which so acts like transfers a one ‘handle’. or two As it is phosphate hydrolysis step of of an most A TP molecule anabolic supplies enough reactions. in a or a single in a The ‘packets’ glucose A TP A TP 1.2.2. of cell. great energy The rather triglyceride reaction; to A TP is advantage than molecule. transfer constantly is that recycled when the energy released Also energy is energy from as hydrolysed it by transferred glucose in acids ‘packets’ and not a mini explosion requires many reactions nucleotides. as you energy cells. ATP The little small manageable from of activation individual Figure oxidising from starch from part low 3. 1 Remember reactions a the energy active sugar has 1 groups about it will is see on pages converted Even when into they 20 to A TP 29. and produce Although not their used own phototrophs directly light to absorb drive light, processes the in (bioluminescence) synthesis hydrolysis of using organisms use A TP as the source of energy. energy ATP to from: There ADP P are two ways in which A TP is produced: provide • oxidation of energy for carbohydrates, substrate-linked phosphorylation , in which A TP is produced by direct biosynthesis, proteins and synthesis in a reaction in which energy in chemical bonds is reorganised movement, fats in active respiration, or ATP chemiosmotic phosphorylation, in which a proton gradient is transport, • light responsible in for synthesis of A TP – this occurs in mitochondria and etc. photosynthesis Figure 1.2.2 chloroplasts in eukaryotic cells. ATP is hydrolysed when it A TP is produced in some reactions that occur on the surface of an enzyme. of an enzyme. forms ADP and phosphate. When ADP and a phosphorylated compound occupy the active site reformed, a condensation reaction occurs between ADP and a phosphate. Enzymes catalyse the formation of ATP. 4 A phosphate glycolysis group (see page transfers 22) and from the the Krebs compound cycle (see to ADP . page 26). This happens in Module Most A TP is established using a form gradient the by of gradient of maintain through In to gradient. from The the the one membrane enzyme form in A TP . The This of a can only A TP energy for is the another down accept from that As ADP by such cuttlesh to for as squids, deep lures signalling and is as and functions: the pumping Animals as by oxidation/reduction reactions that occur between a to during camouage. use variety attract of prey; courtship Search for made bioluminescence available sea sh bioluminescence for the energy provided proton Did you know? to synthetase. to comes provides energy is return shape energy light the gradient membrane protein changes The respiration, compounds. side protons photosynthesis, gradient; organic proton transport. through, protons. of a protons phosphate this oxidation active diffuse inorganic using pumping diffusing protons and produced by 1 and see some compounds examples. in the membranes page 180 to nd A TP functions of mitochondria denitions by binding of and chloroplasts. oxidation and Use the glossary on reduction. to: Did you know? proteins and for movement, e.g. muscle contraction, movement of cilia The flagella is carrier inactive proteins for active total about to activate enzymes, so reactions can to take lot constitute is turned as transfers: phosphate a glucose to glycerate group form to a molecule glucose phosphate so increasing 6-phosphate (GP) in the in Calvin its glycolysis cycle reactivity, (see (see page page e.g. 22) 8000 enough AMP energy to a to provide molecule by to activation increase attaching to note about its energy for reactivity, most e.g. to reactions amino in A TP is not per is acids when that ATP as ATP synthetase A TP is they need cells, not stores The of polysaccharides energy; enough A TP transported it. have This many is also synthase. There synthetase glycogen and starch lipids are long-term stores of is enzymes; glycogen are another in a cell to act as a is between why very cells. active It is cells, synthetase (see are 105). Substrate-linked energy. is also known as store. substrate-level estimated A TP: stored. not is hour. foc us phosphorylation There the tRNA. page short-term as a few cells example in to many to store 12) known Points human to and Note activated a over turnover grams S tudy a not place. seconds. The A TP in is them whole of ATP grams. There transport enough enzymes quantity 50 produced such as by liver cells and phosphorylation. when muscle mitochondria. Link A TP nd does in not older have ‘high-energy textbooks and in bonds’. some This websites. is a concept The energy that you will released Chemiosmotic when A TP is hydrolysed comes from the whole molecule, not occurs bonds between the phosphate A TP is not a high-energy compound. For its molecular mass it has energy level. It chloroplasts is small and soluble, which makes it processes energy membranes, and are in mitochondria. essentially the good same for bacterial an The intermediate across groups. in phosphorylation the (see page 29). transfer . Summary q uestions S tudy 1 Make a simple diagram of ATP. Label the parts and annotate with functions. There cells, 2 Make simple drawings of a bacterium, a mitochondrion and a is on each diagram a the direction in which hydrogen always but the ions 3 Dene and the b where ATP terms: chemiosmosis, is oxidation, is inside too small to an activity without being are recycled. You pumped, some ATP quantity chloroplast. power Indicate foc us their could probably swing a produced. reduction, phosphorylation, substrate-linked phosphorylation ‘energy currency’, golf club you certainly more on the ATP could in your not do muscles; anything strenuous. 5 1.3 Leaf structure Leaves Learning outcomes On completion should be able recognise tissues of and describe cell identify types section dicotyledonous section, the absorbing obtaining producing export import support, explain and of in a structures cell how out of different tissues. They are adapted for: light carbon dioxide by diffusion from the atmosphere and in leaves, a in photosynthesis of sugars and amino acids a leaf of a in of water so and they ions present a large surface area to the source of light. a functions of the tissues shown in the gures are described in the table. chloroplast palisade are sugars the plant chloroplasts carry composed you The palisade organs to: and transverse this are cells adapted Tissue Function upper secretes to photosynthesis. epidermis cuticle light upper cuticle waxy and to that epidermal pass stomata cuticle through (see lower reduces cells to are the loss of transparent mesophyll; epidermis water to may vapour; allow have below) epidermis chloroplast air space palisade palisade cells mesophyll light; contain many chloroplasts to absorb maximum mesophyll large vacuole pushes chloroplasts to the edge of spongy mesophyll each cell; cells are cylindrical and at right angles to vascular bundle epidermis to spongy cells mesophyll mesophyll reduce separated by scattering larger air of light spaces by than cell in walls* palisade lower epidermis sub-stomatal air space guard allow the diffusion leaf**; air of carbon spaces also dioxide act as a store of cell carbon Figure 1.3.1 to throughout stoma dioxide when stomata are closed A drawing made from a cross-section of the blade of a xylem xylem vessels supply water and ions (see pages 68–71); dicotyledonous leaf showing all the tissues water passes from xylem along cell walls of mesophyll listed in the table cells phloem lower epidermis and is then phloem sieve sucrose and parts the cells of are aperture oxygen Figure 1.3.2 of tubes amino by individual transport acids, cells assimilates, away from the by osmosis such leaf as to other plant like specialised absorbed those as of pairs stomata diffuse in the of upper guard through and out epidermis; cells that which some control carbon and water have more are the dioxide vapour and diffuses out. A cross-section of the The leaves of most dicotyledonous plants stomata on the central vein of a leaf of Ligustrum (×10). You can see the blade of the leaf on each side. lower surface epidermis. stomata Light the upper . that Many float have on none water at have all on almost the all upper their surface. foc us would be scattered rather ** through Diffusion the leaves upper horizontally cytoplasm, 6 on However , on S tudy * than which than is air the by cell walls if the cells were arranged in layers vertically. is much faster advantage of than diffusion having all the through large air cell walls spaces. and Module Palisade many cell mesophyll chloroplasts. so that describes they the cells On are are hot, not structures all in adapted bright for days, exposed to photosynthesis chloroplasts the chloroplasts most and intense their as they move contain around light. The in Link table functions. See 2.3 check in Module you have palisade Summary A stoma is between often and Electron Figure 1.3.3b cell of Unit 1 to the organelles when answering in 1. foc us really the used the 1 all question S tudy micrograph of a chloroplast. In the Bioenergetics the the Figure 1.3.3a 1 just guard to the hole cells, mean the but it guard is cells hole. Grana surrounded by stroma and, at the top, a chloroplast envelope (×80 000) Link centre is a starch grain (×10 000) Dicotyledonous of owering Structure Composition also outer and inner membrane protein carriers each composed of export of bilayer and proteins and triose entry of phosphate, and with have group two broad cotyledons. leaves with a Many net- pattern of veins. See Unit 1 phosphate Module phospholipid the have allow like – to that Function embryos envelope refers plants ions, 3. e.g. magnesium nitrate Summary q uestions stroma colourless, protein-rich enzymes catalyse 1 region surrounding the reactions to x Make to grana; contains DNA dioxide and a drawing show many ribosomes enzyme and biological molecules as lipids, amino molecules stack (plural called grana) of membranous sacs thylakoids hexoses, acids provides area for and a and large light electron pumps contain protein carriers, and ATP move proton synthetase sac in cell an surface 2 Label annotate how cell is the it adapted photosynthesis Make diagram to your show to carry Label to the the to shown how structures and form ATP carry based on structures annotate show efciently. micrographs chloroplast of stage inside a electron into space micrograph. and proteins complexes protons thylakoid palisade drawing table; membranes a visible starch, absorption light-dependent thylakoid detail such out granum the produce electron loops, of carbon this page. in the diagram different enable out the the given your the on of the chloroplast photosynthesis efciently. DNA loops DNA of double-stranded (similar to those of prokaryotes) DNA the codes for proteins chloroplast; transcribed of used in genes as chloroplast coded for some by of the 3 require are mRNA; and rest proteins nuclear Suggest why enter smaller than Calculate ribosomes on translation – assembly and within same size reticulum the as prokaryotes cytosol; those in amino acids proteins b how these the in actual length Figure 1.3.3a. of the Show of your endoplasmic magnesium and chloroplasts. chloroplast ribosomes ions, DNA 4 70S chloroplasts phosphate, nitrate ions are a working. to form 5 Explain why species do the upper leaves not of have many stomata on surface. 7 1.4 Introduction The Learning outcomes to photosynthesis process of photosynthesis may be light On completion of this section, you nCO + nH 2 O summarised by this equation: energy → (CH 2 O)n + nO 2 2 chlorophyll should be able to: enzymes state that photosynthesis This involves the transfer of 1, energy to simple sugars chemical equation energy you studied of state the energy raw and materials, products source of of many the two reaction stages stage and state the what such happens as the in photosynthesis. hydrolysis of starch In to Unit form In but you is the then Unit Y ou do is not is you do need not to study have know detailed substrate this 2 rate of the metabolic to an learn limiting If and the overview enough. next. all pathways, In a one slows of reactions these pathway, reaction down which is the of consist the reactions. the The product slower of than remaining one the slow production of the nal product. Y ou will see how reactions this applies to light-dependent photosynthesis on pages Photosynthesis occurs 16 and 17. light-independent stage of reactions of with photosynthesis: summary reactions. equation others, outline sugars. pathway, simple photosynthesis a single in reducing is light precise sites of the in two stages: two light-dependent stage light-independent stage stages. The they S tudy diagram are shows where they are located in the chloroplast and how related. light foc us chloroplast envelope There is no need learn equation, or It important is more the to one this in which to know n = 6. thylakoids that H carbon raw the dioxide materials, product and water simple and are sugars oxygen is light-dependent O reactions O 2 the 2 are the phosphate ions by-product. chloroplast reduced ATP envelope NADP stroma CO light-independent 2 triose reactions phosphate chloroplast envelope Figure 1.4.1 The exchanges that occur between chloroplasts and the rest of the cell, and the sites of the two stages of photosynthesis and exchanges between them Plants Link are phototrophic (phototrophic) Note that all the photosynthesis Mitochondria stages occur are the in autotrophs. in the The absorption light-dependent stage. of light This stage: of occurs involves in the grana chloroplasts. the transfer of light energy to chemical energy in the form of equivalent two organelle for occurs coenzymes, A TP and reduced NADP respiration. The rst + stage not of respiration, occur outside in inside the glycolysis, mitochondria, cytosol (see does 22). the electrons but page involves involves (e the splitting of water (photolysis) to give protons (H ) and ) production of oxygen (O ) 2 involves electron involves that 8 the harnessing of energy as electrons flow along chains of car riers electrons consists of flowing along substances that the are electron transport alternately reduced chain and (ETC) oxidised. Module The xing of carbon dioxide (autotrophic) occurs in the This occurs foc us stage: in the stroma involves the acceptor compound Do combination of carbon dioxide with a ve carbon not and (5C) of use the involves the use of A TP and reduced NADP to drive the production three involves This the T riose of its of sugar , of pathway products one (3C) resynthesis metabolic from after carbon the is does not ve cyclic carbon discoverers, phosphate triose the fixation . Melvin acceptor photosynthesis. The a number of other the acceptor It is Calvin accumulate in substance known as the is Some and is used fructose Glucose which to light- does not happen Link cycle (1911–1997). the chloroplast; it is No-one is protons are quite sure how pumped, the although there converted plenty of evidence that it happens. substances: make hexose phosphates, such as glucose phosphate will nd page this evidence on 29. phosphate. phosphate are stages dark. recycled Calvin You stage two substance. is into light reaction the phosphate carbon as for of in the terms dark reaction independent Bioenergetics light-independent S tudy stage. 1 stored is in used the to synthesise starch grains in amylose the and amylopectin, chloroplast. Summary q uestions Much is exported proteins in the from the envelope chloroplast for use in the through cytosol; triose this transporter is converted into 1 hexose phosphates transport Some is in the and used to make the disaccharide sucrose Name the two stages of for photosynthesis and precisely they state phloem. converted into other biochemicals, e.g. fatty acids, where occur in a amino plant cell. State the acids. 2 Oxidation–reduction reactions occur during both stages. When raw materials for two photosynthesis substances react in this way, electrons are donated from one substance pathway the other . Oxidation Some is the loss substances of react electrons more and readily reduction than is others the and gain have levels. complexes that potentials). While have with when this electron pass low they with from energy gain happens transport molecules Electrons compounds reduced The the energy is as electron composed different compounds levels; is chain they and transferred energy with do so of to pump (redox energy those 3 levels compounds when they protons to the place where are used. protein levels high oxidised of the the high they energy outline they follow from environment electrons. and to lose across to State the products dependent are the it. roles stage they independent of and play in the light- outline the light- stage. the 4 a Name the by-product of the membrane. light-dependent Much of the experimental work on photosynthesis is done algae, such as Chlorella and Scenedesmus . These cells in Chloroplasts lettuce, suitable can spinach blender , or ltering suspension of also solutions be isolated callaloo. the and This from is homogenate chloroplasts. exposed done and Often the it a different leaves by of the good up ltrate, idea to such the leaves which spin the 5 as will in grains and or leave small it to debris stand from in ice the or cells in are a refrigerator so ltrate that what a in Name suspension when it is of chloroplasts reduced. If in light this is is mixed put white of left high in the as the molecules of the blue a dark, dye term by-product the product stage happens Suggest why reaction and blue the dye that mixture is decolourised the blue colour stays be to chloroplasts. on page 18 and 19 the and light- outline the terms light are the refer two should stages of blue. A chloroplast with suspension the blue redox dye reduced. in questions of it. the blue. When light, the to suspensions of algae and suspension is be placed blue disappears. What the used. disappears Link of is dark reaction used for appears Some state explain photosynthesis. mixed quickly b removed. with intensity and a 7 When it, starch not A the independent a be 6 centrifuge to conditions. plants breaking using is to happens are why suspended and with what unicellular stage colour colour after the will the blue dye decolourised? 9 1.5 The light-dependent Chloroplasts Learning outcomes absorb On completion should be able of this section, you light. spectrum absorb to: name the chloroplast Plants between most regions of describe their pigments, absorb the strongly the which light in the wavelengths at either spectrum. If end white are of of coloured visual 400 this light is part and compounds of the 700 nm. range shone – in electromagnetic The the onto a that pigments blue and red suspension of pigments chloroplasts and contain stage role made from a leaf, it is the light in those regions that is in absorbed and green light which passes through. This is why leaves appear photosynthesis green, explain and how used reduced to energy is trapped produce ATP reflected and on a explain how provide or graph the wavelengths transmitted, is an not absorption in the green absorbed. The region of pattern the of spectrum absorption spectr um a photolysis source of occurs electrons table shows the chloroplast pigments to Pigment and Colour protons. chlorophyll a yellow-green Peak Function absorption/nm photosynthesis 430, absorbs 662 in red blue-violet S tudy up the b blue-green 453, 642 absorbs red visual to light see and the the wavelengths other forms with higher and light of of β energy and electromagnetic blue-violet spectrum and light foc us chlorophyll Look are shown NADP The because carotene orange 450 yellow 450 absorbs blue-violet light; lower may protect chlorophylls wavelengths. xanthophylls to 470 from and damage from light oxygen Link If Absorption spectra and light or spectra are shown on of different page unicellular least Link Figure diagram of on proton page 29 for movement The a across The effective action 2.5.2 algae membrane like that of pigments in in foc us the centre has maximum known the ways reduced form of to the write down the as There of a It is perfectly reduced NADP, suspension of chloroplasts occurs are at the The blue and pattern red can shown regions be on a and graph the is an are a two are arranged reaction of these into centre . light-harvesting Each one is a photosystems: I (PSI) each photosystem maximum and P at . photosystem is a absorption 680 nm. Energy is chlorophyll at The 700 nm from (PSII). molecule. and chlorophyll transferred a II in PSII it molecules accessory In PSI has are this a often pigments to 680 centre. but if you of you may many wavelengths is absorbed and the energy excites an electron to the centre of the chlorophyll and accepted molecule in PSII. This excited electron are leaves studying Chemistry a photosynthesis co-enzyme acceptable in write at which region. chloroplast absorption P reaction Light NADP. green around 700 various shone at wavelengths the the arranged photosystem molecule are is rate spectr um complexes At There the the thylakoid. S tudy best are photosystem . a then 18. determined. See wavelengths action wish is by one of the electron carriers in the thylakoid to membrane. As it passes from carrier to carrier , energy is released in small + write NADPH + H ‘packets’ stroma and into is the used by the thylakoid carrier space. molecules This is a to form move of protons active from the transport. Did you know? The One of the polypeptides in ATP electron absorption accepted synthetase rotates. It is the engine found so far! NADP . 10 by now has light by another a lower this energy level photosystem electron carrier . when it reaches re-energises From here it the PSI. The electron travels to and NADP , it the electron and a proton from the stroma to become is which smallest accepts rotatory of reduced Module The reduction outer surface electrons then protons a by NADP membrane. reductase, There are two which is pathways on the for to keep take return leaving their non-cyclic enzyme they – electrons to travel from PSI but Link that You can nd PSII place. – electrons so more W ater is have the travel the on the inner to source photophosphorylation. enzyme catalyses ATP synthetase side from come of This of PSII to S tudy because thylakoid there membrane. O → The the dependent 4H 4e electrons to + is the light that light- intensity. reactions are not O 2 PSII and protons to the pool of protons in much by temperature and the this accumulate space which electrochemical membrane pass stage of dioxide is not involved with space. protons protein rate Photochemical – + foc us environmental factor inuences carbon thylakoid internet. and inuenced The the of PSI from electrons happens the 2 thylakoid on animations instead reaction: 2H provides superb PSI. + which Bioenergetics NADP . water-splitting The catalysed photophosphorylation to cannot somewhere is NADP Non-cyclic Electrons is thylakoid photophosphorylation reaching and NADP the take: Cyclic of of of 1 is A TP now gradient , it has to Part travelling give a which impermeable synthetase. through and a higher lower can down this pH now protons of concentration than be except put for remarkable their the to inside stroma. work. channels protein electrochemical This stage. length) the is inuence an Light and duration (day wavelengths this of light also stage. The through spins as gradient. the protons As the Summary q uestions protein spins, transferred so the a active bond site forms accepts between ADP the and a phosphate terminal ion. phosphate Energy on ADP is and 1 the phosphate ion. This is a phosphorylation Explain the meaning of the terms reaction. chloroplast pigment, electron carrier, photosystem, centre, Z-scheme reaction electron acceptor electron increasing 2 transport Explain the difference between energy chain an absorption spectrum and an levels action spectrum. Name the electron H 3 acceptor pigments main and chloroplast explain their roles. electron transport 4 NADP Explain the roles of the following chain in reduced the light-dependent stage: ‘energised’ photosystem NADP ‘energised’ II, photosystem I, X electrons NADP, ADP, protons (hydrogen electrons ions), NADP reductase, ATP light synthetase, 4H water. O 2 5 Three separate chloroplast P700 suspensions are mixed with blue photolysis redox dye and green and blue illuminated by red, e 4H redox light e 2O light. The 2 photosystem dye I red P680 pathway of electrons in non-cyclic in was decolourised light, green but did light. not in blue and decolourise Explain these photophosphorylation results. pathway of electrons in cyclic 6 Explain how a light intensity, photophosphorylation photosystem II b X site of proton light duration, c the pumping wavelength the Figure 1.5.1 and of light inuence light-dependent stage of The Z-scheme shows the pathway taken by electrons in thylakoid membranes. The energy levels of the compounds are plotted on this diagram with arrows photosynthesis. to show electron flow. 11 1.6 The light-independent The Learning outcomes products supply On completion should be able of this section, large you describe the Calvin series reactions cycle as the stroma as independent describe enzyme state the that describe occur RuBP in the the Calvin roles in plant. plants Neither need for functions reactions is can cannot they be structural such as necessary to be stored used to support, catalysing produce as a build long-term up the information reactions. molecules This to x means carbon and make it possible to produce organic molecules. the at that xation of reduction carbon the diagram of the Calvin cycle and nd the three main occur: carbon dioxide – carboxylation carbon xation resynthesis NADP of carefully processes of a metabolic set therefore Look light- in for that stage in carbon xation, and occur reduced role light-dependent the stage rubisco reduction RuBP the that energy and further and of the molecules storage to: a of of stage of to form dioxide regenerated – carbohydrates acceptor so that molecule the ribulose reactions are bisphosphate (RuBP) is cyclic. cycle of ATP and the Calvin ADP P ATP ATP cycle reduced describe the fate of triose NADP phosphate. glycerate reduction 3-phosphate 2 (3-carbon) NADP Link Plants use the xed carbon to make triose CALVIN phosphate carbon the groups of biochemicals that you 2 CYCLE (3-carbon) fixation studied in Unit 1: – carbohydrates, carboxylation lipids, proteins and nucleic acids. ATP CO 2 Regeneration of RuBP ADP hexose S tudy sugar ribulose foc us (6-carbon) bisphosphate P (5-carbon) Why bisphosphate? The phosphate groups are two attached to starch different carbon attached would be to the called atoms. same a If they carbon were atom diphosphate (as it Figure 1.6.1 The Calvin cycle in Molecules ADP). diffuse the cell the chloroplast The rst product of a 3C compound the they cell dioxide air dissolve wall, cell envelope do this are (PGA). tropical dioxide known as C3 species use a and the rst compound; enters compound product plants such as is and maize are C4 bond related to their in in and where intense there is then through diffuse the stroma. the active ( r ubisco site for of ribulose short) bisphosphate together RuBP . A carboxylation with reaction the occurs is formed between carbon dioxide in and which one of a the RuBP . This forms forms into two an unstable 3-carbon 6-carbon compounds compound known which as is the acid rst (PGA) or product of glycerate carbon 3-phosphate (GP). This xation. little PGA but molecules are also may be reduced used and to make glycerol, phosphorylated amino using acids reduced and NADP dioxide. A TP 12 They and fatty competition for acids, carbon wall. then reach hot The water cell cytosol and they plants. This survival substance temperatures the When a phosphoglyceric is in and stomata sugar immediately cane water through mesophyll . different carbons 4C the leaves spongy plants. carbon–carbon method in into the Plants 5-carbon Many in membrane into carboxylase/oxygenase that diffuse spaces carbon xation Carbon is carbon surface through Did you know? of through from the light-dependent stage to make triose phosphate (TP). and Module TP is at a crossroads of pathways. In metabolism as it may enter a number of recycled to the chloroplast TP may converted The RuBP into hexose phosphates and then into recycling converted into fatty converted into amino molecules produce six of is important would have something to else. example, of it could be produced acids. triose molecules it acids from 12 RuBP produced from For Of of otherwise starch be foc us be: because Bioenergetics different S tudy metabolic 1 phosphate RuBP and produced, two may ten be of used these to are used produce stored waste to hexose or of starch in starch the which energy the rst used would to be a make place. glycerol. Environmental conditions influence the rate at which the Calvin cycle Did you know? can proceed: Rubisco Carbon dioxide concentration – if the carbon dioxide concentration most low, then the rate of carboxylation catalysed by rubisco will be if the concentration T emperature dependent, stage is Calvin slow. Oxygen with will be triose The low as a can Calvin the cycle rate the of are the the active oxygen. the site This active less effect Calvin and at of by result enzymes xed of are rubisco means site; reduces cycle the the denatured the not that rate At at only oxygen enzyme carbon. light of the light low acts so 2 Name the terms but less It active or inactive as a in the dark. Oxygen acts competitive inhibitor. which This competes as carbon of the the and of are in energy the energy turn the available rate to cycle carboxylation, good place to revise the enzymes from Unit 1. is so is supply for of of the of the Calvin drive the formation cycle of high light intensity low light intensity GP RuBP RuBP . TP intermediate effect results the The a of dioxide temperature, NADP; intensities of by is properties an of compounds changes shown in in the these in the reduction, time Calvin environmental graphs. High CO Low CO 2 concentration 2 concentration RuBP evitaler Dene light, the Summary q uestions 1 the accepts concentrations temperature. reduced supply recycling and The and poor concentrations influenced intensity low a are optimum A TP In measured investigated. in light-independent produced. stage. and Earth. temperature noitartnecnoc factors be in fastest phosphate relative cycle this determined on evitaler is – also supplies light-dependent the temperatures produces the be abundant enzyme Link but is of on of temperatures high most higher . noitartnecnoc TP will dependent low dioxide and enzymes these At enzymes active stops. dioxide and reactions at dioxide carbon carbon The the concentration oxygenase xed so cycle carbon – was the important slower is than is is optimum GP the molecules used by plants for structural support, information TP storage and catalysing reactions. time 3 Name the three main stages of the Calvin cycle and explain the importance Figure 1.6.2 of These graphs show changes each. in the concentration of three key intermediate compounds in the Calvin 4 Explain the roles of the following in the light-independent stage: RuBP, cycle rubisco, PGA and 5 State ve fates 6 Suggest 7 Explain the how the graphs of triose the TP oxygen changes in phosphate Figure produced acts in to the (TP). in reduce the Calvin the rate concentrations of of cycle. carbon xation. PGA, TP and RuBP as shown in 1.6.2. 13 1.7 Investigating Rates Learning outcomes photosynthesis of plants. On completion should be able of this section, There how effect light carbon dioxide to investigate intensity dioxide oxygen of rst concentration explain why control variables it is important is aquatic investigated: uptake dry mass production production. two of T o these are measure quite carbon difcult dioxide to do with school concentrations or you college need gas analyser , and measuring dry mass production an involves how to calculate rates of is leaves by used results. and at weighing relatively terrestrial off photosynthesis from experimental of intervals during the day, drying them to taking constant to it explain this and photosynthesis mass which terrestrial on samples in in and infrared rate ways investigated the apparatus. the three be you The carbon are may to: describe of photosynthesis an is easy plants. aquatic called a them to on a balance measure The most plant such oxygen common as that method Elodea. photosynthometer reads to production The and is is 0.1 or using to 0.01 g. either collect the Luckily, aquatic gas piece of apparatus shown in Figure or given commonly 1.7.1. 3 5 capillary cm syringe plastic tube tubing thermometer Link lamp Think about why is it important to use dry mass to measure the rate of scale air (mm) bubble photosynthesis rather than fresh (wet) shoot of Elodea mass. Then try Summary question 1. pond water beaker Figure 1.7.1 of water A photosynthometer set up to determine the rate of photosynthesis of Elodea S tudy foc us This It is most important that you can be used to investigate the effects of three environmental write variables: light intensity and carbon dioxide concentration talking In about both when these cases we writing investigations. are light dealing The light resistor with lamp quantitative investigations and ‘carbon dioxide’ are carbon dioxide concentration temperature. not at intensity and is changed changing different the by plugging current distances from flowing the in to plant. the the The lamp to a lamp, or by actual variable light putting the intensity can ‘light’ be and intensity or measured with a light meter or , if the distance is varied, by calculating correct. 2 where 1/d S tudy S tudy d = the distance between lamp and plant. foc us foc us Notice these instructions refer to ‘gas collection’ rather than ‘oxygen 2 Why is front it of 1/d a ? Put light a piece source so of the card in light collection’. The also contains gas that other collects gases, such is as not pure carbon oxygen from dioxide, that photosynthesis; come out of it solution. 2 covers away an so area light 1 is cm . Move ‘spread the out’ card over a Carbon larger area. Double the of the source; light is now dioxide concentration is changed by making up a series of solutions distance from ‘spread sodium hydrogencarbonate. This dissolves in water to form out’ – hydrogencarbonate 2 over 4 cm 2 ) of original the light of distance, passing original 14 1 cm which diffuse into cells and into twice the is intensity. a to form carbon dioxide, which is then xed in the Calvin cycle. intensity through a single 2 square ), (HCO 3 squares. At chloroplasts the ions 2 (= quarter of the T emperature is thermometer changed checks appropriate. It tube the next to is the best to plant. by adding hot temperature take the and and cold hot temperature water and of to cold the the water water water in are the bath. added A as boiling Module Several 1 precautions Exclude light need from to be other taken: only source of light sources. is the It is lamp. best to When cover the windows investigating one so these light intensity, the other two variables, carbon dioxide investigations must be kept the to identify Over time the plant uses up be the the independent dependent variable, the same. derived 2 should and variable, temperature, you variable, able e.g. Bioenergetics Link In the 1 the carbon dioxide (it is a raw variable and the controlled material) variables. and so much plant the of is 3 an effect kept decrease of concentration in if the up, gas so time it for all emerges is a best plant and use to few probably are carbon prevent the going to dioxide plant does be not have taken, but if concentration maintaining the the may same rate time. the a This results solution the from to a same signicantly photosynthesis Most only decreases. end freshly become of the cut stem piece adjusted to of the and this Elodea. may It seal Distance from Length of Length of time lamp to gas for takes conditions and plant/ a constant conditions volume of become Elodea, 4 Best bulb is gas the pulled therefore are the photosynthesis It and may case they of that the capillary tubing. to in the The pulled length of it 65 180 75 43 120 100 50 200 150 28 210 200 10 200 has pieces inside syringe After so 50 of mass. just tubing. is collect/seconds the when same mm of different stem The set record use the the tubing. plunger each to readings have putting water the for idea take should by is time, good necessary capillary there of a only be obtained end so is produced length lls of which results at rate It constant. in known gas used. gas to to mm reach bubble/ plunger a that bubble the 250 5 250 any At 30 °C and at an intermediate carbon dioxide is concentration measured 5 Repeat with the readings scale should and be recorded. taken and a mean Concentration of value calculated. Results should be sodium Length of hydrogencarbonate critically to see if any are gas Length of time for scrutinised anomalous. If bubble/mm gas to collect/ so, –3 solution/g dm they the should mean. not be Results used can in the then be calculation plotted on seconds of a 0 5 350 5 30 10 55 200 15 63 180 20 75 210 graph. The tables have results from two investigations. 210 At 30 °C with a lamp at a distance of 75 mm Summary q uestions 1 Explain why rates of photosynthesis should be determined 4 Use the results in the rst table to present a new table 2 by using changes in dry mass, not fresh mass. of data rates 2 Explain fully a why it is important to that of carbon dioxide concentration and constant independent repeat when variable readings each under should be of these is not investigation, Plan an investigation b why 5 taken. to nd out how light Plot on plant. a Include method an the as a rate rates presented of photosynthesis the following set explanation how of of of in how the a will will be intensity addition (as to 1/d the ) and the information a rate to of show the effect of light photosynthesis. Repeat the second table plot a steps to in question construct graph to show a 4 using revised the effect the table of results of of the results on the rate of carbon dioxide photosynthesis. aquatic prediction; precautions; be graph intensity an plan: points; results photosynthesis on your numbered of a the concentration inuences in the and and 3 light light intensity intensity the keep provided. temperature, shows photosynthesis collected; calculated 6 Suggest why all the photosynthometer than the true rate results obtained measure of the with apparent a rate rather photosynthesis. and graph. 15 1.8 Limiting factors If Learning outcomes you on On completion state able section, you the like to: the factors that ruoh be this a rate the photosynthometer of one photosynthesis, in Figure to investigate the graph the that effect you of might light intensity expect inuence of D O rate photosynthesis dene the the term context describe of and intensity, limiting factor explain carbon concentration the how light dioxide and rate temperature of explain how a knowledge limiting factors is used to C 10 B 5 A 0 etar photosynthesis 15 fo inuence in photosynthesis 20 mc/sisehtnysotohp 3 look 25 2 the will 1.8.1. 1 should of use of 500 1000 light 1500 intensity/arbitrary 2000 units of photosynthesis improve 0 Figure 1.8.1 Graph that shows the effect of light intensity on the rate of photosynthesis crop Y ou may be asked to describe a graph like this. Before writing an answer , production. read on the the introduction axes. In independent S tudy foc us which Look Notice that gures are given on should quote in any exam a paper description numbers ruler and very to rule read of only off carefully. allow ± 1 when the intensities. lines on line very intensity dependent by on is carefully plotted variable measuring the graph, is the and on the x-axis rate volume which highlight the of of shows as labels is the photosynthesis, oxygen the the it rate collected. at different an It does inflection not and start then a at the origin; ‘plateau’. there There is are a ‘slope’, four then regions, will When Examiners square call A to D, and these are described and explained in the which table. the the small is a explaining ‘slope’ because intensity the relationship light and intensity the rate is shown the in the graph, determining increases. The plateau realise factor . that there Increase shows that the is the rate or remains less The determined at question light the light may been the these we graph. Use variable. carefully there accurately to case both light axes. You has this constant; an increase in the light intensity does not lead to any marking. further increase so it that carbon the it the not dioxide rate The does in rate. increase Some any concentration must be explanations some given more. or , other above other if factor This must could increasing be be these restricting temperature two does not the rate or increase factor(s). can be made much more concise by using 1 the 25 term limiting ruoh increasing O 2 regions B is a and factor . limiting C Any factor . because any environmental Light intensity increase leads factor is to the an that prevents limiting increase the factor in rate. rate in Light 20 mc/sisehtnysotohp 3 intensity with the is not the increases limiting in light factor in intensity. region The D as other the two rate does variables not have increase been 15 kept constant, rate. If so, so they maybe are the increasing limiting one factors or in other of region them D. will Further increase the experiments 10 are necessary. Figure 1.8.2 shows the effect of carbon dioxide concentration, the shape 5 fo of etar If the no graph carbon is very similar . dioxide is provided there can producing some carbon be no photosynthesis. However , 0 0 200 CO 400 600 concentration/parts 800 per 1000 million 2 the will As Figure 1.8.2 be the respires, used up so immediately concentration by increases chloroplasts the rate can dioxide, so there increase but is so any no gas that at produced exchange. 50ppm Graph that shows the effect of carbon dioxide concentration on the rate of photosynthesis 16 plant is equal to the rate photosynthesis is of respiration. greater than Above rate of 50ppm the respiration so rate of excess oxygen it Module S tudy Look at Bioenergetics foc us your Region 1 answer to Summary Light question 6 from 1.7 in this module Description while reading this table. Explanation intensities A 0–100 No oxygen apparent has rate been of released; the photosynthesis All = 0 the the oxygen plant in surroundings B 100–250 Rate of photosynthesis proportional C 250–1250 Rate of to the photosynthesis increase but less is light Light intensity. continues to to 1250–2000 Rate of photosynthesis is constant. Light than diffuses there out is a limiting of the ‘slope’, factor concentration for A TP and increases plateau factor as it is means reduced and more because and leaves a is that raw NADP . oxygen collected. carbon material rubisco carbon other and meaning can The is such the the of the in and cycle. there is photolysis temperature is no and of a photosynthesis be is not released is to used by the collected. increasing, are beginning as same intensity light providing more energy to increasing limit light the rate intensity of is not effect. has energy no further limit the effect; factors rate of other photosynthesis. increases the greater the need stage water . longer light is the Increasing light-dependent concentration as concentration concentration Calvin faster produced dioxide factors, for work rate As dioxide is photosynthesis having D cannot by and chloroplasts. Other factors steeply. so intensity the produced respiration There the is a limiting intensity, are limiting. Photosynthesis of protected countries is a crops have major (e.g. fully factor in tomatoes, automated crop production. lettuce and glasshouses Farmers cucumber) in and growers temperate that: Summary q uestions control light intensity control temperature with articial lighting and shading 1 with heaters and Dene the terms limiting factor, ventilation apparent rate of photosynthesis , enrich the carbon dioxide concentration by burning hydrocarbons (e.g. true rate of photosynthesis. propane) supply water direct supply mineral to the roots or by using direct to roots 2 sprinklers Describe and obtained for nutrients at the to the growth stage of the the Caribbean, growers use plastic and mesh greenhouses to conditions. Plastic protects against heavy rain and the 5 mesh intensities against used, insect so that pests, reducing costs so of salad crops reducing watering are costs as not of scorched. pesticides. water is Both Drip supplied also of eld crops such as cereals, to sugar cane, soya, yams page how such are not able to do much about 4 carbon dioxide 15. growers as the is melons also and of tomatoes, cucumbers glasshouses plants. of can in prevent photosynthesis the of these and plants from cassava, you protect irrigation direct on Explain rate Growers that questions reduces crops light Summary control 3 the graphs results crop. and In the the concentrations drew from appropriate explain being limited by concentration, environmental factors. light intensity drainage apply can or sow each activities of temperature. ensure fertilisers also shade to to their other . that water ensure crops All not mineral at an farmers competitors However , is a nutrients optimum and (weeds), they can limiting not density growers pests do take and provide factor so for limit the steps irrigation growth, growth. plants to do reduce and and They not the 4 Discuss and the steps growers take their to in that farmers the Caribbean maximise the yields can of crops. diseases 17 1.9 Practice Energy Answers to all The following questions For practice questions, see the CD will nd choice and exam-style questions questions. advice about questions are in in the and photosynthesis be found on the of questions: accompanying CD. c examination The multiple-choice accompanies analysing in CAPE can style answering that exam-style this water book. You answering Biology Unit a Outline the processes photosynthesis that was multiple- of light spectrum readings from the light the light-dependent the light-independent a of the gures for calculated from the the sensor. [1] occur What conclusions absorption in can spectrum be made from and the action the spectrum in the gure? ii how a ask 1. during: i Describe how were stage [6] stage. 5 The diagram [2] shows the Calvin chloroplast is cycle. [4] enzyme b through 100%. Suggest absorption d 1 transmission adapted to A carry 6CO 2 out 2 a photosynthesis efciently. [5] 6 Describe how a leaf of a dicotyledonous plant is adapted to carry out photosynthesis efciently. ribulose bisphosphate 12 (RuBP) molecules of [5] 6 ADP b Explain what is meant by the term B 12 ATP limiting factor 1 as c applied Explain of to how photosynthesis. a knowledge photosynthesis is of applied 6 ATP [5] 12 ADP limiting factors to increase the 6 production of crop plants. ribulose phosphate (RuP) [5] 4 2 3 a Explain why ATP is described as the ‘universal 3 energy b currency’. Describe how ATP C [5] is produced during a photosynthesis. i Name enzyme A, substance substances formed c Explain and one of the at C. [3] why: i carbon ii light are B [5] dioxide concentration, ii State the iii Name iv State source of ATP. [1] and intensity the precise site of the Calvin cycle. [2] [5] limiting factors for the number of carbon atoms in ribulose photosynthesis. bisphosphate. 4 Investigations of the were unicellular wavelengths suspension measured was and the a carried alga, passed light light out using Chlorella. through sensor b suspension of a ask behind transmitted a Light the of the c the ask through middle of the oxygen sensor suspension. was Results Discuss the carriers in placed in to plot an absorption obtained spectrum as shown roles and an the i ATP NADP ii vi proton light roles iii of 600 The rate using b Explain used 18 to how plot electron [6] the following a in iv photosynthesis: carotene v carbon RuBP vii rubisco viii ATP synthetase [12] of photosynthesis discs cut from can Coleus be determined leaves. The discs placed in a tube and had all the air removed. of When placed into a tube of dilute solution they sodium all sank to the 700 leaves were kept in the dark and at light/nm intervals is and and pumps. bottom. The what pigments chlorophyll hydrogencarbonate spectrum [2] absorbed photosynthesis Explain in of were rate a shown below. by wavelength of reactions action 7 500 the cycle. were percentage 400 of of a photosynthesis. Discuss ix spectrum advantage the dioxide used the diagram forming the 6 suspension. An Explain different [1] meant by the terms absorption action spectrum. results from the action the oxygen spectrum. light [2] sensor were [2] some were intensities. The to oat was with freshly results are removed time in discs the at table. a placed taken for ve recorded. The cut and of investigation lower in different the was discs repeated temperature. All the Module Distance of Time taken for Time taken for Relative lamp from ve discs to ve discs to intensity oat oat leaf discs/mm at 30 °C/ at seconds 50 125 275 100 210 390 150 360 410 200 600 620 250 none of discs rose to the surface a Explain tube b why and the why Describe and discs to the none of discs rose bottom the at The to indicator hour 0.33 0.06 yellow 0.43 0. 16 orange 0.50 0.40 red 0.57 0.80 magenta 0.67 1.60 purple 0.73 the of the c Explain d i the results shown in the table. [7] [5] trend shown by the Explain the advantage of using a colorimeter discs 30 °C. leaf 1 yellow (darkness) taking the results. [2] [3] ii c after Absorbance for kept solution the they oat. explain Hydrogencarbonate Colour 0 surface sink Bioenergetics 20 °C/ seconds the light 1 discs left in the dark remained on Suggest how this investigation could be the improved. bottom of the tube. Explain why they did oat. d [3] Explain longer why the to oat leaf than discs kept those at at 20 °C took 9 A student the 30 °C. [3] A concentrated culture of the unicellular used effect rate of were 8 [2] not of a photosynthometer carbon dioxide photosynthesis. placed into was made into This by was mixing then it with dripped a solution into a of sodium solution of alginate forms into trapping indicator table shows treated the with pH the solution buffer When Beads tubes of solution solutions air it red of is in obtained different were into intensity/ 1 hour removed solution and and was the the placed Suggest the results using are advantage the a beads in this of a suspension of six light the 3 Mean 0 5 0 0 0 10 7 9 5 20 17 15 13 30 27 36 23 40 32 31 33 test- Look critically at the results and identify any intensities beads b with within rather results. [1] were Copy and mean a light table. algae investigation the 2 0 complete length of gas the table bubble by calculating collected for the each intensity. [3] the diameter of the capillary tubing in the than photosynthometer using bubble/mm the indicator in using gas 0 The jelly-like Length of purple colorimeter shown table. solution. The recorded. The of a 9.2 into different absorbance determined green lter. The a colours in units anomalous for sodium colour. hydrogencarbonate placed of recorded pH. through in collected 0 a test-tubes oxygen 1 when magenta red student pH. The 8.8 bubbled becomes of Hydrogencarbonate red solution. The jelly-like changes 8.4 S. q uadricauda were the to colours orange atmospheric of of 8.0 yellow indicator inside. sensitive range 7 .6 Colour algae is concentrations the plant calcium arbitrary beads, on aquatic alginate. Light chloride. Calcium an small the volumes beads of alga hydrogencarbonate Scenedesmus q uadricauda investigate concentration Pieces different to algae. was 1.0 mm. [2] 3 c b Calculate the rate of photosynthesis in mm –1 min Suggest: for i three variables this ii a that investigation suitable control. should be controlled each light intensity and add to the table. [3] in d Plot a graph e Explain of the results. [5] [3] [1] the student’s results. [6] 19 1 Bioenergetics 2. 1 Introduction Learning outcomes to Cellular respiration molecules On completion should be able of this section, you seen, state that chemical in cellular energy compounds chemical is in respiration organic transferred energy transferred that as in ATP for state that of Protein to and than is the is transfer available form the molecules may is of for chemical cells in a energy useable from form. organic As we have A TP . protein The a in as a their repair diet that in than can be of order are store source growth, energy oxidised molecules short-term used for are These are be required more heat cellular organic is it synthesis. Carbohydrates of energy. energy and that energy carbohydrates, if Fats present replacement. herbivores, harnessed as are in made larger diet these available and long-term fats. stores. quantities Carnivores their from is proteins respire consists mostly compounds is of shown respiration in involves that useable organic A TP meat. so to: The respiration stepwise molecules, the table. breakdown each step –1 Respiratory catalysed name by the four respiration an outline of the stages carbohydrates, of differences and Energy/kJ g e.g. starch, glycogen, glucose, sucrose and 16 lactose glucose between lipids, aerobic substrate enzyme e.g. triglycerides 39 anaerobic respiration. proteins The 17 oxidation coenzyme S tudy cell, foc us so they respiration breakdown occurs of inside confuse it onwards we the organic all with respiration is chemical molecules living cells. breathing. will refer simply as to Do that not From now from of create chain ADP cellular respiration. reduced series a of form is to in nal required the split whole of just are electron to is coupled these oxidised of same to acceptor the reduction available recycled. is as and protons. the This in in the the in of the each happens in Hydrogens Electrons intermembrane called involved way be and into carriers is with molecules phosphorylation . electrons moved gradient the of oxidative pathway of few into protons proton A TP substrates very continually are The The are process and products is so be the NAD the the Oxygen water There gradient. Oxygen one in carriers (ETC). to respiratory have mitochondria Cellular of NAD. electron pass to space a to transport phosphorylation of photosynthesis. on being reduced it forms water , respiration. respire process glucose is completely aerobic to respiration . carbon If dioxide oxygen is and not Link Remind yourself about the available, respiration processes that roles of ATP. See pages this process oxygen Instead with Link is it the an adjective that ‘requiring air’, but in refers to requiring the See aerobic 20 page and 36 for a but without NAD is the recycled use in a of the different anaerobic way respiration available as the of ethanal then electron pyr uvate acceptor lactate. that acts In as plants an does in not enter animals and fungi electron and (e.g. acceptor mitochondria. some bacteria, yeast) to it is produce ethanol dioxide. is therefore common to both aerobic and anaerobic respiration. Biology oxygen link reaction, Krebs in comparison anaerobic to carbon aerobic air. continue literally The it is formation Glycolysis means not acts converted and is still mitochondria. 4–5. If ‘Aerobic’ can in structure and and occur of respiration. respiration only. cycle and oxidative phosphorylation occur in Module Before starting to learn the details of respiration, make sure that you outline The of the intermediate metabolic route acids. In compounds the pH of in body Krebs fluids cycle and and some cytoplasm in glycolysis they all exist are that are named using the sufx is to we this cellular is look Respiration by an is at the pathways respiration a enzyme. chemical Breathing and of is and gas it in breathing consisting exchange or of are detail, gas remember that makes hydrogen physical is better it sound as if it accepts each catalysed processes. foc us (6C) To help you respiration, ADP phosphate (6C) onto you ATP a biphosphate learn copy large read adding ADP fructose it acceptor, exchange. reactions, ATP glucose carrier; hydrogen permanently. S tudy glucose a ‘–ate’. respiration not process hydrogen call which Before a as not anions foc us map. NAD organic Bioenergetics have S tudy the 1 the the sheet the rest details ‘route of of information paper this to of map’ and as chapter keep it. (6C) S tudy 2ADP foc us NAD You 2ATP need information about the reduced structure of fat molecules to be able NAD to answer Summary question 4 in full. pyruvate glucose pyruvate glycolysis NAD Summary q uestions acetyl reduced link pyruvate coenzyme A NAD reaction 1 Explain briefly what cellular coenzyme A respiration CO is for. 2 2 acetyl a List coenzyme A of coenzyme A b the State reduced stages of respiration glucose. where in the cell they occur. citrate (6C) NAD NAD 3 Use your answers to question 2 NAD to reduced NAD Krebs make stages a of table showing respiration, the four the precise cycle sites CO in the cell where they occur, 2 the molecule at the start of the reduced stage FAD and the end products. NAD FAD 4 Explain why 1 g of fat yields more reduced energy CO in 1 g of ADP Pi What are respiring 6 hydrogen Suggest NAD and FAD the advantages glucose why rather marathon of than fat? runners carriers take (reduced than sugar. 5 reduced respiration NAD 2 ATP are sports drinks during their oxidised) oxygen event. oxidative phosphorylation water 7 ATP Figure 2.1.1 ADP Pi The metabolic ‘route map’ of respiration. Keep looking back to this as you Suggest why excreted pyruvate when is animals not respire anaerobically. work your way through the next few pages. 21 2.2 Glycolysis The Learning outcomes purpose ‘hub’ On completion should be able of this section, of been you protein. breakdown state that glycolysis metabolic glucose to describe steps state pathway in is that explain converts the end In of is the the prepare Krebs blood, plants, sucrose to cycle. broken glucose (see page may 74) glucose In have the animals, down or for from been central glucose glycogen obtained metabolic may or from the starch. In glycolysis, some is NAD at Figure products some ‘held’ a as later energy reduced stage. is transferred NAD. No The carbon from energy dioxide is glucose is directly transferred formed during as from A TP reduced 2.2.1 shows more complex, main points the with main more steps of glycolysis. intermediate The compounds metabolic than pathway shown here. that you need to know are described on the opposite cell page. surface membrane molecule Link glucose formula of α of the structural glucose from Unit 1. glycogen See 1.3 in Module A 1. glucose ATP S tudy foc us B ADP Copy onto out a the large glycolysis sheet of pathway paper. glucose Make 6-phosphate (6C) ATP C drawings of the simplied structural ADP formulae of glucose, the fructose intermediates and Question page 1 on pyruvate, 38 to 1,6 bisphosphate (6C) using help you. D triose triose phosphate phosphate P NAD P NAD E reduced NAD reduced 3C intermediate 3C bisphosphate NAD intermediate bisphosphate ADP ADP F ATP ATP Link 3C intermediate 3C phosphate There is more about carrier intermediate phosphate proteins ADP for glucose on page ADP 104. F ATP ATP pyruvate (3C) pyruvate (3C) Link Figure 2.2.1 What There are nine glycolysis, specic to use reactions catalysed enzyme; you by should be See different 3. 1 in enzymes Module is needed for glycolysis to occur? in a a substrate a pool A TP nine NAD. – glucose, glycogen or starch – rich in energy able knowledge from Unit why needed. 22 each your explain different The main stages of glycolysis in an animal cell 1 of phosphate ions to are different 1. enzymes (there are nine steps in glycolysis) is The of carrier yourself and glycolysis. glycolysis. Remind have converted main glycolysis the which from is the pyruvate and glycolysis cell absorbed from to: the of Module Animal the cells situation Sucrose surface steps in is carrier diffusion plant cells broken the is and glycolysis proteins of down membrane Follow A have facilitated in glucose different in is the the from as cell wall and surface sucrose, hydrolysed pathway cell tissue or in read it the fluid not membrane into the glucose passes is though to cell. 1 Bioenergetics allow The transported. the cell cytoplasm. these descriptions of the following carefully. Glucose enters membrane. the cell Glucose is by facilitated either stored diffusion as through glycogen or the enters cell surface glycolysis immediately. Phosphorylation B Glucose is phosphorylated to glucose 6-phosphate; this maintains the Link steep C diffusion gradient for glucose Glucose is phosphorylated again Glucose is phosphorylated because very reactive. T wo molecules of to to continue form fructose although A TP are entering it used is in the cell. One bisphosphate. energy-rich steps B it and is not of raise the roles energy of ATP levels (see in cells page is to 5). C Lysis S tudy D Fructose (TP). bisphosphate This is lysis. is Note split that into the two molecules reactions after of triose lysis occur twice for E each molecule of foc us phosphate is the most important glycolysis from Oxidation the as it conserves substrate, phosphorylation. E Energy from the two molecules of TP is transferred as it dehydrogenated. In this reaction the oxidation of TP is linked happens Energy of which NAD. would phosphorylation of Hydrogen be TP atoms transferred using as transfer heat phosphate is ions from TP conserved from the using it for Remember to by twice for that every with molecule reduction in energy is this the reaction glucose. of glucose that is respired. NAD. the pool in the Link cytosol. Reduced oxidative NAD may phosphorylation be or used may in be the used production in other of A TP in reactions. Some are Substrate-linked ADP and the 3C the enzyme and intermediate one of the bisphosphate phosphate occupy groups is the active transferred to site ADP 3C A TP . This is intermediate pyruvate and of is glycolysis how repeated on phosphate another A TP the and active ADP site react of to another give the enzyme end as respiration lactate is of back into glucose (see to page form which anaerobic converted an reactions phosphorylation from F of reversible, 33). the product molecule. S tudy foc us Summary q uestions Read these carefully 1 Explain 2 Nine what glycolysis many 3 enzymes enzymes Describe what 4 List 5 What the happens 6 State products happens the ATP lysis, of to a produced why catalyse involved phosphorylation, Figure pages list the again three very different is for. products different two and and in not each the reactions just of oxidation, of glycolysis. Why are so answer of glycolysis Summary so you question can 4. one? the following stages substrate-linked of glycolysis: phosphorylation. glycolysis. the ADP formed in in the rst two steps, B and C, and b glycolysis? 2.2. 1 shows glycolysis in an animal cell and not in a plant cell. 23 2.3 The mitochondrion The Learning outcomes mitochondrion occurs. On completion should be able of this section, you Glycolysis glucose. Pyruvate transferred to: is state that the mitochondrion site of aerobic describe the own The is not energy-rich by the reduced in efcient and the three NAD which at rest of of respiration releasing chemical stages from the energy energy that respiration glycolysis is also that a from can be occur source in of and it may be oxidised and recycled as NAD by mitochondria. respiration Mitochondria its organelle is energy the on is the harnessed mitochondria. is structure of have an envelope of two membranes surrounding a protein- a rich matrix. They are too small to see properly in typical school or college mitochondrion light explain how the structure of is related to The images of mitochondria that you are likely to see a are mitochondrion microscopes. taken with electron microscopes. its ribosome matrix crista loop of DNA inner function. mitochondrial membrane Link outer Mitochondria including and have other functions replicating, translating their mitochondrial membrane transcribing DNA. intermembrane Chloroplasts functions. also carry Remind out yourself endosymbiosis from Unit in Module space these of 1. See 2.4 Figure 2.3.2 1. A longitudinal section of a mitochondrion showing location of important processes. The functions of the different structures are shown in the table. S tudy Calculate answer foc us the actual Summary Almost all the longitudinal also see always a The have of as a happens The NAD. to enzyme. NAD is is The on mitochondrion that one are in shape. They branched. during is stages to the in Figure 2.3. 1 so you can the NAD inside give a large will are not see show micrograph. suggesting After site that always replicating of the include and of you electron Y ou might mitochondria this their shape DNA and have they cytokinesis. matrix both that this circular , of cristae recycled the cells oxidised occurs the mitochondria like even products This oxidation of of 1. cylindrical shapes, mitochondrial cycle. Figure 2.3.1 images sections cross-sections variety divide, length question reused the inner surface link the in reaction reduced these two membrane, to take these and Krebs hydrogen stages. carrier , The catalysed enzymes by so an that quickly. A longitudinal section of a Chemiosmosis and phosphorylation mitochondrion (× 25 000) This is very similar to the process that occurs in chloroplasts. A proton Link gradient is substrates. Compare the structures mitochondria chloroplasts. similarities answer with Make and list Reduced of of differences Summary question formed the using Electrons and 4. then NAD on the mitochondria membranes through 24 up energy flow from along an the oxidation electron of respiratory transport chain. in those a set for to into is oxidised same use reach the side. in the matrix on the This the rest of cytosol. in the matrix means the Also side that cell has NAD opposite of A TP the cristae exported to from direction. pass and A TP is from through glycolysis two has to pass Module Structure outer Composition mitochondrial membrane phospholipid Function bilayer and proteins permeable to pyruvate, dioxide, ATP, ADP inner mitochondrial folded into surface cristae membrane to give a – phospholipid large complexes area chain of bilayer with electron and ATP protein transport pumping space lower matrix pH than synthetase protein-rich DNA loop, enzyme DNA loop of (similar not cytosol region; making ATP; and matrix contains ribosomes and many ribosomes ribosomes and within those in you – smaller than endoplasmic the cytosol; double-stranded to those of size but site of high link reaction; with DNA of the or glucose Krebs cycle; of protons production of the mitochondrion; genes are transcribed histone as mRNA; rest of mitochondrial proteins are coded for by DNA in the nucleus and proteins translation to form – assembly of amino acids proteins as Summary q uestions foc us imagine the would form the all ions concentration cristae pinching off from the rest of the inner 1 membrane Explain membrane-lined sacs like thylakoids. Try this and you will why easy to mitochondria see directions in which the protons are pumped and move down gradient is the are light use the calculation on result from the previous same. page 2 in Take and a a your piece make and different you can outline you cut in a of chloroplasts Summarise, and 6 the Why do many as Make shapes then draw cristae will mitochondrion carry to out the respiration. compare the and functions with a of mitochondria. a simple exchanges between a sections. and the as the aerobic table take planes. and the to of the structures occur give clay of sections different how diagram, model Now to these adapted sizes, 5 a of made in Explain Make it think functions 4 modelling drawings you appear is of into types have how 3 it answer. mitochondrion. knife Figure 2.3.3 a their your electrochemical under see microscope; that to hydrogen DNA codes for 13 of the proteins used in not they permeable not prokaryotes); reticulum same intermembrane molecules combined rRNA into carbon glucose prokaryotes S tudy If on oxygen, not urea proteins 70S protons but space; above, intermembrane 1 that mitochondrion surrounding cytosol. mitochondria divide? Chemiosmosis in a mitochondrion 25 2.4 The link reaction Pyruvate Learning outcomes is and an energy-rich mitochondrion On completion should be able of this section, you In the links to: matrix state that oxidation of completed in dene the terms of Krebs cycle. pyr uvate in complex The the that into matrix mitochondrial catalyses components dehydrogenase , the carry a of the a membranes. reaction this out of that complex, following to pyruvate: dehydrogenation – removal of a hydrogen atom to reduce a molecule NAD the link reaction and decarboxylation – removal of the carboxyl group from pyruvate to list form a molecule of carbon dioxide products as proteins enzyme enters dehydrogenation describe the the carrier It decarboxylation to known molecule of and large compound. mitochondria is a cycle pyruvate each is through is glycolysis which Krebs outline the Krebs cycle, state transfer of the (ethanoyl) processes that occur and list remaining 2-carbon fragment which is an acetyl the group to coenzyme A, to form acetyl coenzyme A. the This reaction (actually several reactions) is called the link reaction as it products. links glycolysis reaction to the Krebs cycle. The overall equation for foc us pyruvate (3C) + coenzyme A + NAD reduced → + coenzyme The link 2. 1. 1 on reaction page is shown in Figure 21. link is: acetyl S tudy the Remember molecule that of glycolysis glucose. The produces products two of molecules the link NAD of pyruvate reaction dioxide from each are: For each pyruvate molec ule For each glucose molec ule 1 × carbon 2 × carbon 1 × reduced 2 × reduced 1 × acetyl 2 × acetyl dioxide carbon + A dioxide Link Although this enzyme decarboxylation pyruvate another it is catalyses not decarboxylase enzyme, which called – on page coenzyme A you can read One a (see to RuBP page performs in 12). A is a enzymes; of the catalyses Link role coenzyme A large molecule that is recognised by the active sites of 34. many Oxaloacetate NAD that’s Coenzyme about NAD a a the Calvin similar cycle four of cycle research There are that nine the broken cycle are the compounds Follow the the other into Krebs than matrix. and to A other is known it as who compounds. the one oxaloacetate, Oxaloacetate fragment; cycle, for cycle cycle them of hydrogen and read most is is recycled the did of that to citric much is the by acid of that which a series cycle or the intermediate Also, convert recycle energy the pathways. intermediates. pathways transfer and metabolic cycle using the reduced Krebs coenzyme group (1900–1981) in is the group it. substrates to Krebs acetyl acetyl two -carbon metabolic in cycle the acetyl in involved rather Krebs present this a the reactions down substances of are transfer recognises Hans elucidate compounds are for form Sir to between compound after to is that reaction substance reactions Krebs role enzymes the carbon acceptor its Some them to oxaloacetate. from the amino acids intermediates in other The main role intermediate carriers. these descriptions of the following steps carefully. A reaction delivers B 26 between 2C acetyl fragment decarboxylation coenzyme (acetyl (×2); A group) removal of and into oxaloacetate the carbon cycle dioxide to (4C); form coenzyme citrate (6C) A Module acetyl 1 Bioenergetics coenzyme A coenzyme A reduced 4C NAD compound (oxaloacetate) A C NAD E 6C 4C compound compound NAD 4C compound C B reduced CO 2 NAD C reduced CO 2 5C compound P FAD NAD ATP 4C compound C D FAD reduced NAD ADP Figure 2.4.1 Summary q uestions The Krebs cycle. Follow the reactions of the Krebs cycle and nd brief 1 descriptions of each reaction, A to Outline what in 2 C dehydrogenation substances, and the (×4); which reduction are of removal oxidised FAD of hydrogen coupled with from the aerobic substrate-linked E regeneration pyruvate reduction of NAD What are the Krebs cycle for? 3 A TP link reaction and (×3) (×1) phosphorylation; conditions. intermediate Using the an D happens to E synthesis link reaction as example, distinguish (×1) between dehydrogenation of oxaloacetate (4C and compound) decarboxylation. This table lists the processes that occur and the products formed for each 4 complete ‘turn’ of the cycle and for each molecule of glucose that Explain why go through completely pyruvate carrier Process that occurs Products in the of the per one ‘turn’ Products Krebs cycle Krebs cycle go through the when entering the Make a table to molecule of 2 × carbon dioxide 4 × carbon 3 × reduced 1 × reduced 1 × ATP NAD FAD 6 × reduced NAD 2 × reduced FAD 2 × ATP 6 cyclic 7 the coenzyme but FAD FAD is is the involved in prosthetic the Krebs group of cycle. the NAD is linear succinate hydrogen dehydrogenase substrate, dehydrogenase. following so each each is on to the to In inside enter the FAD face the that the all lysis reaction ‘turns’ of the six the site to NAD. cristae from so the these step steps in glycolysis, twice for glucose aerobically. occur that is it Krebs atoms from a are in molecules of of Explain why carbon respiration succinate not stop at the Krebs cycle. Succinate is easy for its 8 matrix. groups molecules that S tudy are are Suggest what produced foc us Prosthetic protein. carbon enzyme dehydrogenation not S tudy occurs of and of active foc us molecule respired transferred malate, S tudy Remember is rather pathways. cycle, the does (4C), having pathways After two dioxide. complex, cycle. similarities advantages of metabolic glucose coenzyme, Krebs include as differences. Explain the than phosphorylation compare the dioxide as well dehydrogenation mitochondrion. cycle with the Remember to that rather bilayer glucose Calvin decarboxylation lipid per 5 mobile proteins oxidised. than Notice molecules is organic bound to a Copy 21) out and sheet fates of of in the Krebs the link reaction pathway with (see onto paper. Annotate the cycle. foc us Krebs diagram happens to the ATP a page large your information about the products. 27 2.5 Oxidative phosphorylation The Learning outcomes link reaction removing On completion should be able describe carriers of this section, you are all reduced recycled hydrogen Much to in the NAD energy those is the carbon hydrogen coenzymes to: how remove and atoms atoms and still produced reactions from the glucose Krebs as cycle carbon intermediate are responsible dioxide. substances They as the for also reduced FAD. available in in the of the from matrix these there reduced are also coenzymes. some from In addition glycolysis. mitochondria An explain how transport generates the chain a electron in mitochondria proton enzyme NAD protein gradient explain is involved ATP how in by ATP explain the the proton the production of the inside NAD The can electrons complexes protons in of the cristae reused. pass the the of be The from electron the catalyses reaction enzyme transport the oxidation produces to compounds chain. The of reduced protons and within protons join the a matrix. gradient of Each synthetase role of on that electrons. pool so electron there oxygen are lost linked from reduced oxidation and NAD passes reduction through reactions as the complexes shown and here: in reduced respiration. reduced carrier NAD A reduced carrier NAD from carrier B C water Krebs S tudy cycle foc us oxygen You can refer transport it is a to chain good the as idea the to ETC, write reduced carrier reduced carrier A B carrier C NAD electron although out the reduced name in full rst before using abbreviation. Figure 2.5.1 In to these the the and cytosol. the FAD whole of the pump protons A TP table the summarises molecules oxidation reduced 28 the number of the Reduced inner active ATP comes in for Protons foc us reactions energy intermembrane energy except The oxidised state Linked oxidation and reduction reactions of the ETC protons The S tudy state the site by a from is also is less than of A TP at their Oxygen is the protons and nal but pump the gives its it so available of the accepts The a the do the pH not than pass made matrix in the along which of matrix the available impermeable synthetase gradient and and a as to protons, molecules. they phosphate do so, ion to the form reaction. is acceptor . catalysed by The the reaction enzyme produced between oxygen, cytochrome per Process that occurs ATP in oxidative molecule of phosphorylation coenzyme glucose reduced ATP oxidase. produced molecule of produced following of reduced NAD and to NAD. is A TP from transport accumulation lower energy from ADP protons active electrons chain, base of reactions. concentration electron electrons to form mitochondrion synthetase condensation a space that the is redox transport channel down of these This oxidised, membrane the transferred intermembrane electron flow is space. oxidation of reduced NAD 2.5 10 oxidation of reduced FAD 1.5 2 × 2.5 = FAD. × 1.5 = 3 25 per Module 1 Did you know? higher H H H H H H concentration H Cyanide H of H is an irreversible inhibitor of protons H H H H cytochrome H nal electron chain in the whole We cannot membrane proton poisoning oxidase. It inhibits respiration, of aerobic survive respiration transport with step alone, is the inhibiting respiration. on so so anaerobic cyanide usually fatal. pumps S tudy foc us ATP H synthetase Chemiosmosis H was suggested in H 1961 by Peter ATP electrons from in biological independent as synthesis. It a is scientist mechanism now for accepted as oxidation ADP of the Mitchell Pi ATP the molecules lower respiration in way in which bacteria, ATP is synthesised mitochondria and H concentration chloroplasts. Remember from H of protons Unit Figure 2.5.2 Protons are moved across a membrane by proton pumps. This creates a concentration gradient of protons that is a form of potential energy. Protons move down 1 that probably by these two evolved organelles from endosymbiosis bacteria (see Unit 1, the gradient through ATP synthetase. Module 1, 2.4). Evidence for Summary q uestions chemiosmosis photosynthesis 1 Explain 2 State what oxidative phosphorylation roles of the following in oxidative phosphorylation: In mitochondria, chain; proton gradient; ATP in the the role of oxygen in Explain how the structure of a mitochondrion makes an efcient List 6 An the products of was oxidative carried P, Q and phosphorylation. Isolated in a addition of each out using three inhibitors of the ETC R. The inhibitor state of four electron carriers, A to D, is shown in the solution turn into Grana from A B C D oxidised reduced reduced oxidised ATP in an when diffuse oxidised reduced oxidised reduced of reduced reduced oxidised your Make table a respiration the medium electron carriers in this electron medium transferred the energy in are and when can to the acid make an dark. medium synthetase transport chain to make ATP. membranes made from light-driven pumps from bacteria and and synthetase from answer. mitochondria 7 of thylakoids. through ATP Articial ATP explain pH protons oxidised protein sequence suspended and chloroplasts acid phospholipids, the as the the solution providing State the alkaline Protons from R in carrier alkaline Q than table. kept P the after Electron in lower in pumped Inhibitor is chloroplasts sucrose removed from the pH stroma. solution mitochondria, the spaces illuminated experiment lower process. 5 is In oxidative the phosphorylation in respiration. thylakoid 4 spaces matrix. chloroplasts Explain fully pH synthetase. than 3 the electron intermembrane transport in respiration: is for. the and showing the products per molecule of glucose of each of the four stages of aerobic the produce ATP membranes are when exposed to light. 29 2.6 Investigating respiration Respiration Learning outcomes requires environment. On completion should be able of this section, you and the complex to: oxygen state may that be the rate of determined a rate of oxygen explain how to by measuring Respirometers uptake explain how to are They up and use exchange dioxide. green and Gas parts of requires between involves the exchange plants, carbon the in organism absorption plants is as a of the oxygen more photosynthesis dioxide and raw produces material. pieces rely on of apparatus the fact that designed oxygen to is measure absorbed rates by of organisms respiration measure use a and carbon dioxide is released. T wo designs of a rates are shown here. Y ou may well use a different design, but all of respirometers oxygen the gas gases uptake set to in by-product respirometer respirometer carbon of respiration during exchange animals, of because as respiration. the In release an have a container a carbon for a manometer the same living features: organisms control dioxide absorbent respirometer. to measure the decrease in volume of air inside the container . The carbon dioxide absorbent used in this very simple respirometer is Link soda lime. carbon You can work out the effects and dioxide photosynthesis exchange questions 4 in and plants 5 on in form calcium is calcium carbonate. hydroxide, As carbon which dioxide reacts is with absorbed the air , the decrease in the volume of oxygen in the air can be and measured. Summary page 37 . The following The animals is bag to constituent on detected gas main of from respiration The dipped tubing. of coloured soda blowfly water lime larvae procedure are into This movement a weighed beaker fluid of is the is of and when placed into manometer water water followed in with the a dye using the fluid and narrow simple syringe. so a this that drop capillary a of The respirometer . capillary droplet enters detergent to tube the ease the tubing. plunger The respirometer syringe the meniscus plastic capillary gauze air tubing marking again A simple respirometer with some insect larvae and the after the a knowing the the so droplet on length of bench. The decreases. syringe the recorded. diameter the air position known are on of causes start time put inside which the is volume pressure pressure, tube Figure 2.6.1 as the of the The volume it capillary is less in than towards volume tubing and then travelled oxygen can the reduces atmospheric Measurements distance of moves reduction move. capillary time. The that to droplet The be are taken marking by the by it droplet calculated tubing. Precautions: S tudy 1 foc us Soda lime touch Look table carefully and question at answer the results in this 2 Do Summary 2. up 3 not the Leave and them or handle air in the other let the the carbon them dioxide come into respirometer syringe respirometer or so alter that absorbents contact once the the it is set of harmful; the up; behaviour rate are with of do not organisms. handling the movement may heat animal. becomes constant. Temperature/°C Movement of 4 Return the droplet to the end of the tube by pushing in the syringe droplet due plunger . to oxygen 5 Do not leave the animal in the syringe for too long without removing uptake/mm the 10 8 At plunger least three absorbed 20 the results be movement air the should air . be taken so a mean volume of oxygen calculated. heats up of the and droplet expands could in the be due syringe to a change then in temperature. this will cause cools and contracts If the 34 droplet the 30 refresh 16 The 30 can to to move droplet will away move from the towards syringe the and syringe if it (precaution 2). then Module A control respirometer material of suitable. If needs to the there be Barcroft manometer This tube is taken experimental The same any account to up of exactly before shown counter therefore of when the the the droplet calculating below vessel same animals. calculating has movements compensating and in replaces movement respirometer a temperature set respirometer tube is is volume or pressure due in this of affect tube changes both of in Link this the uptake. to Another design replaces the each between other the out. menisci Readings on each are side taken of the by measuring of respirometer syringe tube which can be bath (see Question with put 7 a in on a boiling water page 39). the temperature. Any changes equally of and S tudy cancel Bioenergetics are then attached in sides inert beads fluid oxygen control to some glass control, thermobarometer . will but movement rates a way Small 1 the foc us distance U-tube. Textbooks show this (Figure calibrated and exam type of sure work, how analyse you to the often respirometer 2.6.2). They make papers are tricky understand use them to use; how and they how to results. syringe rubber tube S tudy Rates screw screw clip A clip of foc us oxygen uptake are often B expressed as volume of oxygen 3 water bath of gram desired This temperature of of tissue involves the per hour some (mm careful per –1 g –1 h ). analysis results. respirometer respirometer chamber A chamber B Summary questions glass beads actively respiring 1 Dene the terms gas exchange, organisms, respirometer, e.g. insect 2 larvae soda-lime Explain the results U-shaped manometer the tube soda-lime 2 containing coloured 3 Barcroft respirometer set up to measure the rate of respiration of Plan an how the rate germinating seeds (tube B). Boiled seeds of the same mass are in tube A of seeds. your The advantages into a of this respirometer is that the tubes can also be water bath to maintain a constant temperature, although investigation water bath fluctuations in temperature are compensated for even The a by respiration Include plan: a addition of the absorbed syringe can be means taken by that measurements depressing the of syringe the menisci to their original position. A problem with the germinating the following prediction; a in method set of numbered points; the an results explanation will be of collected volume plunger this how rates of respiration will to be the in out affects tube and return on out how oxygen to nd temperature precautions; of table inserted as B. the page. to 2 Figure 2.6.2 opposite liquid absorb CO a in to absorb CO of germination. is calculated and presented on a that graph. the scales on syringes are often difcult to read and reading errors can be introduced. 4 Explain why respiration Germination is the process that occurs when the embryo inside a dry to grow, seeds. cells to often When following they absorb a period water of this dormancy. activates Most plants enzymes and the respiration most active mitochondria active. stage in Enzymes substrates are the very in dry the and life seeds; hydrolyse glucose high germinating cycle when starch fatty in of a the and/or plant. seeds lipids seeds. There are to Germination are enzymes soaked, give the both changes release causes 5 swell. of of seeds germination. Rates of respiration seeds increase removed. Rates rate pea seed during starts the of their Suggest pea testas why this are is so. is and become respiratory if in 6 Suggest the simple limitations of the respirometer Barcroft and the respirometer shown here. acids. 31 2.7 Anaerobic respiration This Learning outcomes section going On completion of this section, be able concentrate state that some mammals can tissues the survive the in time respiration for lengths time lactate the is reaction in which But there in mammals, although we are humans. an athlete for of explain the role this explain the concepts to the for run athlete’s as the 100 metres, aerobic there muscles. well as respiration will not Muscle tissue needed under to be these provide conditions aerobically. is responds quickly cannot insufcient to to not be the demand supplied oxygen, does carriers be the take to nal reaction place. oxidised, so for extra energy mitochondria There the of is in the enough. form of As oxidative no Krebs fast way cycle for and the the reduced link reaction reaction stop of for lack of NAD and FAD. oxygen This oxygen absorbed phosphorylation produced and takes oxygen hydrogen decit respiration short A TP . describe on anaerobically Glycolysis it oxygen energy respires using anaerobic of anaerobic to: sufcient about mammals you In should to is in also means that the mitochondria are unable to recycle the reduced debt. NAD from catalyses the temporary in the As glycolysis. reduction hydrogen muscle glycolysis way to cells and NAD triose of then large so the pyruvate acceptor produces recycle 2 Fortunately, that phosphate to to form diffuse enzyme form quantities glycolysis lactate. lactate, into of lactate the Pyruvate which starts acts to as a accumulate blood. pyruvate can dehydrogenase there must be some continue. (3C) 4ADP Figure 2.7.1 Some athletes train to 2H 4ATP 2 improve the way in which their body NAD performs when they make huge demands on the anaerobic respiration in their 2 muscles reduced NAD S tudy foc us 2 A common describe there The is question the fate no word of oxygen ‘fate’ on this topic pyruvate in may muscle seem is: Figure 2.7.2 when tissue. odd. The overall equation for under these happens to anaerobic respiration in muscle tissue is: It H 6 what (3C) The pathway that produces lactate in mammalian muscle tissue C means lactate O 12 → CH 6 CH(OH)COOH 3 pyruvate conditions. with a Oxygen net gain of demand 2 A TP . exercise exercise Oxygen during exercise ends and deficit heart increased 2.5 occurs time demand for debt is because to repaid adjust the to lungs the oxygen during the recovery 2.0 1 period is 1.5 used through to extra reload myoglobin, to md 3 negyxO nim /ekatpu Oxygen take metabolic uptake haemoglobin oxidise organs operating 1.0 oxygen at lactate higher that and and than to keep normal rate 0.5 Oxygen Figure 2.7.3 Exercise physiologists uptake 0 2 4 6 8 10 12 14 16 18 20 22 24 monitor the performance of athletes at rest time/mins during their training by measuring breathing, heart rate, blood pressure, Figure 2.7.4 blood composition and other parameters exercise 32 The oxygen consumption by an athlete before, during and after strenuous Module Anaerobic as A TP However , reduces slow respiration very quickly the the down build a increase or stop. supply The race in of of of is to lactate in an the useful since it provides energy muscle tissue us lowers feel athletes tired. are able the pH This to and means tolerate we higher blood. increase in aerobic is is making training, supply how in their difference shows tissue Bioenergetics exercise. enzymes, lactate there This muscle support Through oxygen A TP . graph up efciency concentrations During in to 1 demand known oxygen for respiration as the energy, at the oxygen consumption but rate not an required to decit changes during and after exercise. Figure 2.7.5 After exercise oxygen is during required aerobic the recovery period, oxygen uptake remains high as Anaerobic respiration provides energy quickly so that predators can sprint to catch their prey for: respiration of lactate in the liver re- oxygenating haemoglobin in the blood re- oxygenating myoglobin, resynthesis Link of A TP and which creatine is a store of phosphate oxygen in in muscle muscle tissue Creatine tissue phosphate available supporting high rates of respiration in all organs after transferred high Oxygen debt is the end why of the people strenuous race the athlete to will breathe have deeply built after up an taking oxygen a is a readily phosphate short debt . burst to ADP demand for tissue. continue of that can exercise. be At store It is not a when energy very in there is a muscle large store. This of exercise. Link Lactate into dehydrogenase pyruvate. This catalyses happens in the the reaction liver . in Some which of the lactate is pyruvate converted is Most converted to glucose by the reverse of the reactions of glycolysis. intracellular reversible; requires energy, which is provided by the oxidation of pyruvate reactions are This the enzymes catalyse in forward and back reactions. The mitochondria. direction If to the be athlete supported started at a supported long The fast by by the glucose, table taking by part aerobic speed aerobic endurance fuelled little is the will such as a athlete have to of fat the and event, means slow Glycogen ‘hits advantages This marathon respiration the endurance respiration. he/she event, shows an respiration. aerobic then in and in the that down to muscles run. if a is and disadvantages to of the the If has determined athlete speed glucose. has exercise used However , some wall’ then that up reaction the and takes is concentration of product(s). is muscles is a by substrate(s) during there that a are very stop. anaerobic Summary q uestions respiration. 1 Advantages Why to Disadvantages do be endurance supported by events have aerobic respiration? ‘buys time’ at the beginning of wastage of energy; glucose is 2 exercise until the lungs, heart and converted to lactate, which Dene the terms respiration, blood can provide oxygen to muscle energy anaerobic is oxygen decit, oxygen rich debt tissue 3 provides a lot of ATP very quickly lactate is toxic above a certain the concentration provides ATP for explosive that short-term activity, lasts for only such as a few sprinting, seconds net gain of ATP molecule of Describe the fate absence of of pyruvate oxygen in in muscle tissue. is only glucose 2 per 4 Explain in the what happens body following strenuous to the lactate end of exercise. 33 2.8 Anaerobic respiration Y east Learning outcomes in On completion of this section, is fact be able many state in that yeast are anaerobic produces respiration carbon dioxide Like of that grows on the surface of fruit. There are yeast. found in rotting fruit microorganisms where The decarboxylated As pathway to you form can is not they the ethanal. see from can the oxygen same Ethanal the respire concentration as is in animals. then metabolic anaerobically well Pyruvate reduced pathway as is to this as is become recycles NAD. ethanol describe carbon the reaction dioxide and in which ethanol 2 describe triose phosphate (3C) are produced often many aerobically. ethanol. and types fungus to: low. unicellular yeast you Y easts should a in 4ADP the commercial uses of 2H 4ATP 2 yeast. NAD 2 2 Candida on and is a type inside reduced NAD Did you know? of yeast humans that and is 2 ethanal (2C) ethanol (2C) lives the 2CO cause of oral and vaginal 2 thrush. Figure 2.8.1 The S tudy The pathway that produces ethanol in yeast overall equation for anaerobic C H 6 Pyruvate decarboxylase is in yeast is: enzyme that in (see breaks down a net → 2C 6 H 2 OH + 2CO 5 gain of 2 2 A TP . pyruvate These page O 12 the with yeast respiration foc us reactions are not reversible. Y east cannot respire ethanol. 26). Fermentation Did you know? The term applied Ascorbic acid (vitamin C) is added to make the protein gluten anaerobic it has the more time for elastic, so in in two distinct yeast and ways. other It used to be microorganisms. come to be applied to the culture of any More microorganism cell grown in either anaerobic or aerobic The ability used in bread brewing wine The is of yeast bread acid flour and left There in dough with then yeast ferment sugar to form ethanol and carbon dioxide ways: making ascorbic sugar . to main making. mixed and yeast making role causes of three Bread in is respires a bread to (made water to humid some making rise – a is to process from wheat, make anaerobically. at dissolved The rye dough. atmosphere oxygen produce carbon sometimes The maize), dough 35 °C in carbon or the for the which leavening. sugar is dough dioxide dioxide, called folded yeast but if released Y east (sucrose), and to respire this is forms salt, kneaded the used of up, pockets The baker is kneading the dough, which mixes in some air to provide oxygen for the yeast. Oxygen does not of gas in ethanol the dough produced is causing burnt it off to rise. and The goes up dough the is then baker ’s baked and any chimney. diffuse through the dough so respiration becomes anaerobic during the time the dough is left to prove before it is baked. 34 or conditions. reducing leavening. is Figure 2.8.2 used in eukaryotic the flour is respiration to recently dough ‘fermentation’ to During sucrose the to fermentation, the monosaccharides yeasts and convert respire maltose them in the flour anaerobically. and Module Brewing Cereal grains, usually barley, are the main raw material for brewing. The Endosperm in the individual grains is rich in starch. Y east cannot so the grains are soaked and allowed to germinate. The mixed with yeast to ferment and produce sugar ethanol dioxide, both of which are required. The stages are Malting: The grains produce amylase to catalyse the grains to stopped 70 °C maltose. by to denature Milling: Mashing: Y east heating The the the grains can respire grain to enzymes are a maltose. and crushed The temperature outlined hydrolysis to stop help the germination between and other water soluble is poured compounds over to the 40 °C Boiling: The wort is boiled with concentrates the wort, remove grain the to ‘wort’. hops, which is Fermentation: and top S. carbon fermenters pastorianus called 18 °C When ready S. that (ales) be is added Y easts produce are used bottled, is to of produce then ferment the type ales. dissolve provide for the or the ( S. the put wort the foc us sugars flavour . to why yeast can respire The produce but not starch. You pastorianus 10 °C of the used your need knowledge from Unit to 1. ethanol cerevisiae fermenters between mixture into to (lagers) are type be Temp. Movement of droplet /°C /mm and is ltered. The beer is then 1 2 3 casks. 5 6 6 5 10 8 8 7 15 13 12 11 20 16 18 12 30 28 32 26 35 14 12 13 making such as grapes provide crushed to extract ferment at temperatures known as the skins and Wine makers ‘must’; then productions the put used the contaminants. ferment grape to is Y easts is wild to extracted added from and S. to of a the press wild but the to and left are to fermented remove aged in yeasts cerevisiae Grapes juice The heated, yeast, the making. 30 °C. ltered, kill strain wine through vats, strains treated the is for 20 °C passed settling of sugar Y east between use fruit sugars juice. this into the the and pulp is fruit bottled. commercial and any ellipsoideus other are added to fruits. Summary q uestions 1 Make a table between to show anaerobic the similarities respiration in and differences mammals and 5 °C, put capillary mixture Name the monosaccharides that are produced hydrolysing a maltose, and b a tube the of Explain yeast the in biological bread principles making, wine Dough with added yeast involved making expands and in diameter using yeast place. Plan an as investigation it is left in of the dough is directly recorded. The and glucose kept a at the droplet same along temperature was increased the of to the of the droplet 10 °C recorded. Other to see of were the used as capillary shown tubing in was the table. The 4 mm. if the students results are in the table above. a rate Process proportional to the results and draw a table to show the of mean expansion of brewing. a warm was and sucrose. The 4 movement movement temperatures 3 respirometer by and yeast into temperature. The in yeast. 2 rate of fermentation at each temperature the investigated. temperature of proving. b 5 A student the rate investigated the of fermentation in effect yeast. of temperature 10 g of yeast i Draw a explain on graph the fermentation was of effect of the of results, and temperature ii describe on the and rate of yeast. 3 mixed with 100 cm of a 10% glucose solution 3 is fermentation. complete canned beers. Module 1. cooled. bottom T emperatures grains in sugars. Saccharomyces The lager-type carlsbergensis .) fermentation to Wine Fruits Y east dioxide. 1.5 and use See hydrolysis. form which bread flour. maize of maltose boiling of cornflour. Explain of of below. S tudy Hot provides endosperm of Unit starch store and forms energy endosperm is The carbon the seeds. The wheat and is respire some extracted Bioenergetics Link endosperm starch, 1 at c State a limitation of the method. 35 2.9 Respiration: summary Organisms Learning outcomes compares On completion should be able of this section, you state the be classied different hydrogen types of according similarities respiration how in they terms of respire. the The nal table electron/ acceptor . electron/ Product Type of Examples and hydrogen differences to to: Final can between aerobic respiration and Prokaryote Eukaryote aerobic, Escherichia humans; involving coli yeast none acceptor anaerobic respiration derive yield the aerobic of ATP respiration of in oxygen the water glucose oxygen compare aerobic the and energy yields anaerobic of respiration nitrate (NO ) dinitrogen anaerobic, Pseudomonas (N denitrication denitricans hydrogen anaerobic, Desulfovibrio sulphide sulfate vulgaris (H reduction 3 of glucose. ) 2 sulphate (SO ) none 4 S) 2 3+ ferric iron (Fe ) ferrous iron anaerobic, Shewanella iron putrefaciens none 2+ (Fe The Did you know? advantage electron Oxygen They Earth is toxic evolved were survive muds, in to which such occur prokaryotes. conditions anaerobic places mangrove some when in and as on they wide and in acceptors range of before roles recycling able is the oxygen to that than of other methods oxygen. are among the nal organisms oxygen entered mineral reduction use the absence other survival evolved in being chain material electron anaerobic wetlands organic of transfer ) electron can The prokaryotes, elements, such as able There some Some of have nitrogen and for the respiring organisms prokaryotes. atmosphere. acceptors continue is to a use very which important sulphur . swamps. Organisms are that obligate can survive aerobes. Those only that with oxygen cannot are survive obligate with aerobes . oxygen are We obligate anaerobes Some organisms, anaerobically. The table such These shows Feature the as are yeasts, can facultative differences Type of respire both aerobically and anaerobes between aerobic and anaerobic respiration. respiration Aerobic Anaerobic Yeast Mammal yes no Link You can page 47 . read about denitrication decarboxylation yes oxidation yes on reduced of NAD products per – in yes in cytosol mitochondria using using electron H ETC 6 × 6 × CO O ethanal 2 × 2 × CO by as acceptor ethanol yes in using electron 2 × of 2 glucose net * 36 gain See the 2 ATP 2 2 ATP of ATP table 30* opposite. 2 2 as acceptor lactate 2 molecule cytosol pyruvate Module 1 Bioenergetics Yield of ATP The 15 yield times difcult glucose which of A TP greater to from than estimate molecule does not intermediates is aerobic that since for the gure completely necessarily in respiration anaerobic the Krebs for broken happen. cycle shown aerobic down Y ou may is in respiration. will enter the This table respiration to water and remember other as about difference assumes carbon from metabolic is that a dioxide, page 26 that pathways and S tudy are not respired hydrogen and completely. oxygen atoms This in means glucose that some remain in of the energy-rich compounds. The This tends to reduce the total yield from different table with the shows how metabolic to calculate pathways in total yields. sections methods by which glucose. reduced The foc us carbon, 2.2 Y ou and need 2.4 to and check the back lists the NAD from mitochondria glycolysis are enter beyond the of scope of this book. products. Stage of Input of ATP Direct yield of ATP Indirect yield aerobic (phosphorylation (substrate-level of ATP via respiration of phosphorylation) reduced hexose) and NAD reduced Summary q uestions FAD 1 glycolysis –2 4 3 or 5 (NAD)* 0 5 (NAD) does the ‘net yield’ of ATP mean? 2 link What Explain would why not an be obligate of any aerobe use in bread reaction making. Krebs cycle 2 15 (NAD) 3 3 Make a and mitochondrion a show Totals –2 6 drawing 26 the cytosol gives a theoretical maximum yield of 32 – 2 = 30 molecules of 32 depending enter on the how the hydrogens mitochondria – from there are reduced two NAD methods of rise either reduced to NAD three from or to five molecules of ATP for the of a this, maximum two of A TP 4 (32 or 30) is rarely, if ever , that with occur palisade the daylight mesophyll hours. What a to these plant is exchanges in darkness? molecules glycolysis ). number and which Explain why respiration This and from for when give exchanges them during happens glycolysis chloroplast A TP cell (or a or 28* between This of (FAD) the and processes of photosynthesis achieved are not opposites of each other. because: 5 some intermediates in the metabolism of glucose are converted Plants their other substances rather than being broken down completely (see on page the proton happens gradient is used to power the movement of substances matrix, e.g. pyruvate and phosphate chemiosmosis is not efcient, as some mitochondrial membrane into protons the ‘leak’ through but and important the the none of point difference to remember between net yield the energy oxidative uptake and in the anaerobic transfer respiration occur net here yield of anaerobic the aerobic which the and a carbon plant during a and hours). You may day wish to cytosol. not in respiration, reactions in is oxygen between the draw The of environment (24 outer the ions its to into dioxide the with Describe 26) release gases environment. Krebs what cycle exchange into link calculation respiration is 2. This reaction, is in the table, (about 30) because Krebs cycle and two graphs exchanges the carbon your patterns show one for other for Annotate the – to oxygen and dioxide. graphs you the have to explain drawn. respiration. 37 2. 10 Practice exam-style questions: Respiration Answers to 1 The all exam-style questions diagram respiration represents in a a can metabolic be found on the pathway accompanying CD. in ii State mammal. two the precise types of sites in a plant phosphorylation cell of shown the in the diagram. CH CH OH [2] OP 2 2 iii O O Give THREE between similarities and THREE photophosphorylation differences and oxidative phosphorylation. ATP ADP [6] 2 1 iv POH CH C OP POH 2 2 CH C OH v 2 2 O List THREE plant cell. State FIVE compounds that are oxidised in a [3] uses of ATP in a plant cell. [5] O 3 a Outline the processes which occur in respiration 3 during: ADP ATP i glycolysis, ii the link iii the Krebs [5] reaction, and [3] Pi O O CH cycle. [4] X OH 2 b CH CH OH enables OP CH NAD 2 CH Describe how the structure of a mitochondrion OH aerobic respiration to occur efciently. reduced CH OP OP 2 2 You may use a labelled and annotated diagram to NAD 4 ADP help Y c your There are Suggest O O answer. no [2] mitochondria how they in red blood cells. respire. [1] ATP O O CH C OH OH C OH S tudy C CH CH CH 3 ATP CH ADP H 2 OH You OH CH O foc us OH OP could use a table to plan your answer to question 3a. 2 2 CH OP 2 6 a 5 i Name molecules 2, 3, 4 and 6. [4] 4 a Describe the formation mesophyll ii State where substance 1 comes from. iii State what happens at stage iv State what happens to the during of ATP the in a daylight palisade hours. [5] [1] b Y. reduced cell Discuss the importance of ATP in plant cells. [5] [1] NAD. [2] 5 NAD and coenzyme A are coenzymes involved in respiration. b i Discuss the importance of the reaction that The occurs at X. concentration [2] ii State and the fates anaerobic of molecule conditions in 6 a under aerobic mammal. a [4] a Explain why ATP is a nucleotide. 0.8 µmol g Explain The diagram palisade shows NAD in muscle is very limited, tissue. reduced NAD is formed during Explain [2] how reduced NAD is recycled in muscle [3] tissue b how of respiration. b 2 of –1 about the formation of ATP in a i oxygen when is not oxygen is available, and ii when available. [4] cell. c Discuss the a Describe role of coenzyme A in respiration. [2] oxidative ADP+P photophosphorylation 6 what happens to pyruvate in a phosphorylation muscle energy from the energy from cell and in yeast cells under anaerobic light conditions. oxidation [5] of b Explain the importance of the reactions you compounds describe. [4] ATP c i 38 Explain the term phosphorylation. [2] Explain use of the biological yeast in principles making bread, involved wine and in the beer. [6] Module 7 The the apparatus rates leaves of of in Figure respiration pinto 2. 10. 1 of was used germinating to compare seeds 8 and During strenuous running, beans. muscles fat. Glycogen can anaerobically, a Name a why is suitable chemical to use as X and used. apparatus with the closed clip and time. The was put into open. After the position results Describe are a 10 of water bath minutes the the droplet at 0 the is changes clip was recorded over 10 Explain the Explain why 20 25 30 of as fast changes a long-distance of both only that glycogen and aerobically respired occur why as a a tissue and aerobically. in the during supply of the rst few exercise. that person strenuous Explain 35 muscle strenuous c end 15 of b as follows. 5 within minutes 27 °C d Time/ respired whilst fat as stores [3] energy The be such their Bioenergetics explain a it exercise, use 1 you [4] have breathes described. deeply at [4] the exercise. marathon [5] runner does not run sprinter. [3] minutes 9 Position of 0 0 0 31 65 95 130 An investigation production 162 of droplet/ mitochondria ADP, mm The phosphate Explain i why a water bath is used, why the apparatus is left for 10 closing the Explain clip. The the diameter results in of the the capillary table to the was prepared. To and excess of this pyruvate these four suspension was and added oxygen. substances were intervals. why than pyruvate was used as the substrate glucose. [1] [1] b c into minutes rather before out mitochondria. A and a ii at carried in concentrations determined b was of ATP tube is calculate State what you would expect to happen to the 0.8 mm. Use the rate concentrations of the four the and substances added to of suspension give detailed explanations 3 oxygen uptake in mm per hour. [1] for d Explain how the investigation results was would repeated at differ 17 °C if the and The at experiment [2] c Predict of Explain how the apparatus would be used answer. [4] was repeated but no phosphate was added. 37 °C. e your what oxygen in would the happen to suspension the and concentration explain your to nd answer. the rate valid of respiration comparison with of the the leaves to make [3] a beans. [3] 10 The 13 DNA in a mitochondrion polypeptides. These (mtDNA) codes for polypeptides form ATP clip synthetase and parts of the electron transport chain U-tube in a the Explain a b inner membrane. the role of the electron transport chain mitochondrion. i Outline how in [4] these polypeptides are produced seeds in ii a mitochondrion. [4] Each mitochondrion has more than 13 polypeptides. Where are the rest produced? iii what the other genes in [1] mtDNA code for. X c coloured water Suggest Mitochondrial nuclear genes, [1] genes mutate possibly at a because higher of the rate than highly bath liquid reactive with Figure 2.10.1 molecules DNA. these Explain mutations in in the the matrix likely mtDNA. that interact consequences of [3] 39 1 Bioenergetics 3. 1 Energy and Learning outcomes nutrient flow The The On completion of this section, blue Earth be able define the habitat, trophic terms a ecosystem, ecological niche as state Within and these level that energy flows large border they as and is not that there quantities they are explain of nutrients in chains the borders organisms also open adjacent those ocean are is with and known as composed as ecosystems a interact interact small with community with their each as biomes of a which of that have ecosystems, pond. it many other physical offer ecological niches fill similar niches in different and species. Savannah grassland similar which and Each may ecosystem exchanges species. with Populations other has resources. of populations; environment. for organisms to fill. The organisms that flightless: ostriches offers parts of the world opportunity for are large, rarely the grazing same birds so are in Africa, rheas in South America and emus ecosystems and food advantages of webs Australia. different They have similar ways of life, occupying the same niche in continents. using S tudy food regions through in draw food large biomes are finite recycled into These recycled that state the with Ecosystems ecosystems divided features. to: be is you climatic should planet foc us webs. Ecological the food niche chain – the and role of a species interactions with in a community, other species and including the its position in physical environment. S tudy foc us Energy You should learn these flow studied definitions: at organisms Species that – a group interbreed of to and the nutrient ecosystem and between cycling level the are as two they processes involve community and that can interactions the abiotic only be between environment. organisms produce fertile Energy flow offspring. Organisms Population – all the individuals for the same same species place at living the in same gain food from an energy source or sources and provide energy of other organisms that eat them. A food chain shows these relationships. the time. a Habitat – organism the place where an lives. b dead Community (of all – trophic all the levels) leaf earthworm that live in same area at the same Ecosystem – a primary consumer secondary consumer tertiary consumer time. Figure 3.1.1 jaguar c producer the frog organisms a A grazing food chain b A detritus food chain for a forest ecosystem in self-contained Guyana c A generalised food chain identifying the trophic levels. The arrows show the community features and that interactions all the influence between physical it and direction of energy flow. the them. Each organism occupies a trophic level , which is the position in the food chain: Producer energy S tudy more organisms than restricted you read one to on, are able to ecosystem; one ecosystem note exist others examples in are only. As of these. autotrophic simple biological Consumer – compounds, consumer organisms and 40 an organism chemical that reactions use to fix either light carbon energy dioxide or and foc us produce Some – from a molecules. heterotrophic usually trophic that decaying by levels obtain organism feeding on including energy organisms. by that living obtains energy organisms; decomposers breaking down – there in are organic several heterotrophic compounds in dead Module Food chains are simple descriptions of energy flow. But producers, such more are than eaten one by type more of than food one consumer. organism. There Many are consumers many food feed chains ecosystem. A food web gives a better indication of all these foc us on within In an most ecosystems webs show ecosystems, too but complex. trophic much (use are photosynthesis). relationships. Remember Food producers different phototrophs feeding Bioenergetics as S tudy grasses, 1 they The levels. energy some of rarely food This flows the is as complexity show chain purely and all these food by feeding each relationships relationships web qualitative; indicated show there as energy is no they flow in become not between indication that ecosystems about for there where phototrophs. details of See vent are the some producers pages 2 are and 3 communities. how arrow. large sharks sea of S tudy carnivorous otters foc us fish octopus Herbivores, large parasites, crabs carnivores, detritivores omnivores, and starfish decomposers (sea small stars) scallops are all consumers as carnivorous fish and abalones they invertebrates are all heterotrophic. and sessile invertebrates sea small urchins small herbivorous herbivorous fish invertebrates microscopic floating animals Link detritus kelp algal turf The (very large smaller seaweeds) Figure 3.1.2 (algae seaweeds growing surface of cycling of nitrogen is considered microscopic over floating rocks) in algae more detail on pages 46 to 47 . A food web for the kelp forest in the north-east of the Pacific Ocean. See page 52 for more about this food web. Respiration During is not 100% respiration, surroundings. efficient much Eventually energy all the at is transferring transferred energy that energy as heat entered from to an food to A TP . the ecosystem leaves Summary q uestions as infrared Earth into radiation to the surroundings and is radiated away from the space. 1 State the differences energy flow Nutrient Nutrients elements called are the to make nutrients. inorganic elements building required mineral simple, recycling cycling form. available in blocks those organic organic Autotrophic Unlike the of to molecules. organisms energy, biosphere molecules. there is They Sometimes absorb a finite organisms. If contain these are of not 2 are elements quantity they they the in life comes to a complete niche b biome c these the a between habitat and ecosystem and community. Explain the limitations of food standstill. secondary consumers 4 a and food State each dead O, primary leaves, dead ecosystem. differences and population chains urine, faeces, an between nutrient recycled 3 then State in and the form of N webs. the and S in which elements C, are H, absorbed by consumers bodies producers. b producers that use mineral nutrients to make State one element molecules, decomposers break waste to matter mineral such as amino acids, proteins, use of each biological in organisms. etc. down 5 release nutrients Suggest birds inorganic pool of mineral nutrients, e.g. nitrate of why sulphate ions in the soil and in large, flightless ions and Australia and the South America, Africa are different waters species. Figure 3.1.3 Decomposers play an important role in recycling nutrients to producers 41 3.2 Ecological pyramids Relationships Learning outcomes pyramids. On completion should be state able that numbers, flow in of this section, biomass horizontally level numbers energy is shown and in ecosystems arranged the blocks, blocks are displayed with centred on each top of as block one another . The pyramid simplest shows numbers of organisms at each trophic level: as Producers are at the base. Primary, secondary and tertiary consumers pyramids are identify are trophic Pyramid of a levels about and ecosystem ecological These representing trophic to: information an you between the limitations arranged above the producers in the same sequence as in per m a food of chain. ecological pyramids. 2 Numbers In many each are of given these trophic per unit area; pyramids, the often this number of is number individuals decreases with level. tertiary = 1 consumer The area often of the each block numbers are is proportional so large that to the some number blocks are of organisms; deeper than secondary = 90 000 others. consumers primary Limitations = 200 000 = 1 500 000 of pyramids of numbers: consumers producers Organisms Some treated pyramids support Figure 3.2.1 are large are equally inverted numbers of whatever if the their producers primary size. are large (e.g. trees) and consumers. A pyramid of numbers for a grassland ecosystem. The units are They usually show what we can see during surveys of ecosystems; numbers per unit area. they do not include decomposers S tudy Make by your own should graph Numbers often Numbers are pyramid draw paper so the it is of 1 numbers on page pyramid drawn to 62. the ants Juvenile They in include show parasites in they will type as and large animals often of parasites. If is in of all the bacteria your gut the into on your numbers difficult to give to the same scale, e.g. all feed at a different trophic level to adults. numbers at one moment during the year , in time; due to numbers of reproduction some and species migration. biomass This takes into requires account taking the different samples of sizes organisms of at organisms each them. Dry mass is often used since plants trophic have quantities by of water drying the depending plant on matter environmental and reweighing conditions. to the dry mass of animals is easier , since the water constant content mass. of tissues does about not 70% fluctuate of animal as much as that of plants. W ater tissues. billions! S tudy advantages still at to constant weighing, mass’ drying again. This Much of with this biomass to are that consumers type of is the potential indicated. food However , there pyramid: the plant the material level – wood, is not bone, always hair , for edible to the organisms in the next example. and continues Material that is eaten may not be digested and so therefore does not until provide of of level means mass pyramids trophic limitations trophic weighing of each foc us ‘Weighing 42 and skin are remains huge may pyramid done available the often would The drying, numbers. community. weighing represents run estimating you animal and and have Finding counted sampling become This thousands on pyramids varying inverted, depend considerably ecosystems. level numbers as parasites. foc us in of important scale. This you a stages Pyramids of If are on change S tudy which foc us answering Question You and microorganisms, energy or nutrients to the next trophic level. material They do not indicate They depend how much energy is available to be transferred. constant. on sampling and estimating so may not be very accurate. Module They do not standing were show crop taken; – as changes the mass numbers with of of time, as organisms some they at species the are a time change measure when of the the Bioenergetics secondary = 1 = 4 = 10 consumer samples considerably 1 during primary the year , so does their biomass in the ecosystem. consumers decomposers Inverted Both pyramids types ‘base’ is of and pyramid smaller than may the be inverted, primary which consumer means level. In that the detritivores producer ecosystems such as producers forests, the producers consumers producers, that feed such as are on very large leaves, compared flowers, phytoplankton in fruits, the open with the bark and ocean, many, = 40 000 small roots. Tiny reproduce much Figure 3.2.2 faster than the larger zooplankton that feed on them. The A pyramid of biomass for a zooplankton tropical forest ecosystem. The units are graze on the phytoplankton phytoplankton reproduce but so are continually able to find food as –2 the fast. S tudy Pyramids of It is more can be done foc us energy helpful determining ). dry mass per unit area (g m the by to understand flow of energy drawing how from pyramids an ecosystem one of trophic functions level to the Draw by next. and This on energy. your own energy page by 62. pyramids of biomass answering Question Do not forget to add 1 the units. Pyramids the of energy The flow time. Producers the The of available proportion of a either: stems, level much becomes is the at energy available roots, of productivity flowers this new of each trophic level, or levels. consumption absorb content the trophic trophic for this leaves, energy show between productivity becomes of energy energy each content trophic as sunlight, for primary and fruits growth is of level but the over only a that are made in form year . not heat productivity. confuse all this plant productivity is consumed each year . If it transfer organic were, much planet would not look so green! The energy flow from producers during to consumers is less than the productivity of the producers out how what content of much is consumed. consumers of what organisms, feed they e.g. on This and consume. leaves, is energy flow estimating The found energy by the is determined quantity content burning the of and the material in heat of is is used to a record the in temperature. The energy and by organisms combustion and a to in shows water with measure of increase primary calorimeter material. The thermometer the a colorimeter. Calorimeters transferred Not foc us of Do the each S tudy that period small consumers primary food a kJ is calculated knowing that 4.2 J finding energy or parts oxygen in raises by the temperature of 1 g of water 1 °C. a calorimeter . S tudy Pyramids types of of energy pyramid include do not. the The dimension units for of time, pyramids which of the energy other are usually It –2 is impossible pyramid The advantages organisms blocks. a to have an inverted –1 year kJ m as foc us two or This of pyramids parts is pyramid. of the energy organisms best They of way show to that do are not have represent the that an the energy the size effect and on functioning transferred edibility the of from size an one of of and the page of then energy. Think try Summary about this question 4 on 45. ecosystem trophic Summary q uestions level why not to the few next food enough decreases chains energy have to with position more support than in four another the food trophic trophic chain. levels. level of This There explains simply predators that is 1 Suggest the ecological on other external predators. and There internal will, however , parasites of these be enough large energy to support limitations of pyramids of 2 Discuss The work involved estimating, since can not be all time-consuming of the organisms and in a involves sample c much can be As with pyramids of numbers and biomass, they suggest pyramids pyramids feed only on the of numbers, trophic level below them. of of biomass, and energy. Explain why it is impossible to that have consumers limitations of burnt! 3 the pyramids energy: b drawing pyramids. the predators. a The reasons for feed Many an inverted pyramid of top energy. predators often feed on several different trophic levels. 43 3.3 Ecological efficiency The Learning outcomes efficiency of energy flow between energy trophic available levels to a is calculated trophic by: level ______________________________________ On completion of this section, Ecological you efficiency = × energy should be able describe how the efficiency transfer between shows available is what to discuss the transfer by in efficiency of energy that the can other often foc us Y ou the two laws thermodynamics from be are organisms Both ecosystems. as heat eaten apply Look have forgotten to your study the of energy the consumed energy entering by a one trophic trophic level level is in by as body they maintenance the respire. organisms This and much in the leaves next very passes little as to the new growth level. them Summary losses of the can next steep from The trophic energy trophic levels available level and to for decomposers and, consumption explains why possibly, limits pyramids of to the energy are sided. analyse about the data on energy flow on the opposite page to learn up and if of energy flow in ecosystems shows the following: in you then question this. of energy flow them also very Analysis Producers Ecological 4. absorb The efficiency between much energy into very efficiency well-managed net of Much of more answer next. ecosystems. growth S tudy physics. percentage the ecosystems. There Remember 100 level determined surroundings trophic trophic used levels previous of is energy by to: This consumed crops is radiated of it the about might variable than atmosphere is it consumers; lower little light 1–2% be as between may be as that for strikes producers, high as as often less; in 5%. producers high them. and 20%, consumers, but more and often it is this. Energy their is used body by organisms maintenance and at all trophic levels for movement. productivity gross Only the energy in new growth and new individuals productivity (reproduction) is available from one trophic level to respiration the next. Energy is transferred to the surroundings as heat 37 44 when organisms respire and move. secondary Energy is transferred to detritus food chains at all consumers sresopmoced trophic 131 levels. 175 faeces – 105 Energy transferred surroundings as to heat detritus is food available and biomass. to and to the consumers, so 280 limiting their numbers 750 1 478 dna primary consumers In open to other ecosystems, ecosystems, serovitirted consumers (for organisms so or limiting example, their energy detritus in wastes are available river lost to ecosystems 1 890 3 368 is carried dead faeces – downstream bodies sink to to the the sea; in the open ocean bottom). 800 Energy 4 168 flow diagrams are another way 5465 energy 25 833 flows through ecosystems. producers 11 977 37 810 Figure 3.3.1 An energy flow diagram shows 1 700 000 the energy transferred between trophic levels energy from that strikes the Sun plants in and the ‘losses’ as heat to the surroundings and as dead matter to decomposers. The –2 the 44 chains not ecosystem figures are in kJ m –1 y . to show how Module 1 Bioenergetics Summary q uestions 1 The table shows energy flow through a crop 3 of The table shows energy flow through –2 potatoes. The PAR is units are kJ m photosynthetically wavelengths between –2 per active 400 and growing radiation season. ecosystem. The energy intercepted by solar leaves energy energy PAR transmitted energy leaf transferred organic by by result leaf the transferred from transferred stored next Ecological to photosynthesis to The to the 900 by respiration and heating to herbivores 58 energy transferred from plants transferred from herbivores to leaf 72 litter 214 500 to environment as environment 190 000 in biomass trophic by respiration and to the 31 heating and available transferred from calculate efficiency the herbivores to 13 carnivores 24 500 level = potatoes the that the ecological transferred from percentage is available of to by carnivores respiration and to the 8 heating efficiency. the the energy energy living next transferred to decomposers from 92 organisms level. energy 2 1 946 respiration the figures, trophic plants transferred environment input photosynthesis energy energy Using in 2400 energy to plants compounds of energy 65 800 2400 energy energy woodland 600 000 surface through a –1 week input environment reflected from kJ m 1 000 000 energy that cannot be absorbed (not PAR) PAR are – 700 nm. energy fixed solar units table shows the energy flow through a transferred from leaf litter to 153 decomposers bullock, –1 which is a primary consumer. The units are MJ day energy transferred from environment energy intake energy transferred by to environment in faeces a 4.93 assimilated Using transferred to environment in urine Draw the figures, transferred respiration and by to environment by an the the stored next 4 in trophic biomass and available to 10.29 page, Ecological input to trophic calculate efficiency the the ecological and the herbivores. diagram like that the information on in the the table ecosystem. Use the information between in Figure gross 3.3. 1 to explain productivity and the net productivity. bullock = the that is the ecological Explain the relevance percentage available of to to of the first energy flow and in second laws of ecosystems. efficiency. the the energy 6 Use the primary trophic foc us information efficiency next level. S tudy using woodland thermodynamics the figures, plants level 5 Using 110 14.71 heating difference energy calculate the energy flow opposite 0.89 for energy to heating 25.00 b energy and 30.82 efficiencies for energy decomposers respiration 7 a of in this energy flow consumers, and section between b to a discuss the producers consumers at and different levels. Explain more why many food trophic chains do not have five or levels. You will find ecological efficiencies of 10% given quite often. b Suggest why some food chains in marine This figure was derived from the original research done in the ecosystems may have five or more trophic levels. 1940s and involved a miscalculation of the data. A study 8 Many natural and man-made habitats are green, even carried out in the 1960s found the transfer between primary though they may support populations of herbivores. consumers and secondary consumers to be about 1%! Suggest a reason for this. 45 3.4 The nitrogen The Learning outcomes cycle element compounds. On completion should be able explain explain describe this section, identify you importance in the the is your an important knowledge nitrogen-containing (e.g. NAD, NADP of component Unit 1 you compounds: and A TP) and of many should amino nucleic biological immediately acids, proteins, acids. of S tudy biosphere term From these nucleotides to: the nitrogen of nitrogen foc us fixed nitrogen Remember from Unit how fixed nitrogen 1 that proteins have structural roles (collagen) and roles is in metabolism (enzymes). Nucleic acids are involved in information storage recycled and explain the importance decomposition, retrieval. of ammonification, Nitrogen gas (N or dinitrogen) forms nearly 80% of the Earth’s 2 nitrification, deamination and atmosphere. denitrification in the cycling it nitrogen explain is unreactive oxygen the roles microorganisms of is As it has a triple covalent bond between the nitrogen atoms of and respiration named and of environment nitrogen. oxygen, available dioxide, many ). (N Nitrogen carbon, Most is most are readily that that called nitrogen organisms. However , molecules somehow. or to which photosynthesis. so hydrogen dinitrogen not carbon component recycling and it is by nitrogen must be is to this organisms an with in important absorbed attached fixed enters used Compare other from the atoms, such nitrogen to distinguish it communities in ecosystems as as from 2 Link nitrate ions ) (NO absorbed by autotrophic organisms and used to make 3 amino This is the place to recall acids. of biological the 1. Revise nitrogenous the as plants, can use simple forms of fixed such as nitrate ions; heterotrophs need more complex forms of molecules fixed from Unit such your nitrogen, knowledge Autrotrophs, structure nitrogen, such as amino acids. of compounds. You Autotrophs use nitrate ions to make amino acids. They reduce it to + should apply your knowledge and nitrite ions ) (NO and then to ammonia (NH 2 understanding of proteins to the rest reactions that ) in energy-consuming 4 occur mostly in chloroplasts. Fixed nitrogen in the form of + of this section and then is NH answer now ready to attach to products of the Calvin cycle to make 4 Summary question S tudy amino 1. acids in the chloroplasts to be Autotrophs foc us group Take care when writing from In this book the element refer unreactive gas (N), (N of acids acids amination. the for rest to of the make the These are exported from the organism. proteins; biosynthesis they of also purines use and the amino pyrimidines. ), and decomposers digest proteins to amino acids. They use to amino acids to make their proteins. The processes of feeding, dinitrogen digestion the by about we these nitrogen amino amino Consumers nitrogen. use process used and biosynthesis of proteins continue, along food chains. and fixed 2 Consumers nitrogen (N combined with of atoms). Often, if you just their it may not be energy clear to acid what you amino proteins acids and or proteins. therefore all Carnivores these animals gain break most molecules that they do not need for biosynthesis to down release the ammonia. examiner store from write amino ‘nitrogen’ cannot other The rest of the molecule is converted to glucose and stored as mean. glycogen animals or is respired excrete (see ammonia; the Krebs cycle mammals on convert page 26). Many ammonia to aquatic urea and birds Link convert You studied protein synthesis it to uric in Unit Decomposers 1. See Sections 1.3 to 1.5 in Module remind yourself of the break down all materials that are excreted and egested by 2 animals. to acid. They also break down the dead bodies of plants and animals. They details. digest They proteins also to amino deaminate acids, excess absorb amino them acids and and use them excrete in biosynthesis. ammonia. Some Link bacteria use production There is more nitrogenous about the of as a source ammonia by of energy these and convert microorganisms it is to ammonia. The ammonification excretion of compounds on page 110. Ammonia use 46 urea does ammonia not in remain their in energy the environment transfer reactions, very long. oxidising Some it to bacteria nitrite Module ions, which reactions ions is they and excrete. excrete nitrification oxidation of Other nitrate and the ammonium bacteria ions. The bacteria ions to use nitrite conversion are nitrite called ions ions of in ) (NO by Bioenergetics similar ammonia nitrifying 1 to nitrate bacteria Nitrosomonas , 2 which lives in soils and fresh water with available oxygen: + + 2NH 3O 3 ammonia oxidation of → 2NO 2 oxygen nitrites ions + 2H + 2H 2 nitrite to nitrate ions O 2 ions hydrogen ) (NO by ions water Nitrobacter, which also 3 Figure 3.4.1 lives in soils and fresh water with available This scanning electron oxygen micrograph of the inside of a root nodule + 2NO O 2 nitrite → ions shows it is packed full of Rhizobium bacteria 2NO 2 3 oxygen nitrate ions S tudy In both cases similar to the the oxidation provides light-dependent stage energy of for synthesis photosynthesis. of A TP in The A TP is then The used to provide energy for carbon relationship nitrogen started this growth of factor for which growth fixed These energy dinitrogen The story. now This producers containing nitrate. has cycling the process in are from mass is Nitrate is form fossil nitrate, nitrogen which the to are an farmers compounds produced fuels) is is important ions why of which by the used to where to add legumes we maintain important bacteria is similar + to natural discharges O 2 the known is as a form acid → in forms of lightning 2NO 2 (HNO ) of and symbiosis mutualism. limiting fertilisers such Haber as ammonium process combine in hydrogen and NO 2 + nitrogen cause H 2 O these → fixation. During reactions: HNO 2 3 Figure 3.4.2 Nitric nitrogen- (Rhizobium) air . energy N of producers, fertilisers thunderstorms, recycled ecosystems. nitrogen (mostly from Haber of in been between fixation. fixing Fixed foc us ways forms nitrate ions in soils and bodies of water . Many trees that grow on poor soils in the Caribbean are legumes 3 like this poinciana, Delonix Some prokaryotes are able to fix dinitrogen. This occurs in regia. The anaerobic supply of fixed nitrogen by Rhizobium conditions, These they requires bacteria use to use make the enzyme hydrogen amino to nitrogenase reduce and nitrogen uses to much form energy. ammonia, gives it a competitive edge over other non-legumes in nitrate-deficient soils. which acids. S tudy Some as of these Rhizobium nitrogen-fixing spp. Denitrification balance this loss Pseudomonas dinitrogen is so live the of use that inside bacteria root conversion nitrogen nitrate this is in a from their loss of → NO are free-living nodules of nitrate the fixed NO ions to transfer nitrogen → N 2 O soils; others, foc us such legumes. atmosphere. energy 3 of in → dinitrogen, Bacteria reactions, from the which such may as 6 is chemists; if you Chemistry reducing it to for biosphere: help that in occur oxidation N 2 Question designed ask do not who the nitrogen appeal to study someone explaining to to in does changes terms of states. 2 Summary q uestions 1 Use the examples term of nitrogenous compounds to explain 4 fixed nitrogen Use and 2 Outline what amination, protein putrefaction, fixation, 3 Name in in the following synthesis, 5 deamination, ammonification, the following: an amino most nitrification, which has excretory H common protein as product its of R in information show how it nitrogen State of the is how in this nitrogen exchanged importance nitrogen: Rhizobium, iron-containing acid nitrogenous the the to is with section cycled the to in draw a flow ecosystems atmosphere. processes: denitrification. plants; the happens all chart protein animals; group; the mammals. 6 Find the the following Nitrosomonas, legumes, oxidation information of to in Nitrobacter, the cycling Pseudomonas, herbivores. states explain of nitrogen. Use what happens processes you described in question reduction and oxidation reactions. 2 this during in the terms of 47 1 Bioenergetics 4. 1 Ecosystems are dynamic Organisms Learning outcomes interact interactions On completion should be able name explain terms of this section, with between other organisms organisms are in an examples ecosystem. of biotic The types of factors : you competition cooperation predation disease. to: examples what is of with organisms of the same and other species ecosystems meant biotic factor by and the abiotic factor Competition discuss factors how biotic interact in and a abiotic There is water , energy, competition with other species for resources, such as space, named and nutrients. This can either be: ecosystem discuss as how dynamic interspecific competition – competition between different systems. intraspecific competition – competition between members same If two other , but two groups of factors one the their the survival of organisms biotic factor – any factor results from the results of the different physical or – any chemical aspect of the environment species. prey known means that each competing competitive of competitive occupy will starve competition that or they not nd will ght each anywhere to niche within species nd an ecosystem themselves is occupied excluded. This is exclusion exclusion slightly Republic animals as but resource more at in different found seven avoiding the past niches. can For different direct partitioning on with grazers. different others about compete specialist be seen example, in a anolis study species feeding on in the competition (see Question with 5 on each page other . This 63). In heights; leaves. together , In each other tropical there the being for forests are some African food. there that at have grazers specialise savannah specialists Many are on antelope, feeding on evolved that eating zebra different into feed on plants fruits and and wildebeest plant species. abiotic factors Giraffes page species the means or coexist on of which Grazers is rarely species abiotic factor There requirements, This of same is a successful other Dominican same of niche intense. that activities organism This principle The the identical be in environment: another less species; lizards, will that the influence the foc us by are have them reproduce. There of species. species between S tudy species ecosystems function feed on trees at a great height. 59. Cooperation Cooperation Did you know? within bees. Competitive alien species invade ecosystem. The tropical Individuals means house released most likely during the work some soldier ants association an example in levels. social together The insects for the best such example as benet ants, of the of cooperation termites colony, and even honey when native Antilles by by do not bees. get This a chance to cooperative breed, as is behaviour the is case altruism between of two mutualism. or more The different polyps of species many for coral mutual species benet contain algae protection, called carbon zooxanthellae, dioxide and which photosynthesise. nitrogenous waste from the The algae polyps competition and even worker gecko, gain Gonatodes antillensis, individuals and 1980s, single-celled is displacing the in exchange provide carbohydrate in the form of sugars. Coral grows predation. near the There sh, surface are less which species 48 different in is maybe at seen gecko, Any Hemidactylus mabouia, and is an with Curaçao exists species exclusion often occurs that when a are of the water , intimate clean them obvious. so providing mutualisms. of parasites their Sharks that are infest algae with often them. sufcient attended The by benets light. pilot to both Module have a variety of adaptations to nd and catch their prey. Corals Females are composed of many tiny polyps that have stinging cells, which of the smooth-billed into These any are Ranging small sessile across Carcharhinus barracuda, the animal Chaetodon comes within reach of their in the same nest in incubating a coral perezi , reef are green moray barracuda , Coral reefs predators, eels, that Sparisoma parrotsh, ocellatus . larger as Gymnothorax prey on viride , are such open reef funebris , herbivorous and spotn ecosystems, cooperate sharks, move between Eretmochelys sh, another and such ecosystems imbricata , that such as feeds the on hawksbill is parrotsh algae will a form are of predation. ‘predators’ grow to of occupy On algae much a are damaged by storms of and reef, grow the are important and thus in grazing Populations Predators more of restore carnivores rarely usually the it have on space. much is the birds – altruism. attracting animals foc us butterflysh bare This rock. and Left happens does ungrazed, after means not move place. Coral of the coral is lost. seaweeds, creating space for that an organism about from polyps have place to limited coral as they move their Herbivorous coral larvae to catch their prey. At to trophic level is coral? ecosystem. depend any of all young turtle, which settle the as tentacles sh turns eggs. They butterflysh, movement reefs eggs take sponges. coral that the example ‘Sessile’ Grazing their and to feed S tudy that lay tentacles. predators. Sphyraena stoplight that ani, they Crotophaga ani, re Bioenergetics Did you know? Predation Predators 1 effect other on in way the presence controlling of prey species. populations of their prey; Link around. Nitrogen xation within the root by Rhizobium nodules of legumes Disease is Pathogens fungi and by of and are disease-causing various protoctist expelling balance killed. such worm-like parasites their with as that their recovered which in often the parasites, there are struck cause Many losing the are viruses, infected animals epidemics in is bleaching, some populations Caribbean Most Coral of the bacteria, viral, live them but through staghorn them not the nutrients most would visible not be components recycled. of respond in a not sort S tudy being Pollinators Acropora have More an and not ecosystem, visible See 47 . birds plants are mutualism. foc us populations, coral, Populations of fungal polyps plants to sweep the 1970s. and energy that as by example page since. Decomposers without that zooxanthellae. Occasionally cervicornis, organisms. animals. an are in such as bees, moths, bats obtain food from flowering return for pollen. Flowers attract pollinators transferring are adapted to but in a variety of the ways. detritivores, such as crabs material. Decomposers, produced by these and such sea as cucumbers, bacteria and which fungi, eat feed and on shred the dead faeces animals. Link The effect of predators on species Summary q uestions diversity 1 Dene 2 Use the the coral terms biotic factor, information in this abiotic factor, section to draw detritivore, a food Section decomposer. web for in ecosystems is explored in 4.3. a Caribbean reef. Link 3 Make a table to elds used for show how livestock biotic factors affect tropical rainforests and The grazing. recycling such 4 ‘Ecosystems are dynamic.’ Discuss this statement using examples from two named the dynamic Study an ecosystem organisms each other at close different and mineral is elements, another nature example of ecosystems. ecosystems. 5 of nitrogen, at of least as how to your trophic they school, levels interact and with college describe their or home. how physical they Name the interact environment. with benets cycle on of (see page Now you drawing the of see the Summary the nitrogen question 4 47). 49 4.2 Biodiversity The Learning outcomes On completion should be able dene the explain of this section, term what diversity and different number of species, number of individuals is meant genetic We species genetic diversity. live been At the history one became sixth when was the extinct. Are great of 65 its and terrestrial each species each species present in an area. of great of Earth): areas ecosystems many biodiversity the on are species to (perhaps tropical Earth. suffering We the forests also severe largest and live in there coral a reefs time problems and has are when, our ever two of thanks activities extinction. country biodiversity or even the is a catalogue whole world. of all But the living biodiversity things also in an includes diversity of habitats and ecosystems in an area and the genetic within species. dinosaurs we entering the Ecosystem diversity there region species of within species-rich simplest, a the are different world the: the Did you know? top ve time history many Within endemic of million extinction? The Caribbean a driving diversity ago measure great the years a ecosystems, variation the most area, in in in us, are been ve last is by to Earth. The area biodiversity Did you know? extinctions an you the have of to: ecosystem diversity, There biodiversity and has is many one of ‘hotspots’ for a Caribbean different terrestrial Caribbean region marine the ecosystems. country with dominant ecosystems the Here ecosystem along is position an of the imaginary many is open coastlines ocean. and cross-section ecosystems But many across indicated. the marine elfin woodland biodiversity. Think dry rain about coral reefs, mangrove forest swamp seagrass beds and rain forest swamps, forest tropical forests. forest hydrothermal coral vents reef mangrove forest seagrass bed deep sea Figure 4.2.1 A line transect that crosses an imaginary island, showing many of the ecosystems typical of the Caribbean region The importance niches many others that different and S tudy Figure 4.2.2 UK. There is also a dome for the tropical biome and an uncovered area devoted to temperate biomes. The project displays some of the ecosystem diversity in the 50 ecosystem ecosystems. then biodiversity opportunities listing We them for is the species discuss some wide diversity. in this variety The book; of ecological Caribbean try has thinking all. foc us Inside the Mediterranean dome at the Eden Project in Cornwall, biosphere. of provide Species richness list, greater the is a the measure richness. of the species diversity. The longer the species of Module Species diversity Species diversity is S tudy simply the number of different species in One way of investigating this biodiversity is cataloguing species diversity than is one there is in and because to The living is light expend Central diversity may to the be rare. further are high energy and is warm. only 40 in the you case resist that go the are more for or for (no pine many the frost, 600 of the temperature internally from diversity snow or species ice), do of The not need a single more species. aware domesticated of Coleus of Many animals. and the wild of alleles flowers animals diversity Y ou can of than heat absorbing it birds in in Genetic an is the sum organism diversity of of or a all in a the species. species is the Canada. diversity genetic body foc us genome genes of a within the genes in the and when see the hibiscus. plants we look look diversity Similar at in very the genetic diversity, a they different species. All do have not the all alleles the the individuals same have of genes, of of those the same genes. We plants colouring in the genome similar . cultivated all species alleles are generating surroundings. S tudy but of endotherms possibly of the are constant forests Genetic diversity is by rather their genes diversity a by sum Genetic birds other endotherms about and maintain species dominated biodiversity, and However , two natural are stable abundance one the habitats round There in more changes. is by which extreme year to they Species ecosystem and centres too details). dominated provide north for an able Canada, trees all makes are in not 58 diversity important are page more This intensity keeping America it and forests conditions of as species However , tropics (see ecosystems temperate species. list important Some although decreases. species element species tree species, there limited species. other a considered with Florida several making another different and – foc us all – the Bioenergetics an Mammals ecosystem. 1 and leaves although Link not so obvious, Genetic differences because of their This an to species, adapting to is be also important changes alien and natural may There is in between populations range. diversity adapt exists in biotic evading changes populations adapted genetic in new of the slightly abiotic same within factors, predators, such resisting salinity, in each populations temperature, species differently diversity providing and in populations. different the ability competition new parts strains humidity of and example to with disease rainfall. you estimated genetic variation different diversity that forms intracellular by different order of between exists (or and the in a species proteins. variants) of extracellular alleles. bases of in The the investigated example, proteins, enzymes. alleles DNA is For are that such The for identifying as the so that primary forms we can is sickle studied that polypeptides population – in amino cell in Unit there all in of the are the anaemia, 1. It is about 900 haemoglobin human with acid slightly sequences. the often haemoglobin different sequenced codes by populations variation different variants different The of haemoglobin which population. with as An exist have and are see structure coded how for the differs variants. Summary q uestions 1 Dene the terms biodiversity, ecosystem diversity, species diversity, genetic diversity 2 Explain within 3 Print a how a map Explain species species, different 4 a of types what may diversity be you ecosystem think is an ecosystem, and b genetic diversity investigated. the Caribbean of in and as identify you meant by can the one location for as many list. term ‘hotspot’ with respect to Figure 4.2.3 biodiversity. Amazona The St Lucia parrot, versicolor, is an endangered island endemic species. This parrot was 5 Discuss the signicance of biodiversity. bred at Jersey Zoo in the UK and reintroduced to St Lucia. 51 4.3 Species diversity This Learning outcomes section diversity On completion should be state able that related to of this section, diversity to: species the of important you diversity stability of The is gives species species within most you is some decreased diversity an examples is in by an of what happens ecosystem. looking at the Y ou when can effects of the work out changes how to the ecosystem. catastrophic loss of species occurs when the dominant species disappear: an ecosystem explain how increases species the Hurricanes diversity interactions in loss of a and rich chainsaws and diverse destroy mangroves ecosystem, most of with the which is almost under total water . an Coastal development has destroyed many seagrass communities ecosystem around dene the term conservation the Deforestation range of Did you know? topsoil to is worst example of loss diversity was caused by niloticus, of into the Nile perch, Lake Victoria in to rain and away, become the It 300 has led species to of the loss examples of 200 temperatures often makes and it for The often a wide forest the impossible floor is thin for the same or show one what invades it happens or when a experiences a species disappears population from an explosion. Following and typhoons waters. for Huge the coral or larvae so, then Sea otters food Enhydra 19th the as web sea small and in the Great of whales Barrier Reef the the 20th that apex Nassau aggregates to catch at algae, the to time, if which become the explosions recover; a are the the have sh pivotal occur in provides adults. numbers happen they less now prey of in on fur as The decrease every 10 more hunt there urchins loss otter , of the In was the a exploded one in species, food herbivorous are numbers are sea urchins. web, sh, such many scallops. ecosystems their sea from smaller and Pacic and sea species octopus they to web crabs, and the their forests. loss role of feeding for food kelp and protected but position hunted of of the abalones, Epinephelus grounds times Caribbean. sh, with survive some consumer were larger these leads biodiversity. shows whole spawning ecosystems T ogether nutrients being known preyed because of as increased upon keystone in the by latter killer overshing. predators throughout herbivorous 41 catastrophic grouper , at to the not. century, may time increases phytoplankton, many After population has stipes a play otters of Pacific the to so coral. these animals large that Sea Loss of easy ate flooding growth starsh secondary invertebrates, species. The a Pacic, the coral page to led other Organisms half the If may as change otter , kelp, it on lutris , numbers this eat the in the century striking of then then the encourages recolonises. frequently The in This numbers years A keystone species – a sea starfish of food 52 which habitats Lates cichlid sh. otter eating a sea urchin high many microorganisms. central coastal Figure 4.3.1 provide and re-established. The Crown-of-thorns Africa. that the ecosystem introduction wind, trees animals of These species plants, washed ecosystem the removes other exposed Perhaps Caribbean. to has The population with other it intense factors at striatusis , a certain been loss of a shed large of almost top or apex in smaller has pressure led to coral on reef the explosions feeding this is time sh year . to is very from predatory lower it extinction predators reefs that As sh trophic losing and levels. their Module Sea In urchins coral reefs in Caribbean prior to 1983, coral the reefs was thought to be long-black-spine a keystone sea species Diadema urchin, for controlling the pandemic on the reefs and for creating space for the coral larvae to on 1983 and reefs herbivorous urchin reefs this has have of sh not is it recover coast a to to to some Jamaica to of original higher of and killed Thanks grazing algal lack places is the its high the disease Bermuda. continue result due in to recovered the is pandemic Panama moderate cover whether to 1984, from cover levels intensity. Since T oday, and is of there nutrients Sea algal percent of overshing numbers. grazing. the 99 to covering of the the as were and severe few the The by reported for disease a was pathogen, years, no one a mass marine die-off most but likely even knows organism. caused after what it 30 was. whether are along most Caribbean to waters, numbers reefs urchins pandemic most debate in urchin the there the settle. ever In is algal widespread growth Bioenergetics Did you know? This antillarum, 1 or beginning the north decreasing. Conservation Conservation designate areas are species as a restore not managed are their is just protected so removed habitats habitats catastrophes, without that from are they have as the some and In the kept by eruption it in is possible interference. habitat extreme damaged volcanic cases human maintain threat. been In any habitats under that such preservation. area zoos to often, Some botanic gardens conservationists human on features. and cases, More action or by natural Montserrat. Figure 4.3.2 Red lionsh, an alien species that escaped into the Caribbean and is Some conservation practices are not so benign. The red lionsh, Pterois causing havoc on coral reefs as it eats volitans, originates Caribbean such as in a Belize in very the short which use Far East period divers and of to has time. spear spread There them throughout are to the programmes reduce their many reef animals in places populations. Did you know? In Jamaica, threat the from Black two River invasive quinquenervia , and Morass plants wild – ginger , is the a large freshwater bottlebrush, Alpinia allughas , wetland under Melaleuca which are Some spreading techniques species upsetting the balance in this ecosystem. There is no substitute for can go remove seriously alien wrong. digging Prickly them to and pear, Opuntia spp. invaded out. Nevis Conservation damage simply and a habitats involves encouraging matter that interactions protecting of are survival. preservation. at that their risk of sustain species, The damage It habitats is, however , continued or loss and ecosystems much survival involves of more all from than species maintaining and the was introducing eats it. The removing the them. and in it by whose in pear from then moved populations the caterpillar succeeded prickly but native elsewhere moth moth the island, attack a removed of on to Opuntia region. Summary q uestions 1 Suggest 2 Redraw otters 3 Dene b Explain Dene 5 Suggest Find a 7 the food a and species on feeding 4 6 why the the why out report Suggest it on page is important for 41, showing the the stability effects of of the ecosystems. loss of sea relationships. keystone species importance term human web term the diversity of some keystone species in their ecosystems. conservation is difcult to restore habitats following natural catastrophes interference. about the explaining why damage the invasive caused ecological plants can to ecosystems reasons for cause by killing serious the red lionsh. Write it. damage to ecosystems such Figure 4.3.3 as wetlands. These attractive owers belong to the invasive bottlebrush tree, Melaleuca quinquenervia from the Pacic 53 4.4 Maintaining biodiversity There Learning outcomes are Intrinsic On completion should be able of this section, many state the to: reasons for for maintaining biodiversity. reasons: you Some people should reasons 1 believe therefore that value humans and have protect the custody of organisms the Earth and that share the planet maintaining with us. Others go further than this and consider all creatures to be biodiversity sacred. discuss the importance maintaining of biodiversity it important describe People examples of also on planet in situ There world and Direct value to Many of the bacteria; roseus, in much and Many Wildlife Belize, Our who is Puebla plants in if climate it is by should that are grade ores. and of the not by religious feel beliefs. ‘connected Many to also believe other and living since organisms making damage and, we them have have changed as much right hostile where we to can, conditions other Organic Plants Soil fertility Reefs waste to organisms, restore it so that Water is the we those view that as humans, ancestors hold it in but trust are for we just have not renting future it inherited from our the natural descendants generations. study drugs Fish near organisms. such stocks as currently can be Antibiotics the much mass are Madagascan interest produced. in isolated from fungi periwinkle, cataloguing Herbal and Catharantus plants remedies, once used which have of world in animals the Caribbean as species a result we comes from have been now sh diversity. There continues countries to provide as the diversity. The genetic disease and the useful are much or other spread agriculture, we heavily shed lower many down amateur inspiration for use quantities provide in of the hot dioxide might to visit of need in continue since the food the is ltered to waters contributes maintained mangroves by through to nutrient protect soils to 17th chain.. Timber ornithologists artists, and photographers, to of popularity. Countries their maize Many National grow widen these in the is the states of Oaxaca diversity relatives are of spring enzyme, Taq polymerase, in Yellowstone chain bacteria may and broken cycling, coasts from rock reaction are used help to reduce threatened to Park. This (PCR), routinely extract was enzyme metals, used such is discovered mass e.g. it by by forensic as in a produced and copper, from the effect of increases in carbon dioxide down. cycle to provide decomposers us enters the with and erosion. before and cultivated low us: and water as Parks. the genetic wild such crops. heat-stable polymerase DNA. Other services for carbon of GM increased relatives catastrophes. products. The a we has tourists wild resources Thermus aquaticus, from bacteria for ecotourism developed facilities for genetic many added in widespread lines. domesticated extinction; appeal many much absorb is that similar our of plants biodiversity. natural provide of increase material transpire, and on thrive. our we do atmosphere. 54 that nature’. people. destruction source bogs are of widespread ecosystems peat loss Rica our along and wild. aesthetic have habitat to the creative can provide humans income for modied scientists Forests that isolated from developed globally with bacterium, genetically can wildlife. The they the other Indirect value; the from we often the can Taxus brevifolia. There plants from affected change, Organisms been they be and Costa do Mexico; thermophilic also other source Dominica crop maize a tree, if species enjoy and originate from have yew see appreciate writers use the food for and many people poets, to may of we drugs extracted from forests botanists that Pacic animals century the the Caribbean, harvest drugs medicines Although is we in humans: anti-cancer and Chinese is as much, limit organisms that believe Earth so should conservation. originates locally exist view globally and is This supply. drinking nitrifying water. bacteria (see pages 46–47). in the Module best The Latin way to conserve any species is to do so in its natural habitat. RAMSAR phrase in situ means in their original place. Maintaining sites habitat means that all the life support systems are to tends to concentrate on individual species or groups High-prole programmes have centred on mammals, such pandas and whales. Equally important are ecosystems threatened the most popular of these is the tropical rain be are many other , less well-known at an international Ramsar Find out if in there a is Iran in Ramsar ecosystems that near where you live. should conserved. National in there under signed forest, site although the are by 1971. development; important for wildlife. They as treaty giant be of of designated species. wetlands provided. conservation Conservation are the considered natural Bioenergetics Did you know? In situ conservation The 1 situ area and international conser vation. of land, The although in bodies term the designate National Caribbean by Park that legislation is is often not areas applied necessarily of to land a the for S tudy foc us large case. The International Union Conservation Morne Diablotin National Park is in the northern mountain range It was set up to protect the habitat of the Five (Sisserou) Blues karst Lake Parrot, National limestone with all an endemic Park ve in of bird Belize the cat is the conservation 200 bird region are for T errestrial Bonaire, Nariva areas, particular reserves which is Phoenicopterus of about an area species of found 100 000 in that acres the different use the categories and then of website to research some country and vulnerable species species. smaller one out species. from Reserves you status species. Try nding endangered and Nature tell endangered many Imperial of will of about Dominica. website include home ruber wetlands which species in to may or the an for focus on providing protecting 135 acre a flamingo estimated a special 40 000 your country. protected ecosystem. sanctuary Caribbean on flamingos, ruber T rinidad is an important site for many endangered Summary q uestions species, It is including both a RAMSAR refuge the West and an Indian manatee important and breeding blue-and-gold site. It is a parrots. designated 1 Outline the reasons for site. maintaining Marine reserves are found throughout the Caribbean. An example 2 the Little Cayman ‘no -take’ reserve that protects one of the biodiversity. is Dene the term conservation spawning grounds of the endangered Nassau grouper (see page the standards world and of management the region. of Some parks and countries reserves have the varies throughout protection and careful management; resources others do to situ conservation does not just involve putting a line area of natural interest and preventing Find a around development, shing that are not and hunting. designated It as also involves special areas, enforcing such as way of map of Rica. the measures parks or List national the parks types that are of protected by logging, national parks and identify in any areas this a these poaching, in biodiversity. provide ecosystem particular the not. of Costa In outline involved maintaining 3 excellent and 52). principles The in situ last reserves endangered species that are of protected. one sort or another . Examples are: 4 reclaiming and in ecosystems natural that have catastrophes, been such as damaged volcanic by human eruption, Use the website nd the endangered of the IUCN to activities hurricanes status of the and following and also outline the flooding steps creating new habitats, for example by allowing vegetation to their over ’ land abandoned by people; digging ponds; deliberately taken to conserve natural habitat: to provide new surfaces for corals to setting up exclusion zones to prevent shing at certain times of turtle, particularly during breeding Dermochelys the coriacea; year , leatherback colonise sea resplendent quetzal, seasons Pharomachrus mocinno; preventing the pollution damage to or placing limits on levels on pollution to reduce Amazon parrot issuing be permits removed Imperial (‘Sisserou’), ecosystems Amazona imperialis; in manatee, sinking Trichechus manatus; ships them ‘take to from companies important so that timber ecosystems and without other products causing may long-term grouper, pribby, Nassau Epinephelus striatus; Rondeletia buxifolia. damage. 55 4.5 Maintaining Learning outcomes On completion should be able explain of this section, you biodiversity Some species is a not from are realistic their so threatened option. habitat 2 and In in this kept their case, habitat animals somewhere that and in situ plants conservation are removed else. to: the term conservation Zoos ex situ and why it in conservation is Zoos have existed for thousands of years. W ealthy people used to collect necessary animals describe zoos and and explain botanic maintaining the roles gardens of Sometimes animals in them biodiversity and describe and explain the roles banks, sperm banks in banks these plenty them were of space. in menageries open conned Lympne in to for visitors cages, This Kent for to although continues, in the UK. their enjoy more two Set private as well. by In many enlightened famous up enjoyment. examples John cases people being Aspinall, large gave Howletts these zoos of opened to the public in the mid 1970s. The zoos have had notable and success embryo keep were Port were seed and with western lowland gorillas and have introduced captive born maintaining animals into the wild in Gabon, W est Africa. Other zoos are owned and run biodiversity. by zoological functions can see The in and societies addition study functions protecting with of up captivity. A tamarin from the coastal zoos researching at zoos enjoyment they and of would vulnerable tamarins programmes example the the that These and not have a variety interest otherwise for be of different visitors, able to who see. are: breeding good groups. providing animals breeding A successfully Figure 4.5.1 to other endangered captive setting or Fota is Wildlife biology of for that – species cheetahs, Park to Jersey Zoo is involved Brazil those for species species from in Cork gain a that which in will are breed in bred Ireland better understanding of forests of Brazil. As their habitat has been breeding habits, habitat requirements and genetic diversity. The destroyed they have been rescued, bred in Zoological Society of London (ZSL), like many large zoos, has a captivity and reintroduced to protected scientic reserves. contributing T rinidad S tudy programme method of conservation organisms, of seeds, an tissues or any organism bank. is known as It is not a store of bits educating but whole ways listed. genomes in one does Sperm Zoos in cheetahs is because extinct few they 10 000 descended from an aim of the the nearly years survived. All Maintaining living these genetic a are diversity conservation bit being only individuals. do 56 and cheetahs although female by the to the USA; Nariva Swamp Przewalski’s in collaboration horse, Equus with ferus has to been the bred very Dzungarian successfully Gobi Strictly at many zoos Protected and Area in where the this public wild horse about became wildlife and extinct 30 years conservation. ago The in Belize is a small zoo that houses Caribbean rescued animals not deliberately school take students any about from the the wild. wildlife of It specialises their in country. banks cooperate do not so that become breeding inbred – programmes a risk when generate genetic maintaining diversity small and populations. became ago species, their in very species low Zoo of Did you know? diversity in Centre educating Genetic V alley blue-and-gold of and the bred a Wildlife DNA Emperor other gene The captive that Mongolia part schemes. re-introduced gametes, transferred embryos, ararauna , Zoo przewalskii, whole reintroduction successfully Ara Cincinnati keeps research foc us macaws, Any to has of of is many As part zoo in to the other . of many another . animals A much for many years Collect T est breeding This kept in a option sperm animals inbreeding captivity. cheaper in programmes prevents Zoos is and cooperate collecting bank. The are and sperm process transported promotes is semen from suitable the sperm for motility. (or the only) males. from one diversity with keeping follows: cheetahs promiscuous! consult and as genetic it each frozen Module Dilute with a medium containing buffer and albumen (a plasma 1 Bioenergetics Did you know? protein). San Put small Store volumes into thin tubes known as Diego Zoo facilities for the sperm samples in liquid nitrogen at sperm (AI). samples Y oung cheetah sperm are animals and a of then over Chinese thawed 30 and different pheasant, have used for species, been articial insemination including produced cell using sperm banks damaged lots of by more the freezing water , surrogate which Eggs from of or tends to stored ice in and that the more They are large of zoos’ now largest sperm, embryos it endangered their Frozen Zoo. not foc us confuse cells such wild placed in with (IVF). inside reproductive with internal. time as in a and IVF lab. The small ox articial (AI) in vitro In AI the sperm are as be embryo hold species way to internal until including vulnerable same likely damage frozen technique species ‘Frozen and much are then This many antelope. endangered in they crystals vitro for as processes. available. used African many be freeze form fertilised been also to thawing becomes has species resources can difcult are mother transplantation different embryos are membranes. a and call insemination fertilisation Eggs the from S tudy (oocytes) sperm. storing cultures from species. They Do Eggs of rhinoceros, banks. Embryo one –196 °C. and The has straws. the female’s tract zygote embryo uterus so fertilisation occurs and outside divides is the is body to form inserted into a the or frozen. genetic case they Link should ever be needed. Many Botanic The in rst 1764. gardens botanic It garden received seeds of tropical plants orthodox. See Question the was rst established breadfruit in the trees Caribbean brought in from St 8 on are not page 63. Vincent T ahiti by Summary q uestions Captain William Bligh (of Mutiny on the Bounty fame). 1 The roles of botanic gardens are Dene the term conservation Protect endangered plant species. Many Caribbean countries gardens conditions in which the often gardens grow are the species endemic to each if Research methods cultivated and Research to they new in of 2 suitable. botanic can be reproduction gardens be growth grown in so that maintaining Discuss appropriate conditions 3 the habitats if their species to original habitats so plants habitat where can has be introduced, been they roles become and very rare the and of in zoos and conservation. limitations botanic conserving perhaps destroyed. have way biodiversity. gardens Suggest zoos methods this species propagated. conservation Reintroduce can and justify the botanic and have of botanic ex situ to: of gardens endangered in animals plants. or 4 Explain the meaning of the term extinct. gene bank Educate the public in the many roles of plants in ecosystems and their 5 economic value to a Describe material banks Seed is genetic and kept by sperm embryo banks. banks b Seeds how us. are storage. collected Many from seeds plants (known in as the wild orthodox and are seeds) put are into stored dehydrating storing them them at so that the seeds contain only 5% the techniques long-term role in of these conservation. by: 6 Explain a Describe are water b –20 °C. how stored Explain in why orthodox seed seed seeds banks. banks are necessary. Removing remain seed water viable banks removed for from Collections from for seeds many ever . Every storage, continue slows years. ve thawed to be down However , years and made if their seeds some tested metabolism do seeds to possible see to not from if ‘top so remain each they up’ sample will the that they viable in are germinate. bank for each 7 Explain why records of animals, have zoos the such limited keep careful breeding as of cheetahs, genetic that diversity. species. 57 4.6 Sampling ecosystems All Learning outcomes biology classroom On completion should be able of this section, you explain describe describe is meant how to to how laboratory their gives natural you biodiversity described biodiversity measure eldwork. makes Much much of more what sense you if learn you in the study habitats. in this some when ideas you section you do of the some could techniques eldwork. do yourself, you Some might of the somewhere use to techniques near your home. Species richness abiotic Imagine factors. This is most you not key a of to – of may rst some and of for and soil can them will be and animals, see you as very are help to on so you into you a nd. B, a etc. some and to you Y ou of live of others ask key – plant take plots arthropods. Many forms recording. some and certain If the identication dichotomous need for animals, catalogue use different do search length not could identication. be be is small On time the photograph land Search of know the most thoroughly photographs. in newspaper . will are identify collection nd. out and The larger identications; these plots with the observation species small which of your that you to it of much A, There 4.6.1). ground. Biologists with studying probably a harder spread of skills of identify guide (Figure waste some list. nd. eld species will to common within make many they a species to is species good look animals possibly soil most different task photograph some and photographs from not area the just plants a that in area, rst up or need someone animals of may the ask The you Y ou small those quantity You do not need to be all The build these the identify common Some you these. and of that large organisms this Divide like the drawings one do record them the and questions. T o are species. have sight names, for bird use samples. habitat conservation species name species. At a organisms some series you in special obvious types keys are a particularly Figure 4.6.1 the do sample assess to section assess by sampling ecosystems in should to: what qualitative and organisms This students 1 the soil. Search arthropods. Dig up through, Other ways a small looking to catch anywhere special to do eldwork. Every small arthropods are: patch of waste ground and vacant lot is an ecosystem! pitfall lid that traps level prey sticky some Y ou can species survey about – a line line it they you hide a list in from One an soil intervals see sampling are (tape or parallel looking could to also at see be catch of These the tell you One right if what way stretched the angles is to in it, with newspaper into insects. much be as do across the the it in a wall are together is most 3.2 to It a distributed in of use certain use the of obvious to repeat may your not Module present, to to number species area. or the a but be 1. not line could also be an road. regularly areas. If or at their Aquatic habitats like this distribution seems to show a pattern, can you think of a reason for this? pond make good places for sampling and The underlying reasons may studying the adaptations of organisms to their environment 58 its so trap Cover better need in are this an is Y ou some species to jar up fall pyramids to species clumped It example. of jam biodiversity year , limitations that flying tend for a rolled jelly. ndings. measure area. rope) or your like with predators will animals, distributed. jar petroleum throughout the jam any that as something the from board include of place Fill such can. present round; they along random; if and level. can make rarely year hole species methods imaginary Figure 4.6.2 a regular how a soil material species all transect W alk – names and present These traps make at dig the species sticky scientic different – with interaction between the two. be certain biotic or abiotic factors, or an Module 1. cylindrical flat, 2. leaves blade-like leaves 3. 4. 5. 6. strap-shaped less leaves, leaves in pairs leaves in whorls leaves with ne leaves with at than teeth leaves 4–15 mm less than leaf apex tapers apex does than of the the long 40 mm long stalk edges to to 2 go to 3 go to 5 go to 4 Halophila decipiens Halophila johnsonii wide Thalassia testudinum wide one not go Halophila engelmanni edges 4 mm leaf top on leaves 40 mm greater the smooth leaves go point taper, to 6 Ruppia maritime leaf tip has three teeth Halodule wrightii Figure 4.6.4 Figure 4.6.3 Bioenergetics Syringodium liforme or blade-like, strap-shaped 1 An ecosystem dominated by seagrass off the coast of Honduras. This A dichotomous key for some Caribbean seagrass species sh has its mouth open awaiting cleaner sh to remove its parasites – an example of mutualism. Abiotic factors There are numerous interactions between organisms in an ecosystem and S tudy abiotic are factors. associated These with a often limit collection the of range of physical an organism. conditions. Coral absorbs Make calcium from water , using it to make calcium carbonate to form a list Molluscs do the same thing. Forests modify the is much canopy forest less of the than the floor; wind in forest as a speed open that result is reduced; ground; little there is so the much available are many effect light for is any epiphytic of rainfall on absorbed plants that species by the and Humans influence Examples have had such as the red branches of making lionsh bauxite bromeliads almost direct obvious – effects it all influences on possible (see extraction, page are directly dynamiting shing, reefs. alien and But species causing runoff, we to and also the effects oil spills have all affected coastal on marsh and coral reef. These invade indirectly. and as When dredging, indirect sewage which effects, happened Sediment effluent, ecosystems, chemicals are each one. the you foc us carrying should minimise including abiotic out always the a study do effect your you like this best have to on the with environment. Do not unnecessarily and trample from and if you disturb the oil e.g. by taking soil to where you found samples, mangrove, return salt of on habitat, from that and the grow growing have pollution. industrial ecosystem examples. are for fertiliser orchids ecosystems coral 53), and abiotic factors soils S tudy trunks the a forest environment explain considerably: of the influence skeleton. foc us Ecosystems factors, although them it them. is humans Species that are not distribution to is investigate influenced a measurements is or more plant of by the linked to of a in water the presence. throughout abiotic species soil their biotic distribution one for evenly determined of species responsible distributed the by distribution plant are and water factors. species For wetland content soil abiotic named factors. a ecosystems. Y ou see example, area? to and see if Y ou the Their may if this what could be asked Summary q uestions is limits the 1 take be distribution of the a record could line the Y ou out in see There begin in might oxygen be an study absence of At species measure walking your area. the and cylinder . merely This the intervals, and the now line investigations take e.g. a volume makes soil of your observing much the more 1 metre, sample. the abiotic recorded factors anemometer , marine concentration that are habitat, Explain why salinity then of a list small such as would area of a forest. with you a can samples of wind 3 Air and as a list. species Suggest hygrometer . use meters to If 4 you important when to use compiling Suggest study the of limitations biodiversity other factors be record the compiling we soil can is names assessing distribution. speed it scientic that investigation quantitative important. thermometer , humidity ecosystems, and a species natural any with a Y ou water section. other be the sample make next can or or soil than to with freshwater across measuring the temperature measured the a rigorous can shall presence squeeze comes more transect how compiled for content. 2 T ake Explain a species list without information. how biotic influence plants of by on a and the abiotic distribution wetland ecosystem. water . 59 4.7 Sampling Biodiversity Learning outcomes On completion should be able of this ecosystems section, you present in T o an take might to: an explain what is meant state what is meant species by abundance the species locally or of presence is by W ays a organisms of extremely globally. making only rare of is one and list also or on assessing of species important. two the the individuals edge of biodiversity assessing abundance as well as need to distribution. standard piece of apparatus for assessing abundance of plant species species density the quadrat. There are different types of quadrat: and percentage the simply sampling is frequency, the example, that either assessed by The be ecosystem; indicate include quantitative not extreme extinction should 2 an open frame quadrat, which is a square of known area. A typical cover 2 school explain the advantage of using a gridded a described in 0.25 m which is divided by wires into smaller sections, 10 larger quadrat, marked surveys are out carried with out tapes. qualitative 1 the and ecosystem that were diversity 1000 km in by the over Amazon very much region was larger areas. assessed For with 1000 km. this quantitative. You remember from Unit between × biodiversity quadrats techniques are is foc us example, section quadrat, 10 much Some The quadrat index. perhaps S tudy college a diversity or should difference quantitative data. A small certain The quadrat species. abundance percentage This it gives of This quadrat in you the is nd size several to walk for of For animals the numbers the of do of animals is area and that a the calculate are size area cover is of of – assess as be the the the the distribution of recorded. species each frequency – what species. species. quadrat Gridded that percentage sometimes area, the recorded by to can of is quadrats occupied the area of make by each the occurs. length and is timed the ground absence covered the plant this specic the is the or species assess through a times the to on percentage abundance present, put quadrat which way be presence indication easy species. simple of the no relatively The can The of count. counting time. sedentary or of the time each mobile, to assess. identied of each One the species species chosen different for very have number actual numbers not difcult you the The abundance mean more After will species. that depend Repeat on this species. use a quadrat and count 2 times unit with area Some ACFOR Another a or as can far way too how will or give to so apply to be use mark of In case of before you mobile This can use per rst or scale how their have done actual of is as this record making the it such much you population is plants, T o how Once than numbers scale, rare). description; several density abundance quicker a the Repeat mean species example. them. small. calculate the an are occasional, for far numbers and you present recordings estimate and each ‘frequent’, they count. frequent, to have your number quadrats plants common, rst if 0.25 m numerous animals to This individual make e.g. positioned ‘common’ certain area, species. decide plants you catch are isolate to abundance that, each (abundant, have many for to that randomly species difcult you within counts. animals sample (S is to ). 1 Release some these time animals later . This back is the into the second environment sample (S ). and It repeat should the catching contain some 2 marked individuals and some unmarked individuals. The smaller the Link number an Use the 9 on equation to page of marked estimate of the individuals, population the size larger by the using total the population. Lincoln Calculate index : answer Question number 63. in S ________________________________ 2 population size = number in × S 1 number marked in S 2 60 Module Y ou could collect a small quantity of each species and weigh them to you biomass. are If you then studying you can estimate draw the numbers pyramids of present numbers in and the foc us ecosystem biomass. The This Diversity symbol index that two index Σ means different indices are used to assess species diversity. They individuals quantitative samples. One you could use is known as of not can will belong to species or group. (Often it identify organisms diversity. of the count the randomly sample possible to to their Many of ’. Simpson’s is index a sum probability involve a different taking ‘the measures the selected from Many Bioenergetics nd S tudy their 1 whole plants individuals. area, students in on waste some that so we Barbados grow It in would have to They take take counted ground. waste the ground too long samples. number recorded are to In of their individual count this each all plants, the plants example, species results in in this so we in species so they are identied to genus or family.) Use this example to answer Summary question 4b. some 10 quadrats table. Summary q uestions 2 Species Number of Number of plants each in 10 quadrats (n) individuals of species number of (n) (n/N) 1 ÷ total individuals In studies be (N) using important samples. 40 0. 154 to take Explain necessary thick-leaved quadrats and it may random why this suggest is how you 0.0237 would do this. grasses 2 thin-leaved 150 0.579 0.3352 Describe grasses species be Pride of Barbados 3 0.012 0.00014 5 0.019 0.00036 18 0.069 0.0048 15 0.058 0.0034 3 heart seed ways abundance in of a poppy Evaluate the a named the cress piece points wild dolly 11 0.043 4 0.0018 In a of who sage 17 0.066 0.0044 259 for of (A to numbers these Tree formula animal habitat may obtained carried diversity by the on ground. When should as give good criticisms. trees in a dry forest, identied ve E). They in out a tree counted large quadrat 0.3738 with The you well students species the Totals as into waste survey some black the and results students evaluating wild which determined. investigation Mexican in plant calculating Simpson’s index of diversity results: species Number is: 2 D In this (D) is example 1 When – the number should waste is index high realise ground. invertebrates Complex stable loss not on can 62 small 1) this The resist We or the (near 0) is below shows another very but high as how of on very species the low made or for any the diversity actual of keystone the are of species more and structure. B 48 the C 12 on D 6 E 3 the such as mammals. alien are 56 you groups, and A mean? When plants from that diversity this course, likely is apex be a the Simpson’s diversity for the trees index in the forest. dependent by b Explain using predators Question Calculate of the such affected See to species, any communities species community Of other recover of does diversity. birds introduction or index What diversity. surveyed ground the ground, a only stability the loss effects is ) gures). high damage, the on is not the such that waste there a have with (Σ(n/N) signicant environmental seen 1– calculation and alone, have in 2 there students catastrophic for (to changes, Research have page that diversity change. is plants 0.63 (near above species change. the = communities and of of 0.3738 = 4 and on a the data advantage on species abundance diversity in of richness calculating index. example. 61 4.8 Practice exam-style questions: Ecosystems Answers to 1 The all table exam-style questions shows investigating a one-day eld data collected terrestrial by can be found on the accompanying CD. students ecosystem d during Studies a trip. less. 10% Trophic level Numbers Biomass 2 per e per 5 842 424 the efciency levels why this most food Discuss m of in food energy chains efciency is transfer is not 10% more or than chains. advantages show feeding [3] of drawing food Explain how relationships energy ow in and an webs to ecosystem. nutrient [2] cycling 809 are Primary Explain in that trophic 2 m f Producers show between 708 624 37 important for sustaining ecosystems to remain as self- units [4] consumers 4 Secondary 354 904 The of 11 starsh, rocky consumers the Tertiary 3 Pisaster ochraceus, the Californian shores starsh in mussel, the were is the main predator Mytilus californianus, western coasts removed from an of on the USA. All area of rocky 1.5 shore (A) in 1963 and in subsequent years. The consumers effect the a Use the data in the table to draw two on graph was paper. i Discuss the reasons for the shapes of The how starsh graph it is possible to have on were not lived area removed. After dominated shows the the rocky on (B), area several years A number of numbers and shore of after species removal in the two of inverted P. ochraceus pyramids that another [5] areas Explain animals the pyramids. ii of with [4] M. californianus b diversity compared pyramids where on species shore biomass. from area A. [3] 20 The at students each also trophic investigated level on the the day of energy available their eld 18 trip. with c Suggest how The at the and using endemic nowhere their of to [4] draw a pyramid each trophic level results. Explain why. species else. There level. able is are one found many on island one in to the 14 12 [1] 10 island 8 6 endemic 4 species in Pisaster 16 energy rebmun island not productivity ecosystem An trophic were the fo show 2 each students determined seiceps available d they without Pisaster the Caribbean. 2 a Suggest an explanation for the existence of many 0 endemic species in the Caribbean. [4] 0 b Explain why it is important to conserve 1 2 3 4 5 6 7 8 9 10 these time/years endemic c Some a endemic gardens. botanic gardens species Discuss may the are conserved difculties encounter in by Explain the Explain conserving it b is nitrogen between habitat and important for and the terms sulphur, elements, to be [4] such recycled ecosystems. as the with in the on an [2] it Outline the available should ways in plants include answer. 62 to the which xed in terrestrial role of nitrogen is in species diversity in area B. likely in on was studies role of P. ochraceus on the rocky the Canis lupus. The taken [4] on energy ow Lake Superior. The island preyed in upon wolves by A [3] the was by the a were only out large moose, Alces alces, population received carried about of 1% wolves, of the moose. made ecosystems. You microorganisms change area ecosystem. island energy c the 1970s, herbivore and in that shore In ecosystem. Compare Explain [3] differences why carbon, a that species. ecological niche, b [3] plant botanic these 3 species. in your [5] c Discuss the in the implications for results of the two this question apply in situ ecological to other conservation if studies described ecosystems. [3] Module 5 There are many species Caribbean. Some threat. Seven small patch of live these of forest Republic. All of in Anolis species at lizards fed lizards ecosystems La in insects the and the are were found Palma on in that 9 under living in mark–release–recapture estimate a Index Dominican other The is sizes one population of mobile method and it is of 1 Bioenergetics technique is used populations. The estimating calculated the to Lincoln size of a as follows: small S1 × S2 _______ estimated arthropods, but they were distributed at population = different nm heights in the forest. where a Suggest how seven different lizard species S1 = number in rst prey on the same food animals can all in the same ecosystem. Describe the implications for and released = number captured in second sample [3] nm b marked sample exist S2 together captured, that the = number of marked animals in second in situ sample conservation of lizards if this nding applies to In species on other Caribbean islands. a set c Outline the roles of zoos in the study conservation up small islands. a Explain b Discuss the term the biodiversity c i Explain biodiversity. effects in of [3] abiotic factors it is important to Outline to the steps conserve that Ecosystems a Explain are [5] a [3] b Moths again. Of governments Use what context of is meant ecosystem as can take [4] dynamic by Outline FIVE different is a dynamic system ways in Describe how the in of damaged by changes in moths hawk biodiversity such You which a Explain c Explain an ecosystem the biotic and/or why reasons for refer to ‘Coral maintaining named biodiversity. ecosystems and the reefs every estimate Moths the in of had number the the could be many terrestrial is been of population. population [1] size improved. moths, is important animals size of in their [1] invertebrate not well catalogued to identify the the Caribbean species and populations. recover from unless ten about [4] they catastrophes, occur such as more frequently years.’ the differences are Discuss reefs what before we we can need help to them [3] a Explain the importance of producers in the between in situ and of ecosystems. [3] ex situ Some students counted organisms at different [2] ways genetic of storing genetic use. Gene banks are levels and information embryo of banks stores particular are in a dry forest and drew a pyramid information of numbers. Suggest why their pyramid was the with many more primary consumers species. than banks coral recover. inverted, examples producers. [3] of The students then studied a rain forest and banks. discovered Explain how gene banks are used in of endangered animals. of many tropical species, on such as cocoa, are cannot known be frozen as recalcitrant and stored in seeds seed plants of these species must be banks. The grown International Cocoa Gene Research Station a collection of over 11 000 on Explain Bank in Trinidad cocoa parts of the rather told than them on that the forest oor. A these and that he plants had found 195 are species one tree of the genus, Ficus. the than advantage for on plants of living the forest oor. on trees [2] is Discuss how species diversity, such as that found and tropical rain forests, is related to the stability trees from of different species in eld in has producer as d at UWI’s Cocoa trees scientist rather gene many banks. c The the epiphytes growing they were coconut called and there [5] research Seeds that the living conservation d 17 species of c caught, set [5] possible future gene it invertebrate trophic Sperm marked were abiotic answer. banks complete night, traps may conservation. for moths the [5] b Gene the rst night estimate hawk the Caribbean. functioning b on [4] may your were named 10 in of as to this for know Discuss 38 Hawk of than a traps elephant [3] factors. 8 of results hurricanes, be light Large the system. stability total how The d c moth, Eighty systems. biology. dynamic a Elephant estimate ecosystem hawk caught Suggest of b of reserve. were these Large conserve biodiversity. described species released. The following animals, 7 a nature marked. biodiversity. ii up on the Caribbean. why a [4] and 6 in of Hawk species from of [2] ecosystems. [3] world. Explain the importance of eld gene banks for cocoa and other crops with recalcitrant seeds. [4] 63 2 Biosystems 1. 1 Introduction Learning outcomes maintenance to Transport Flowering On completion of this section, be able plants dene the context term of and different mammals parts of are their large organisms bodies. Think with about long the distances heights of the to: tallest systems you separating should transport transport in the multicellular Also trees think Earth, on Earth about and the and the their blue distance extensive whale, from its the root largest heart to systems animal the tip of (see to its Figure have ever 1.1.1). lived on tail. organisms Cells explain why owering mammals need a plants and transport often system outline the For the differences transport owering systems plants and need between a constant multicellular If long distances example, this is near cells in the the cells from surface energy as and owering sources require the of of such from animal obtained cells supply organisms, of raw materials plants the and substances oxygen so that surroundings by simple the body will receive a they to survive. mammals, that can they aerobically . then supply . large are require. respire diffusion, suitable In cells All only the the other of the body will have to respire anaerobically , and as we have seen this mammals. is inefcient and will will activity and organic compounds, be not supply wasteful such of as enough food. energy The sucrose to leaves and of amino support plants acids. a high make These level of complex compounds Link are Look at about page how anaerobic energy to 37 to remind inefcient respiration and is yourself made from assimilates. seeds fruits and at supplying Most multicellular (e.g. gills or exchange carries is a good foc us animals idea and substances could sh look and which the look plants at their transport insects which how other and the in the is great to ways in and differ. plants but These gases spaces the photosynthesis distances respiration to and have cell specialised in system the respiration, glucose, So not the are known roots, as owers, growth. body. the amino carry The of transport in acids, also gas exchange from gas also reverse of food minerals, carries the system the absorption fatty system for oxygen dioxide, site acids, transport structures to carbon from the is of the transport for oxygen through body solid to all the vitamins nutrients and – systems and for carbon water and dioxide. air even structures trees. movement organisms. This up one diffuse plant seemingly trunks specialised have throughout systems in mammals is tissues the of bodies achieved and transport organs systems. of by that These are: mammals – consisting of plants are known a a as system blood vessels as owering plants – transport systems word and the of xylem tissue and phloem phloem described blood, heart consisting vessels. Xylem circulatory and tissue. plant Figure 1.1.1 vascular and stems, foc us systems from often of substances and are for transport distances have do simply within through meaning gas for a every diffuse. nutrients, make vascular to waste specialised owering them animals and Similarly, too water T ransport Transport lungs) Flowering like S tudy need in long bodies. You mammals they made transported water . systems and nd resemble in at transport around they ways to that surface direction. cells It phosphate are wasteful cells. S tudy triose These tissue. The regions of xylem These systems rely on the movement How does water get to of the tops of these giant redwood trees, and phloem in stems and leaves are uids inside tubes in a single direction. Sequoia known as vascular bundles. This flow 64 type of transport is known as mass sempervirens, and how do plants like this absorb enough ions from the soil to make all this biomass? Module This table compares the Feature of transport nutrients transport systems systems of owering Flowering plants and sucrose others amino water in transport plants Mammals glucose acids, of respiratory gases the ions (minerals) amino no xylem (supply dioxide spaces transported xylem tubes is in of by and sap, oxygen xylem – carbon through phloem sap of ow phloem sieve tubes to prevent loss of Y ou sieve may be asked to make sections of plant oxygen and carbon dioxide arteries, capillaries pull heart pumps hydrostatic and veins transport) blood, giving it a pressure pressure ow faster production uids – blood (extracellular slower wounds vitamins, blood transport) transpiration – acids, air (cohesion–tension) phloem the yes acids, fatty (minerals) cells) (intracellular mechanism and diffusion xylem vessels, sealing maintenance mammals. ions rates Biosystems transported: carbohydrate uid(s) 2 of callose to seal phloem blood clotting tubes material to stain and view Summary q uestions the different stems that tissues, are especially almost the xylem. transparent, such Good as materials balsam, for this Impatiens are balsamina, 1 and stalks of celery, Apium graveolens . These stalks are in fact Dene the elongated petioles of celery leaves. The stem of a celery plant the term transport in the is context of multicellular very organisms. short, and the at parts of the leaves are raised into the air by the long 2 petioles. Explain why owering If you are going to look at your sections under low power with a mammals plants need and transport hand systems. lens in a or dissection microscope sections. This single-edged microscope at medium should razor be they or done blade) and do high with you not need power, a ver y should you to sharp take be need thin. to blade care For cut (such while viewing ver y as thin 3 a Explain why systems cutting the plant are intracellular sections. blood transport described whereas system in as the mammals is extracellular. Y ou can and then stain the remove sections excess with stain toluidine with lter blue, paper. leave Add for a a few little minutes glycerol 4 (glycerine) and then put cellulose pink/purple a coverslip on top. T oluidine blue List the similarities differences a colour and lignied walls of xylem a bright can some also nasty look at plant chemicals, so cells in instead macerated it is best to tissue. use Macerating with a or small put something volume of suitable water. T ake a like lettuce some small or tinned amount celer y of in the a fr uit slide with water and a coverslip. Examine under low and a microscope. cells. Look net-like you for Y ou xylem thickening nd! should vessels in their be able with cell to their walls. see individual characteristic Y ou may be cells liquid, high or rings, surprised Outline how oxygen, reaches the respiratory put cells in a gas, the on of a owering plant, and power groups spirals by and or b of plants blender root a transport of owering mammals. uses 5 vegetables between blue. systems Y ou and stains muscle of a mammal. of or what a 6 Make drawings distribution plant of stems, to show xylem roots the tissue and in leaves. 65 1.2 The uptake There Learning outcomes On completion should be able of this of section, water are four absorption movement state that of to water transport and ions in plants: from the soil of water and ions over short distances within organs to: roots take up ions diffusion and stems and leaves) by facilitated aspects ions you (roots, and long-distance transport of xylem sap and phloem sap from roots to active leaves, etc. transport explain how carrier proteins evaporation Plant root hair cells and move ions by state that roots of water vapour from leaves to the atmosphere. roots absorb ions and water from the soil. T o achieve this, they absorb the following adaptations: active transport loss the have endodermis and in water by long tap roots extensive, fast that reach branching sources root of systems water that and ions occupy at large depths in volumes the of soil soil osmosis explain how down water a roots absorb potential of water growth ions gradient. of phosphate which epidermal branching ions are that mobile cells with roots to remain in the root seek new bound to sources soil of ions, particles, especially unlike nitrate soil hairs that increase the surface area for absorption S tudy foc us Facilitated diffusion and both use thin thin cellulose carrier carrier proteins about these hair movement by looking 1. See also at across 2.7 6.2 in cell 1 of Unit Root hairs Further module. an cells and for are away near from impermeable Ions are channel in the the Root hairs of thyme, Thymus Root is soils Did you know? hair are only is roots infected as by for host assimilates. This cell surface also membranes have many of special as aquaporins. where root hair the epidermis cells die and is permeable. they are replaced by ions so are are interior through have uptake low, require pass membranes of of energy respire the carrier proteins concentration by transport facilitated charged for active ions uptake aerobically available than to in have of ions. of of in cell ions to diffusion by of and some order attracted ions. provide and Some breathing The A TP . well-aerated aerobically uptake muds with bilayers through the cell. respire active phospholipid active absorbed oxygen for The use positively cannot anaerobic ions. plants also the there cells not of contain waterlogged soils. is species roots In In these enough mangrove trees (pneumatophores), can oxygen. diffuse There are throughout large is the air root spaces within the roots so tissues. a in (see return symbiosis legumes page water is Roots than are the surrounded root hair by cells. bilayers, soil water , There so is water which very is has limited absorbed a higher water movement through of potential water aquaporins. through W ater and from the soil down a water potential gradient by osmosis into 47). root 66 in they absorb plant between bacteria ions; known less absorb moves Rhizobium of roots phospholipid similar to that have symbiotic phosphate, which transferred to the they short part of the (mycorrhizae). These such cells these Absorption of ions, particles; are especially trees, oxygen fungi in not the which available live which plants, proteins tips tips, do very Some cells there energy that cells soil distances ions hair charged conditions, have also mitochondria, Many water , root root for proteins; negatively sp. (× 40) Root them. channel hair channel for and proteins soil absorb story. between tissue. charged membranes. Root extend diffusion absorption proteins Absorption of Figure 1.2.1 can so membranes Module in this that walls methods channel of hairs cell proteins. root Remind yourself root active transport very hair cells through the aquaporins in the cell surface membranes. the Module The pathway taken by water and ions from root hair cells to the xylem 2 Biosystems in S tudy the centre cell walls of the and root is the intercellular one of spaces least resistance. through which There water are and plenty ions having to go across cell membranes. This is the can pass this point Some water and ions will enter cells and pass from cell to 1.2.2. the This interconnecting is the symplast plasmodesmata as you can see in and should water revise potential from cell 2.8 through you apoplast osmosis pathway. foc us of At without maintenance in Module 1 of Unit 1. Figure pathway. soil soil water particle root hair xylem vessel Figure 1.2.3 The Casparian strip around each endodermal cell is a barrier to movement of water and ions in the apoplast pathway Did you know? apoplastic Figure 1.2.2 The German route symplastic epidermis route cortex endodermis botanist (1818–1887) rst Water and ions travel from root hair cells to the xylem tissue along cell walls and from cell to cell through plasmodesmata impermeable Robert Caspary described strip that this bears his name. Summary q uestions S tudy foc us 1 Explain and Plasmodesmata interconnect movement animal all. small and page holes cytoplasm between cells See are by cells you 75 for is may more that through is controlled. wonder about the cell wall. Adjacent continuous from No whether these similar plant cellular cell to cell, structure cells are ii exists 2 between ‘individual’ cells Distinguish and tissue in roots is i ions, at the the pathways apoplast across root. interconnections. What and vascular absorb soils. between symplast their central roots cells although 3 The how water from surrounded by the endoder mis, are role ions plasmodesmata? in movement across the of root State water to the a xylem. single layer of cells that controls the movement of ions from the cortex to 4 the xylem. The cell walls contain suberin, which is an Explain by substance that does not allow water and ions to ow the role performed impermeable between the the Casparian strip in the cells. endodermis. Instead, everything young roots, and known is control this what as has to travel suberinised the Casparian passes into the through strip is strip . central the visible This cytoplasm in cross allows vascular of the sections the cells. of the endodermis In root 5 When low to tissue. rate roots oxygen of cell xylem. ions surface This enter diffusion. Figure ion Some in 1.2.2). carrier into creates these endodermis the selected membranes a cells ions the The the pass uptake proteins carrier from can are the endodermal concentration apoplast endodermis by low of walls all the pathway of ions specic through proteins of in at for the a in cells way in from without the certain hair pump endodermal the the cortex soil entering endodermis symplast root the cells ion or is into cells, by to cells more the (see selective, Ions have so in that already an in soils of ions with the decreases. explanation for this. the facilitated water any ions. pathway ions kept concentrations, uptake Suggest The are that pass been 6 The roots trees of grow which have potentials. trees are water, these many in very low Suggest adapted and mangrove anaerobic b a obtain muds, water how to these absorb oxygen under conditions. cells. 67 1.3 Xylem: structure Xylem Learning outcomes tissue plants. On completion should be state able that of state water that and in and the xylem consisting section, of roots, explain xylem roles of a xylem xylem stems how ions transport support. tubes differentiate wall and and is also lose in sections leaves structure related and to of their support. Also a in bres provide two the roles plumbing in for plants: ions from from cell end specialised cells meristematic contents. walls than and have resist xylem the so they ow of compound Xylem The tissue this to cells They form – xylem to gain become a water . that a dead, continuous The gives tracheids the supports tissue pulled is in by vascular walls the cellulose in centre wind bundles vessel thick elements , cellulose empty cells. column are walls in the conduct role various of roots blowing of cell They without impregnated any strength with and provide aerial provide plants impregnated water xylem. and non-conducting Xylem tissue is ways: to the stem (non-woody) walls that structural plants the the herbaceous Thick are contribute and keep thinner to complex that strong support parts back for and ‘strengthening plants forth. rods’ to help upright. with lignin resist the forces of xylem (pulling) and compression (squashing) when stems blow about perforated the wind. walls. Woody tissue plants, as support S tudy and leaves. low power under they the such grow; canopy as trees, this of shrubs provides branches and the and lianas, bulk to a continually trunk to add enable xylem it to leaves. foc us carefully microscope the provide waterproong. in then and made their their walls lignin, foc us elements are lose tension Look that that vessels, bres cross water which vessel of These when are vessels cells are Tracheids of cells transport S tudy xylem ‘tubes’ tissue tissue the vessels in are long xylem is parenchyma recognise ‘tubes’ of you cross The consists to: transported this and function at some slides Look to of at the power cross-sections stems them rst locate high prepared roots, of under xylem to and identify xylem vessels. Figure 1.3.1 The vascular tissue has been Figure 1.3.2 dissected out from the rest of the tissues in Xylem vessels with spiral, ring-like and net-like wall thickening a celery petiole These photographs provide the evidence that water travels in the xylem vessels. Figure a 1.3.3 root. thick Y ou cell prepared lignin. Y ou shows should walls for may be and the Their some be xylem able are to wide microscope cell walls asked to are make vessels recognise cells they often with are from the no drawings cell often stained of the xylem central contents. stained red in xylem to these Xylem vessels in cross- section. It is these vessels that are stained Use Fill a sharp pencil, e.g. HB, and never use a pen. when dyes are used to follow the pathway taken by water (× 50). 68 at least half the space with your drawing. as In they tissue the cells with sections. If of have sections locate vessels. advice: Figure 1.3.3 vascular vessels so, follow this Module Choose Draw Look three or four xylem vessels to 2 Biosystems draw. S tudy around the carefully inside at the of one of these. thickness of the cell It wall. seems xylem Make some faint dots on the paper to indicate where to draw of the continuous Draw in xylem adjacent xylem vessels and then draw these with are are lamellae, joined which is where the cell walls of Draw the and the and wide insides or four you of will cells complete If asked to label If asked to add leave adjacent these xylem your to both say thin that and enough so that wide. there contact cellulose between is wall for water enough to adhesion allow large together . to the three or four that you cells vessels drawing, annotations, in unnished your use write so that you have of water to ow easily from are roots drawing; are adjacent volumes thin sufcient middle vessels contradictory vessels clear , lines. the foc us the They inside maintenance to leaves. three drawing. lines your drawn notes with (as a well pencil as and your S tudy ruler . labels) foc us in Calculate the mean width of the pencil. xylem vessels compare Adaptations of xylem vessels Features that Xylem allow vessel flow of elements water are throughout arranged in with mesophyll question the extend from roots to Cellulose walls are the cell. 1.3.3 width See of and a palisade Summary plant: columns, forming ‘tubes’ that give a low resistance leaves. to Figure 6. Features that in hydrophilic so water molecules adhere the flow of water in the xylem to vessels: them and Xylem support vessels the are columns thin enough of to water . support columns of wide no lumen, up cell contents membranes, Features that resist – no cytoplasm or nucleus compression: empty 0.7 mm tension dead, and to water . thick walls walls of cellulose impregnated no cells end xylem walls vessel separating the elements with lignin. xylem thickened vessels are continuous columns. lignified Feature of xylem leaves, that allows vessels stems rings or in and stretching Feature of that of xylem pits wall allows of lateral water (in and out of vessels): pits allow xylem that movement in small Figure 1.3.4 stretching wall growing roots: spirals thickening cell the cell regions walls; of thin these are cellulose The adaptive features of vessels cell wall, which allow easy xylem vessels so they plants do not grow break as diffusion longer . from of one water xylem and vessel ions to another . Summary q uestions 1 Make the a drawing different of a cross-section tissues. Indicate the of a root position to of show 4 the Explain in a how xylem transport, and vessels b are adapted for their roles support. xylem. 5 2 Find colour make images of xylem drawings following vessels the advice in TS and given in LS and Make a table element to with a compare palisade a mature xylem mesophyll vessel cell. this 6 a Calculate the complete xylem actual Calculate the width of each of the three section. 3 Make a diagram of a longitudinal section of a composed thickening. (See of three Figure vessel elements visible in Figure 1.3.3. xylem b vessel vessels with mean width of the vessels. spiral 1.3.2.) 69 1.4 Transpiration Learning outcomes Pathway of W ater On completion of this section, moves be dene able the terms transpiration, transpiration pull explain how in ow. in the the distinguish is and into cohesion–tension the movement transpiration between is of stream cohesion W ater the The cells of plant through as of the the that is and are stem the to the pathway leaves. with Most least of this resistance directly from the as the absorbed reason for within water by this lms fully leaves diffuses through water leaves vessels passing and into then the plants is through passes that cell cytoplasm of through stomata are surfaces of walls cells. A stomata open to photosynthesis. surfaces moist moves evaporates water for xylem without The dioxide exchange which through leaves atmosphere. gas cells, cell in are walls cell saturated the into them from walls. with from the This water the the xylem. makes vapour . of W ater the If mesophyll interior air spaces the adhesion explain how root contributes to outside movement will diffuse in the the saturated through the then there stomata. is a This gradient, loss of so water water by and diffusion is transpiration xylem T ranspiration explain less out of evaporation water is pressure vapour roots apoplast travels carbon atmosphere the proportion throughout and in mesophyll absorb responsible for water to large capillarity the a to: transpiration stream, cohesion– tension, from in you movement should water role of stomata leads to the loss of large volumes of water , which means in that plants must always absorb large volumes. This is one reason why transpiration. they need large such volumes consequence soil cytoplasm root hair water of cell cell wall hair of However , there is symplast cell There a W ater is pathway cells are pathway cells W ater through cells pathway through through stem xylem vessels and symplast into pathway is of cells needed cells made are needed are involved mesophyll of mesophyll vapour in air of water the such since it is a in atmosphere. transpiration: to stream of water up the xylem, cells. material for photosynthesis, for maintaining vapour as a solvent phloem in a cells. transport medium for the leaves. a variety the of functions opening magnesium of as water and ions helps to inside closing for of making keep plants cells, guard e.g. potassium cells; chlorophyll. slightly cooler plant the than pull vapour cells movement energy T ransport plant for in is from the aerial surfaces of a is main driver this the through – the xylem the energy by plant. to The plant evaporate transpiration pull does water is a not comes passive need from to provide the process as Sun. far as concerned. spaces loss of water vapour from the cell surfaces causes the water mesophyll Cellulose through surrounding stomata to atmosphere imagine This air is a to is shrink away hydrophilic meniscus attraction of capillarity of to this the cell attracts water water and from and a surfaces water contracting surface sets up a by and where deeper hydrogen is in pressure the cell bonding. becoming water negative into more low plant to the atmosphere This exerts apoplast all a pulling the way action to the on water xylem in into the the leaf. cell and can concave. contact (as wall. Y ou with as through the –30 MPa). The pathway taken by water as it moves from the soil, through the 70 with evil’ surface of temperatures. water molecules Figure 1.4.1 ‘necessary exchange loss cells The within in in need Transpiration the water a This between any water raw the for evaporation ambient of walls to systems. be gas transpiration ions a and in ions Loss cell and as Ions The leaves apoplast through mesophyll advantages water chloroplasts pathway to extensive stomata) root between cortical endodermal root considered an continuous assimilates from is (through needed turgidity apoplast water having extensive apoplast through symplast and/or root delivering cortical of of communication pathway deep the Module This – pulling the result evaporation the action of of cohesive mechanism is due hydrogen water , forces that to forces bonding. capillarity between results in of cohesion The in water ‘pull’ the cell walls molecules transpiration between from is the of water leaves the molecules driven mesophyll 2 by cells Biosystems maintenance Link the See Question and cohesion–tension how pull rates of 8 on page absorption transpiration change 81 to see and over a 24-hour period. Not only walls of do water xylem maintaining described a molecules vessels ow each of by of water them ‘stick’ together adhesion. as in the having This is narrow a wide but they also obviously xylem lumen, vessels. they ‘stick’ to important are Although not so the in we wide that S tudy the force of attraction the columns of between water . This is water and important cellulose in cannot drawing help water across the Place small spaces in the cell walls between xylem and other a piece tension in xylem vessels is very high and may be –30 This tension, generated by transpiration, is sufcient water in xylem vessels to great heights. The will tallest see trees 115 metres high. This may be the limit to water movement above pull. stomata, Certainly low internal leaves at the tops concentrations of of giant carbon redwoods dioxide, and low growth rates. This tension a tends of very water. to pull water rise up the the is meniscus capillarity, in the but in movement it in is xylem have low rates as they do not have menisci. of They photosynthesis the involved vessels fewer with beaker by not transpiration a are beaker. This about tubing into to tube transport bore atmospheres You (–3.04 MPa). of tissues. narrow The foc us maintain have continuous columns of xylem water. vessels inwards, which is why they need strengthening against inward collapse. Did you know? Root The pressure continuous movement of somewhere, a very far . It great is absorption water so it force into moves and important water xylem upwards does in of the not some from in the the into the account herbaceous soil root. stem. for the by This osmosis water This root movement (non-woody) leads has to to plants water that is not very are Sometimes dissolved of pressure of a go solution to form xylem. It is when this tall. Often absorption of water at night occurs at a faster rate Root pressure causes the water to move into the happens. Gas columns of – a it is exuded as the asked top’ by ‘pulling’ explain 7 that on how water water draws page However, loss up is transported from in mesophyll columns of water the cells from xylem, that the begin acts roots. as ‘at into others through 1 controlled Explain are dependent on the size of the stomatal by inside the humidity, leaves. plant night this when and open rhythm cells then They guard cells. pump is in absorbed temperature are water also is during in the reversed. These day, cells are sensitive carbon the Stomata the there cell lower dioxide signalling although to from to to supply. open, ions osmosis and sensitive short T o potassium by to the statement: are surface the cells’ apoplast so to some be released closed species membranes water the swell. The cellulose microbrils in the cell by 2 the of any wider . As each guard cell enlarges it become prevent the lengthens, the opening other the pore guard cell between at either them. T o end; both close, cells bow potassium cells so that they become accid. Energy for pumping the chloroplasts, which generate lots of pressure pull; and and capillarity and Explain how hydrogen bonding cells capillarity are involved in the pushing and ions of water in plants. so water leave Transpiration involves the loss comes to from the cohesion cohesion–tension. 4 the of photosynthesis’. turgid outwards ions root transpiration is transport against consequence between pairs: adhesion; guard W ater Distinguish and becoming inevitable exchange for following at where potential. cells walls plants concentrations chemicals tend in owering light 3 and pits. pores, gas intensity, can ow xylem vessels Summary q uestions 81.) transpiration is as the is which xylem (See cells of water blocked ‘Transpiration Rates in known droplets. describing force Question Guard to bubbles water phenomenon laterally out of When in the ‘clicks’ leaves cavitation. where bubbles hear than vessels transpiration. gas possible to come out not break the very gases the atmosphere of very large A TP . quantities of advantages water. of State the transpiration to plants. 71 1.5 Measuring A Learning outcomes On completion should be able of this transpiration section, simple state that measure explain to into test-tubes The volume measure or asks water of uptake water as by you plants can see is in to place Figure cut shoots 1.5.1. you of water absorbed by the shoot can be measured by marking to: the way rates a potometer water how a uptake is used by potometer to plants can levels lost. The of water on Alternatively, rate of the the uptake is test-tube shoot and could calculated be nding placed out into how a much has measuring been cylinder . as: 3 be volume of water absorbed in cm ___________________________________________________ rate used loss to in measure rates of explain effects on how of rates of water = water time to investigate the environmental factors of transpiration. and Often can the also rates be of used water not cells by are W ater the with partially into that test-tubes shows method whether transpiration only placed determine this know are turgid. 1.5.1 Did you know? do shoots to Potometers limitation we atmosphere if compare uptake taken in are how how water goes into placed much this all or the cell a water be that it cells has some when cut absorb vacuoles balance is only water whether turgid on could is the actually has from water will and measures been lost been a and to the different plants, to different The to some use for plant might problem methods fully be So possible Figure is time with that to it these takes a obtain those The volumes of conditions. species that absorbed over the you short could cells. the apparatus. atmosphere. water Suggest the by when become it results. adapted so done. uptake especially uptake the absorbed in weighed, lost water to plant, remain long of hours transpiration The of term are very small, this. so potometers Figure 1.5.2 Shoots are capillary possible that so to it measure of of is the tiny water period in used. attached to volumes rubber are tubing absorption short like of over a time. tubing three-way tap Figure 1.5.1 This apparatus measures the volume of water capillary absorbed by the shoot and the tube mass of water transpired to the top of scale atmosphere S tudy air/water bottom of foc us scale Measurements of transpiration and water uptake by crop plants, forest trees meniscus and beaker of natural potometers. Parts measure increase not plants involve can be taking enclosed cuttings in and placing transparent them chambers into the using in humidity; pulses of heat the and movement of thermocouples water to in xylem to detect their can be passing. A simple potometer that can be used to measure water uptake over short periods of time. It can be made even simpler by omitting the three-way tap and syringe. 72 of do water determined Figure 1.5.2 vegetation It is also involved possible in to use remote transpiration. sensing devices to detect the energy changes Module When need setting to Cut be up this sort of potometer there are various precautions the leafy S tudy twig under water so that air does not get into the block Make an oblique foc us of transpiration are inuenced them. by maintenance xylem Rates and Biosystems that taken: vessels 2 cut to increase the surface through which water the degree of opening of stomata, is the steepness of the water potential absorbed. gradient Use a Place syringe the leafy attached) avoid Use Leave a the moves the air to of has meniscus to back tubing water . into (with Push the with the water . rubber twig rubber or or into leaves plastic the plastic tubing quantity tubing rubber tubing that support for a set to the while become put of potometer and until air the constant. conditions more the between and can to will the of water bottom will rate The be at the the the leafy drawn which plant before into of with into the results are capillary air water suggest inside vapour hold. Try Question and how 4 that on results the the page these factors the the and air 80 are recorded. twig. the capillary meniscus should the atmosphere, responsible for readings new reservoir tubing water . to take any the of bubbles stand not capillary and bowl apparatus Do adjust the twig a upwards syringe ll absorption clamp tubing. to into getting prevent to be given taken. tubing Use and Summary q uestions time 1 the Explain push Figure tube. water why 1.5.2 the potometer measures uptake and not in rates of rates of transpiration. The be distance recorded travelled and transpiration and dividing is by used by to the determined the meniscus calculate time by the over rate of calculating taken for the certain water the periods uptake. volume meniscus to of of time The water move the can rate of 2 Write absorbed set up a is another design of a potometer in Question 6 on page potometer of 3 factors fairly on are the easily presence used rate using light air and of Discuss water the of to determine the transpiration. simple effect These of different factors can of environmental be absence water of light for investigated plants in Explain why and their it temperature humidity intensity leafy twig. of rates transpiration natural habitat. is important to and light keep intensity investigating the temperature. speed on water movement table shows ways in which these ve Environmental factor Design of presence place a place another place a place other measure place a place another air the the potometers: uptake and absence light light a determining uptake effect of wind of by limitations constant when The on affect transpiration 4 investigate different factors potometers for Potometers to setting 81. uptake Factors that instructions for distance. effect There out intensity movement potometer temperature the light the fan adjust the set up in leafy twig. investigated. or drying potometers in the agent at dark is well room netting with room hairdryer of that lit or in a box Sun movement humidity a a a under potometer air in intensity potometer using in full potometers adjust be somewhere potometer potometer and could a investigation continuous humidity factors by a with still identical over to air like the give give different degrees of shading meter air and no conditions draughts except use a fan or hairdryer to create in plastic plant different around calcium different to light times the wind speeds potometer chloride during or the by silica day enclosing gel and to give record it dry the a clear bag air temperature 73 2 Biosystems 2. 1 Phloem maintenance The Learning outcomes movement translocation , On completion should be able of this section, you transports and state that movement of is state which Sucrose transported sap simply and are amino the source means which across from leaf from to sink one place compounds acids into are the is known to another . produced produced nearest in ne as by the Phloem plant’s mesophyll endings of cells the phloem phloem sap phloem assimilates, metabolism. to: of sieve tubes. translocation that sucrose assimilates are and Phloem tissue phloem sap is always found close to xylem tissue. The composition of other transported is very different to that of xylem sap as it contains in assimilates. phloem sap In state that sieve tubes plant where composed of sieve tube recognise phloem substances tissue microscope in Section slides in draw and label companion sieve tubes and 1, the in the water is loaded leaves. It will xylem is in potato again, new back to information pages on the 8–13 for products sink are unloaded used from to describe transport the places tissue. As we into also xylem be vessels unloaded in in the roots owers, and fruits one direction from the sources and (roots) seeds. to stage mature, stem these can be seeds tubers. over stores and are and quite different Rhizomes very dry leaves sources or and cold sinks not in store and yet assimilates are such sinks rhizomes in When amino the to of acids roots, ginger form growth are photosynthesising. phloem are transported as energy periods. sucrose are since and organs, tubers very and that and leaves storage mobilised young both is photosynthesising fruits, survival shoots transport of begins sent to Some transport. the The light-independent for organs of by Phloem owers, starch Link etc.) produced stems, cells. and Look and and photographs (leaves, source into and T ransport in terms loaded in unloaded prepared the are elements saw transport, are conducting cells in phloem form sieve tubes, which are made from of specialised cells known as sieve tube elements. These cells differentiate photosynthesis. from meristematic different sizes. are companion the cytoplasm, cytoplasm a that larger divide cells Sieve tube companion many are longitudinally sieve tube elements cells mitochondria lose retain to to form elements their their provide nuclei nuclei two and and and cells the of smaller much have a of dense energy. – across sieve plate companion Figure 2.1.1 cells cells. but with sieve tube sectioned The cell A cross section of phloem tissue from a squash plant, Cucurbita pepo (× 60) sieve tubes – Figure 2.1.2 A drawing made sectioned from phloem tissue similar to that between sieve in Figure 2.1.1 (× 100) plates Figure stem. thick a 2.1.1 Y ou cell shows should walls companion cross-section. Figure 74 2.1.3. and cell. Y ou some be able are to see tubes the adjacent sections also sieve recognise usually Some can phloem have sieve from sieve to a sieve plates much plates in a vascular tubes the as they thinner as you bundle do cell, can not which see longitudinal in in a have is the section in Module Sieve tubes plates are within them. companion as sucrose, When tube the cells, are a elements of are drawing Sieve tissue tube is 68. are thought hydrostatic and to prevent pressures between sinks and tissue, Do an not where follow shade annotation cytoplasm and cytoplasm tube sieve that sieve develop tubes and assimilates, such is that more the to to same show indicate there is heavily advice the as for contents that dense the of sieve cytoplasm stained than in the for sieve tubes the transport of phloem sap. have: Figure 2.1.3 cell membranes maintenance elements. phloem adapted elements sources phloem label The sieve that high plasmodesmata in page some cells. Adaptations of Phloem a walls the Biosystems unloaded. of on use have the of many and tissue companion end result especially Instead contents a loaded xylem cells. as There making drawing the perforated expanding 2 that retain sucrose and other assimilates within A longitudinal section of phloem tissue from Cucurbita the pepo showing sieve tubes with sieve plates cells (× 40) little of cell contents phloem sieve any reduce resistance to ow sap plates resist to to hold internal sieve tubes together and pressure mitochondrion sieve sieve pores to allow ease of ow between sieve plate tube elements. nucleus Companion many cells mitochondria solutions many have: into the to provide sieve plasmodesmata energy to companion move cell tubes to allow easy movement of rough phloem sap into and out of the sieve tubes endoplasmic pump cell proteins surface and co -transporter membranes for proteins absorption of in reticulum the sucrose Golgi from the some cells apoplast pathway plasmodesmata for transport pathway (in of some from shared sucrose mesophyll with via sieve tube mesophyll the body cells element symplast species). Figure 2.1.4 This drawing was made from transmission electron micrographs. It shows a sieve tube and a companion cell in longitudinal section (× 300). Summary q uestions 1 Indicate of the position cross-sections for Summary of of the root, question 6 phloem stem in 1. 1 and of on the leaf this drawings that you 3 made Make tissue module. three light 2 Find colour companion following page images cells the of in TS advice phloem and given LS in sieve and this tubes make diagram of composed companion a of longitudinal three cells as sieve they section tube of phloem elements would be seen and in the microscope. and drawings section a and 4 on Explain how phloem tissue is adapted for its role in transport. 68. 5 Calculate the mean C. pepo shown in diameter Figure of the sieve tubes of 2. 1. 1. 75 2.2 Translocation Phloem Learning outcomes bright On completion should be able of this section, you it explain how assimilates is and unloaded in that has from owers, pulled move in good leaves seeds upwards either conditions to roots and by direction fruits. for and a plant. For photosynthesis, also Xylem transpiration. in upwards sap the phloem from moves During leaves only life example, of in a sap to one on a hot, moves growing direction plant, phloem as sap are may loaded day may downwards points, to: sap travel in both directions through an individual sieve tube. When a leaf the starts to grow , it is not photosynthesising but using sucrose imported from phloem other explain the phloem mechanism sap by which moves. leaves ow through There S tudy to provide photosynthesising, are sieve three Sucrose it and its cells with becomes tubes in a the energy. net opposite main principles other assimilates Later , exporter with loaded when the sucrose, direction involved are of to that at transport at the leaf which the in source is will then start. the phloem: where there is a foc us build Translocation is another example of A up of pressure through mass ow. The gradient sieve Sucrose low hydrostatic and is tubes other hydrostatic mechanism pressure. responsible from source assimilates for to are movement of phloem sap sink. unloaded at the sink, so forming a pressure. for phloem transport is pressure ow. Pressure flow Figure S tudy 2.2.1 opposite shows these three processes. Look at the gure foc us while reading about the processes of loading, pressure ow and unloading. Loading and dependent you fully and on osmosis. understand water involved unloading potential in phloem are Make how sure 1 osmosis gradients Mesophyll Sucrose are absorbed species, transport. in S tudy for foc us 2 These those proton in their energy redox are mitochondria chloroplasts. as pumps of transport chain as in (see not the 11 cell The passes maintain and similar cell change cells from cells by a it products pathway form of is gradient converted of along active plasmodesmata diffusion cells the apoplast through the have energy wall that from the to surface proteins electron pages use protons use ATP the companion companion Companion These coupled the to the sucrose for photosynthesis. cell from and In as another soon form of is some mesophyll sucrose, into walls transport. cells; as it sugar transport. the these energy, transferred from reactions to and However, source similar into make through sucrose order enters cells passes A TP in pump sucrose transfer in of spaces. and protons into cell the the creates membrane. cytoplasm a gradient into for mitochondria. cells on surface from This companion and them the protons chloroplasts membranes to pumps to intercellular those accept shape proton the have co -transporter external surface and cytoplasm. and The proton gradient drives this active transport of sucrose into the 29). companion 3 Sucrose cell, diffuses plasmodesmata 4 The movement potential very far than away, Remember membrane, and The to 76 to from of so that turgor the the the of is into moves tube of water pressure of to concentration cells phloem the sieve tissues. by cells intact loss high companion surrounding sieve a adjoining sucrose water which prevent maintaining into the absorption the so sieve tube into are the surrounded allow the absorption sucrose. extensive tube. creates There osmosis are through of by of a lower xylem sieve cell water vessels tube not cells. surface water by osmosis sucrose. builds other up a plant high hydrostatic cells. pressure similar Module 5 The the be pressure pressure upwards may be the sink, enzyme active 7 The cells also uptake so areas of cells sink of water the Also in or of sucrose some the is loaded sieve points, storage energy out as Some tissues is greater tube. owers This or maintenance than may fruits; or organs. neither required sucrose by will tubes Also it invertase) the takes sink the is loaded sieve be nor tubes unloaded down broken into absorption of the sieve it. also into out decreases of using known sugars end is Biosystems as the to stems. are moves sucrose growing roots diffuses that other where provide absorbed. water the where leaves, towards (also by movement loss tubes at new in for sucrase gradient, The sink sucrose into are sieve mitochondria. energy gradient which cells probably lack provide At the downwards unloaded 6 in the towards Companion latter in 2 of its glucose sucrose concentration down by and is the fructose, passive, but place. tissues sieve creates tubes hydrostatic into a the pressure, so water sink potential Figure 2.2.2 tissues. maintaining a This transmission electron micrograph shows a specialised companion cell – a transfer cell. Notice pressure gradient from source to sink. The pressure gradient drives the ingrowths of the cell wall (× 5000). movement of phloem Sealing damaged Damage to pressure drops pores. phloem Plants response to See the model of this on page 79. sieve tubes tissue suddenly make sap. is callose, wounding repaired within and a sieve by plants tubes, polysaccharide this also helps to very quickly. proteins made seal block from If up the the S tudy β-glucose, damaged sieve foc us sieve in tubes. Look then carefully answer Think about companion read when at Figure Summary 2.2.2 the function cells that 6. of you answering and question the have just question. water chloroplast Summary q uestions 1 water source in the terms translocation, assimilates, source, 2 sucrose Define Explain why parts sink of a plant may made be cytoplasm a source year and a at one sink at time of the another. Key 3 Transport in the described as an phloem is sucrose active process. molecules 4 Explain why Explain the in loading phloem: starch this is roles of sucrose proton so. the following into the pumps, proton grain gradient, co-transporter proteins water and 5 sink plasmodesmata. State three transport ways in the in which phloem differs water from 6 Suggest in water Figure 2.2.1 transport why Figure in the 2.2.2 the xylem. transfer has many cell wall ingrowths. Mechanisms involved in translocation. Read carefully the notes on each stage. 77 2.3 Assessing the evidence for phloem transport This Learning outcomes section which On completion should be able of this section, you tubes in to: has so the compare xylem the sap composition with phloem compare the structure with phloem analyse and transport in the extracts study because have most of investigations plants been bizarre phloem sap is to into used to seal to use phloem transport, wounds investigate the compare stylets with in sieve movement of sap-sucking xylem sap. feed on phloem sap by inserting (froghoppers) insert their their stylets stylets into into individual xylem sieve vessels on xylem sap. The young stage of spittlebugs, which are pests and which they of tissue interpret evidence for to the techniques perhaps obtain Spittlebugs tropical difcult V arious of xylem feed tissue to Aphids sap of proved fast. some of tubes. about phloem; insects is the methods of insect, plants. or with radioactively a for single be a tubes a long phloem under exude have miniature continue sieve stylets injected grasses, Researchers leaving xylem single leaf pasture themselves. to ow and time pressure for tube out. xylem to sieve it to frothy liquid through through They total Phloem This continue stylets the been volumes element. with the which have vessels. give tube a cut far to excess that that cover types of sample exudes in shows both contents able sap of the of the the from of from cut contents phloem length phloem sap the the of sap of must owing for time. used investigate the movement external the xylem stylet aphid Ringing solutes (also in removed, sieve known stems. as A shown in The concentrations that were stem of ringed. an as girdling) complete Figure of unringed were were control of to tissue to of is 2.3.2. sucrose Samples is ring determined also plant. taken The in from results several the are same shown parts of a positions in the stem on the table. tube Part of the aphid phloem plant sap where Concentration of Ringed stylet drop from oozing liquid sieve tube Figure 2.3.1 units plant Unringed (control) plant oozing anus a sucrose/arbitrary sample taken in the stem above the ring 0.60 0.43 in the stem below the ring 0.00 0.41 in the roots 0.03 0.30 b a An aphid feeding on phloem. Aphids have mouthparts that are like a hypodermic syringe, which they insert into individual phloem sieve tube elements. b Aphid stylet used to collect Radioactive tracers became available in the middle of the 20th century. liquid from a sieve tube. Leaves were supplied with carbon dioxide labelled with the radioisotope 14 carbon-14 C). ( This was done by enclosing 14 with a leaf in a transparent bag 14 C some labelled carbon dioxide ( CO ). Radioactivity was detected 2 in up the a rest of stem, well as in the plant some radioactivity the roots. was hours later . detected Radioactive in sucrose When applied growing was tips, detected to a leaf owers inside halfway and fruits as phloem sieve phloem is ringed tubes in leaves, stems and roots. area The most mass popular ow, with mechanism movement proposed due to for transport differences in in the hydrostatic pressure transverse between section of sources and sinks. This mechanism was modelled in 1926 by stem Ernst with Münch (1876–1946). explanatory Figure 2.3.2 shows a diagram of his model notes. longitudinal section Figure 2.3.2 of stem S tudy foc us A cross-section and a longitudinal section of a stem to show the It is possible to see that aphid stylets are inserted into single sieve tube elements procedure of ringing in which the phloem by taking is removed from a stem 78 sections of stems infected by aphids and observing with a microscope. Module glass Cell A – has membrane tube linking cell A to cell B represents the 2 phloem permeable Cell only to water. with sucrose. a It It contains high a solution concentration represents the leaf direction of of of sucrose flow of solution B – has only to with little a membrane water. It permeable contains sucrose. It a solution represents a respiring or storage regions of the plant glass tube linking plant, A the Water enters cell A by e.g. osmosis two vessels represents the – xylem Water because it has a lower than leaves because it is forced water out potential roots B the due to the high pressure water direction surrounding of water flow potential created in A it Provided sucrose is continually produced in A (leaf) and continually removed at B (e.g. root), the mass flow of sucrose from A to B continues Figure 2.3.3 Here is a Münch Ernst Münch’s model of pressure ow list of the proposed most his important discoveries about translocation since Did you know? model: Aphids The distance travelled by sucrose in the phloem is very long – up crops about 100 The serious such as pests peppers of and many beans. metres. Not are to speed at which sucrose travels in phloem is between 0.05 by –1 only do they reduce the yield and removing assimilates from the –1 and 0.25 m h may be as high as 1.00 m h . Sucrose diffuses from cell phloem, they transfer disease- –1 to cell at speeds of less than . 20 mm h causing When leaves freezing and decrease. phloem and to stems low Adding are oxygen exposed to temperatures concentrations, respiratory inhibitors to ow just rates phloem in organisms such as viruses. above phloem prevents any ow of sap. Summary q uestions The hydrostatic pressures Phloem Over tube of sap time, 1000 to moves the changes. growing, pressures but 2000 kPa in opposite direction Phloem is inside exported have is been directions taken sap phloem by phloem those tubes are high – recorded. in transported from sieve 1 adjacent sap into leaves in phloem an new when sieve individual leaves mature as tubes. the differences sieve they Describe are of xylem of phloem 1.3 and and similarities and between the tissue and tissue the (see structure structure Sections 2. 1). photosynthesising. 2 The concentration of sucrose in phloem sap is between 10 and Summarise between in mesophyll cells it is Companion cells have many mitochondria; A TP is present in in higher concentrations than in other sap and The Sucrose pH The of the contents of companion cells phloem of sap. Suggest why aphids are likely to cells. show faster differences composition these 3 cells the 0.5%. xylem the 30%; is about growth rates than 8.0. spittlebugs. is loaded into phloem sieve tubes but other sugars are not. 4 cell surface membranes of companion cells have pump Explain as for hydrogen ions and co -transporter proteins for sucrose the shown in the of ringing table on the and opposite hydrogen effect proteins page. ions. 14 The water tubes The the potential gure mechanism mechanism of observations loading at of mesophyll about ow transport. about source and cells is about –1.5 MPa, for sieve 5 –2.5 MPa. pressure phloem made the is of is when generally However , phloem. The unloading at it accepted does pressure the by not gradient sink. The scientists explain is all created companion as between use energy source and and both sink processes does not are require active. energy, The so nectar roots by and of living intact and not dead through case, answer to the why are sieve xylem, cell are may protect membranes like walls. they be tubes they do Sieve there that against vessel elements sieve not a offer xylem tubes are under lignied? have necessary plates since bursting not are This support resistance lignied high may do are xylem? be sucrose to not due and to ow. have pressures. sieve that both starch sucrose grains in in the plant. Identify the given this in pieces of evidence This If this may fact is that, ideas and that: be the loading sieve the may case the of sucrose into away tubes is an active process The plates which section for act why unlike b movement phloem Explain is of by your C, became tube ‘leaking’ them? sieve In in leaves, movement why in prevent vessels not the to a in to radioisotope, cells a because the applied against elements how incorporated the the 6 involved Explain solutes in the pressure ow. answers. function. 79 2.4 Practice The exam-style uptake minerals; Answers to 1 Plants a all exam-style questions absorb Explain mineral why potassium, A solution plants was was prepared of seedlings maintained table. After a require magnesium concentrations Some ions from with mineral were at the week in [6] in soil solution, concentrations given of six water. b which in within the root cells were Explain, of plants ii water are shown in the and phloem terms the Dene ii Explain the of absorb moves i water potential, water from across the the how: soil cortex [3] of the root xylem vessels. the term how [3] transpiration. transpiration movement of water is in [2] responsible for the xylem. [4] the Xylem vessels are adapted for the transport of water determined. The over results in i the 4 ions a into as found this water accompanying CD. 3 ions. of the same concentrations the in phosphate, sulphate the ions grown be found on the soil. nitrate, and transport transport can the and questions: long distances. table. a Describe b Explain the structure of a xylem vessel. [3] –3 Ion Concentration/mmol dm how transport Soil solution Root cell water 1.00 used uptake they 0.01 a of are long potometer leafy were at to shoots different able to adapted for the distances. [4] measure of croton, the rate of Codiaeum times investigate during the the effect day so that of 1.00 temperature. The potassium 1.00 calcium 1.000 table shows their results. 75.00 Experiment magnesium over 8.00 variegatum, phosphate xylem vessels water contents Students nitrate of 0.001 0. 10 Temperature/ Wind speed Mean °C (setting on rate of fan) movement 0.45 of gas bubble/ sulphate 0.25 9.50 –1 mm h b With reference i describe ii explain to the the the suggest the 2 a cell to explanation for the function cells; in between potassium concentrations Describe plant an of each of of case ions the calcium each of relate the endodermal ii sieve 15 low 2 15 high 22 difference 3 25 low 24 4 25 high 45 5 35 low 64 6 35 high in ions. [2] the following the structure of the cell element Using b companion iv xylem vessel Explain the transport c Explain 80 in how transport cell in [3] element. terms source and [2] sink as applied plants. transport the the data in the table, describe AND explain [2] the iii 120 [2] c tube 12 [2] its function. i 1 [3] difference concentrations iii table: results xylem. the phloem students d Make of the two changed two on criticisms conditions the of rate the of that the water design of uptake. the differs from [4] e Columns process plants of [2] water known survive [6] students’ investigation. to [2] in effects as in xylem vessels cavitation. when this can Explain happens. break, briey a how [2] Module 5 a b Flowering plants they a need Outline the Figure a of sucrose described 2.4. 1 ginger in shows a by cell sucrose in a leaf as to storage rhizome. along the in plant period. The you b. [6] potometer set up ready to take debrosba readings. leafy shoot water well results watered are of plant water during a hot throughout shown water in Figure the 2.4.2. end shoot transpired 24 20 16 water 12 absorbed 8 4 ssam of kept rates a 28 fo syringe cut was of maintenance 32 retaw reservoir of the transpiration 24-hour the pathway investigated and day. The [4] involved students absorption it a Some ro 6 as mechanisms movement have taken mesophyll 8 [3] deripsnart the why h/g such Explain a Explain system. Biosystems 1– organ, multicellular. pathway travels from c are transport 2 0 0 4 8 12 16 20 24 tap time/hours rubber calibrated air/water capillary meniscus Figure 2.4.2 tube tube a Describe b Explain and the the results shown changes transpiration in over in rates the the of graph. water 24-hour [4] absorption period. [4] 3 scale calibrated in mm c Suggest how plants survive periods of severe Figure 2.4.1 drought. a State THREE precautions that should be 9 when setting up a potometer such as [3] taken the one a Explain why all owering plants that live on land in transpire. the gure. b b Explain how the potometer can be The measure rates of water uptake effects the rates conditions Explain wind and how speed the on effect the transpiration of rates can light of be intensity water and absorption investigated using potometer. ii Describe in the diameter of stomata of transpiration under different of evaporation were investigated with [3] leaves i changes and transpiration. c of used on to [2] [3] [5] how potometer a the results would be taken from processed to of birch evaporation rate of the in table. the were water under trees, Betula pubescens. determined loss from same pieces by of conditions. The Rates measuring damp results of the paper are shown the give reliable Rates of Rates of transpiration evaporation/ stomatal diameters/mg 25 cm at different –2 data for the volumes of water absorbed and –2 transpired. [2] mg 25 cm –1 h 0 7 Silk cotton trees, Ceiba pentandra, Mucuna sloanei, transport from to their roots the water leaves on and over the lianas, great –1 h µm 4 µm 6 µm e.g. distances 100 0 60 62 200 0 102 120 600 0 330 375 1000 0 590 625 topmost branches. a Describe the from soil the pathway to the taken tops of by silk water as cotton it travels trees and lianas. b Explain [4] how water is transported to the tops of i these tall plants. Suggest how conditions c Discuss the conditions these effects on plants. the the scientists changed the [5] of changes rate of in water around the birch leaves to give environmental movement different rates of evaporation. ii Describe the iii Explain the effect around the leaves Explain the effects [3] in results shown in the table. [4] [8] iv the rates of of changing on of rates of the stomatal transpiration. conditions transpiration. diameter [3] on [3] 81 2 Biosystems 3. 1 Blood The Learning outcomes On completion should be able of this maintenance section, a closed a double state that system is a the is closed body. there blood is a At because no blood point does ows blood inside ow vessels out of in these its journey vessels is a cut; and blood clots quickly to seal external and except internal to composed of red and white describe the and blood through the loss. The heart circulation. is There the are pump three that main keeps types the of blood blood blood vessel platelets limit tissue owing circulation circulation that cells, is closed, wounds state mammal system system where a mammalian around double of to: the circulatory system you The circulatory in a closed system: arteries, blood high capillaries and veins. plasma composition Arteries transport delivery to at pressure from the heart, giving efcient of tissues. Capillaries are where substances are exchanged between blood blood outline the formation of blood. and the tissue accommodate The one double any uid volume circulation complete that of surrounds blood means circulation of and that the cells. return blood body. V eins it at ows There stretch low pressure through are two to the to the heart heart. twice in circuits: Did you know? Sir William who Harvey discovered Pulmonary (1578–1657), the circulation in the body, famously said the a that last to it is ‘the rst die’. description Search of to live Systemic and the that show how one-way ow published in of blood The is the heart in heart the to the lungs pulmonary in circulation through – blood to the body ’s arteries heart main in vein to is all pumped veins the by that leading organs, the heart empty into the except into into the the the vena lungs. aorta cava, Blood which of blood in heart. advantage of the of body a double at circulation different is pressures. that blood Blood ows is sent to through different the lower pressure than that in the systemic circulation. lungs This does damage the the of rest there capillaries the body, would example of mammals. at high of mass Blood found from be A in the the lungs. blood If would insufcient high pressures and is a in tissue. other those blood so pressure there cells spun in plasma a Red is in blood be oxygen in an the owed supplied to at on a from very support the means that aorta efcient watery as they pages uid, all – liquid chemicals just supply cells of as a the low high lungs to pressure metabolic of blood is rate delivered oxygen. in the for is blood more Every the blood the at to is the bottom cells lifts’ roles in of in bone blood. the to of composed materials equivalent the white ‘hitch about tissue hard cells; If tube are and white of cells and blood (55% of blood volume) – plasma consists of water it: 3 10 cm • nutrients, e.g. 3 5 such sodium • wastes, • blood • hormones, as and such as proteins, glucose, chloride urea such and as amino acids, lipids, vitamins ions carbon albumen dioxide and antibodies cm white blood such cells as insulin, and Blood cells photographed red blood Figure 3.1.1 glucagon, platelets cells using the high power of a microscope The composition of blood is with 3.1.1. blood dissolved true use settle Figure part the disease). such plasma, the in are 144–149 against shown plasma with cells substances, centrifuge, top and (see defence The on blood tissues tissues extracellular cartilage. 82 at not blood ow. (× 1,100) is 1628. another Figure 3.1.2 the veins. foc us movement vessels from the that and S tudy ows to valves much he blood returns Harvey’s famous parts ensure then returns online for The experiment – and of and blood arteries of blood circulation pulmonary and adrenaline. and mineral ions, Module Blood Figure 2 cells 3.1.2 shows some microscope. Figure 3.1.3 blood cells shows a under labelled high power drawing of of a light some blood cells. phagocyte The table shows the features of the cells shown in Figure 3.1.2. red Production of The blood bone populate The is of cells, blood originate platelets, in different neutrophils and places: monocytes are made in marrow. Lymphocytes cells blood components Red blood are lymph water ltered in in also plasma the made nodes in where is bone they absorbed kidney, which marrow, divide from the reabsorbs but during early stomach most in life they infections. of it and intestines. leaving a little It Figure 3.1.3 to The main types of blood cells that you should be able to recognise be lost as urine. Substances, such as ions (e.g. sodium ions), proteins, in slides of blood and in photographs amino acids, removed Type of red from blood blood glucose, it as cholesterol blood cell ows and fats through are added capillaries to in plasma and tissues. Features cell small shape: exible no Functions cell (7 µm diameter) biconcave disc can membrane nucleus; no organelles RER, Golgi body) cytoplasm is full contains the change (mitochondria, more space transport of shape and t easily through capillaries to ll oxygen with and haemoglobin carbon to dioxide haemoglobin enzyme carbonic anhydrase catalyses reactions to help transport carbon dioxide neutrophil large lobed nucleus small nucleus: polymorphonuclear mitochondria, leucocyte many (phagocytic also known ‘white lobed cell) as meaning blood cell cell (10 µm diameter) lobed cytoplasm ratio RER, Golgi body lysosomes protein for with lymphocyte larger bean-shaped cell (12–20 µm mitochondria, smaller large highly cell specic body blood through synthesis to make digestion hydrolase of bacteria enzymes and pathogens which are long-lived phagocytic cells diameter) cytoplasm cell leave where they become long-lived macrophages, RER, Golgi to cells these cells are in the blood travelling to tissues, diameter) nucleus (4–6 µm nucleus helps walls intracellular other nucleus’ monocyte nucleus capillary surface activated ratio secrete receptors to become antibodies; specialised for for be certain page secreting pathogens; activated (see plasma many by are cells which memory antibodies ready infection by and cells specic waiting those to pathogens 144) Summary q uestions 1 Dene 2 Explain 3 List 4 Explain the the terms why closed circulatory system, blood is components the a double circulatory system tissue. of advantages blood to and state mammals of the main function having a double of each. circulatory system. 83 3.2 Blood vessels Blood Learning outcomes of On completion should be able describe veins of section, blood explain body in blood vessels. There are three main types vessel: artery structure of vein capillary. arteries, capillaries how the structures three are vessels are related lined by an endothelium, which is a single layer of of squamous blood the you All around to: the and this ows to cells. The endothelium forms the wall of capillaries, but the their walls of arteries and veins are also composed of smooth muscle tissue functions and make labelled drawings arteries of and annotated cross-sections and bre-secreting elastin. of The between veins. very the triple There from stretched are that make collagen. and recoils capillaries in produce structure polypeptides different when cells helical it the brous collagen very Rather when the of resistant like an proteins and to elastic all collagen the stretching. band, and hydrogen it bonds Elastin is elongates released. walls of arteries and veins, supplying oxygen Link and far Revise the structure of nutrients away from of Module 1 muscle the blood cells in and the bre-secreting middle of these cells. These vessels to be cells are supplied too by collagen from diffusion, 1.8 to in Unit and in most veins and some arteries the blood transported is 1. deoxygenated. The S tudy Smooth foc us muscle often table describes the functions Blood vessel Function artery carries of these blood owing blood vessels. away from the heart at high causes pressure problems. As would be vessels. its name good for suggests lining Endothelium, the which it stretches delivers is not lining tissue, forms of the blood the recoils to maintain the blood pressure blood to organs at a pressure slightly less than a when muscle and blood it left the heart smooth vessels. vein carries expands blood owing to take towards increasing the heart volumes of at low blood, pressure e.g. during exercise as by capillary blood carries allows water Figure 3.2.1 is low, valves at blood owing pressure pressure semi-lunar and the low of blood is prevented between arteries and veins at low speed exchange between backow intervals of blood respiratory and gases, solutes and tissue uid Cross-sections of an artery and vein (× 10) Figure 3.2.2 This electron micrograph of a cross section of a capillary shows that a red blood cell is about the same diameter as that of the blood vessel (× 4250) 84 Module Blood vessel Structural features Relationship 2 between structure and function endothelium artery thick smooth inner lining to reduce chances of layer of high muscle ratio of wall thickness: turbulent ow, which promotes blood clotting and diameter elastic fibres of lumen elastic tissue stretches as blood is pumped into thick layer of elastic tissue thick layer of smooth thick outer an artery; it recoils to maintain pressure muscle smooth muscle maintains a tension in the artery to help maintain blood pressure thick small space outer through layer of collagen bres collagen bres give strength to prevent which layer bursting blood flows vein two endothelium outer layers low muscle and are elastic ratio smooth wall thickness: lumen lining diameter of (see vein above) increases to take more blood diameter fibres thinner little than of elastic tissue and smooth blood pressure is low so less of these are arteries muscle large present space thin outer through outer layer of collagen bres which layer semi-lunar blood flows capillary only an valves prevent endothelium, no other short cells or bres red blood a diffusion vessels of blood distance so no cell is far from a capillary cells pores inside thin backow between the endothelial perforated with pores to allow water and capillary cells solutes to pass out into tissue uid by pressure ltration When the heart contracts, blood surges into the arteries. The high blood S tudy pressure in the causes blood the aorta, stretches the which elastic is an elastic bres. The artery, ow of to widen. blood in The foc us energy arteries is Answer Question pulsatile; energy the as the stored blood blood in their forwards. pressure falls stretched The the state stretch and is elastic bres returned recoil to means recoil the that so that blood. the This blood the about the factors that end than of high for in the the Arterioles the main aorta. arteries, blood to provide a Blood as they ow pressure enter the straight resistance to entering organs, into the blood the small is thin-walled ow which 98 to nd the exchange of water inuence forces and solutes pressure only plasma and tissue uid slightly as less page out between the at 2 on the arteries is blood ows through capillaries. too capillaries. reduces the blood Summary q uestions pressure. pass Flow through is still pulsatile, capillaries but without the pressure bursting them, becomes but high low enough enough to to 1 enable pressure filtration to occur (see page Explain how capillaries are adapted 114). for the functions they carry out. Blood that ows out of capillaries has a very low blood pressure, which 2 makes it difcult for blood to return to the heart in veins. The blood is Explain the roles of the following in in blood vessels: endothelium, danger of pooling in the veins or owing backwards. The contraction of smooth muscle, collagen, elastic skeletal muscles around the veins squeezes them and helps to push blood tissue. along. helps with The The to pressure draw blood it blood has semi-lunar a in the back chest into negative valves decreases the heart. pressure, prevent when When which backow by you the also breathe heart draws lling and in and expands blood closing to from veins this ll 3 veins. contain ows the wrong why the walls of arteries capillaries. when 4 blood Suggest Name an artery that caries way. deoxygenated that 5 carries Make a veins and and oxygenated table structure blood to compare and function a vein blood. of the arteries, capillaries. 85 3.3 The heart Figure Learning outcomes The On completion of this section, 3.3.1 heart is be able a state that describe mammals the structure make a section of a have into a be heart external the and internal heart drawing of external muscular structure pump that of the forces of a the It This is what blood pulmonary pumped a into good happens atria and consists of two pumps blood through working in the series. both relax the ows into systemic opportunity as it beats. ventricles the circulation; side of the blood heart, returns which to the pumps heart it to circulation. to watch Y ou contract right oxygenated an should to force animation see the blood of events out, and the of heart systole, diastole, showing when when the they longitudinal and ll with blood. heart. The Blood vessel Type of table shows blood the functions of the main blood cavae vessels near the heart. Blood travelling from venae heart. to: four-chambered large system. Deoxygenated the you circulatory should shows deoxygenated all to the organs except the right atrium lungs pulmonary arteries deoxygenated right pulmonary veins oxygenated lungs left oxygenated left all aorta ventricle lungs ventricle atrium the organs except the lungs coronary arteries oxygenated base of aortic coronary veins deoxygenated aorta ( just above capillaries valve) capillaries within heart cardiac muscle aortic within heart muscle right sinus emptying into atrium arch superior (anterior) aorta vena cava left pulmonary right pulmonary artery pulmonary artery vena cava artery pulmonary pulmonary veins semi-lunar veins right valves left atrium coronary cavity of artery right atrium cavity right left ventricle coronary left right artery atrio- valve ventricular cardiac vein tendons valve right of atrium ventricle inferior (posterior) vena cava vena cava left descending aorta apex cavity right Figure 3.3.1 of ventriole right ventricle The external structure of the heart showing the ventricle apex septum main blood vessels and the heart’s own blood supply Figure 3.3.2 valves 86 The internal structure of the heart showing the four Module Structure right Function atrium tricuspid collects valve deoxygenated vena right ventricle from ventricle right collects from into cava; atrium to prevents atrium; pulmonary blood of systole diastole contracts relaxes opens closes contracts relaxes contracts relaxes to blood right blood pumps arteries blood to lungs Figure 3.3.3 left atrium collects maintenance backow deoxygenated right blood pumps one-way ow ventricle; right Biosystems Action during from ensures 2 oxygenated pulmonary veins; blood from pumps A heart dissected to show the internal structures of the left-hand side. You can see the left atrium, bicuspid blood valve, left ventricle, valve tendons and the to left ventricle papillary muscles at the base of the tendons. bicuspid valve ensures from one-way ow left atrium prevents left ventricle collects left left blood opens closes contracts relaxes ventricle; backow oxygenated atrium; aorta to of and pumps blood from blood systemic into circulation S tudy semi-lunar ensure valves from one-way ow of blood open close We ventricles into have three types of such of the chambers of the heart are different thicknesses. The muscle, as the skeletal walls are thinner than the walls of the ventricles as they have less Atria contract to develop a low pressure to move blood into muscle, left ventricle which blood there the The are as very ow. are a of blood The left the the tissue capillaries. to ventricle right with ventricle arterioles high right from spongy many different therefore wall pressure is blood in to how present needed is the and the high a rest much a than pumped arterioles determine Arterioles thinner ventricle few pumps is the to low of the is to is which as its attached to our muscle, which all of the appearance lungs, body, in organs name skeleton; makes up heart. They differ in the to and in the under the microscope way they function. where distributed resistance systemic of resistance the blood wall is blood vessels; the almost ventricles. which and cardiac cardiac muscle. gut atrial suggests walls muscle tissue: arteries smooth The foc us ow into and circulation. S tudy foc us Summary q uestions Arterioles 1 Draw a ow through the chart diagram heart and to show through the the pathway pulmonary taken by blood as it ows circulation. conditions but 2 Outline 3 Describe the systemic circulation in the control capillaries. They they by are pulmonary 4 State valve, 5 the artery position semi-lunar Explain and why the in of the following vein, the valves. coronary heart of chambers of the blood vessels: opening also to and into local closing, controlled by vena cava, aorta, centre in the the cardiovascular brain. artery. the following: Describe blood ow body. nerves from the functions the respond the function heart do not bicuspid of each have valve, tricuspid valve. walls of the same thickness. 87 3.4 Pulse and blood The Learning outcomes pulse routinely On completion of this section, be able dene the terms pulse and blood the role of blood the is the factors that felt as by the aorta. an aspects indication a surge of contraction The The the page of of our our circulation state of that are health. blood elastic stretch pulse. The of tissue and the ows into the ventricle. stretches recoil pulse left aorta rate travels is The under and then as wave a equivalent to surge recoils along the of blood when the heart the arteries rises and falls considerably in the left ventricle rate. (see The Figure 93), but less so in the arteries thanks to elastic recoil. table gives the minimum, maximum and normal pulse rates and pressure. pressures circulation. exercise; values S tudy foc us vary question 1 may heart calculate cardiac humans. maximum normal apply values when people does not Blood gures are people so it pump pressures is a for people are not out are for xed more blood responds pumping pumped out out beats min easy volume by returns in the by expanding the increased each to a veins to of per greater volume ventricle is of and strenuous minimum and decide blood systemic the rates minute the Blood pressure in cardiac volume blood stroke 3 blood what all the is pressures ‘normal’. time. During than per during at rest. beat. volume. diastole The The This and volume is about then of blood between 3 at 60–80 cm rate/ doing rest, Pulse the output. heart Pulse for people at asleep. always are to nd exercise, to for The the amongst The Summary how contracts, relaxes. on blood out give two affect The Answer to are circulation discuss blood the pressure 3.6.2 pressure pressure blood in heart created stretches and explain measured the ventricle pressure blood to: pressure and you When should pressure rest, output is increasing the volume to 200 cm of blood during pumped strenuous out per exercise. The minute. –1 arteries/kPa (mmHg) Pulse Systolic Diastolic The maximum 36.6 200 (275) 23.9 (180) Y ou the normal 60–100 minimum 40–50 15.8 (120) 13.3 (100) 10.5 (80) 8.0 (60) person your right should wrist artery and as be relax the mean pulse Now star for take 30 while you second until the Blood Blood are pulse the pressure 88 Taking the pulse at the wrist in dilate the wait radial you Make sure T ake rest feel your another could spot 30 then for stabilises is in to 2 vary that 3 a who two in artery, is a take runs swelling sitting minute minutes and over of the down and write calculate amongst regular of photograph. which are for ngers the slight you pulse or as considerably those do for repeat each at step a ups, few seconds. W rite this your shuttle minutes. your people, exercise after resting runs, Now down procedure minute rapidly increase as arteries all and by If The of the body but and your so ups, your pulse you exercise. press take have Keep pulse rate 30 going value. resistance and There is the not distribution arterioles all blood veins. the ows. body. it. the on blood the determined to overcome acting which vessels is needed pressure through blood drops Figure 3.4.1 the Place way pressure capillaries and in pulse. same volumes. the and her the What often Y ou recorded rate at are on then waiting pulse atmospheric vessels exercise. rates it. for rates in pulse minutes. stroke run taking skin. this rate large and the the is wrist through Pulse just seconds feel few pulse with or a left to Repeat rate. some jumps to surges for low hearts your close value. with photograph on able blood then have the bones down those in hand these ows that into at ow blood once, capillaries to the blood blood to ll all through reduce the and from small enough of constrict open to many blood there blood ow pressure is little left Module Constricted greatest lungs in than ventricle diverted is greater V olume of (see page are blood to be left-hand by by the ow fewer pumped than on of blood. arterioles out oxygenated circulation. side three the are by and This the the blood means This in is the right is not that blood right. factors: heart; blood pressure increases if in the blood blood vessels; vessels. It blood falls if pressure there is is high blood loss if there or is more arteries; harden. blood This pressure happens rises with if age the and arteries with become some Figure 3.4.2 Link 161). sensory Taking blood pressure diseases cells in the body that detect changes in blood pressure. There The maintenance capillaries. the or the systemic pumped in into of elastic the all to There Biosystems increases. blood less resistance tissue the inuenced blood ows as lung in on blood of of Elasticity There is volume V olume blood as a circulation. organs through pressure plenty other goes stroke in provide systemic elsewhere pressure Blood arterioles the 2 cardiovascular centre in the brain responds by coordinating is more about the coordination the of the heart and blood vessels on following: page changes loss constriction or blood circulation; of in the water heart from rate the and strength kidneys if the of 90. contraction blood volume is too high, and S tudy in the dilation of arterioles to constriction alter the increases distribution the blood of foc us the pressure and When you draw the dilation High and blood decreases low blood pressure enough may oxygen. problems, such it, restoring pressures mean High as so that blood heart are it to indications tissues, pressure of people’s especially is graph for normal. an the indicator health. brain, of do many Low not receive health disease. Summary question 5, you the vertical pulse on the axis for can draw left and the vertical axis for blood pressure on the right. Alternatively, you draw two this, separate graphs. put one directly other and scale. This use the underneath the same helps to can If you do horizontal make comparisons. Summary q uestions 3 1 A person has a stroke volume at rest of 70 cm . The heart Time/min rate The is 75 beats cardiac 3 25 dm per minute. Calculate output for a man doing the cardiac strenuous exercise ; calculate the stroke volume if the rate/ beats per Blood pressure/kPa heart min Systolic Diastolic is –1 min Pulse output. rate is 0 65 16.0 10.0 5 69 16.5 10.3 –1 120 beats min 2 Suggest why ventricles volumes 3 Dene the terms Distinguish 5 The table 20 a Draw who minutes a volumes the during rates rested for graph then to blood at ejected any one by time, left and and b right the 7 100 19.5 10.3 9 120 21.4 10.0 11 121 23.7 10.5 13 122 25.0 10.3 15 121 25.4 10.7 17 123 25.6 10.2 19 124 25.7 10.6 20 123 25.3 10.4 21 115 16.3 10.3 23 80 21.3 10.3 25 68 17 .3 10.2 exercise. and systolic pulse and of same pulse rate between shows athlete for the always increase 4 an a are 5 and and diastolic blood minutes, rested show blood pressure the blood pressure took pressures. recordings for vigorous exercise again. changes in pulse rate and blood pressure. b Describe pressure. and explain the changes in pulse rate and blood 89 3.5 Control of the Every Learning outcomes split On completion should be able of this section, heart time second arteries. you the later , These dene state the term nervous myogenic the sino-atrial node heart’s state that specialised cells throughout explain conduct the how activity discuss affect the the as the muscles contract heart in described skeletal comes from heart the of brain the together together muscle need forcing to be and then, blood a into the coordinated. on muscle your arms pages in and 120 that it to is legs 125. is done entirely Cardiac myogenic as muscle the by the is stimulus to within muscle the cells muscle that itself. initiate There (start) is a the system heart of beat impulses, which spread across cardiac muscle so it by contracts and that the way. It ensures ventricles that contract the from ventricles the base contract upwards. after the in atria This system is: right atrium; inuences sino -atrial node (SAN) situated in the muscle of the this heart internal factors heart cardiac coordinated is of contract impulses the ventricles atria cardiac a two pacemaker emitting muscle of from specialised the is contract the the actions system different that beats to: Coordination heart often called the heart’s ‘pacemaker ’ that atrioventricular Purkyne node (A VN) situated between the atria and the ventricles action. bres muscular that wall run between down the towards ventricles the and apex into of the the heart within ventricular the muscle. Did you know? S tudy The human heart beats about Muscles –1 75 beats min . Heart rates of are very resting muscle. They skeleton that we are not use myogenic. The in movement instructions to are skeletal or contract come from different. The the elephant’s attached to the other striated mammals foc us heart rate is brain and the muscles are neurogenic. about –1 30 beats min and the tiny Etruscan –1 pigmy shrew’s is Cells 1500 beats min in the impulses Cardiac SAN that act travel muscle as the across consists of heart’s the ‘pacemaker ’ cardiac muscle interconnected by in cells emitting the so atria. that the superior aorta vena impulse cava spreads across the muscle in all directions. This impulse pulmonary stimulates the atria, which begin to contract. The impulse vein sinoatrial cannot pass directly from the atria to the ventricles because there node is right a ring of impulse atrium passing non-conducting reaches to the the AVN Purkyne brous where bres it that tissue is separating slowed conduct for the the 0.1 s two. The before impulse to the left atrioventricular base of the ventricles, and then to the rest of the muscle in the atrium node walls of the ventricles so they contract from the bottom upwards. left right ventricle ventricle S tudy foc us Purkyne tissue Figure 3.5.1 ‘The AVN The positions of the SAN, AVN and of the delays and relays’ – a way to remember the role of this part heart. Purkyne fibres in the heart The but AVN after therefore a short The heart The activity rate is relays the impulse from the SAN to the ventricles, delay. not entirely dependent on the rate of ring of the SAN. Did you know? of the SAN is inuenced by the nervous system and by hormones. Purkyne bres Purkyně them. named (1787–1869) His Purkinje. are name is after Jan who also discovered spelt as The cardiovascular monitors by the internal The heart and cardiac accelerator 90 centre rate in and external factors. accelerator nerves to the medulla increases There centre the SAN, oblongata and are sends AVN at decreases two parts impulses and the the to via base rate this the throughout as of the centre: cardiac the brain inuenced heart. Module The cardiac inhibitory centre sends impulses via 2 the brain cardiac Figure The decelerator 3.5.2 shows terminals of the the neurotransmitter nerves to the SAN arrangement cardiac of these accelerator nor-adrenaline. The and AVN. nerves. nerve SAN release also the responds cardiac to the hormone adrenaline. The terminals of the inhibitory centre cardiac decelerator decelerator nerve release acetylcholine . These three sinoatrial nerve chemicals of SAN bind cells to and receptor proteins inuence the in rate at the cell which membranes they (inhibitory) node cardiac emit (SAN) accelerator atrioventricular impulses. centre node (AVN) Did you know? spinal The cardiac nervous accelerator system that nerve we use is part during of the times sympathetic of cord (stimulatory) danger Figure 3.5.2 and stress. The cardiac parasympathetic decelerator nervous system nerve that, is part of amongst the other The activity of the heart is controlled by the cardiovascular centre in the brain, which sends impulses along these nerves to increase or decrease heart rate and force of things, contraction controls digestion. sympathetic Some system, people but it is have survived impossible to without survive a without Did you know? the parasympathetic system. The cardiac part Factors that affect heart rate a of Latin There Stretch receptors changes to the in in blood heart in the aorta, pressure. the vena carotid During cava arteries exercise, increases. and the This in the volume increases vena of cava blood the and increases impulses to the brain, which an a and rate via carotid increase heart in the cardiac artery are impulses accelerator stimulated in the by cardiac nerve. high When blood decelerator receptors of pressure, nerve this and a the the pass neck down dioxide and oxygen increases and/or increases to During metabolism heart slows nutrients, such mammals that oxygen also decrease that spend rate and glucose. in long diving the is is spend mammals, periods the dioxide decreases, decrease demand even such in leads to decrease the the the spine excitement, exercise increasing the the and then stimulating the more as as for and thorax an viscera in and even viscera the most and or the gonads. The comes from bowels of the Latin guts. carbon concentration heart in seals, the rate Summary q uestions and down dormancy. dolphins 1 Dene 2 Explain the term myogenic body ’s oxygen slowing periods anticipation brain frequency the branch the innervating in and in those Heart rates the the whales, the roles initiation heart beat: of the following and control SAN, AVN of and Purkyne bres. of to increase impulses in of danger the heart the cardiac and rate. the start This is of done accelerator The SAN 830 ms by nerve SAN is emits in a not release of adrenaline. Both stimulate the SAN impulses person at every rest. inuenced by If the any and other factors by side submerged. anger , stimulate either throughout abdomen, 3 Pain, the blood. less long changes carbon pressure there There or of blood and hibernate If detect concentration oxygenation down as arteries concentrations. the improve sleep, carotid that brain. They in word for the nerves hind aorta rate. in is wandering. these originate from term Chemoreceptors of is this increase in meaning pair nerve nerve. Vagus returning stretch stimulates word is ‘wander’ heart decelerator vagus detect of vein the what is the heart and rate? AVN to increase the heart rate and force of contraction. 4 The heart rate increases during digestion to increase the blood supply Explain and the gut. The blood supplies oxygen to support a higher rate of the nutrients needed to make body temperature increases during a fever , the heart rate pump more blood to the skin’s hormonal rate Name when the body temperature heart rate increases with system the heart surface to lose heat. The decreases as in the factors heart inuence beat. rate. that Explain inuence how the rate responds to changes in the hypothermia. factors The of heart heart slows system increases the to nervous enzymes. 5 When the respiration the and how to that you have named. age. 91 3.6 The cardiac cycle On Learning outcomes page 86 Remember On completion should be able describe of this section, you to: the changes that the heart during saw that the left side the same the contraction the the right pumps on left taken side of oxygenated and of route right the as two by the heart blood. the blood two it ows pumps Changes atria ventricles. as The deoxygenated that contract two through occur in together sides of the the heart. blood the and heart followed heart are by go occur through within we one the same changes simultaneously. heart beat S tudy explain that the cardiac usually depicted as the cycle pressure Trace changes that occur in the the left ventricle explain how and the heart pressure open and atrioventricular changes close and in to ensure taken within the blood using through Figure the 3.3.2 heart on and page the 86. pulmonary Do not and confuse the by blood heart with during the one cardiac heart cycle, which is the changes that occur beat. the biggest changes in pressure occur on the left side of the heart so it is one-way ow usually of by by semi-lunar The valves taken circulations aorta route route left systemic atrium, foc us is the left that is used to show the cardiac cycle – all the changes blood. that occur There are relaxed in and valves two and drawing right within empty main lling blood left into pressure are during phases with to The arteries As venae blood is beginning This ll heart cardiac this cycle. and than with is Imagine the the though phase beat. happens cavae ows higher to one the blood. the ventricles. the and heart from atria. the in the heart the open blood. T o make heart is veins into the atrioventricular During ventricles, the expands, pulmonary diastole. the that this which sure phase are blood nearly blood does not from from ow back from arteries to ventricles, the semi-lunar valves at the base of lungs body the arteries phase the heart diastole are known systole. blood right left atrium atrium into on the either Y ou can graph side see arteries. of As SAN contract full rst, spreading start happens because systole the the blood This begins, so contract valves contraction open. upwards to atrioventricular the emptying valves ventricular and ventricles the initiate with blood and pressures into atrial squeezing the shut is are opening different valves. you changes are the the atrioventricular base This these if the forcing valves. this shows at from atria the ventricles increases, semi-lunar The keeps starting the Impulses systole. which When pressure the as ventricles contractions filling closed. follow in the blood graph pressure in in Figure the 3.6.2 left side carefully. of the The heart during left one heart beat. Follow the changes by putting a ruler vertically against the ventricle y-axis At right the and moving beginning it of to the the right. graph the heart is lling with blood. The left ventricle atrium heart full of and left ventricle are relaxed and blood is owing from the blood pulmonary bicuspid veins valve into into the the left left atrium. ventricle. Some The blood SAN ows sends through out an the impulse open and to to the atrial muscles contract. Blood pressure rises in the atrium and blood lungs is forced The into atrial Purkyne the muscles bres contract. left to Among ventricle. stop contracting; muscles them at are the the the base of papillary AVN the sends impulses ventricles muscles at that the through start base of the to the heart tendons of the bicuspid tendons become valve. The papillary muscles contract, the valve systole pumping Figure 3.6.1 Diagrams of the heart at different stages of the cardiac cycle 92 upwards. than in Blood the taut is aorta and forced so the the into ventricle the contracts aorta; semi-lunar pressure valves open. from is the bottom greater Pressure in is the ventricle greater in the Module 2 Biosystems S tudy left atrium left ventricle contracting You relaxing should graph. It maintenance foc us be able helps to interpret to follow the this changes relaxing in semilunar valve opens semilunar valve the heart with searching for (X) an animation. Try closes ‘cardiac cycle (Y) animation’ to nd something to help 15 aPk you. / erusserp 10 5 atrioventricular atrioventricular valve closes valve S tudy opens foc us (Z) (W) 0 We are using pressure mc 3 the is SI units given medical as in this kPa. profession book, so However, uses mmHg / elcirtnev tfel (millimetres 150 pressure. that 80’ If your then of a mercury) for health blood that worker pressure is is a systolic and a diastolic blood tells ‘120 you over pressure of 100 fo 120 mmHg emulov of 80 mmHg and is pressure perfectly normal! 50 0 0. 1 0 0.3 0.2 Figure 3.6.2 / 0.7 0.6 0.5 0.4 time 0.8 s This graph shows the pressure changes in the left side of the heart and the aorta during one cardiac cycle left in ventricle the than tendons atrium. forced Blood out of in the prevents pressure the left the rises ventricles, atrium valve to a the so the from peak bicuspid ‘blowing and muscles then relax. valve back’ as all Blood closes. into the blood has pressure T ension left Summary q uestions been in the 1 ventricle falls, but thanks to elastic recoil in the aorta the pressure Explain term maintained below the above that pressure in in the the ventricle. aorta so the Pressure in semi-lunar the ventricle valves close from the aorta into the ventricle. As pressure lower in the ventricle than in the atria so the bicuspid Explain what valves graph shows that at W and Z the pressures in the left atrium and ventricle the W, left change ventricle the with and respect the aorta to each change other . with At X and respect to Y, the one Figure 3.6.2 pressure This in forces the the left ventricle bicuspid valve increases to close. above The that blood ‘aps’ of the valve and the valve tendons prevent the in the moves left X, the the into the Explain valve Y, This in the causes left the ventricle semi-lunar increases valves to so that open so it is above that blood that left why the so atria Z, blood ventricle that aorta the in it lls blood the blood the does heart in pulmonary not ow the venae veins while is relaxing and expanding. The blood is lower the than ‘pockets’ that of of the the blood semi-lunar in the valves left pressure atrium of so the the ventricle bicuspid decreases valve to blood-pressure that side of occur the on heart the and right- in pressure aorta. and below contract. the changes The they pulmonary that of artery during blood cardiac cycle. The maximum close. blood At and Sketch one from beats of the decreases in ows aorta. the rate ‘blowing hand At heart minute. atrium. pressure aorta. the 0.8 s. left 5 the that lasts for under the At one pressures cavae into shows cycle away from back’ closes during another . 4 atrium. the and heart the per At opens the cycle. Calculate in in again. cardiac left the valve 3 The by it cardiac opens meant prevent decreases the becomes is cardiac cycle decreases to 2 backow what is the artery pressure is in the pulmonary 4.0 kPa. opens. 93 3.7 Haemoglobin Haemoglobin Learning outcomes four On completion should be able of this and section, you parts with molecule outline the structure of of explain molecule is are two associated iron changes protein in the shape, how haemoglobin haem Each haemoglobin to form the transport group. When easier structure. polypeptides for and two Oxygen this The β-globin combines happens, haemoglobin molecule can transport the to whole accept four molecules more of oxyhaemoglobin: the oxygen one interacts molecule → 4O HbO of with oxygen oxygen to 8 in a cooperative haemoglobin makes it fashion. easier The to binding bind dissociation another; adult + 2 of curve for quaternary haem group. it of Haemoglobin describe a oxygen is oxygen a α-globin with making Hb suitable for with of haemoglobin oxygen conjugated Each the transport a oxygen. molecule a the polypeptides. loosely to: of is the once the second one has bound, it makes it easier to bind the human third and so on. This cooperative binding is responsible for the results haemoglobin obtained explain what the shows about the supply is S tudy haemoglobin oxygen bright foc us dark a good idea to revise binds of it at all oxygen is a it dark Deoxygenated volume in haemoglobin to take up changes of red colour . blood oxygen colour . Blood that in that the Oxygenated does body has haemoglobin blood about can in not 70% carry the have of and body the is also fairly colour . pressure example, is the the pressure atmosphere exerted is a by one mixture of gas as oxygen, part of a carbon gas mixture. dioxide, haemoglobin from Unit nitrogen before reading these two haemoglobin and and other gases. The percentage by volume of oxygen is 21%. sections The on of the For structure in red. red Partial 1 ability oxygen. maximum is the oxygen. any It into transport As of investigations dissociation and curve from transport pressure exerted by the atmosphere is 101.32 kPa, so the partial of pressure of oxygen ) ( pO is 21.28 kPa. Blood is oxygenated in the alveoli 2 oxygen and carbon dioxide in the in blood. See 1.8 in Module 1 of Unit the lungs where more humid means the in shape of a pressure oxygen the in pO is less water the – it is vapour alveolar air allostery. The non-competitive concentration of is the same, but about exerts is a 13% since partial the in is Module binding inhibitors another 1 of Unit to parts of the much This Partial example. oxygen can be equated pressures See 3.5 1. The in in with the tissues are oxygen is of much being The 13.3 oxygen lower used table pressures as of parts of 5.0 shows oxygen the muscle in muscle, e.g. 3.5 in during different )/kPa 2 active partial (pO partial atmosphere. concentrations respiration. Did you know? pressure of body resting strenuous body. exercise 3 100 cm is too. 13.3 kPa. Tissues of different the Each air pressure lungs enzymes the oxygen protein in is air 2 The molecule of and Link change total 1. concentration The the of blood of oxygen. About can carry 3 about 20 cm 3 0.3 cm same of oxygen volume oxygen of know it animals, copper such rather molecules animal would be as in life as like we impossible. lobsters, than iron in Thought experiment Y ou know the water. Without transport haemoglobin, dissolves have transporting that you experiment. exposed to changes can We increasing of in availability haemoglobin carry will out think in in schools through concentrations of the of oxygen blood. or what inuence This colleges, happens is so the not an let’s do when a blood is oxygen. blood start with let’s just see what happens to blood when exposed to oxygen. oxygen. Blood of oxygen to stand, This 94 how capacity thought T o for to investigation Some their need oxygen-carrying is in the our it taken even colour blood from a though goes sample vein it even is is dark called darker which has red in colour . deoxygenated as no oxygen oxygen blood. leaves in it. This the has If quite this is a lot left haemoglobin. Module Part A. Bubble some oxygen from an oxygen cylinder through some of 2 Biosystems the S tudy blood sample. The equal volumes blood will become 3 (e.g. much brighter red. If you 5 cm ) of this bright red blood with the dark This red blood, you will have an intermediate colour which has 50% of thought volume of oxygen that the blood will carry. Carry on experiment can be the carried maximum foc us mix 3 + 5 cm a maintenance out for real with equipment doing that controls the pressure of the 3 this with other mixtures of these two samples of blood (e.g. + 7.5 cm gases and determines the percentage 3 ) 2.5 cm and record the colours. saturation Part in B. it) the Now and a valve take another cylinder on the of sample oxygen nitrogen of and cylinder dark a red blood cylinder and of expose (without nitrogen. the blood any Start to oxygen by opening nitrogen at recording of haemoglobin changes the blood. The the pO in the graph is by colour printed of out as the changes. 2 pressure of air haemoglobin nitrogen low be in the nitrogen lungs. of not and W atch at the the is until colour blood remains nitrogen. the Keep oxygen oxygen The absorb open Look some and lungs. oxygen. lungs. as the does slightly pressure slightly in valve the of total colour of Now the gas the Now it the change as you dark reduce oxygen keep gas red the pressure It the will mixture the to same in the the as of as it a very Summary q uestions would very pressures alveoli oxygen the allow change changing increase colour cylinder pressure blood. absorbed. reaches a in pressure of the up Use the and in found in the 3.7 . 1 have blood dark comparing the results red to from bright colours with our red. our It thought is experiment: possible mixtures of to the quantify blood made colours these in part of results the Is the low by percentage 3.7.1 shows the results of our thought experiment when oxygen these saturation with the is a oxygen of partial low, and high pressure b or of high? A. 2 Figure section alveoli. qualitative from this answer to haemoglobin W e in to questions. 1 that information Figure plotted on a What is the likely percentage graph. saturation a the c active of lungs, haemoglobin b resting in muscle, and 100 80 3 htiw f o noitarutas negyxo muscle? What happens to the saturation of the pressure percentage haemoglobin as 60 partial egatnecrep nibolgomeah decreases to the of oxygen likely range in 40 the 20 4 The of tissues? P50 is oxygen the at partial which pressure the Figure 3.7.1 0 haemoglobin 0 2 4 6 partial Why is when this you curve(s) read to the (which from right a the represents left called an right. left, you With loading represents to pressure oxygen graph 8 of of 12 start this at the graph with unloading of dissociation it is (on better oxygen oxygen dissociates dissociation curve origin from in the to the from curve? left) start and at lungs) the follow the and blood). Remember , as you answer the oxyhaemoglobin questions, that the right move As – with oxygen. your graph. you the 5 does (which respond to tissues the read hence graph How and of response an of experiment haemoglobin to investigate to the graph of oxygen. represent the Some S tudy points in – but only a few. Notice that What part of the line coincides is the Make a copy of the pressures where of oxygen in the respiring oxyhaemoglobin 75%, haemoglobin dissociation provide decrease them in the with oxygen. in pO the dissociates A respiring oxygen? the pressure of percentage of and haemoglobin b is 90%? The on a piece of graph partial can annotate show which your part is slight tissues to loading which in part is the pressure of oxygen curve the lungs is 13 kPa. What paper. You graph to the percentage to if the partial pressure equivalent in to of oxygen saturation tissues lot partial when happens partial a through actively on the the with are up saturation foc us in steep blood ows the 7 body as the different situation P50 from the shows a concentrations saturated the oxyhaemoglobin that using oxygen results 50% State Normally 6 name. is An oxygen haemoglobin 14 oxygen/kPa haemoglobin blood oxygen 10 lungs the lungs falls slightly? and equivalent 8 to Explain how haemoglobin is 2 stimulates a lot of oxyhaemoglobin dissociation, giving its with oxygen to the unloading in to the answer the tissues. Use questions. it adapted the to lungs transfer to the oxygen from tissues. tissues. 95 3.8 Haemoglobin and the transport of carbon dioxide More Learning outcomes for On completion of this section, you carbon this be lists able the dioxide that a ions (HCO is of ), transported the carbon which are in the blood. dioxide is transported The reason converted in the into plasma to buffer the blood against changes in and pH. to: ways is oxygen proportion 3 help in which carbon Loading the dioxide than large hydrogencarbonate which should is transported in blood with carbon dioxide the Carbon dioxide diffuses into the blood from respiring cells. It is highly soluble blood in explain the role of water and in the transport dioxide describe dioxide the on the plasma not effect haemoglobin it dissolves in the plasma. About 5% of carbon dioxide of in the blood is carried this way . Some also reacts with water in of the carbon of carbonic transported anhydrase some carbon to catalysed form by hydrogencarbonate an enzyme. concentration gradient diffuses through easily into the Most red ve of the blood cell ions, but carbon cells. surface this is a dioxide Carbon slow diffuses dioxide membranes reaction is into down not red as polar , blood it is its so it cells. oxygen dissociation curve. Some of –NH terminals the carbon of dioxide the that enters polypeptides red that blood make cells up combines haemoglobin with to the form 2 carbaminohaemoglobin . transported S tudy are the ve membranes that cell carbon remaining ions. surface dioxide Inside anhydrase, 85% red of blood which carbon cells diffuse also pass through intracellular pages dioxide in the blood is is transported of the as hydrogencarbonate enzyme carbonic reaction: anhydrase carbonic water hydrogen → hydrogencarbonate → membranes from production. What are + acid ion ion their carbonic See carbon two + of the molecules this dioxide site of through? They carbon will 10% dioxide are catalyses carbonic molecules About way. foc us The What this anhydrase they? + CO 84 and 24 for answers. Did you know? enzyme into hydrogen two dioxide Let’s anhydrase is one in take acting O → H ions the the is CO 2 catalyses ions the and most → H + HCO 3 3 formation of carbonic hydrogencarbonate important for the acid, ions. which What transport of dissociates happens oxygen next and to carbon blood. hydrogencarbonate ions rst. While the red blood cells are of travelling the fastest H 2 The these Carbonic + 2 the enzymes. along capillaries in respiring tissues, the hydrogencarbonate ions Its accumulate inside the cytoplasm of the red blood cells. Their −1 turnover number is 600 000 s , concentration which means that as cells though capillaries tissues, one in respiring molecule can through to 600 000 associate molecules of per second, with for the cells into hydrogencarbonate the lungs reaction it just catalyses as rapidly. the reverse lower ions sodium hydrogen they the plasma into the so they plasma diffuse where out of the they ions. would ions. If lower Haemoglobin on as the When it constant the absorbed carbon which is the the these the acts as rate there by of of a dioxide allows lead When were pH and buffer , to in oxygen to the for allowed this to would absorbing of happens oxygen. accumulate decrease the from in the hydrogen blood aerobic reduces production the increases more as ions red activity ions oxygen stimulates: in the of effect it the link reliance lactate the to and in in release occur of to of and anaerobic last The the cells, during more are in oxygen, decarboxylation Krebs cycle. respiration, to has tissues. increase more more a sentence dioxide tissue red have hydrogen respiring the with eventually that muscle in of carbon released. reaction on Read that does is haemoglobin absorption produced respiration compounds makes oxyhaemoglobin hydrogen so it The oxyhaemoglobin. understanding more more this afnity haemoglobin dissociation would or respiration are intermediate extra pH. dissociation key unloading exercise, of a ‘attractiveness’ promotes again 96 in proteins ions. maintain In that converting enzymes. them than channel carbon blood dioxide greater special process Now up is blood ows fatigue. This which Module 2 Biosystems maintenance 100 partial f o noitarutas CO S tudy pressure 1.0 foc us kPa 2 2 O htiw 80 Look partial carefully dissociation CO at the oxygen pressure 1.5 curves in Figure 3.8. 1 kPa 2 egatnecrep nibolgomeah 60 and re-read loading 40 Notice the blood where paragraphs with the Oxyhaemoglobin 20 tissues because carbon word the dioxide. more unloads of about is used. oxygen low pO in but, if 2 the pCO in the tissues increases, 2 this 0 0 2 4 8 6 10 12 stimulates more. partial pressure it to unload even 14 Do not forget to use the word /kPa of O 2 ‘more’ Figure 3.8.1 when explaining this effect. This graph shows the results of an investigation to find the effect of carbon dioxide on the oxygen dissociation curve Unloading When the reverse. carbon dioxide from the blood There reaches is a low the lungs, all concentration the of blood changes carbon described dioxide in above the go lungs into so S tudy some carbon dioxide concentration of starts oxygen diffusing in the out alveoli of and the blood. this Also, diffuses there into the is red a blood What cells. At high concentrations of oxygen haemoglobin has a higher foc us high are the ve membranes for oxygen than hydrogen ions, so these leave and provide a substrate reaction catalysed by carbonic that surface carbon dioxide for molecules the cell afnity diffuse through in the anhydrase: lungs? carbonic anhydrase + H + HCO → H 3 The red carbon cells, dioxide through diffuses ve cell CO 2 down surface → H 3 its O + CO 2 2 concentration membranes into gradient the out of the alveoli. Did you know? The can effect be study seen this difference this, of put tissues. x-axis. in the graph ruler Y ou Put at could your with dioxide graph. more between a saturation that carbon The choose oxyhaemoglobin is is The any less when unloads more shifted each of partial and of to important at pressure vertically oxygen saturation curve saturations partial ruler the carefully . the a on the pressure off carbon right. point partial oxygen read haemoglobin Use about pressure between values of dioxide is 3 and from a this corresponding the with oxygen ruler is oxygen. to that 5 kPa the present. This to the the T o in on with the after Christian The of oxygen effect the y-axis. This see effect is of it. the famous dioxide on haemoglobin known the Bohr discovered means carbon saturation as Danish the (1855–1911) His son Bohr physiologist was who Niels Bohr, physicist. oxygen. Summary q uestions 1 Describe cells to how red carbon blood dioxide passes from respiring cells. 5 Copy a 2 a State four ways in Figure which carbon dioxide in the The partial which of these is the the most of the carbon and answer these pressure saturation of oxygen of in tissues haemoglobin is with 5.0 kPa. oxygen pCO is 1.0 kPa and 1.5 kPa. Describe Explain the role of carbonic anhydrase in red blood cells. Explain carbon the role of the following in anhydrase the transport of State the haemoglobin c plasma. of increasing with name on the the carbon saturation of oxygen. given to the effect you have described. d Explain the delivery b effect concentration haemoglobin c dioxide: carbonic the dioxide. dioxide a paper responsible for b 4 graph 2 Explain transporting 3 to blood. when b on is State transported 3.8. 1 questions: of signicance oxygen to of this respiring effect in the tissues. 97 3.9 Practice The Answers to 1 a all Explain The total some why was multicellular need diameter also of three a the were can animals, transport and blood vessels thickness mammalian exam-style questions mammals, exam-style the measured. The tissues in determined. The the b walls results are walls i ii the table. c i pressures along Calculate the the at in the length effective the two table of the blood ends of do not capillary. [2] pressure for the capillary. [2] Blood vessels ii Artery Vein Capillary 4.0 5.0 0.008 Use the overall blood [1] other change filtration Feature pressure of the decreases these vessels the why: the hydrostatic of relative of in Explain [3] of system accompanying CD. as system. thickness circulatory be found on the such questions: diameter/mm thickness of thickness of wall/mm 1.0 0.5 0.0005 0.5 0.5 0.5 of d the results directions the of your taken calculation by fluid at to the state two ends capillary. [2] Explain: i the role ii how of tissue fluid its volume is [1] kept constant. [2] endothelium/µm thickness of elastic 0.730 0.025 3 0 Figure the a of smooth 0.34 0.30 is a diagram B of A tissue/mm thickness 3.9. 1 heart. i Name A, B, C and D. [4] ii Explain C 0 why the muscle/mm D chambers b Describe walls of the functions of the three tissues in the blood vessels. and [3] Y labelled have different walls X of thickness. [3] X c i Calculate, for each blood vessel, the b wall Explain the meanings of Y thickness as a percentage of the the overall terms i blood pressure, Figure 3.9.1 diameter. ii Discuss the significance calculations for the of the transport results of of blood a The to function table exchange shows the between a as of capillaries that capillary involved and the in pulse. the [2] roles atrioventricular controlling 4 allow exchange vessels. pressures ii Explain [4] State THREE features them c your in these vessels. 2 and [2] [3] The out cardiac by The the surrounding the of output diagram is shows cycle over sino-atrial and beating a of in 1 the node, Purkyne fibres the the volume each ventricle cardiac the node in heart. of [6] blood pumped minute. events period of that two occur in seconds. the During 3 tissue fluid. The the arteriolar distance end and along the capillary the venule end Arteriolar end is between this time the was 75 cm 0.8 mm. 0 Pressures stroke volume Venule 0.5 1 1.5 2 end time/s atrial hydrostatic of pressure 4.26 a potential of 3.33 b pressure i Calculate the heart ii Calculate the cardiac 0.07 diastole rate. [1] State THREE output. internal factors that [1] influence the 0.07 cardiac of systole 3.33 blood/kPa hydrostatic ventricular Figure 3.9.2 blood/kPa solute systole 1.33 output. [3] tissue uid/kPa c solute potential of 0.67 Describe the roles of the following in the action 0.67 of the heart: tissue uid/kPa i atrioventricular septum ii bicuspid valve iii papillary iv semi-lunar valve [1] [1] The formula for effective blood pressure for filtration is: (HP of (SP 98 blood of – blood HP – SP of of tissue fluid) tissue fluid) – muscle [1] at the base of the aorta. [1] Module 5 a Describe what b Describe how happens in the heart during one cardiac cycle. i the sudden heart responds demands of of a exercise at an increase in race could Explain in 6 a b how are the blood pressure. some have responses a you have described distance [4] closed, double circulatory one. Plot area and Explain what is meant by this blood (e.g. Discuss the table gives advantages The table also data statement. of this type on five features see vessels of each arterioles, all type the total given capillaries, Blood vessel table in of circulatory of six different cross-sectional the table: all veins Length/mm the to draw x-axis and the of the the axis) to each cross-sectional blood ow the relationship on between the the graph two system. through area aorta, both venae the [3] have to do this because blood vessels. of all all the range of lengths is so great. blood arteries, all cavae. Overall Lumen diameter/mm sectional cross- Blood pressure/kPa Speed of blood –1 area/mm flow/mm Minimum left s Maximum 550.0 25.00 250 12 18 40 35.0 2.00 500 10 16 40 4 000 9 14 10 170 000 8 11 3 renal as systemic 2 aorta the same [2] the shows the giving on the gures for circulation. You The in Make vessels, 10 mm speed blood ows ii data graphs. system. to i the [1] coordinated. Mammals use [2] different c foc us the yourself ii maintenance to: You beginning Biosystems [6] S tudy the 2 artery arteriole 3.0 0.07 capillary 0.8 0.008 left renal vena 7 cava b Describe c Explain d There flow One of vein and why is not 75.0 6.00 25 000 1 300.0 12.50 1 000 –2 explain two enough through the blood blood organs the functions of relationship pressures is in the human controlled blood is to between (maximum to body make transport the and diameter minimum) to fill sure that all of of the demands carbon given for capillaries of and each at different 0.3 0.5 the vessels are 0. 1 the the 20 speed of the blood. [3] blood vessel. same tissues are time. [3] Explain how blood met. [3] 100 dioxide. partial a Outline shows dioxide the on respiring effect the of when partial [5] pressures dissociation curve haemoglobin. of 5.0 kPa at the two partial pO 2 pressures of carbon dioxide, 1.0 kPa and 1.5 kPa. c i State the pCO on name the of the effect saturation of of [1] 80 1.0 kPa 60 partial pressure CO 2 1.5 kPa 40 20 increasing haemoglobin 2 egatnecrep State the percentage saturation of haemoglobin with oxygen at a pressure CO it cells. two oxygen dioxide nibolgomeah for b 3.9.3 carbon carbon O htiw of blood from to 2 Figure the happens f o noitarutas enters what with 2 oxygen. [1] 0 ii Explain how ensures tissues an the effect efficient during you have delivery exercise. of 0 named oxygen 2 4 partial to 6 pressure 8 of O 10 12 /kPa 2 [4] Figure 3.9.3 99 2 Bosystems 4. 1 Homeostass Learning outcomes mantenance Working Y ou On completion of this section, will recall be able dene point, and the terms homeostasis, set negative feedback, receptor effector explain the effectors in of will roles of receptors and in then stop. a to enzymes Most keep explain enzymes Changes work in efciently these two if kept factors at cause a the the enzymes multicellular reactions to denatured work in inside the organism change. and the cells. cytoplasm there is a If The and limit the changes reactions to cells have nucleus what they are catalyse various constant, each can but achieve. homeostatic near concept homeostatic that pH. are conditions Homeostasis explain 1 and enzyme-catalysed extreme ways mechanisms Unit temperature to: rates from you constant should efficiently that and of using the maintenance level. various This ways is to of done conditions by inside monitoring maintain these the body physiological within narrow at a factors limits. equilibrium negative feedback mechanisms is constant are Temperature control dynamic. Birds and methods these mammals to control animals are the their varies, only own but it animals body is that have temperature. usually complex The somewhere in body the physiological temperature range of 35 °C of to Link 42 °C. below) This the is a good effect enzyme and 3.6 of opportunity temperature Module 1 1. of Unit only that of can their they maintain surroundings, the temperature they can keep it above (or slightly constant. revise and activity from Unit in to Not pH See on T emperature control is achieved by: 3.5 monitoring comparing the temperature of the body and the surroundings 1. the temperature controlling actual or set body temperature with the desired point effectors to conserve heat, generate heat or lose heat. body temperature effects on °C humans The body increase Figure 47 cells damaged 4.1.1 44 temperature heat stroke limit body of normal lower 34 temperature beats 23 breathing receptors heart of normal of very narrow little. temperature Y ou limits. can change see outside It does from serious, if not this fatal. This is an example mechanism of has one the of the body ’s following homeostatic components: that monitor core body temperature and the temperature of range control coordination centre effectors systems – nervous system circulatory system and hormonal and muscles system irregularly in the skin, to bring about stops stops to alter the temperature of the body. beating body ’s does it spinal from Effects of changes in body temperature on humans thermostat have flowing 100 effects very regulation fails The Figure 4.1.1 within surroundings changes 20 kept temperature 36 25 is fluctuates range the limit the are control mechanisms. upper mean range T emperature 37 that but regulation fails 42 fever 37 .6 temperature decrease permanently narrow 45 core and its own through cord nerve and the endings of useful the when warning’ that heat and loss the the cells but organs in the hypothalamus that it skin. starts body promote to the Skin and get in the the information temperature this lose fall conservation is from of in if heat. body. is It nothing the the often information and will brain. Not temperature temperature cold temperature heat monitor receives about surroundings body the in brain, other temperature is nerve only the nerves blood close blood in and to the also the particularly acts is of as done an to ‘early reduce Module If the temperature is less than the set point, the posterior part of 2 Biosystems the S tudy hypothalamus from the skin instructs surface. the skin Muscles to in conserve the heat arterioles by in diverting the skin blood contract blood supply to capillaries. This is vasoconstriction. If this to fails the core temperature near the set point, the posterior to the body to produces generate heat. The heat. rate The of contraction respiration in of the muscles liver this heat. heat is individual Blood then hairs flowing through distributed to trap a muscles around deeper the layer and body. of air , the liver Mammals which acts is warmed with as about of the homeostasis, terms a set point, used narrow in limits, during increases receptors, fur effectors and learn details to corrective release use section: monitor, shivering write make hypothalamus this instructs you to try keep foc us away When reduce maintenance action. and raise the good S tudy foc us insulation. The are effectors to take ‘correct’ actions the actual that are level of called the corrective physiological actions factor as so their that it effects You of back to do the temperature hypothalamus the need to the temperature control. We have normal. used If not goes skin is more instructs surface and to than the the the skin to sweat set point, lose heat, glands. the by anterior part diverting Muscles in of more arterioles as a principles the blood to it good of example of the homeostasis. to the Summary q uestions sweat glands allowing and more the blood rest of the skin relax flow to capillaries. so This these is vessels widen, vasodilation. 1 The hypothalamus which helps Animals to seek also control out controls heat shade or the way in conservation, go into which heat burrows mammals loss during and the heat behave, gain. hottest parts of When it is cold they curl up, reducing the body surface exposed the heat, generate heat air . Humans temperature The monitoring make have and and adjustments narrow limits. process – a outside this a since variety we control to the one of body Maintaining dynamic of don’t – behavioural have body so this that fur we responses rely temperature that the core homeostatic never stops. If on to carries on equilibrium to all is is temperature keep the time kept a warm. 3 range, cells function less efciently. State the Dene fluctuates at all, but internal and external changes location in the of temperature body. the terms homeostasis, negative feedback, receptor, effector and corrective action. continuous fluctuates Y ou will and body. set point, might ask Explain always why homeostatic control why of it the to within 4 narrow in that heat changing clothes temperature lose to receptors the effectors conserve the 2 day. Identify body temperature is a dynamic influence process. the core there body are factor temperature. changes has to that fluctuate Also the stimulate in order control effectors for the to system make control does not corrective system to work unless actions. The 5 work. Draw to the show Negative feedback a feedback the one in what loop, Figure 4. 1.2, happens temperature of similar to when the blood decreases. The control negative always mechanism feedback for because counteract the body the change temperature responses in body is negative stimulated temperature. by A feedback . the It is hypothalamus negative 6 The temperature aeroplane system like this is always attempting to reduce the difference between cabin body temperature and the ideal temperature or set point. shows how negative feedback is involved in controlling person when The the blood corrective temperature actions can be increases ‘switched as off ’ it does when of returns showing how to normal. this The control feedback loop in Figure into 4.1.2 is store a in vasodilation in and the temperature is –18 °C. in the Describe changes that body to occur keep in a the constant normal temperature. blood the the sweating hypothalamus nerve nerve impulses impulses hypothalamus promote heat temperature 7 Make flow blood at original temperature = turns to off corrective chart diagrams loss summarise that Figure 4.1.2 at loss thermoreceptors centre temperature store skin heat blood cold a core central in 36 °C. operates. person’s rise is aircraft blood the way landing the during the cold temperature on leaves airport. The exercise. air body walks temperature an 23 °C. The Figure A 4.1.2 is the temperature actual in feedback measures negative feedback occur the when temperature a changes the body increases, and b decreases. This feedback loop shows what happens when the temperature of the blood increases, for example during exercise 101 4.2 Hormones Learning outcomes n mammals Cell signalling Communication On completion of this section, chemicals should be able dene the terms hormone, ductless (endocrine) gland and target cell identify a This tends to for some electrical impulses, explain of the the how coordination section of activities are Cell is Did you know? that some four of Cells in severe contains Nerve is known name which and used you in is a long to are communicate, specialised distances, cells allowing although that quite send fast chemical is communication in Chapter using hormones. 6. in which cells signal to each by cells other using chemicals: chemicals is area. are released These histamine (see glands are sometimes page secrete to influence called local other cells hormones; 144). hormones into the blood 104). endings release other neurotransmitter neurones or effectors chemicals such as at synapses, muscles and which glands (see 124). Nerve endings page release hormones into the blood; this is neurosecretion 116). may nd paracrine secretion (b) nerve impulse nor-adrenaline, neurotransmitter is way websites. A compound, hormone, slow Nerves In (a) related release distant as (see this Cells and allergic adrenaline. adrenaline epinephrine electrical. neighbouring people the USA, a over nerves ductless page page reactions by immediate stimulate case rather often ways example (see TM in be functions. about signalling the an carry and other in in EpiPen of hormones function mammals. The chemical ductless There in is activity mammal Communication cells the communication. some of influence adequate This glands to to: cells. between you known in and the USA a histamine as (c) endocrine secretion nerve nor-epinephrine. target cell direction cells of nerve adrenaline impulse S tudy Sending energy; foc us nerve impulses sending uses hormones blood is a much ‘cheaper’ blood is circulating in much the option as (d) concentrations of anyway and hormones in blood the neurosecretion antidiuretic the neurotransmitter hormone blood are tiny so few molecules need acetylcholine to be produced. That signalling via the makes blood chemical muscle energy cell another efcient. receptor target or nerve cell cells molecules S tudy Ductless foc us glands are Figure 4.2.1 also known as This endocrine with glands. ducts that sweat glands These are glands. Examples you and will know salivary examples of of glands are glands. exocrine section glands Figure and that is are 4.2.1). directly into carry these in about hormones, transported Ductless the the information of 102 Different methods of cell signalling blood glands rather secretion about Unit 1. the long to which contain than another main are distances secreted in cells that secreting place. hormones the in ductless (see secrete them The by blood into table c in hormones tubes, or ducts, summarises mammals. Y ou studied some Module Hormone (chemical Ductless gland Target cells 2 Effects nature) antidiuretic (peptide; see adrenaline from an page 91) insulin page hormone page posterior cells 116) adrenal acid; lining the convoluted (derived amino pituitary see gland (medulla) distal tubules collecting ducts liver cardiac cells; cells in the in stimulates and the (protein; see pancreas liver cells; tissue; water muscle stimulates heart from adipose muscle cells in fat heart stimulates cells and release page (protein; liver cells are hormones. binds compound The that means its is soluble an cannot these When messenger with further it arrives an quickly the inactive to to to stimulates target for the to as cell enzymes out cells. to the synthesis release hormone is a passes steroid hormone through the that is not phospholipid of glucose liver a in the activate signal effect. Calcium many animals. ions are second processes See page in messengers plants 124 for and an example. so This message. adrenaline T estosterone glucose Link surface, within the of glycogen; these produce ‘signal’ amplify carry the at enzyme taking able their specically enzymes enzymes respond enter cells activates interacts activate can and second activated cells of example. receptor a and surface messenger many the the as enzymes are that to acts second These there water on Adrenaline adrenaline them. are receptors glucose rate uptake storage from hormones There that pancreas 104) Some cell. see of liver; stimulates fat glucagon of kidney increases 104) reabsorption water bilayer soluble. and in the blood This interacts with a cell receptor inside the cytoplasm. It acts to activate transcription of certain genes. of Hormones then circulate broken molecules urine or down. that do broken in the This not down bloodstream, happens interact in the within with liver . interact their target The with target cells are receptors cells. of a inactive are over time. concentration very short in The the half-lives half-life blood (e.g. to of a hormone decrease adrenaline by a is half. 160–190 the out time Some in longer ones (e.g. testosterone > 30 taken hormones seconds) cell enzyme the and for have others enzyme its ATP cyclic AMP have Figure 4.2.2 much liver hormone active decreases a Hormone passed concentration and surface membrane minutes). Adrenaline acts at the cell surface membrane to stimulate the formation of cAMP, which is a second messenger. cAMP activates the rst of Summary q uestions several enzymes in a cascade that results in very many enzymes becoming active to 1 Dene 2 Explain the the ductless of a terms principles glands hormone short term, hormone, in c 3 Explain the 4 Explain why ADH 5 Outline 6 Suggest term what the has long signalling each half-life as secretion may Include of by in break down glycogen. target cell using your the following hormones answer effects: at a secreted least one by example instantaneous, b term. happen advantages multicellular cell mammals. that and of ductless gland, organisms. of applied is an to hormones. example when a using chemical of hormone neurosecretion. arrives at a target communication cell. within Figure 4.2.3 Adrenaline will be coursing through the blood vessels of both horses and riders at the start of this race 103 4.3 Regulaton Learning outcomes of Blood Our On completion of this section, be able state that blood glucose cells but within the in roles the the explain blood how involved supply in the of glucose brain, only so use that they glucose can and respire. cannot of insulin parts of the body work together to supply include: digestive the system – digests starch to glucose and absorbs glucose blood and the endocrine system insulin and – the islets glucagon to of Langerhans control the in the pancreas concentration of glucose glucose negative feedback with Many These homeostatic in else. glucose. secrete of those limits control constant as anything with into glucagon a such is maintained describe require cells, to: concentration fluctuates concentraton sugar cells respire glucose you Some should blood blood the blood is the liver and muscles the circulatory store glucose as glycogen glucose system – transports glucose, insulin and glucagon control. dissolved The glucose narrow in the plasma. concentration limits. It is not in the blood constant. The fluctuates but concentration is is kept within usually within the 3 range 80–120 mg glucose per blood 100 cm and is normally about –3 90 mg 100 cm . glucose ltered in the that urine. is If it This rises too from happens high the if then blood the the and kidney some concentration cannot will of be reabsorb lost glucose from in the all the the body blood is –3 above urine , 180 mg 100 cm is obviously not which respired is the or renal stored threshold . as glycogen Glucose or as fat. lost If in the the –3 glucose concentration enough for When Figure 4.3.1 the the brain falls cells concentration below and a , 60 mg 100 cm person increases may above enter the set then a there is not coma. point: Islet tissue is scattered throughout the pancreas. The surrounding 1 β cells in the islets of Langerhans act as glucose detectors. This is tissue produces enzymes, which are because they have protein channels in their enter cells cell surface membranes secreted through the pancreatic duct into that let glucose molecules the as the concentration rises. the small intestine (× 175). 2 β cells secrete glucose in released enzyme-secreting cells the into insulin blood. the as in (α blood glucose acts the Insulin circulates response cells by stop liver to an increasing releasing cells.) The concentration glucagon so increasing glucose of is not concentration of stimulus. cell cell 3 target 4 The insulin membrane adipose 5 in the bloodstream and binds to insulin receptors on cells. Binding receptor of the is a target transmembrane cells, which are protein muscle in the cells, cell liver surface cells and cells. of messenger insulin that to its receptor activates target blood stimulates cells to the absorb formation and use of a second glucose. containing glucagon fall normal in liver blood the glucose cells in blood pancreas glucose gluconeogenesis concentration concentration Figure 4.3.2 The α cells secrete glucagon and the β cells secrete insulin blood into the capillaries within the islet. These at normal glucose concentration turns off hormones are carried away via veins into corrective measure = negative feedback the hepatic portal vein that carries blood directly into the liver. 104 Figure 4.3.3 This feedback loop shows how glucagon raises the blood glucose concentration Module Insulin stimulates muscle cells and adipose cells to insert more 2 Biosystems glucose S tudy transporter to increase proteins the (GLUT uptake of proteins) glucose. into The their cell enzymes in surface glucose to glycogen are activated. The muscle enzymes cells that that other to fat are activated in adipose hormone as insulin has a number of effects on liver It stimulates of more the glucokinase GLUT carriers It increases It stimulates activating increased enzymes, the use the the in of uptake which the conversion of glucose by phosphorylates for of example glucose glycogen increasing glucose, the not activity by putting See It inhibits the enzymes It inhibits the conversion this stored activity as storage. blood results glycogen The for overall in that of fats glucose is in the the page 134 for of failure to and/or the to respond secrete to it. in into respiration. glycogen ( glycogenesis ) Link by synthetase. break short-term effect glucose insulin down glycogen to and proteins being ‘put storage that the or into away ’ described in 1.4 of 1 in Unit 1. glucose. for later . converted concentration is glucose. Module All of consequences Glycogen same membranes. glucose, enzyme the decreasing cells: blood. in cells. concentration Insulin has convert effects glucose foc us membranes No convert maintenance to of Glucose fat for glucose is long-term in Link the decreases. Read pages 115 and 117 to nd out When the concentration decreases below the set point. about the reabsorption of glucose in 1 α cells in the islets concentrations cells to stop of of Langerhans glucose secreting by respond releasing to decreasing glucagon. They the kidney and the simple test to show also stimulate β that glucose is present in urine. A insulin. positive result may indicate problems 2 Glucagon receptors 3 The circulates on liver receptor as of the bloodstream and binds to glucagon with blood glucose control that is not cells. interacts concentration effect in cyclic adrenaline in a homeostatic equilibrium. with other AMP (see membrane inside page liver proteins cells and to this increase has the the same 103). Summary q uestions Glucagon has these effects on liver cells: 1 It stimulates glycogenolysis (literally: splitting glycogen) by Explain why glucose the enzymes that break down It stimulates the conversion concentration of in the blood must not be glycogen. allowed the activating of fat and protein into to fall too low or rise too intermediate high. metabolites that are converted into glucose – this is known as gluconeogenesis These liver two cells processes so that 2 lead glucose to an increase diffuses out in into the the concentration blood. The of glucose glucose in the blood increases and this keeps cells the synthesis in supplied with Explain Negative feedback with temperature feedback. and β The cells 4 the control, concentration monitor If the the this of method blood of control glucose concentration and is kept respond involves within when it negative limits. The increases concentration of glucose rises, then insulin is to a lowering of the concentration. If the released concentration falls, then glucagon is released by α cells, leading to an why insulin surface α by the of insulin control of and the of Draw This maintains the homeostatic are receptors glucagon liver on the cells. loop similar to one in Figure 4.3.3 to show of increase happens when the blood in concentration increases equilibrium. above 6 S tudy there and a feedback glucose concentration. concentration. β what the insulin. and the leading glucose roles in glucose Explain for 5 decreases. cells, of and resource. blood As sites glucagon a glucagon valuable precise of concentration 3 of State the Explain set why point. there are no foc us receptors for glucagon on muscle cells. Show axes the fluctuations on glucose graph in paper. The blood glucose horizontal concentration. Add by axis is some gures drawing time to a and your sine the wave on vertical vertical a axis axis from pair is of blood this section. 7 Why is serious insulin deciency medical a condition? 105 4.4 Plant hormones Communication Learning outcomes Unit On completion should be able dene the of this section, you 1 you cytokinins ethylene, to: term between learnt and about the three gibberellins. which is also different parts different A very known as groups different describe the (ethene) on discuss the of commercial C uses of Ethylene is a is small diffuse other hormones plant growth different diffuses out into plants are also substances known and auxins, hormone is in that from is the other volatile through the H air and spaces, atmosphere. vicinity. plant forms a are other no regulators gas influences Unlike There growth almost its PGRs, other as target it similar (PGRs). soon cells has as and effects It it is may on compounds regulators. In this that as a like or effects. ripening section, has effects on growth, ageing, leaf fall and cell death. The only plant role regulator similar as Ethylene described have plant Fruit growth hormones: plant In foc us Plant is quite molecule It ethylene ethylene of chemicals. C H of fruits formed. growth plant type by H ethylene ripening ethylene. S tudy of is plant regulator effects the plants ethene: H of simply as of ethylene that you need to from Unit 1 know about is its effects on fruit a ripening. regulator molecule. Y ou will remember containing dispersed. the ripening illustrate seeds. Fruits Ethylene of the Unripe fleshy tomatoes in fruits. changes synthesising protect helps that are that the the fruits seeds are until coordination The effects fertilised of they of are the ovaries ready to processes ethylene on be involved tomatoes in will happen. green. chlorophyll At and the start start of ripening producing the they red stop pigment, lycopene. Enzymes V olatile convert characteristic Figure 4.4.1 Many forest trees produce Enzymes succulent fruits that are eaten by monkeys starch chemicals together are organic acids that give to sugars. ripe tomatoes their smell. hydrolyse and and produced once pectins broken in cell down, walls. the Pectins fruits hold become cellulose much bres softer . that disperse the seeds, either by throwing them away or passing them through their These changes which in are all stimulated by ethylene, which stimulates ripening, guts. The simultaneous ripening of many turn triggers even more ethylene production. This is an example fruits attracts monkeys like this Capuchin monkey, Cebus capucinus, in Nicaragua. of a positive production effects Did you know? why Polygalacturonidase is the enzyme In a of hydrolyses pectins in cell some engineers ethylene that did a the that not express to there which events rise attract stimulate the to a climax animals enzymes that that – eat in this them. produce it, case One the of which the is occurs. is a and steep rapid increase increase in in ethylene the rate production of that respiration stage of ripening. This rapid increase in just respiration is climacteric codes for this resulting ‘non-squashy’ were very and banana, avocado and tomato are examples of the fr uits. The climacteric is the time when these fr uits have enzyme. The the best taste and texture. Figure 4.5.3 on page 109 shows the changes tomatoes in not is sudden nal climacteric gene fruits, feedback fr uits, which produced GM the tomatoes ripe in walls. before Genetic of positive stimulates that feedback successful in ethylene concentration and rate of respiration in banana during the UK ripening. because – even tomato 106 of fears the use paste. about GM food of GM tomatoes in Since fruit it is a nearby. gas, ethylene released by one ripening fruit influences other Module Not all fleshy fruits are climacteric; examples are citrus fruits and 2 Biosystems grapes, S tudy which release ethylene, but without it triggering the rapid rise maintenance foc us in respiration. You can carry out a controlled –3 Ethylene By is active comparison, greater . trigger An at the apple ripening very concentrations, concentration that in low has begun surrounding inside to an ripen apples as little apple releases and the as may 1 ppm be 2500 ethylene whole lot times that may experiment ). (1 µl dm in will go and sold. such the as Apples summer or long-ter m want any apples by cold the the grow their and of air fr uit throughout the for sale the that the over to the next dioxide dioxide. carbon dioxide year. crisp Carbon are put 10 can dioxide of the some happens over you a ripe unripe to banana tomatoes. the time. What control use? or the be They to the be into do keep store removes to late apples they for mation sent inhibits so. so times going in their apple fl ow at are har vested ethylene, air ripen they months inhibits apples all many through The can where and producing carbon r m, apples, places Growers start carbon and the climates autumn. apples fl ush and near temperate 3–5% so tomatoes nowhere in storage atmosphere from are during of what putting applications bananas, fr uits with tomatoes would Commercial when bag Watch soft inedible. Fr uits, a by to not the give an ethylene of ethylene markets enzyme that produces ethylene. Figure 4.4.2 Bananas are picked when they are still green and unripe. They are Harvesting bananas. Fruits then that are to be shipped overseas are picked shipped in damaged containers by chilling refrigeration ethylene at board which with that is ship, uses a the may and any again, this to the to kept 17 °C sodium the risk convert which fruit Any does bananas or lower not into potassium bananas of for 24 sealed for may hours. The that about reach in 3 to and taste plastic bananas good. bags manganate( the is ripened the or kept air are green and packaged into plastic bags that are carefully labelled. Where with VII) 4 higher then days by at for an and The an to The fruit the The 100 an is ethylene, mixed generator are to range the then occur . 30 to is 1000 ppm accidental is packed ethylene and remove room ripening in using ethylene 17 °C. vented temperatures by sometimes between accumulated. or gas, ethylene. and Any room has of explosion, ethanol is are canisters concentration dioxide fruit 13.3 °C. ripe packing from the explosion. at the a sealed an as at the ripening. reduce to kept and arrival, room, carbon time on give room cause such introduced catalyst into introduced and or either are available, preventing nitrogen tightly not absorbent, effective On is that injury spark ethylene closed During 40 °C and Figure 4.4.3 they from release the large quantities of carbon dioxide, which must be vented Bananas packed in plastic bags for sale in a supermarket in the UK store. Summary q uestions 1 Explain ripen the as advantages for described on the plants of opposite having fruit that 4 page. Explain and 2 Suggest release the advantages ethylene as they of trees having fruits Suggest 5 ripen. the require Avocado be airtight, refrigeration rooms yet and have in temperate good heating ventilation, equipment. start pears are ripening climacteric fruits, until after they yet they do have fallen from why: the a banana-ripening must that not 3 why countries temperature of bananas increases tree. Suggest what prevents avocados ripening during before they fall from the tree. Explain how you might ripening encourage b carbon dioxide ripening must be vented from avocados to ripen. banana- stores. 107 4.5 Practce exam-style questons: Homeostass Answers to 1 a b all Dene the Outlne blood c exam-style questions term the role can be found on the homeostasis. of the ler [2] n the control the 3 of ways n whch cells chart pathways carbohydrate [3] dfferent The flow the glucose. Descrbe accompanying CD. n Fgure noled n the 4.5.2 n the human shows some metabolsm of of body. sgnal carbohydrate to 2 each Thyroxne other. s a [6] hormone secreted by the in food thyrod A gland, whch thyroxne body. s s to a ductless ncrease gland. One the Negate feedback of producton s noled n the of roles heat the of by the control glucose of in blood thyroxne. B a Explan why the thyrod gland s a gland. the chart release of n Fgure thyroxne 4.5. 1 by shows the the anteror control of in J acids glucose liver in and the glucose liver muscle in tissue ptutary D gland F [1] amino The flow C ductless E H G hypothalamus. glycogen hypothalamus in TRH anterior pituitary a State each TSH thyroid muscle in tissue Figure 4.5.2 gland heat glycogen liver the of letter or letters, A to J, that ndcates the followng: i glycogeness [1] ii glycogenolyss [1] iii gluconeogeness iv processes promoted by nsuln v processes promoted by glucagon. gland [1] thyroxine thyroxine [1] [1] body b TRH = thyrotropin TSH = thyroid releasing stimulating c Explan to there arrow why t concentraton 4 the why drecton hormone hormone Figure 4.5.1 Use Explan nformaton aboe to answer Insuln and s s no arrow glucagon the opposte F. [1] mportant of n blood hae to regulate the glucose. [4] antagonistic effects to the followng mantan the homeostatic eq uilibrium for blood questons glucose. Ths b State what wll happen to the secreton s a dynamic process that s acheed by of negative feedback. thyroxne nto the blood f: a i the secreton of TSH ncreases Explan the ii the secreton of TRH decreases context the producton i State of heat ncreases greatly. a target organ for n the thyroxne. The half-lfe of thyroxne s about 7 the term half-life as the of terms the n talcs n concentraton appled blood. of [4] Explan fully how nsuln and equlbrum for glucagon blood mantan glucose. a [6] days. c Explan by control [1] homeostatc ii meant the [1] b c s of [1] glucose iii what [1] Explan how the acton of the plant growth to regulator ethylene dffers from the acton of hormones. [1] anmal hormones, such as nsuln and glucagon. d TRH s a neuropeptde. Explan what ths means. e Explan how secreton 108 of negate feedback thyroxne. s noled n [2] the [3] [2] Module table nsuln lfe of n a shows the the blood concentratons plasma at of glucose dfferent tmes and n 7 Fgure shows and the the rate changes of n concentraton respraton n a teenager. 140 h 1– g 1– Insulin 120 concentration in the in the plasma/ OC l 2 concentration plasma/ prolonged 100 cm arbitrary 60 respiration = ethylene 25 20 100 units noitaripser mg = / –3 6 starvation 80 15 60 10 40 fo an 80 etar during of banana frut. 30 Glucose during 4.5.3 ethylene the maintenance 9 overnight fast enelyhte The Biosystems mpp/noitartnecnoc 5 2 5 20 0 1 after a large 160 2 3 4 5 6 7 8 9 10 70 time after harvest/days breakfast Figure 4.5.3 after the 70 absorption meal a is of a 10 b complete Descrbe Descrbe the the relatonshp between i concentratons of glucose and State the fruts as gen Explan the n the nsuln n the changes n the Outlne the and nsuln n the concentratons when t s Dscuss blood durng a Explan the absorbed. low Use concentratons of nsuln s terms controlled: the set pont, n to explan how stmulus, s the a plant correcte acton Durng when the conerted rpenng to ethylene a descrbed. [3] s used to prode frut of [3] hormone of whch the 4.5.4 at that s produced secreted danger. One by of the ts adrenal target t stmulates to release organs glucose term hormone. [2] shows the what surface of happens a ler when cell wth adrenalne the of the second messenger, cyclc AMP. by rpen. in the blood enzyme process reducng hae [7] regulator they you and adrenaline bananas the blood. Dene producton s controllng receptors, negate feedback. Ethylene n blood arres 6 [4] ethylene qualty. tmes ler, Fgure effectors, of [3] a glucose clmacterc durng and fastng. the followng n rpen. role that how Adrenalne nto d occur [3] [5] s staraton ethylene meal medulla c the respraton. of 8 and that of [2] marketable glucose between rate blood table. c b the changes they changes as and the ii plasma relatonshp concentraton a n bananas starch s cell of sugars. surface a liver membrane cell enzyme a Outlne how you would nestgate the change n carbohydrate content n bananas as they rpen. b Bananas are clmacterc fruts. Explan the [5] term ATP climacteric. Potassum ethylene c manganate to Explan preent how an (vii) s used bananas from ethylene as an absorbent rpenng. absorbent, such activates of manganate (vii), preents enymes in the cytoplasm Figure 4.5.4 as b potassum cyclic AMP [1] Explan why adrenalne does not enter the ler cell. bananas [2] from rpenng. [1] c d Outlne and the anmal dfferences hormones. between plant regulators Use Fgure adrenalne 4.5.4 to arres descrbe at the what surface happens of the when ler cell. [2] [3] d Explan the role of a second messenger, such cyclc AMP. e Descrbe the f the as [2] response producton of of the ler cell followng cyclc AMP. [2] Adrenalne stmulates arteroles n the gut and skn to constrct. Explan the adantage of ths. [4] 109 2 Biosystems 5. 1 Excretion maintenance Excretion Learning outcomes products On completion should be dene list able the of this section, you term of are removal metabolism The produced and table and from body substances lists the the the of toxic that excretory metabolic substances, are in excess products processes that in the waste of mammals, make where them. excretion Excretory the the requirements. they to: is excretory products product Site of production Metabolic process in carbon mammals dioxide all respiring cells aerobic respiration: decarboxylation in the link explain why excretory products reaction and Krebs cycle must be removed from the body (see page 26) outline the produces describe the process which urea the kidney: gross structure external and ammonia liver deamination urea liver urea of the vertical cycle (also known as in ornithine cycle) section. uric acid liver purine metabolism (breakdown S tudy and foc us guanine and from Remember the denition of of adenine in the nucleic diet acids and nucleotides) metabolism from Unit 1: all the bile pigments liver breakdown of haem from chemical reactions that occur in (biliverdin and bilirubin) haemoglobin organisms. The most important of these is respiration; in this section you These excretory substances have various effects on the body if allowed to see that deamination and the reactions accumulate: that produce urea are also important in producing metabolic waste. Acidosis is normal The cytosol cytoplasm is the that organelles. It is part of the surrounds where all range. place (see page blood; increases such as caused cells the are pH in respiration by high concentrations damaged if blood cytoplasm; and with it pH of falls interferes receptors for carbon below with the metabolic neurotransmitters brain. is highly diffusible potential cytoplasm very so that and passes water is into cells; absorbed by this decreases osmosis, their making the ‘watery ’. glycolysis takes the Urea water the the Ammonia in foc us condition in processes S tudy a dioxide Uric acid can form crystals in joints, causing a form of arthritis called 22). gout, Bile which causes R Urea H an is pigments a very – painful. accumulation yellowish appearance in the skin known as and other areas of the body jaundice. production amino COOH Excess amino acids cannot be stored; they are a good source of energy , but acid the group –NH has to be removed before they are respired. Once this is 2 H R removed, the rest of the molecule is an organic acid, similar to those in the an Krebs cycle. The group –NH immediately forms ammonia and the 2 COOH NH organic 3 ammonium ion. This is highly toxic, so is converted to urea. The process by acid ammonia Figure 5.1.1 110 H Deamination of an amino acid which and this partly happens in the is a cycle cytosol. of This reactions cycle is that shown occurs in partly outline in in mitochondria Figure 5.1.1. Module 2 NH Krebs maintenance Link 3 from Biosystems cycle CO 2 and link reaction See Question 7 on page 119 for an 2ATP example of O O a blood-eating animal 2ADP that H C N O P produces large quantities of urea. (1N) O 2 carbamyl phosphate – O ornithine P (2N) citrulline (3N) O ornithine cycle C H 2 NH 2 urea (1N) 2 from (2N) (an H arginine O aspartic amino acid acid) (4N) 2 Figure 5.1.2 Urea is synthesised in liver cells from ammonia and carbon dioxide by a cycle of reactions. The numbers refer to the number of nitrogen atoms in each compound. This to cycle uses produce Urea the diffuses hepatic production tigers The and amino little be in a other who than are proteins to are nitrogen are a cavity of from see the as of a a is of is diet, are their a acids less In of nitrogen nitrogen in to are acids, External view of the kidney of a lamb showing the renal vein, renal artery and ureter people muscle the they Figure 5.1.3 to in contrast, and life. said nitrogen balance protein of give amino energy; deaminated negative its lions, way diets people diet. source in as acids. excess excreting in as little away such people’s These dioxide, A TP . uctuates amino by carbon of carried blood high-protein excrete. tissue than and the lot There they a in and form high-protein eat proteins in the inuenced to amino organic and are are eating. excretory organ bean-shaped the with organs diaphragm. the surrounding different as in urea below kidney the urea are main pair just a proteins. the people is often muscle down, These eat ions in blood urea deaminate balance using the of daily little energy into that muscle muscle and are the view dissected can produced consuming are broken kidneys Animals building are cells concentration nitrogen more abdominal liver ammonium require carnivores, make they Kidneys Figure the urea starving excreting Y ou of respired. external top are positive who The of The deamination urea acids out products: reactions uctuates. acids so waste The vein. quantity Athletes two urea. renal vein, connective regions of the situated Figure renal tissue kidney in the fat back shows artery and a at 5.1.3 and of the an ureter tissue. vertical section as in Figure 5.1.4 5.1.4. An internal view showing the cortex, medulla, pelvis and ureter Summary q uestions 1 Dene 2 List the term 6 excretion Explain: i the excretory products in mammals. State why rates higher and where each product is Explain from why the excretory products need to be 5 Outline what happens during Explain how urea is be in produced and list the production are in the some mammalian quantity day to of urea species excreted than others may uctuate day. which it travels from why a bodybuilders positive and nitrogen elite athletes are likely balance. Make drawings site of of the external view and the vertical structures section production to of the kidney from Figures 5. 1.3 and 5. 1.4. site Label fully of urea deamination. 8 through and body. to Explain why from removed 7 4 deamination made. ii 3 of how and annotate with the functions of each excretion. structure and region labelled. 111 5.2 The kidney In Learning outcomes nephron 4.3 two On completion should be state able that draw and this section, you nephron unit of the describe is a hormones The and into the pelvis in cortex, medulla sections insulin The The islets and islets are functional of Langerhans glucagon – functional unit of the in that the pancreas control units kidney as is blood each the one secrete the glucose performs these nephron. nephron structure nephron recognise – the the kidney the that concentration. Each of saw functions. to: the functional of we of the nephron a Each consists collecting nephron glomer ulus; is duct of a that lined collects associated surrounding tube with each a by urine tight nephron a simple from knot are a epithelium number of of capillaries many more that drains nephrons. known as a capillaries. kidney branch recognise the parts of a of renal artery efferent arteriole nephron glomerulus afferent in sections of the kidney arteriole draw sections of the kidney from distal convoluted Bowman’s the tubule microscope. capsule cortex describe the appearance of the branch regions of a of nephron. renal collecting vein thick duct region ascending proximal S tudy of limb of convoluted foc us loop of Henle vasa recta tubule You should be able to make a medulla descending labelled diagram of a nephron of this one from limb like loop of Henle thin memory. region ascending ‘hairpin bed’ of of loop Did you know? of of limb loop of Henle Henle tissue urine to pelvis, ureter fluid and The total length of the in your body is bladder kidney Figure 5.2.1 tubules then about A kidney nephron with associated blood vessels. The flow of blood is shown 80 km. with solid arrows; flow of filtrate and urine with open arrows. glomerulus lumen of Bowman’s distal capsule convoluted tubule (no border of brush microvilli) proximal convoluted tubule (with of brush border microvilli) glomerulus Figure 5.2.2 A glomerulus surrounded by capillary the Bowman’s capsule (white space) and sections of proximal and distal convoluted tubules (× 300) 112 Figure 5.2.3 Drawing of part of the section shown in Figure 5.2.2 Module capillaries the vasa loop of 2 Biosystems maintenance of recta Henle (thick) nucleus collecting loop of duct Henle (thin) Figure 5.2.4 Figure 5.2.5 A cross-section through the Drawing of a section through the medulla showing some loops, collecting ducts and capillaries medulla of the kidney showing loops of Henle and collecting ducts (× 600) Y ou may be expected photographs and to study drawings microscope should help slides you to of kidney interpret tissue. what The you see. S tudy Features light of the different regions of the nephron that can be seen with Search for microscope: Glomerulus are large – cells capillaries known as containing podocytes red blood which cells; have in between prominent foc us the some micrographs of and you the glomerulus is a white space which is the DCTs so this capsule is surrounded by squamous have PCTs an nuclei; of the three- Bowman’s dimensional capsule; electron glomeruli, there appreciation around scanning the epithelium. structure of the Figure nephron. 5.2.6 is a drawing of scanning electron Proximal convoluted made of made up a glomerular capillary and a podocyte made from micrographs cuboidal tubules epithelial (PCT) cells; – cross-sections cells are lined by are a near brush circular; border basement of many membrane microvilli. endothelial Loops of Henle – cross-sections are circular; thin sections of loops cells have thin squamous epithelium; thick sections of loops have of blood thicker , capillary cuboidal Distal epithelium; convoluted no brush tubules border . (DCT) – Surrounded cross-sections by are many capillaries. circular but not podocyte as wide as the PCT . Cuboidal epithelium without a brush border . cell foot-like Collecting ducts (CD) – cross-sections are wider than those of other process parts of the nephron. Cuboidal epithelium without any brush circular Summary q uestions pores endothelial Figure 5.2.6 1 Explain what is meant by the term functional unit as applied to of podocyte border . between cells A small part of a capillary in organs, a glomerulus with surrounding podocytes such 2 as Make duct a the kidney. large and labelled associated diagram blood of a nephron vessels. Add to with your a glomerulus, diagram collecting drawings of cross- S tudy sections of boundary the PCT, between loop the of Henle, cortex and DCT the and collecting duct. Show medulla. Put 3 Write 4 Find a description of the structure of foc us the the nephron. the ngers between of hand. The ngers more photographs of sections through the kidney; print them out you have now left hand your in right a model interdigitate of the them fully. projections 5 of and and label your the ngers Name the parts of the nephron in a the cortex, and b the medulla. you can see of in the podocytes Figure that 5.2.6. 113 5.3 The excretory functions The Learning outcomes kidney useful On completion should be able of this section, you that state that excretory the kidney is the complex The the such waste as system excretory everything includes substances a substances. principle This to: has of below for ions in certain that and kidney ltering system a products glucose, the blood mammals size are the to amino is reabsorbing operates ltered be and from excreted on the and the blood. useful acids. main organ Ultrafiltration explain the how kidney blood and is ltered explain how glomerulus and capsule adapted for are in the Blood ows occurs Bowman’s efcient in into all the glomerulus capillaries, but the at high pressure. glomerulus is Pressure adapted for filtration efcient ltration. ltration describe selective Blood head outline the processes the formation of involved pressure arterioles reabsorption of The pressure capillaries in each need a diagram of you read this notes in to the diagram that on answer page The to Summary is sometimes excretory only is a acts mass capsule. by form described The which efferent builds up a pores in their walls that are at least basement like a membrane mesh to allow that is made everything of with (RMM) This is the of less only than barrier 69 000 through a between blood into and the the accumulates in the Bowman’s capsule. capillaries podocytes, are cells suspended with within projections that the do Bowman’s not lining around the capillaries. Instead the form cells a interdigitate are organ. Urea present because lose it is in and sodium sweat, but of to heat, those substances. not to the excrete to The enlarge carrier the of cells is of from Figure 5.2.6 reabsorbed the and of region ltrate to membrane surface one area that the for changes facilitated this the surface cytoplasm molecule in cell. a on the the page 113.) proximal blood. the are convoluted adapted Figure lumen and carrier ion. move The tubule absorption. Each to the glucose sodium shape of lining for move diffusion. 5.3.1 of This tubule them absorption they into shows one of of these PCT has microvilli has many molecule When movement membrane sodium the for ions has are the from two both the sites full on the – the cytoplasm. depends ltrate one to for carrier This is existence a of form a foc us concentration The ltrate (See reabsorption molecules glucose S tudy pores. ltrate The substances cells. made from ltered blood slit as (PCT). chloride and glomerular Selective foc us Most an heart. 113. S tudy skin the question to The near arterioles, you complete 2 are afferent glomerulus. numerous capillary molecular that capsule drew the kidneys the section. Add the than the ltrate as as foc us Bowman’s will in have proteins relative nephron high diameter . Around brous You is narrower in urine. 4 nm S tudy are has composition as the same tissue uid 82). Try Question lateral 2 to test (see and of for sodium membranes concentration gradient into concentration gradient for move the ions. Sodium sodium tissue ions uid. pump proteins against This in the their provides the page absorption of sodium ions and glucose at the your luminal understanding gradient basal surface. The sodium potassium pump proteins require A TP , this. which is supplied Selective by the reabsorption many mitochondria involves movement in each through cell. the PCT the upper cells. The Link cells are cells. Look at the data on the attached These blood plasma, ltrate Question reading the 5 the on page next answers to 119 and urine a and b. of Reabsorption about As more ltrate be 114 ‘sticky tight strips’ junctions that hold around the cells together part and of the prevent uid between cells from the lumen of the PCT into the blood. in before section. Think parts like by composition movement of are together by and and continues more blood active is until all removed, becomes transport. the the steeper . glucose is removed concentration This explains from gradient why the ltrate. between movement has to Module lumen of 2 microvilli PCT S tudy tight The junction absorption example of transport rough foc us of glucose secondary in that the is an active movement endoplasmic needs energy, but the gradient is reticulum provided by something ions. The mitochondrion lateral pump else, this pumping of case sodium sodium and membrane potassium ions is transport. These cleft proteins for in in basal called indirect primary active are and sometimes direct active basement membrane transport. membrane basal Figure 5.3.1 membrane A cell from the proximal convoluted tubule, showing how it is adapted for selective reabsorption The luminal membranes of PCT cells also have carrier proteins for the S tudy reabsorption across the of amino cells of the acids. PCT About as 50% these of the molecules urea in diffuse the ltrate easily through Many membranes. The movement of solutes across the cell creates an small and gradient into water moves from the ltrate down a water are to loops too such the ltrate that blood transport as leaves the PCT , it enters the loop of Henle. Mammals iron, transported big to and like are are proteins. they some this. be ltered substances After the Some blood. ions, Into the in potential attached the substances osmotic transported gradient foc us moves so carry vitamins Proteins are the are not ltered have either. short loops loops that and As short the limb that loops ltrate of the The uid is less role in of it extend the ltrate loops medulla. and is the far that to all into to from which a the and water of up end of the the tissue the of long medulla. ascending loop loop to from in uid the long less solution from and mixture the then enters concentrated tip a and concentrated reabsorb medulla have the limb concentrated that the Humans extending passes highly to at descending provide used if medulla. more than This is very the 10–20% rst concentrated ducts of down gets The tip about moves the the collecting not to with loop concentrated. DCT do extend the the the PCT . tissue surrounds the Summary q uestions urine. 1 The highly concentrated tissue uid is mainly the responsibility of Make the upper part of the ascending limb, which has cuboidal epithelial a large, labelled cells many pumps tissue mitochondria reabsorb uid; sodium this part is to provide ions from A TP the impermeable for protein ltrate to and pumps. pump nephron and the dilute uid enters the them into the 2 water . descending Make a table components limb of the loop it are a region permeable potential to with more water , gradient. The concentrated which walls diffuses are tissue out of uid. the impermeable to The ltrate ions epithelial down and a urea. bend lower at part the of base the of the loop, ascending the limb is uid is at permeable its to most to water 3 Explain and urea. the high chloride tissue Sodium solute ions passively uid. ions Sodium diffuse concentration are either through in pumped channel ions the as are into the medulla. well proteins. recycled ltrate as like Along sodium this the ions ions, from to that the ltrate do and not. how the following are their functions: PCT cells; cells at the but of the ascending limb of the the of Henle; DCT cells. maintain nephron, or of the blood concentrated. sodium loop surrounding show the the top not with section. walls water At that glomerulus; The to of part adapted for hairpin annotate each passes those through of These become As of lled the functions with diagram the diffuse 4 Make a table permeability of the water, to of nephron sodium compare different (PCT ions the parts to CD) and to urea. 115 5.4 Osmoregulation The Learning outcomes kidneys volume On completion should be able of this section, would you to to: dene the explain term the role coordinating contain of ADH the duct and but much dangerously water controls in activity of water when to of osmoregulation. this is reabsorbed; dehydrated dissolve the in the volume of with solutes water that lost in The if fatal we the kidneys not, then lter the consequences. need to urine remove. by a large tissues Urine has The water in in the the body is dehydrating compared to when reabsorbing there is more sufcient body. the ltrate that enters the distal convoluted tubule from the loop is very determining dilute volume effectors osmoregulation The collecting the water , become kidney of are concentration as most of the ions have been pumped out. The DCT is of responsible for determining how much of the remaining ions are urine excreted. explain the feedback role in of duct negative (CD) straight osmoregulation The uid has the through concentration. describe and explain changes potential of ltrate in the discuss the presence in signicance uid glucose and protein through urine change the in and the it collecting may pass composition collecting ducts, or to maintain the high concentration of some solutes urea in is the in the to medulla. water The cells depending on lining how the CD much we can need change to their retain. ‘Osmostat’ hypothalamus that narrow blood monitor limits. plasma osmosis plasma causes them to ADH the water water too too and send the and blood. and websites or duct and to the ADH. target If posterior When cells you of by less the blood osmosis. water the cells function point, by the point, out This potential pituitary stimulated, are the gland these epithelial where cells cells of the textbooks of collecting duct 0 H 2 alternative vasopressin. This luminal membrane will nd ADH H its set cells efciently. set nerve within DCT . lumen the USA, by and kept foc us collecting called the passes the into special is burst. of The This below water above passes less contains dehydrated increases impulses vesicles it blood. decreases water may as the become function cells contain into potential of concentrated potential the ‘ osmostat’ potential which dilute swell cells body ’s water tissues, much terminals release read the ‘ osmostat’ nerve S tudy too the the becomes increases The If If is the becomes from efciently. you dilute little into urine. cells from as trickles of The If ows with and nephron clinical of DCT composition bladder urine helping permeability the the and tissue urine same to As leaves in reabsorbed water that 0 2 name suggests that it tight junction tight increases the blood pressure. It vesicle doesn’t, at least not at the aquaporin concentrations in the junction with 2 H 0 2 normally found body. aquaporin 3 lateral membrane Cyclic H 0 2 AMP ADH receptor ATP blood Figure 5.4.1 A cell of the collecting duct responding to ADH. Aquaporin 1 is in the cell surface membranes of cells in the PCT and descending limbs of the loops of Henle. 116 H ADH plasma 0 2 Module ADH the interacts with movement towards with the ow and urine water on the of membrane. into of the the potential cell containing membranes sur face the membranes low receptors vesicles luminal cell from lateral the the of the membrane, epithelial makes Other epithelial in the This cells. sur face aquaporins. cells much aquaporins cells. medulla it These The are where easier are solutes sodium leading vesicles in that ions, for fuse water basal contribute chloride to and to ions that have the is reabsorbed same shape solute concentration When restored half-life cells Australian genus hopping to (10–30 remove decreases to mediated by the the set to Notomys are remove the of so ADH its blood of vessels Henle secretion concentration from these excess second the loops to in the the producing urine. They can of ×25 of the world concentrate compared of record concentrated their it with blood by a the plasma. medulla. maintain the high medulla. aquaporins water the point, minutes) the permeability in enters as mice holders for concentration water They maintenance Did you know? factor urea. The Biosystems move they the to 2 the cells water . luminal decreases. The messenger , effect cyclic stops. in the surface The of and urine ADH AMP ADH blood (see has a short decreases. The the concentration on its page target cells is 103). Counter-current ow Y ou will parallel have with concentrated limbs of the between sodium vasa that another . tissue loops them and diffusion the noticed one uid are from in all through chloride the ions which blood ows down blood ows up to into the recta medulla. together tissue in lose vasa and arrangement the close ascending recta, loops, This the uid. lower and medulla. The the sodium are ascending substances concentrates same and all a and medulla The reverse ducts produce exchange nephron of limb. gain to descending they The part descending water The and collecting helps because principle chloride exchanges the there ions occur is applies as as to the the Figure 5.4.2 These test strips are used to test urine for albumen, ketones and glucose in urine through the use thick section away and This point is kept of of the method blood the medulla. energy the to control within triggers events is the limbs. effect of negative narrow that counter drive ascending concentrating of This limits return current pumping Without the the of any water sodium this medulla feedback and multiplier as the the ions solutes would slight be water of works from potential the the would diffuse lost. deviation potential only from blood of the to the set the set Summary q uestions point. 1 Dene 2 Explain the term osmoregulation. Urine tests T est strips like those shown in Figure 5.4.2 are used to test urine the following glucose to – its conrm ketones, for the presence the diagnosis which body to using fat of diabetes, to may are indicate (see present in metabolise; instead. Their page the they diabetes, but requires more urine presence in gland, ADH if there produced indicates is not when poorly enough the body glucose 3 switches managed Explain involved in which is a plasma protein and should not be blood. A positive result suggests high blood ltered pressure, a Imagine or problems with kidney. is osmoregulation. you are given someone a yellow with from diabetes and told it kidney is infection pituitary negative feedback undiagnosed the posterior and how liquid from albumen, the control 4 of osmoregulation: hypothalamus, tests 134), are roles for: urine. Explain how you would ltration. use it 5 a chemical contains Explain a why indicators of test to reducing urine show that sugar. tests are useful health. 117 5.5 Practice The Answers to 1 all Excretion a kidney, exam-style questions is a feature the of term exam-style all living can questions: excretion be found on the organisms. Dene ii Explain why carbon dioxide must be excreted excretion. osmoregulation accompanying CD. 3 i and Figure 5.5.3 shows a kidney nephron and associated blood vessels. [3] L A from the body and outline how this happens. [5] B Many have b humans, a along high-protein Explain are why with large produced many other mammals, diet. by [3] quantities of nitrogenous C waste mammals. D K c Outline how this nitrogenous waste is processed J and excreted. [5] H 2 The kidneys main of are excretory the body. E the C organs Figure G 5.5. 1 F B shows a vertical section Figure 5.5.3 of a a kidney. i Identify the parts the of kidney A ii to a the following labelled D. Match letters given in Figure 5.5.3 to the statements. i site ii region of ultraltration [1] iii blood vessel with the highest concentration [4] Describe briey D of lowest water potential [1] A the functions of urea [1] Figure 5.5.1 of the parts iv labelled C and D. b Selective reabsorption site of action occurs in the tubule of Explain the functional each nephron in the 5.5.2 shows a hormone ADH. [1] cell from this part of of advantage structures E, of H, G the and parallel J in the kidney. medulla Figure the proximal arrangement convoluted of [2] of the kidney. [3] a Diabetes insipidus is a rare condition in which large nephron. quantities this of dilute condition peptide was urine are treated hormone. The produced. A with person injections mean volume of of with a urine 3 produced After per daily day before injections treatment given over 10 was days, 5.75 dm the . mean 3 volume c of urine Suggest explain taken d an Explain 4 The a kidney Outline it had to the be peptide injected, hormone rather [2] effect of the the volume is of peptide roles of hormone in urine. responsible for the and than mouth. the reducing 3.45 dm identity for why by was [3] the formation ultraltration of urine. (pressure Figure 5.5.2 ltration) formation b Explain how this cell is adapted for Explain what composition through 118 the [5] happens of the to the volume convoluted b as tubule. Explain of and glomerular ltrate proximal of selective reabsorption in the urine. [4] selective reabsorption. c and it ows [5] c urine Discuss how is the nal volume determined the roles homeostasis. of by the the and concentration kidney. hypothalamus [3] in [6] Module 5 The table shows the glomerular ltrate composition and of blood plasma, b Describe urine. to c the increase Use this 2 Biosystems response the water example to carried out potential explain maintenance by of how the the effectors blood. [3] negative –3 Component Concentration/g 100 cm Increase feedback is used to maintain homeostatic equilibrium. Blood Glomerular plasma ltrate 7 The common vampire found protein 7–9 [5] Urine 0 0 in Trinidad glucose 0. 1 0. 1 0 urea 0.03 0.03 2.0 – the 60% blood of its of and Central America. This sleeping body mass protein-rich food bat’s 0.0001 0.0001 ions 0.32 0.32 blood 0.30–0.35 blood 90–93 97–99 Explain is mammals, bat feeds blood the stomachs same is very ingesting with each water potential ‘watery’ of vampire about meal. This with bats a as the high concentrate quickly. ×1 96 collected – urine a in but meals very Urine from water has plasma volume. The 0.0400 the sodium Desmodus rotundus, – on ammonia bat, a captive during and the an urine common vampire investigation. The concentration bat rate were was of ow of determined 1 why: over a period of 8 hours. The bat took a blood meal 2 glucose but not [2] 2 hours results in [2] in the in is plasma of [2] urea in the urine is the ltrate are present the factors by [1] in the which urine. the [2] concentrations compared c Urine is waste with the routinely are blood increased in the urine plasma. tested for etar nitrogenous [2] glucose and are the shown what steps might be taken by a in of the Figure investigation. The 5.5.5. 4 of flow concentration 0.25 3 0.20 0. 15 2 0. 10 1 0.05 0.00 protein. 0 0 Suggest start rate marg fo of after 0.30 the ydob ions the ltrate ssam than in rep Calculate the ltrate, concentration concentration sodium the ltrate mc/wofl eniru b in in 3 the as present present ruoh urea protein rep urine the higher v is the same iv no yrartibra/eniru ii iii is fo noitartnecnoc there stinu i 1 2 3 4 5 6 7 8 9 doctor time/hours who identies glucose and protein in the urine of Figure 5.5.5 a patient. [4] a 6 The water potential of the blood is maintained Describe the narrow limits. The ow the water chart potential of in the Figure blood 5.5.4 is it of effect urine and of feeding its ow on rate. You shows use gures from the graph to illustrate controlled your when immediate concentration should how the within answer. [4] decreases. b X Explain the effect of feeding on the rate of urine Y production. c Explain of effectors why [3] D. rotundus excretes large quantities urea. [3] decrease d Vampire bats are concentrated water the produce that a much produced more by humans. Suggest how they are able to do this. [2] blood Did you know? Figure 5.5.4 a to than increase potential response of able urine Name: Search i the part ii the hormone of the iii the effectors. brain shown shown by Y by box X [1] [1] of online for ‘common D. rotundus feeding two other parasitic species of on vampire livestock, vampire bat’. You such bat. These as can nd lm pigs. There three are the are only mammals. [1] 119 2 Biosystems 6. 1 Structure maintenance of Learning outcomes neurones Structure of the The On completion should be able of this section, nervous describe to: and the motor structure of central describe neurones the functions divided into two parts: nervous system (CNS), which is divided into the brain and cord sensory peripheral nerves is system you spinal system nervous nervous attached to system the (PNS), brain and which spinal consists nerves of nerves attached to – cranial the spinal of cord. neurones nerve in the transmission of impulses describe the structure of There are two which are also state the effect of myelination distances. speed of outline the surface within neurones, the nervous transmit system. Nerve information very cells, fast These cells are supported, protected, and in some over cases by glial cells impulses There types as on insulated, the cell known myelin long main structure membranes of of are three types of neurone: cell neurones. sensory relay neurone neurone (also known as connector neurone or intermediate neurone) Link We used unit in the the kidney. idea of pancreas (See page No the functional and in motor neurone simplest the consists 112.) which SENSORY nucleus NEURONE cell body neurone can bring functional of one controls myelin node sheath Ranvier of about unit each the in of knee a piece the the jerk of behaviour nervous neurones. reex, system In there some is no Sensory of on is a its own. reex reex arcs, connector The arc, which such as that neurone. neurones: axon transmit impulses from sensory terminals cells on (receptor or sensory relay nerve or cells) endings to the CNS motor have their cell bodies in neurones axon dendron swellings on nerves just outside sensory the CNS dendrites Figure 6.1.1 A sensory neurone terminate neurones Motor MOTOR NEURONE dendrites myelin node of sheath Ranvier axon on connector within the CNS. neurones: axon terminals on transmit to impulses effectors, such from as the CNS muscles and effectors, glands such as have their cell bodies within the muscles CNS. or nucleus cell glands body Relay Figure 6.1.2 S tudy neurones: A motor neurone transmit impulses to neurones motor from sensory foc us are found entirely within the CNS. Take care structure neurone over using with many is a nerve the terms nerve cell. nerve cells and neurone. A surrounded by nerve is a multicellular protective fibrous tissue. A Myelinated impulses without 120 neurones much faster myelin. transmit than neurones Module Component Structural features cell nucleus body (with 2 Function nucleolus); RER and transcription and translation to produce membrane proteins mitochondria cell surface phospholipid + membrane impermeable bilayer; + to ions; + /K Na pump channel proteins; pump proteins dendron long, thin dendrites similar, axon long, process(es) from terminal swollen endings mitochondria but thin allow smaller than process from end molecules of of axon and cell body cell body release large of in; ions towards surface for impulses through across cell away from synaptic the membrane body in synapses from neurotransmitter impulse neurotransmitter K impulses transmits with and movement provide containing vesicles out transmits dendrons + Na cell sensory many other neurones body molecules from cleft; neurones reform vesicles to carry neurotransmitter molecules Myelin The and neurones sensory Schwann columns cell . of Schwann some rich in of that are with layer axon or allows the tiny of nodes of the the from very the of phospholipid. uid to in as ‘gutters’ is Myelin ions cell cells the formed exposed and upon The by to of the cell membrane through about there neurone. is the diffuse covers meet motor dendrons) layer insulates cannot All the myelinating (axons layer between. of called develops, is Schwann surface cell neurone processes there Schwann the myelinated. glial system uid Each two reach the proteins. tissue are of within of cytosol few Where lie nervous until 6.1.2 type neuronal quantities with a length continues dendron. tissue As and by neurones whole around This membrane thick the grow 6.1.1 supported The uid. phospholipid neurone this tissue cells Figures are cells. neurones. membrane in Unmyelinated these surrounding of shown neurones is 1–3 mm a These gap gaps Ranvier Structure of the cell surface Figure 6.1.3 membrane A cross-section of the axon of a myelinated neurone. You can see the Conduction dendrons their ow forward of and is high ow neurone. nerve An impulses axons. of These and ions, action relies ions impulses action do on the not decay is the very quickly. potentials potential movement travel net occur effect In at of far of as order to intervals ion ow ions the along layers of cell membrane that make up the resistance ‘boost’ along to myelin sheath. the the across the Summary q uestions neurone neurone. membranes. In In myelinated unmyelinated neurones neurones action they potentials occur occur all only along at the the 1 nodes of Make a motor Cell surface cells, except types, large but membranes they four have voltage-gated voltage-gated potassium of axons large concern and numbers dendrons of ion are just channels. the same There are as and several us: sodium of ion potassium channel ion proteins channel neurone, neurone. other 2 Label annotate each Explain part the proteins leak channel leak channel addition, membranes. there are with a a b a sensory diagrams the functions have labelled. differences pairs: nervous and between central and spinal systems, nerves, proteins. myelinated In of proteins cranial sodium and both you the following peripheral diagram Ranvier . sodium potassium pump proteins in these and unmyelinated neurones, sensory neurones, axon and and motor dendron. 121 6.2 The nerve Learning outcomes On completion should be able of this impulse Resting section, The neurone that if outline is how the how resting and potential maintained nerve cells voltmeter , negatively resting to transmit explain has placed a potential either side difference of the across membrane it. This and means connected a difference charged potential with is is recorded respect usually to of the the written order outside as of of 70 mV . the The neurone inside to so is the –70 mV . resting potential is the result of an unequal distribution of ions impulses across are are The stimulated electrodes to: established explain membrane you a potential how action potentials how action potentials are membranes. resting potential. All The membranes, factors that even plant contribute cell to a membranes, resting have potential a are: formed explain contribute to the transmission the presence charged of sodium impulses. two the foc us resting a potential may find it varies given –60 mV to the leakage all cells potential membrane cells have even similar to in have those across is the cell a feature that common. Some action plant potentials described here for of As of the core as negatively pump out three sodium ions for every in membrane which does proteins through some the ions proteins for A the to not are ions. The permit shut so phospholipid the movement sodium and bilayer of ions potassium ions them potassium inside so of few , are sodium cell neurone at resting concentration higher the in very ions concentration is nothing cell in when ions cell fact, through is the negatively diffuse selective. so is through attracted of there out There is channel by the the very potassium charged through are very little a resting negative sodium sodium ions ions this leak channel attracts these few channels. leak diffusion of channel sodium ions ions in the attraction inside proteins negative charge and the down interior , a the cell. With sodium so inside cell can the – an a with – there is a higher happens be put only all use cells, in interior do gradient in to negative not concentration cell ions and This ions making the potassium gradients neurone. for potential. outside concentration ow added at has for The current an of is potassium unusual. the there it potential gradients concentration forwards neurones. S tudy such foc us into resting cell, –75 mV. proteins surface the the Channel A inside between in potassium S tudy anions that pumped channel diffuse proteins. range organic pumps ions hydrophobic voltage-gated cells. You potassium potassium cannot The many impermeability has S tudy of proteins they but electrochemical so driving of the diffuse they are gradient. foc us Action potentials occur along the whole length of myelinated neurones, but only at nodes of myelinated Impulses travel gradients the sodium which ions along cell out and constantly neurones continually potassium recharges all uses the ions itself time. energy in. using in T o maintain the The form cell energy is of the A TP therefore from concentration to pump like a battery, respiration. neurones. See Question 6 on page 127 . The resting potential potential difference hyperpolarised To fire or Motor If the reach no the of stimulus 122 effect is threshold, frequency . the receive neurones. the change. less Membranes negative potential or are depolarised more difference positive; becomes more when they the become negative. not to fire? overall impulse base when neurones connector can becomes is sent. axon, The the impulses Some to of then an is threshold is are the impulse the determines the these depolarise This higher from many sensory excitatory neurone is sent between frequency –50 mV (see the rule. impulses some membrane along all- or-nothing whether and neurones are and Question The sent on axon and inhibitory . If to not, hillock at then the their the page many sufficiently neurone. –40 mV ; 8 are and greater 127). the Module Action If the potential axon hillock S tudy initiates a nerve impulse, then an action The membrane is depolarised and current ows foc us potential The occurs. 2 forward along movement voltage-gated neurone. which to triggers open. and triggers feedback more current some Sodium gradient This This in yet The feedback more This to potential sustainable and to their open. one the of ends is for sodium ions facilitated is leads ‘spike’ to the a to of for the shown +40 mV . sodium The and in No Figure positive action foc us of what is responsible impulse online for nerve impulses happens occurs at along when one a some an place that action along a neurone. potential + + – – + – – + + – – – – + + – – + + + – – + + S tudy Refractory The of an Search animations show channels potential propagating neurone. potential direction is positive more close. action proteins diffusion. S tudy There +30 when through electrochemical amplitude the ions channel membrane, more. depolarisation stroke of proteins down some difference this region channel increase upward next axon proteins slight opening the the depolarises initial is maximum is into channel the the voltage-gated diffuse proteins depolarisation. 6.2.1. the depolarises membrane which channel of ions the ow of the foc us means existence of ‘unresponsive’. refractory periods impulse means that each action potential is a 40 Vm/ecnereffid laitnetop discrete event. Action potentials do repolarising polarised not fuse (resting (resting potential) potential) together continuous 0 to give a depolarisation. Summary q uestions 1 State the resting values enarbmem potential action of potential; difference potential; change the following: maximum in during an maximum potential difference depolarised hyperpolarisation noxa during (action an action potential. potential) 2 The action potential is described 65 as 0 1 2 3 4 an all-or-nothing Explain what Explain how this response. means. Figure 6.2.1 time/ms The increase that there neurone. in are sodium more This ions positive current An action potential reverses ions the that depolarises charge can the ow next inside as the patch of the neurone current strength so inside membrane, 3 the 4 Describe be the next node in a myelinated neurone. Meanwhile, the to the across potential so potential is the that not membrane another achieved action by needs to potential pumping out be restored can occur . sodium to the Instead the voltage-gated channel proteins for That the ions ow out down their takes potassium electrochemical and potassium channels passage an gradient. ions potential. channels shut’ open The (albeit While are briey; again period when when restore is the is they when the resting the sodium) thrown another potassium It is back, open are as if the the open, these The of The ions do not the loss diffuse out in potential. Draw a diagram and of an action annotate it with of potential sodium are ‘bolted proteins of the changes in will 6 difference. The conduction of impulses in neurones is influenced significantly by temperature. Suggest why respond overshoot action resting gates channel the and depolarisation. channels period . restores proteins open. sodium refractory more not are by not channel do ‘bolts’ stimulated because and potassium and the time depolarisation potential the closed of potassium during too explanations positive sodium voltage-gated resting potential potassium that potential 5 long. changes resting Restoring ions. the stimulus. voltage-gated channels difference a encode which occur will of neurones restoring than neurones conduct impulses at to resting necessary to faster speeds at temperatures near 40 °C than at 10 °C. potential. 123 6.3 Synapses Neurones Learning outcomes are continuous On completion should be able describe of this section, that you have separate very along structure of cells. gap describe that synapse the occurs The synaptic sequence during the of events synapses is target it synapse, of cells of are to section, and tiny one another anemones impulses gaps to and travel between form jellyfish in the both nerve the term side rather of in than the and tends gap. width. the to be region applied The gap of the to the itself T ransmission post- is called across the these electrical. are such either as other muscles neurones and or , glands. in the case Synapses of between are as interneuronal synapses and those at muscles as junctions. categorised about roles of synapses is according impulses flow in between look to the neurotransmitter Synapses of the this synapses that use in which released. acetylcholine nor-adrenaline are is Y ou the Within the central nervous system there are adrenergic many different one neurones. out for importance cholinergic to neurotransmitters; direction into sea which are neurone 20 nm neurones known know synapses. that in there although other effectors neurotransmitter . show in foc us need the fuse synapses. Synapses of the about chemical neuromuscular One systems cells, pre-synaptic on is neurones, neurones S tudy a the neurone cleft ; The roles is of synaptic motor outline nerve not Even synaptic transmission nervous their do a terminations simple directions They structures. to: the cholinergic cells. multicellular In this acid (GABA) that one acts of at the most inhibitory common is gamma amino butyric synapses. explanation role. Cholinergic A nerve here terminal contains cytoplasm When an events 1 An 2 In impulse are impulse to arrives calcium with at a called a channel bouton. proteins The and membrane the acetylcholine. a sequence of events occurs. These diagram. synaptic ions The this is diffuse into the concentration a steep the bulb. voltage-gated channel proteins for cytoplasm of calcium down ions their inside electrochemical cytoplasm is very gradient. Calcium ions trigger the movement of vesicles containing along neurone ion synapse the the often open. gradient. vesicle in at 4 synaptic swelling depolarisation, 1 presynaptic a vesicles arrives Calcium so in summarised response low, ends voltage-gated contains calcium 3 synapses microtubules towards the pre-synaptic acetylcholine + _ _ + membrane. 2 2+ 2+ Ca + Ca + 5 2+ 2+ The vesicles fuse with the pre-synaptic membrane Ca Ca 2+ open 2+ calcium Ca Ca and channel release molecules. their This contents is of acetylcholine exocytosis. 3 + + presynaptic 6 Acetylcholine molecules diffuse across the synaptic 4 gap membrane synaptic + Na 7 acetylcholinesterase postsynaptic membrane 8 open ion dendrite + channel postsynaptic neurone Synaptic transmission. Follow the sequence of events described as 1 to 11. 124 post-synaptic channel membrane. The channel proteins open to allow diffusion 9 sodium Figure 6.3.1 the chemical-gated 10 7 + on with + Na 6 15nm combines proteins 5 + Na cleft and ions synaptic into the neurone. cytoplasm of the post- of Module 8 The 9 Acetylcholine post-synaptic membrane is 2 Biosystems depolarised. S tudy down by groups the and With enzyme choline, membrane 10 molecules (or removal into of leave the protein channels acetylcholinesterase . which the diffuse back surrounding acetylcholine, the The into glial and are products the are acetyl Neurotransmitters pre-synaptic cells). post-synaptic If the sum greater membrane is of all its the impulses threshold, arriving then an at the impulse post-synaptic is sent (see although they between travel between neurone page are molecules, is than foc us broken repolarised. 11 maintenance very neurones cell the signalling distance neurones and or effector cells small. is 122). Link Roles of synapses Many T ransmission of impulses. The main role of a synapse is to at impulses to be transmitted from one neurone to another . They so that the pre-synaptic pre- and post-synaptic proteins). systems membrane post-synaptic membrane The have neurones vesicles has has in and vesicles receptors sea of membranes are receptors on and both jellyfish there and Integration different release Synapses both neurone. stimulate lowers depolarise the the Summation. neurone. The a allow excitatory neurotransmitters neurones impulses. neurones, synaptic This of that and inhibitory. stimulate hyperpolarisation potential difference, This means several neurones also achieved that firing at if from released the making one the different neurone same time of this these on 174. of impulses Excitatory by in more in neurone. difficult nervous Expect post- inhibitory post-synaptic it neurones the is neurones to does may not do converge stimulate so. much to learn about the from to your the Summation one hear of especially of exciting brain lifetime. You yourself on system, the field number impulses about Did you know? neurone. Many more channel nervous depolarisation in is sides. integration neurotransmitters receptors one the There is different. neurotransmitter (chemical-gated anemones with Nicotine are page The interact synapses. and polarised drugs allow of synapses the during amuse estimates neurones, in brain. discoveries research can by finding the glial of cells the and brain. next, may Did you know? be neurone so by that increasing the the frequency depolarisation is of impulses sufficient to from stimulate one the next. Electrical Dispersal of impulses. The axon may divide into many branches gap stimulate many other neurones, so that information can spread one source to many effectors in the body or from one source areas within the central nervous system. This is exist neurones important and post-synaptic the body to meet dangerous 3.5 nm. The membranes so close together that impulses in cross them without the preparing in which the is to are many between out prefrom synapses to use of situations. chemical transmission. They Filtering out impulses. Impulses with low frequency are filtered out and the depolarisation of the post-synaptic neurone does not reach sometimes sensory the prevents the CNS being inundated with some in our and we brains. unimportant information. Memory in This bidirectional the have threshold. are fast as is thought to be a function of the many synapses brain. Summary q uestions 1 Define 2 Make the a explain large, Describe 4 Electrical 5 how and chemical Identify the showing It may cholinergic synapse. labelled the function 3 of term a an each impulse chemical synapses in structures junction help diagram of you to is of part a visible a exist. nervous between make you transmitted synapses the cholinergic that in the two sketch across Explain and a synapse. the advantage system. electron neurones of synapse label. the micrograph (Figure structures 6.3.2). and label them. Figure 6.3.2 Electron micrograph for Summary question 5 125 6.4 Practice The Answers to 1 a all Explain nervous exam-style questions the exam-style difference can between a questions: system be found on the neurone and a nerve. accompanying CD. 3 a Describe how differences in the permeability of the [2] cell surface membrane to certain ions contribute to the resting potential of a neurone. Figure 6.4. 1 is a diagram of a [3] neurone. Figure 6.4.2 shows an action potential in a sensory A neurone. D 40 B Vm/ecnereffid 0 laitnetop Schwann cells region A region B enarbmem C noxa 65 Figure 6.4.1 0 b i Name A, B, C and D. 1 2 3 4 [4] time/ms ii State the direction taken by nerve impulses in Figure 6.4.2 the c Name neurone the describe in the neurone its role in diagram. shown in [1] Figure communication 6.4. 1 within Explain a [2] the role of the Schwann cells. [2] c 2 Neurones are organised into reex arcs. The Explain what i from –65 mV ii from +40 mV Nerve impulses arc is a monosynaptic reex arc that involves neurone and a motor Make a table to show the FOUR structure b i motor and function of neurones. how impulses this travel synapse in one ensures 4 a [1] Stimulation neurone of does the not in (region either [3] B). [3] direction neurone. towards the Explain central why why stimulation The speed of a motor always motor by a and not in the opposite system direction. Explain how the sensory strengths neurones of stimuli send to skin is nerve about neurone result in [3] by the Describe Figure that direction. neurone sensory the structure of a myelinated 6.4.3 sodium a ion [5] shows closed channels from and the open voltage-gated cell surface membrane neurone. sensory may not respond to [3] , touch but from receptors some in pain –1 receptors it is about 1.0 m s d Explain what causes impulses from 126 these [3] sensory impulse neurone. impulses from 80 m s [3] information the CNS. –1 the an impulses nervous transmission. Explain in neurone. of c –65 mV travel (region A) [4] cholinergic synapse. Explain what this means. Explain to +40 mV sensory The synapse between the two neurones is a ii membrane comparisons about and the neurone. d between to can sensory travel (CNS) a change a only sensory to simplest isolated reex happens potential: mammal. d b and the difference receptors. in speed Na of [2] Figure 6.4.3 Na Module b Describe proteins the changes shown in that the occur diagram to the during Explain Biosystems Compound Effect at curare competes roles in i voltage-gated ii sodium Sensory synapses [3] the neurones potassium potassium neurones ion channels sites acetylcholine for and blocks them [3] pumps. terminate with of: eserine a cholinergic action receptor 5 maintenance channel an potential. c 2 competes with the site acetylcholine for [2] in the CNS active of on acetylcholinesterase connector synapse b between Describe when neurones. the an Describe the two sequence impulse of arrives the structure of the neurones. events at the end methylmercury [4] that inhibits of the to stimulate the connector neurone. Outline the roles of synapses in the activates [4] b State on Some information about neurones from is shown in the and An explain transmission antidote for the effect across of each cholinergic compound curare poisoning synapses. is to use [8] eserine. table. Explain Animal chemical-gated channels different c animals some ion nervous system. 6 that acetylcholine [7] sodium c enzyme sensory nicotine neurone the synthesises occurs Myelinated or Diameter/ Rate of unmyelinated μm transmission 8 why. [3] An isolated neurone was placed into a trough containing a physiological solution resembling tissue of impulses/ uid. Electrodes were placed at one end of the neurone –1 m s to stimulate it. Recording electrodes were placed at crab unmyelinated 30 5 squid unmyelinated 500 25 the other end to record the passage of nerve impulses. a Explain why resembling frog myelinated 12 Stimuli 30 of neurone frog myelinated 14 35 cat unmyelinated 15 2 the different and neurone tissue uid, has intensities impulses to rather be kept than were in applied recorded. The a uid water. results to [2] the are in the table. Stimulus Impulse or Frequency of applied/mV not impulses/number s –1 cat a myelinated The table rate of shows 20 that transmission i State the ii Explain 100 two features of inuence impulses. two features. how each one Suggest of c 7 the neurone roles cats, as Explain how along myelinated a The following inuences action of the shown two in the rate potentials structures are none 0 30 none 0 40 none 0 50 yes 10 60 yes 25 70 yes 70 80 yes 100 types table. [2] propagated [6] are found ion channel at calcium acetylcholinesterase, channel 10 of neurone. mitochondria, ion different the voltage-gated sodium 0 [4] likely in none [1] transmission. b 0 the synapses. proteins, vesicles, chemical-gated proteins b a Describe in the the function transmission of of an each of these impulse structures across drugs interacting The table that act in the table information to about explain the how strength neurones of [3] [10] and with shows at data stimuli. c Many the encode a synapse. Use poisons have their effects by synapses. the properties cholinergic is d of four synapses. compounds Suggest able Make other to a table between ways transmit to in show FOUR coordination coordination by which the information the by nervous about [2] comparisons hormones nervous system stimuli. and system. [4] 127 3 Applications 1. 1 Health Learning outcomes of Defining Health On completion of this section, be able is to not define of and the social discuss the the health Physical physical, aspects explain of mental and health Physical the term name eleven and at categories describe least category an have S tudy up as of one example of each disease. refers is not injury it can health mean tend different to physical health, mental health and social health. health to in and symptoms many the proper good have that people condition Mental Some foc us many health find. Also out as of functioning health some may have broken of a the body disease bones. If or systems. may someone is have ill, they can identify and report to a they doctor . of that this and ask compare disease different understand your definitions own by the with the you people may does feel not ‘healthy ’, yet show but any in fact may be developing a symptoms. can and those of no perfectly may be health that healthy they when hypochondriacs, Depression physical may imagine and restrict a person’s but the inventing anxiety symptoms, have examined are there ability to by a severe many function of health symptoms more are symptoms a disease, worker . and pain conditions behavioural normally in but People when where like none there problems are that society. what terms. Write definitions them as of aspects of people exist. they satisfactorily Denitions the features appear terms dene people. each give Look to of disease disease of things: aspects of who However , disease three health Someone will term groups meaning suffered easy to: term discuss an different emphasise health you things should biology Social Y ou others. aspects of may point know that cannot we the are sur vive people live in health phrase highly totally large, ‘No social alone dense man is an animals and island’, that without populations. live others. Y et, no which in makes family Most matter of the groups the how and world’s dense the Did you know? population between WHO is an It has organisations, American seven social own interactions personal with space. others and The our compromise solitude we seek constitutes our health. Pan In 1946, the World Health Organization (WHO) dened health as: Health Organization ‘a state of complete physical, mental and social well-being and not has offices throughout merely the Caribbean. The the absence of disease and inrmity.’ PAHO website Society pages for benets from having a healthy population. Not a society simply several Caribbean free regional our regional including the (PAHO), which hosts web need agency of the United social Nations. we of disease, but one where people are able to participate actively. Many health organisations. people view services tness On the with and as purchased a commodity in the form – of provided dr ugs, by government health foods and health access to clubs. other holistic about ‘health’ hand, health how the for their yoga, both meditation the mind breathing, stresses and diet strains of and and and tai body; chi spirituality modern teach people us are can to achieve taught help to them think to deal life. Disease Figure 1.1.1 Each child is born with a Disease is often dened as a malfunction of the mind or body. A disease genetic potential; children need good is usually a disorder of a specic tissue or organ of body due to a single cause. physical, mental and social health to realise that potential and to play a full and active part in society 128 Some diseases causes and are affect many described as parts the multifactorial. and others have several Module 3 Applications of biology Categories of disease Different These aspects aspects of disease include are causes, used to effects classify on the diseases body , into duration, categories. tissues or organs S tudy affected and associated disease, which we risk have factors. limited in There the are table to many just different eleven. categories Almost all The diseases t into more than one category as you can see in the categories there Definition Examples know are and plenty about permanent or temporary multiple damage to any part of the body dengue fever, diseases sclerosis, measles changes may or to may physical acute disease disease mind, not which have that and answer a depression, (or a rapid short often lasts for causative onset that influenza, S tudy with a slow long onset chronic agent is a pathogen disease caused degenerative a cause the way infectious they listing Summary are some and question 4. not foc us bronchitis dengue fever, caused by a related HIV/ to measles stroke, pathogen deficiency of give us other ways to time AIDS, any by types dengue fever time communicable) non-infectious Start different anxiety categorise infectious you but schizophrenia, Risk factors that that table, cause with lasts for chronic the the more. the transmitted. Try then mental disease in 2) organisms physical are (from Units thinking 1 of table. should Category foc us of to diseases as some occupations, are income and poverty. multiple sclerosis by a poor diet iron deficiency in coronary anaemia Summary q uestions gradual decline body functions heart disease, HIV/AIDS 1 inherited (or a genetic) genetic faulty disease allele recessive or caused (either by a sickle dominant, cell terms anaemia, Huntington’s severe the in of the disease. different viewpoints disorder, meanings health and Consider haemophilia. codominant) Discuss your cultural answers. combined 2 Explain, with a named example in immunodeficiency each syndrome case, why and damage to the body brought lung cancer, by a person’s own dependency, Type some disease often influenced by lung cancer, different Suggest behaviour of others a living put them at risk of conditions, social environment and a increase the degenerative developing vectors active (see puts likelihood disease. page you 130); certain diseases. There are risk at risk of Some living of catching an infectious in being or infectious diseases visiting Huntington’s disorder is infected. highly are places disease or to who those develop by insect vectors inherits the or lung the allele biggest cholera who cancer , for risk are smokes but increases the chance Huntington’s factors more for to their diseases; spread risk much developing many likely is that for where of less developing than the example, there and are are be a both risk factor for Illustrate your with diseases that occur the Caribbean. the 4 List as List some many diseases as you can. are categories of disease allele than those given in the condition. chronic person condition. to diseases. table. Try Someone poverty, developing transmitted where Someone likely a lifestyle factors other for non- occupation in that of dependency answer can categories why western many behaviour , List disease. considered People’s diseases drug b social infectious non-infectious. diabetes 3 social as as 2 infectious actions are drug five about diseases (SCID) categorised self-inflicted some who Poverty is water-borne insanitary bronchitis inherits one of the diseases like diseases about categorising you have different medicine compile may your all the listed. Thinking branches help you of to lists. conditions. 129 1.2 Dengue fever Dengue Learning outcomes and On completion of this section, you is in on the spread. should be able fever other name the an Some infectious of increase, the both facts disease world. in about It terms is of dengue that is common considered number fever are of an in the Caribbean emerging cases and summarised its in disease as it geographical the table. to: Infectious is parts causative agent diseases, like dengue fever , that are always present in a of population are said to be endemic. Dengue fever is endemic in the dengue fever Caribbean state that aegypti, is describe the the the mosquito, vector of with outbreaks, or epidemics, dengue transmission Causative agent four outline fever the in of dengue Method of transmission not with we an the term epidemic. Also, used ecological are is a year. deaths the the to term DENV-1, virus, DENV-2, related tropics and 4 mosquito of Aedes species sub-tropics days action of pathogen white blood cells; liver and bone marrow see Clinical features high fever, nausea and painful Method of diagnosis made from symptoms; blood that body aches that endemic – number health period of reported in page 50. incidence in the tests varies: region 130 000 show also low (2010); by laboratory white approx. cell count 20 000 (2011) of cases Annual incidence Annual mortality time: is is the during more worldwide 50–100 million that in the varies: 130 (2010); worldwide 12 500–25 000 14 (2011) authorities week, a period about this region month number of Annual mortality of The causative agents of dengue fever are a group of related viruses, the in dengue Section – dengue endemic remember context Mortality time. There and approximately period virus of DENV-4 Incubation Caribbean or years. foc us reported during RNA and across Caribbean Incidence an Global distribution Annual S tudy some foc us confuse have in (strains) vector: female aegypti Site of Do insect the Caribbean. S tudy is DENV-3 impact occur serotypes which of dengue fever that Aedes fever viruses known as DENV . Each virus consists of genetic 1.5. material in surround form a from host once the the form RNA smooth Dengue female a host viruses that gain protein to stop blood for gut to takes of structural the completely codes for virus; proteins. the surrounds enzymes their of that while are to be They they Female take a mosquito, salivary blood an a other lipid help to Capsid two proteins proteins bilayer derived replicate uninfected an is a the meal. the and The take While blood. after 8 viruses uninfected people vector anticoagulant blood replicate This mosquitoes within glands. to to aegypti . inject transferred transmitted another infected Aedes pathogens. eggs. the from species mosquito’s mosquito mosquito the viruses cells the three core transmitted of clotting person, the transfer female are transmits to infected that RNA and the virus cell. mosquitoes organism enter The RNA form surface cells. inside of to blood in their they The to 10 by an meals saliva feed on an viruses days remain person – in when the the meal. Replication of the virus Figure 1.2.1 Aedes aegypti the vector of dengue fever taking a blood meal 130 When blood the cells virus in enters the skin. the human The virus body, binds it to attaches a cell to the surface surface protein of and white is Module taken fuses into the cell with the membrane (capsid proteins release the reticulum lumen many The of RNA, the RNA viral plus (RER) times and particles endocytosis. which and give the of RNA). where ER to by is is cut new by The capsid to into a The assembled membrane from on the within break rough of to the of virus the apart the virus RER the is term vector engineering for liposomes copied cells. See that protein attach the to needed Golgi to body enter so that new the host cells. to make surrounded proteins These by 4. 1 within vesicles to the cell surface are where new viral glycosylated. they leave more white blood a short by The flu-like high 40 °C a rash, pain period, symptoms, nausea, in typically 4 to 7 days, an infected severe muscles infected 2 may online for the animations replication virus. They using this and such as headache, high fever , vomiting with and temperatures is feel lost with unwell from bleeding dehydration There are people is no swollen lymph glands may can likely drugs the dengue is usually ill for about 10 to 14 days, question longer plasma occur , to than as this. Complications capillaries for example become into may more set State the meaning as a available, so treatment giving plenty the gut lumen. fluids usually and consists perhaps and joint risk of pains. Aspirin should of be to Some increase cases can haemorrhagic About 5% of the develop form, these in the which are applied to infectious such as dengue fever. Explain how the dengue fever making is virus that causes transmitted. painkillers used as Draw diagrams to show how this virus: bleeding. into cases terms Severe using not the and result. of of endemic and in. permeable 2 occur muscle 3. but dengue tends you to joints. for the comfortable, reduce help Summary q uestions 3 to the description Summary diseases internal of as vector as Fluid 1. foc us emerging disease, they in Unit person 1 Anyone Module and into symptoms: painful as genes to answer viruses transfer cells. incubation developing plasmids, genetic viruses exocytosis when starts in particles dengue After used new showing infect of is the Search pass biology replication. S tudy envelope of Link The to enters Applications virus endoplasmic DNA the RER core formed RNA similar the the then protein The process surrounding releasing proteins sections. in are so ribosomes translated. RNA proteins coated membrane vesicle, travels it The the 3 more there fatal – is severe and internal usually sometimes and external amongst young a enters b is c leaves a white blood cell fatal replicated bleeding. adults the cell to infect and others. children. prompt People can treatment. also die Severe from cases dehydration are often if treated they in do not receive You hospitals. will need diagrams in to the protein include organelles in your involved synthesis. Prevention 4 Health the authorities vector of the throughout disease. the There Caribbean are specic direct prevention measures that can Explain why dengue fever serious health is a against be problem in the taken, Caribbean. such as fumigation, predators ditches. of draining mosquito People bodies larvae should into avoid of standing water being water courses, bitten by such and as placing irrigation mosquitoes 5 A vaccine for available wearing long mosquitoes clothes tend to to avoid exposing skin during polio became by: the day when the reasons bite fever in the why did a not 1950s. Suggest vaccine for become dengue available th putting up entering keeping using screens on doors and windows to prevent in mosquitoes houses areas houses tidy and free of possible breeding coils and insect repellents. Repellents with DEET ingredient Search tend to be the most effective. DEET is the annual of the four and with on for may the page that there types they target 3 2012, an of is odour enzymes 156). type, no virus soon that be approved that mosquitoes that not vaccine cause available. for by any one of dengue Drugs replicate Infection but 20 actively the provide fever . to treat virus strain the to (see immunity are disease those provides website in annual the Caribbean dislike. V accines the and an region for As the PAHO/WHO incidence mortality figures insecticide of as for active half places 6 the second century. around mosquito the for natural to being are HIV of tested likely in active any to Question immunity How 2010 do the last full these when epidemic countries in there the are year. compare was a with serious region? Which most at risk of dengue fever? others. 131 1.3 HIV/AIDS HIV Learning outcomes On completion should be able of this section, you stands infects cells HIV not is between to: person. state that human (HIV) infection with may lead to of virus syndrome the different transmission of methods outline the HIV social of of an system, virus and infected but is it person transmission is only not Like DENV , transmitted transmitted and the blood by of the by a direct an virus vector . contact uninfected are: aspects of anal sex between a person who is HIV+ and a person who a needle someone or who sterilised by between syringe is a not; that this health is can worker intravenous used on happen HIV+ when following drug an use a person needle or when or a and then syringe needle is is users of blood in blood or in shared the robust virus. uninfected not describe immunodeciency immune a Methods blood on (AIDS) the such vaginal is the acquired immunodeficiency of human the immunodeficiency development for from blood an HIV+ products, person such as is used clotting in transfusion factors used to or is a treat contaminant haemophiliacs HIV across at the placenta during pregnancy transmission outline the life cycle of birth blood of a HIV+ mother incubation period of and the blood of her baby mix. HIV There is flu-like HIV outer when envelope is is the a short symptoms a that retrovirus. reverse of are Its what often RNA is used normally several weeks. Then there are mild misdiagnosed. as a happens template in cells. to make The DNA, virus has which surface glycoprotein proteins that interact with proteins on the surface of enters the T-lymphocytes. The transmembrane virus fuses with the host cell and the RNA cell. Reverse glycoprotein transcriptase lipid uses the viral RNA as a template to assemble double- membrane stranded capsid proteins RNA DNA, which integrase attaches provirus. It DNA is may used as it enters to host remain a the DNA. inactive template nucleus for This for host where the viral incorporated several RNA years. enzyme viral When polymerase to DNA is a activated, make the complete protease RNA as the genetic material for new viruses, and mRNA to make viral reverse proteins. Protease cuts the protein produced on ribosomes into short transcriptase sections that are assembled around RNA to make new viruses. These integrase travel Figure 1.3.1 to the cell surface membrane and leave surrounded by host cell Human immunodeficiency membrane with HIV glycoproteins incorporated. virus The infection until the thrush, is then appearance tuberculosis, symptomless of a a variety rare form of for a fairly lengthy opportunistic of pneumonia period diseases , and of time, including Kaposi’s sarcoma (a Did you know? rare form of cancer). T-lymphocytes At the beginning of the in the 1980s, people inherited disease decreased as develop they have because been the number destroyed by of Acquired Immunodeciency Syndrome or AIDS is HIV the term with applied the diseases HIV/AIDS infection. pandemic has These to the collection of opportunistic diseases associated with HIV haemophilia infection. were treated agent that with was a blood-clotting contaminated with The start HIV. These people sadly rst of are Now people provided produced with using with AIDS pandemic that as promoted were HIV identied spread in the through early 1980s. populations This was worldwide. the its spread The were: haemophilia clotting agents recombinant people ease had unprotected sex with many partners DNA. of travel Caribbean and from poor long worldwide, and migrant North e.g. tourists workers from travelling North America between visiting countries and America diagnosis period symptoms 132 of developed factors AIDS. a cases of time when people were infectious but showed no the to Module no cure the and no 3 Applications response distributing and of health appropriate providing sex authorities information education in and about governments the the denial by some transmission of HIV AIDS HIV/AIDS sexual is and governments that HIV existed. the transmission, Widespread but to control Health they testing not a single reasons for Compare AIDS of as it is authorities cannot control populations for transmitted can primarily distribute people’s HIV is sexual (see page also S tudy about foc us behaviour . expensive Obtain and some leaflets authorities organisations have term AIDS. SCID and TB. health that with during information impractical. Methods disease. Work the control difcult intercourse. is schools 156) Prevention foc us in out biology vaccine S tudy slow of been employed by different countries in the published and working by voluntary with HIV/ region AIDS. Assess the they to information that include: providing that people HIV+ information should should providing countries still testing the HIV those organisations AIDS A testing and to stigma, fear there a is occurs sex active during in sex in in Sint those Maarten prison, through Cuba testing pregnant as who provide becoming are to live with and condoms clinics; clinics for in of both at was Caribbean people if HIV+, how HIV/AIDS. are sexually mandatory and providing with and for awareness with HIV . prevention and national HIV/AIDS. Although women, example, and Partnership in individual men even women activities associated for high risk antiretroviral many that support In most is Against and levels, many is the countries transmission associate illegal. groups HIV/ control. have HIV Some with people been killed. antiretroviral those and many drugs (AR Vs) has improved the life Figure 1.3.2 expectancy prevent infected HIV+ Pan Jamaica against, of in the between HIV/AIDS provision of associated men; discriminated The hatred that precautions others the distributed coordinate problem, and example and the some status as HIV/AIDS, (STIs) identied such stigma between for of infection schools, centres; is (PANCAP) widespread are risks infecting for high the avoid avoid infections groups drugs to condoms, condoms voluntary to through transmitted take take free distributed about living with HIV/AIDS and helped to reduce the HIV/AIDS awareness death campaigns stress the importance of using rates. Provision received these varies drugs; between in countries. Jamaica it was In Cuba about in 2010 all patients condoms during sexual intercourse to reduce the chances of transmission of HIV 50%. Summary q uestions 1 i State ii State AIDS what is which and meant by categories justify your HIV of and AIDS. disease apply to 5 Identify 6 Contrast the Describe of the the virus transmission may be Explain HIV+, the fact but not Make a table information risk of HIV infection. the response of HIV and how the epidemic of Cuban with the authorities responses of to the other countries. spread controlled. that someone can be diagnosed Suggest vaccine as why to it has protect so far proved against difficult to develop a HIV. have AIDS. 8 4 at HIV/ 7 3 most choices. HIV/AIDS 2 people similar about to that on page 130 to summarise Outline the ways in which HIV/AIDS differs from dengue fever. HIV/AIDS. 133 1.4 Diabetes Learning outcomes and cancer Diabetes Diabetes On completion of this section, be able state that diabetes and both not degenerative, are two explain T ype 1, 1 the difference and Type outline the T ype 2, 2 risk factors discuss 2 the awareness seeking and do not disease respond or in which respond poorly. by usually develops pancreatic early in life in which no insulin is β-cells which diabetes and importance of develops later in life and is usually associated with a of risk factors, including diet and obesity 2 diabetes in the the more Caribbean common and form elsewhere. and is Some a serious people health have it for a long cancer before they seek a diagnosis of symptoms, such as these: of symptoms treatment for is associated time degenerative cells diabetes problem with Type target between T ype its types: which variety Type non-infectious, or diseases a non- secreted infectious is secreted cancer are is to: There mellitus you insulin should mellitus feeling very extreme itchiness recurring thirsty; urinating a lot, especially at night and cancers diabetes. the tiredness; around weight the infections growth of this loss vagina of with or Candida yeast-like loss of muscle tissue penis causing fungus is the disease promoted known by as glucose thrush; in the urine Link You studied aspects of blurred in Unit 1. See 4.3 of in Unit 1. Another type of factors diabetes insipidus – see this that Prenatal page the be promote the malnutrition . famine have because ‘thrifty Genetics . family onset Studies a higher prenatal phenotype’ Diabetes members themselves. S tudy the eyes becoming glucose is diagnosed tolerance done Summary and by test. then question using Find a out Native how answer 7 . of T ype 2 have Age . researchers cannot controlled also In that of people diabetes whose than mothers others. predisposes to obesity This thanks to in which fat to in T ype alone run 2 are is diabetes not stored in families, are at times and risk responsible: of diet, the effects lack Diet . A USA, does is diet Obesity . more not to high the Greater a high Americans, prevalence common secrete experiments on to fat, of and in insulin older as T ype people. efciently 2 It of interferes conditions have an years from Some have been carried is thought target cells with not enough bre, and much rened increases with the Fat were born during or Holland sugar the risk that target cells do not body ’s ability to 10 seconds from a person diabetes. insulin. High blood pressure and high blood the 2 same people 10 seconds, after develop disease. to studies people shortly in the become tissue dies use generation on that and impact long-term out and diabetes. diabetes. bulk insulin. cholesterol. in it exercise Hispanic-Americans of the famine of easily many have insulin. in risk African have In malnutrition generation. plenty. who developing Every people; of those important. the responsive respond conduct Genes Diabetes increases Did you know? over dry. diabetes: found prevalence malnutrition tends with Americans pancreas Medical are Ethnicity . less like very foc us obesity Diabetes is in unit. this lenses 118 may of the diabetes suffered is by Module 2 caused diabetes Risk mellitus vision who the coronary diet, These arteries obesity increase the two and and lack risk of factors together of damage with exercise, diabetes. 1944–45. T reatment involves Later it for T ype careful may 2 diet become diabetes control usually and necessary exercise. to take Figure 1.4.1 insulin. Awareness of diabetes is highlighted each year on 14 November – World Diabetes Day 134 Module Cancer T esticular testes. Cancer is parts the a group of diseases that affect body. Each one arises from a single grows uncontrollably to for m a tumour. such caused Breast by mutations in genes that control and division. Not all tumours are are either malignant or benign. Cancers place tumours where they as the arise cells and may invade may migrate via lymphatic spread from adjacent vessels to areas remote in the body. breasts. as for med the in body other (metastatic) is metastasis parts of the agents, factors Further are factors proliferation a of or that of to both cancer cells by cancer: Lung (see page cancer: and/or to countries at risk early DNA. mitosis. substances so Environmental hazards: ionising chemicals (e.g. radiation, dioxins, Food organisations longer There have is nitrites in red with that meat toxin in are by of viruses carcinogens processed processed meat These to several cancer: (HPVs) Human the breast vaginal vaginal or cough; cancer as bleeding, e.g. discharge pain that during coughing up sex. blood; pains. have mass screening programmes for cancers. of is very cancer . and is effective Cervical cancer for checking by taking the detecting of cancerous laser for treatment. of the signs important the are X-rays images is at smears signs destroyed involves Mammography lumps Failure to cannot check help treatment of be a cure. It for of a because 40% felt. symptoms, reduces also may or the have chances lengthens be the necessary T reatment radiotherapy and may of screening time and for reduces involve or seek successful which the chances chemotherapy, surgery. be added as S tudy foc us formation botulinum viruses are no foods. may are prevent Chlostridium shoulder screening The treatment. regulatory nitrosamines cancer . with development cervical use that and by potential the certain benzpyrene) safety colourings Infection (papilloma) for gastric and for any evidence with botulinum Viruses. tested approval preservatives of so some associated are get discomfort cells. medical additives of examine (in carcinogenic. a microscopically breasts light X-rays, asbestos, abnormal periods; examined of sunlight), men persistent Mammography 174). ultraviolet of stages tumour . that unpleasant; Cervical the of Note normal Some are damage groups to spreading secondar y promote damaged contains cause cause one tumours carcinogens , required these smoke potent are in how women. between those environmental is body the lump learn blood cancers. Cancer-causing T obacco the and should Cervical chest through painless tissues. or This a Women the stream the lumps. cancer: smells They on regularly are malignant lumps testes cancers; well they their cell their growth painless examine biology Cancers breasts. are unusual should of cell that Applications different for of cancer: Men 3 is Cancer is linked wart main not can cause is often the thought case. This affect younger to be section ‘a disease’ of concentrates old on age, which cancers that people. of cancer . Summary q uestions Liver cancer infection with the may with develop hepatitis Epstein-Barr B after and virus leukaemia/lymphoma many C and virus years viruses. the of Infection 1 T-cell risk of blood cancers. (HTLV-1) HIV+ risk Kaposi’s of blood cancers and the difference between Type 1 and Type 2 increases people are Outline rare the factors that influence the development of at Type greater the diabetes. 2 the Explain 2 diabetes. cancer , 3 sarcoma. Define the terms tumour, cancer, mutagen, carcinogen. Genetic more factors . often in population. BRCA1 and percent of alleles BRCA2 breast inherited types families Mutations all are Certain some in are either linked cancer in a of cancer than in of to the The dominant rest of the 4 genes about cases. occur the ve Explain the be aware 5 Outline the benign 6 Explain the risk factors for cancer. how people can reduce their risks of fashion. 7 of and mutant awareness should malignant ten Find out Sketch People between tumours. to developing Symptom difference symptoms of cancer , a how Type a graphs 2 diabetes, glucose to show and tolerance what you b cancers. test is would carried expect out. to find as in: early diagnosis tumours damage four can and be other treatment removed tissues. often before Here are means they some that spread and symptoms of a a b someone free person with Type of 2 the diabetes disorder. cancers: 135 1.5 Health statistics How Learning outcomes should outbreak On completion should be able of this section, you with rst to: explain the differences is and mortality incidence in Haiti about is in the of the 2010 or to the Caribbean? accurate some respond data about different emergencies, increasing Before the health such number responding, diseases as of one concerned. statistics that are the people of the This collected, between and published by organisations, such as CAREC, PAHO/WHO and and between authorities throughout requirements collated morbidity cholera diabetes section of medical the UN. and prevalence Morbidity data explain the calculating importance rates of of incidence and mortality Morbidity diseases. records. analyse main and interpret indicators of data health on data This and data incidence – particular 1.5.1 the is the shows how many people come expressed have from certain doctors’ illnesses records and and hospital as: number the of of time – incidence 2006 in prevalence – or certain the El new cases usually of a diagnosed week dengue or fever a and reported, month from or January a over year; 2005 a Figure to Salvador number of people with a disease at a particular time foc us within change of us morbidity period December Most on the disease. S tudy tells Details Summary questions a in time prevalence of period, e.g. HIV/AIDS a in year; the Figure 1.5.2 Caribbean shows from the 1990 to on 2010. pages data 140 in to 141 are these four based on the pages. 2500 Before answering graphs, to take right, where on noting an the run trend paper, significant troughs, on it from or mark occurs plateaux, 1500 etc. 1000 fo peaks, and exam anything as questions ruler sesac pattern; such a 2000 fo left foc us revef eugned S tudy rebmun S tudy 500 foc us 0 For more information about HIV/ J AIDS see the websites of Figure 1.5.1 following organisations: F M A M J J A S O N D J F M A M J J A S O N D the Monthly incidence of dengue fever in El Salvador 2005–2006. The rainy PANCAP, season runs from May to October. Avert, PAHO, WHO. T able 1.5.1 second Did you know? 2010. There fever and were in epidemics of the Caribbean 2010. Search in 2005–06 online for This region. dengue slow down about these will help and with the page Summary question of the the on involving living health can be infection AIDS region the ser vices provided and patients taking of with several TB, dr ugs with throughout with control have world HIV/AIDS dr ugs the in the that the which over a itself is long of time. Over with the time, the number HIV/AIDS of new epidemic cases falling peaked steadily in the since then. 1 from AIDS-related diseases 140. fallen 136 treat, impact Many is population HIV/AIDS development to the summary Deaths on with infections. disease mid-1990s, questions Caribbean of epidemics. This period research the considerable living the opportunistic news that proportion has People dif cult reports shows highest since the mid-2000s. peaked 10 years later and have a Module Applications of biology snoillim 300 150 ni upper estimate lower estimate 200 elpoep 150 fo 100 rebmun 50 0 0102 9002 8002 7002 6002 5002 4002 3002 2002 1002 0 00 2 9991 8991 7991 6991 5991 4991 countries a 3991 Prevalence of HIV in the Caribbean: the number of people living with HIV 1990–2010 T obago, with 2991 The 1991 0991 Figure 1.5.2 and 3 in the Jamaica great deal of region and with the the highest Dominican uncertainty; quite prevalence Republic. frankly no All one of HIV quoted knows are Haiti, gures the for exact the Bahamas, prevalence size of the are, Guyana, Suriname, however , HIV/AIDS estimates T rinidad made pandemic. Table 1.5.1 Region HIV/AIDS among children Incidence/numbers of new cases in and adults Prevalence in Numbers of Sub-Saharan Africa Middle East Eastern and Europe Western 1 and Central 22 900 000 5.0 59 000 470 000 0.2 270 000 4 000 000 0.3 30 000 840 000 0.2 58 000 1 300 000 0.6 12 000 200 000 0.9 100 000 1 500 000 0.4 3300 54 000 0.3 88 000 790 000 270 000 4 000 000 Caribbean Oceania South Figure and South-East Asia 1.5.3 shows the Percentage of total 900 000 North America East Asia and adult Europe Latin America adults children North Africa and Central Asia 2010 2010 population 0. 1 0.3 4 10 progress of the HIV/AIDS Caribbean in the total people as have of been having AIDS latoT country. in Dominican Republic 10 sesac each changes number who recorded in as 3 dedrocer countries, Caribbean SDIA fo rebmun epidemic Bahamas Jamaica 2 Cuba 10 Bermuda St Vincent and Grenadines 1 10 Dominica Turks 10 Virgin and Caicos Islands (UK) Anguilla 1 1978 1982 1986 1990 1994 1998 2000 Year Figure 1.5.3 137 Module 3 Applications of biology Table 1.5.2 Country T able 1.5.2 adult populations gives estimates of some of the prevalence Caribbean of diabetes amongst the countries. Prevalence/ percentage of The adult late population data in 1980s the and table was 1990s. If collected repeated from now samples the of gures populations would all in likely the be higher . Barbados 16.4 Cuba Mortality data 11.8 Details Guadaloupe on mortality come from the information recorded on death 5.8 Jamaica certicates. When people have who collated, died and this information what they have tells died us about from. the number However , of doctors 12.6 are Suriname not people 8.7 that Trinidad 12.7 and Tobago always die of make sure them factor had such diseases T able to 1.5.3 has to as save gives been the although susceptible contributory certicates what pneumonia, their to pneumonia on Many and have and who may members from of have died Many their and elderly conditions been of a major AIDS recorded of diabetes death. long-term have tuberculosis to mortality cause may pneumonia deaths. embarrassment data actual they on have their death family. all causes in four Did you know? Caribbean mortality Outbreaks of disease are on a large across Pandemics scale, are affecting continents or rate is world. In the people across past assess standardised the to relative permit importance comparisons of a disease between the years and countries and regions (see Summary question 3 on page 141). epidemics Table 1.5.3 the Parameter whole T o called between epidemics. countries. there Aruba Belize Cuba St. Vincent and have the Grenadines been and pandemics cholera. We of bubonic are plague currently in the Deaths from middle that of the began in HIV/AIDS the early diabetes (all causes) pandemic 1980s. Males 14 (278) 38 (649) Females 21 (216) 89 (457) Population 817 (36 814) 1283 (26 135) 16 (341) 18 (260) (thousands) Males 48 153 5673 53 Females 53 149 5710 51 Health the statistics number whole area. For is area only for or of it be who such workers. rates. Incidence population may women diseases, as the as They part are at some are of at is risk. the risk may population of diseases, population at risk, for be in developing respiratory the calculated This the an cervical only not the population. in includes Haiti, an it groups expressed reported of example, 1.5.4 cancers often Occupational certain general T able are cases population cancer . affect of shows 26 all of annual countries Caribbean Guatemala standardise the the the and death and mortality in the Central Nicaragua. rates (see in 2008 WHO American Population Summary for the Americas ve countries data 4 which except allows question leading region, on you page Cuba, to 141). Did you know? The last medical case 138 smallpox photographer laboratory from of and smallpox. in died from transmitted naturally Birmingham, UK, the disease in was tragically 1978. This in Somalia caught was the in the last 1977 . A virus in known a death Module 3 Applications of biology Table 1.5.4 S tudy Total Annual foc us mortality When population All Organ-specific discussing the prevention and cancers control (thousands) of diseases, do not just causes consider Breast Cervix Colon Lung can take, taken Males also 235 894.25 1 574 755 121 0 16 812 precautions that individuals Stomach 36 809 at by but the also those that community health are level and authorities, 26 236 governments and governmental inter- organisations. Females 242 163.65 1 256 277 33 055 25 592 17 546 17 930 16 236 Did you know? Prevention and control One Collection of data is essential if we are to follow trends over time. of the modern example in Figure 1.5.4 shows the eradication of smallpox from India whole successes of medicine is the eradication and of the great The smallpox. The WHO declared the world. world free This was of this largely disease due to in 1980. many young 500 000 people who volunteered to carry India 450 000 out world surveillance for vaccinate people at the disease and risk. 400 000 350 000 sesac 300 000 fo rebmun 250 000 200 000 150 000 100 000 50 000 0 1950 1955 1960 1965 1970 1975 1980 year Figure 1.5.5 Figure 1.5.4 Ali Maow Maalin, the last person to have smallpox that was The eradication of smallpox. Number of cases of smallpox in India and the transmitted naturally whole world between 1950 and 1980. Summary q uestions 1 Define the terms prevalence, 2 Explain is epidemic, why usually morbidity, the data expressed mortality, 5 incidence, pandemic collected data on per 100 000 Discuss health of the and disease population. 6 All the Explain why rates of incidence, prevalence rather 4 are often than for Discuss the national the expressed for whole reasons and why the diseases are could such of about be of as collecting those health to included statistics diseases. collected and Suggest measure publishing in given some the this in section. this statistics health of the and peoples mortality importance examples section that 3 on the of the Caribbean. population at risk population. the international statistics published organisations may by not be accurate. 139 1.6 Summary questions Answering statistics. health Y ou issues examiners your 1 questions also in will need the to will nd Caribbean expect you help to and and have you read in to analyse and information the rest up-to -date of the interpret about world. information health current The to illustrate answers. Use a these Figure i 1.5.1 Describe in answering the incidence these of questions. dengue fever in El Salvador in 2005–06. Figure 1.6.1 ii Explain the pattern iii Explain the advantage you have described. A health worker in Cuba fumigating a house with insecticide to kill mosquitoes during an epidemic of dengue weekly or monthly of recording rather than incidence from dengue fever annually. fever b i Suggest other need order in shown S tudy foc us ii in Outline the how incidence Developing vaccines for dengue experimental virus are that used may to make an strains would be there and against infection much in an is animals; culture protection other as infects difficult that it be the that relative the health authorities importance of the might changes graph. health authorities dengue should respond to the changing fever . Explain the difference between acute and chronic diseases , with animals reference cannot statistics assess is c difficult; of health to no the it one by more to dengue fever and diabetes. similar d Assess e Compare the impact of dengue fever in the Caribbean. viruses is feared one of severe disease the than the incidence strain 2 unvaccinated Use a – Figure i in 1.5.2 ii b Suggest Explain in c Explain why prevalence data the in the Caribbean another with the insect-born WHO. questions. 1990 pattern Figure in – prevalence between for of these in fever malaria region changes region the for dengue from answering reasons why estimates African the Caribbean of mortality the Describe person. incidence and of and you 1.5.2 HIV/AIDS in the 2010. have described. includes upper and lower HIV/AIDS. prevalence data for data dengue for HIV/AIDS fever . (Refer to is more Figure useful 1.5.1 in than your answer .) The mortality around Figure 1.6.2 d The Pan American Health Organization coordinates the activity of 2005 Explain rate and why for has the HIV/AIDS fallen trend in the Caribbean reached a peak since. for mortality differs from that for prevalence. health authorities throughout the e Use the information in T able 1.5.1 to compare the HIV/AIDS Americas, including the fight against epidemic in the Caribbean with other regions of the world. malaria in Suriname. Here a laboratory worker tests blood samples for signs of the f Use the PAHO website and others to assess the impact of HIV/ malarial parasite. AIDS 3 a in Suggest the why the Caribbean 1.5.2. Assess region. 140 different countries in the prevalence of diabetes is the likely to be Caribbean. higher importance of in than diabetes the the for adult gures population given populations in in in T able the Module Use the information answering parts b in and T able 1.5.3 5 when a i Describe cases c. ii b i Calculate the Suggest deaths from diabetes as a percentage deaths mortality in each rate 100 000 mortality the for number in the of Figure pattern 1.5.4. you described. Explain why as the deaths from all had WHO been could be eradicated certain when it that made causes statement to that effect in 1980. population b in shown biology country its per as explanations smallpox changes smallpox of of iii all the Applications following: have of 3 rate from diabetes per Read about the WHO campaign to eradicate 100 000 smallpox and summarise the reasons for its population. success. ii Use the the results countries of in your order calculations for the two to put to (There eradicate is more infectious about other diseases on campaigns page 153.) mortality 6 Use Figure 1.5.3 in answering these questions. rates. iii Present the data calculations c i State the data authorities the four ii from one that might of the table and a your Describe international to from assess diabetes the over b health each next c 20 Suggest to shown and why an authority like this such a long time span progress the reasons in give for some what in of the HIV/AIDS Caribbean. is the likely Figure to 1.5.3 reasons faster countries for progress than happen over your the of the others. to the next patterns 20 years suggestions. should d consider in epidemic likely the Suggest of years. Explain the epidemic table. collect countries importance 30 in with Outline the impact that the HIV/AIDS this epidemic has had on countries in the disease. Caribbean. iii Outline the steps that health authorities 7 should take to combat the increase Dene some diabetes in the The WHO analyses risk data by country and also others Use the information from T able 1.5.4 this i Use we Explain can do why there something are about that refer to we can’t diabetes, do anything dengue about. fever , Y ou HIV/AIDS the cancers listed on page 135 in your answer . question. 8 a factor . that to and answer risk by should region. term factors Caribbean. and 4 the in the data in the table to How that mortality rates per 100 000 does income influence the types of diseases calculate for males people have and die from? and 9 T o what extent does occupation put people at risk females: of for each for all developing Read about the data in the table and the present of your calculations Explain the calculations on b different i Describe ii Make data iii like these Outline one of have when the patterns offer three plan, in the mortality observations explanations studies that for the each one. based on the 2010 some data on the This epidemic. should by about the eradication and Wellcome Trust research the likely causes of Type 2 diabetes you looking for such information foc us epidemiologists observations made. the WHO include S tudy and on of ndings. rates. about of websites. up-to-date associations, American can find outbreak your data Link smallpox on out analysing diabetes You cholera based table. carrying You could Haitian report diseases. signicant and in advantages a results should iii the causes. and Present diseases? cancer 10 ii different as the Centers for the Caribbean obesity such Food information and and about diabetes as do provided Diabetes UK Diabetes Association. as WHO, provide summaries Health and in Institute, degenerative news national the organisations, Disease Control Nutrition by the USA also diseases, such as media. 141 3 Applications 2. 1 Defence against or completion should be dene able the of this section, you terms parasite and outline the infectious defences viruses, bacteria against describe the non-specic specic differences responses responses to e.g. , fungi, infection. worms, prions agents are some, like to see Viruses and as have they hookworms, with prions no in gain these harm different live to nutrients in the a sort host and/ of are forms: Epstein-Barr cholera tetani (cholera), Mycobacterium tuberculosis (tetanus) Plasmodium Candida e.g. albicans Schistosoma americanus (infectious have virus are or falciparum (malaria), T rypanosoma cruzi (thrush), Pneumocystis jiroveci a mansoni (schistosomiasis or bilharzia), (hookworm) proteins), variety of e.g. ways CJD in (Creutzfeldt-Jakob which they can enter Disease). is injected by a mosquito; HIV enters via the body. blood the are cells naked not and through sexual contact. Other pathogens are to blood transmitted via large droplets enough of cause and microorganisms contact but host Many that come a of Dengue Most on disease) e.g. Pathogens disease. or (pneumonia) causative those HIV , Vibrio in organism. but pathogens Clostridium e.g. live diseases between and foc us are host DENV , e.g. that host, Human Necator Pathogens the the protoctista, S tudy from with (Chagas organisms protection harmony (TB), diseases infectious are pathogens. to: pathogen biology Parasites Learning outcomes On of in the air and also in food and water . eye. organisms There are three main types of defence against infectious diseases: no mechanical – tissues provide physical barriers that pathogens cannot metabolism. pass through chemical – unaided substances environments them for secreted pathogens, reproducing and/or by trap the body them, growing, stop provide cause them inhospitable them to entering burst, cells stop and kill them cellular – presence to protect Details Once in Figure 2.1.1 cells of of the these pathogens spaces secrete hormone-like pathogens; body against defences gain between ingest are entry cells or the in to and to alert pathogens; spreading the of the body secrete to the chemicals pathogens. table. tissues, enter chemicals digest cells. blood or Worms lymph can live they in either the gut, remain reducing Transmission of diseases, especially water-borne diseases, is much more likely following catastrophes such as the quantity nutrients of from digested the food plasma. we absorb Most of or the in the blood, pathogens that absorbing enter cells enter the Haitian earthquake specic of the both S tudy often foc us about pathogens all the enter ways the in body. groups of these and then are question Make a system as itself. pathogens, destroying non-specic Non-specic M. tuberculosis , There but the are defences removing infected defences and DENV them host that from and are HIV enter effective cells is cells against difcult and cells. specic defences against pathogens. defences different are present pathogens and from they birth, give the they do same not distinguish response each time answer pathogen enters the 1. not 142 such which particular Summary of involves between list Some, defence There Think cells. always highly effective. body. They usually act very fast, but are a Module Defence Mode of action Sites 3 Applications in the of biology body Mechanical: skin epidermal physical mucous membranes cells, cells with keratin provide a tough skin barrier e.g. goblet cells, secrete mucus to trap trachea, pathogens vagina, bronchi, bronchioles gut Chemical: lactic acid, fatty hydrochloric acids provide inhospitable environment with low pH skin, acid vagina stomach histamine hormone-like action to stimulate interferon hormone-like action to protect interleukins hormone-like actions to cellular cells regulate defences against the viruses immune most tissues most tissues blood, lymph and most tissues blood, lymph and most tissues system complement proteins from antibodies that the aggregate, toxins; help mark and remove pathogens body immobilise prevent entry and of kill pathogens; pathogens into neutralise blood and lymph cells Cellular: phagocytes ingest (neutrophils and digest pathogens; present antigens blood, lymph nodes and tissues and macrophages) mast cells B-lymphocytes (plasma secrete histamine most secrete antibodies blood, tissues lymph nodes and tissues blood, lymph nodes and tissues cells) T-lymphocytes Specic not produce type to is defences present of be from of response is and, that it or and are that known if effective, are exists defences because pathogen) We born, lymphocytes that changes lymphocytes highly activated specic sequence should are birth. specialised pathogen selected, why coordinate as slower an responds successful, pathogen invade to a will slower with The to the and us in to to an every act. It the an in are of every need response. This The specialised adaptive environment survive cells to involved defences. is infected They strain effective increase the kill potential lymphocytes response . change help pathogens; non-specic select immune to much produce than to to antibodies exist. divide occurs but however , and will response our (entry of a environment Figure 2.1.2 Vaccines provide protection from infectious diseases by stimulating again. immune responses by the body’s specic defence system Summary q uestions 1 Outline of 2 Explain and 3 how the body defends itself against the entry 5 pathogens. the Dene the antibiotic, as difference cellular Explain defences terms between against mechanical, parasite, pathogen, vaccine, chemical 6 disease. Explain has antigen, antibody, immune response 7 why Make a table defence to compare the non-specic Find and and specic why the incidence decreased out defence of signicantly which neglected concerned 4 the system is described adaptive many over diseases WHO diseases about and infectious the past identies explain why 100 as diseases years. emerging we should be them. specic systems. 143 2.2 Non-specic Learning outcomes defences Mast cells Pathogens On completion of this section, be able skin describe the function phagocytes defence outline in of non-specic against local disease the function complement describe a enter break happens, respond to target cells. in the the to may body at mucous promote presence that The complement of it the hormone attach or of does site, for lining example the a airways. cut in When receptors on local travel of and a reaction in bacteria is by mast releasing the antibodies mast by blood, aided that but by cells. These histamine, diffuses the combine action with cells which to is a adjacent of bacteria and cells. proteins the function and localised pathogen not detection proteins a of mast alcohol cells a membrane to: this usually histamine you the should and histamine in direct injury during wounding nonmast cell endothelial specic defences. receptor for activated complement cells protein, C3 of capillary Did you know? The interleukins chemical in 1 the is signals immune released stimulate by the are a group released system. of by cells Interleukin macrophages brain, to causing fever histamine infection by bacteria activates complement protein, C3 neutrophil and sleepiness. Fever is one of neutrophil non-specic attracted to bacteria by blood through defences. complement Figure 2.2.1 1. leaving our Chemotaxis and chemicals released by bacteria leaky capillary wall When stimulated, mast cells release histamine by exocytosis to influence surrounding target cells including the endothelial cells that line capillaries bacterium Histamine stimulates inflammation . As a part range of of this, non-specic neutrophils defences are known attracted from as the blood to complement proteins and chemical the infected area and tissue phagocytes are activated. products neutrophil of 2. 3. Adherence bacterium Fusion A variety of changes capillaries white occurs become when a tissue becomes inamed: leaky lysosome and plasma the cells, the such as neutrophils and monocytes, leave the blood tissues proteins, area from phagosome nucleus blood enter such becomes hot as complement and red and the and antibodies, tissues swell leave with the uid blood derived plasma forming 4. tissue phagocytes (macrophages) are activated to become more Killing aggressive in engulng bacteria. phagosome lysosomes lytic into 5. release enzymes Phagocytes phagosome Neutrophils, macrophages other particles foreign by and other phagocytes engulf pathogens and endocytosis. Digestion Numbers Breakdown debris of out of of the capillary neutrophils bone walls marrow, into increase circulate tissues. They rapidly in do the not during blood live an and for infection then long as leave after they pour through engulng and bacterium digesting replace Figure 2.2.2 bacteria. those that More die. are produced During a lung and released infection from they capillaries 144 leave marrow the bacteria. and See digest page their 176 for way the through the consequences lining of of this. alveoli to to alveolar A phagocyte engulfs bacteria and uses enzymes in lysosomes to digest them will bone reach Module Antigen Tissue presentation phagocytes that are do macrophages. not Applications S tudy These are larger , longer always digest bacteria fully. Instead from the transmembrane specic them proteins immune proteins. in outside and system. same the bacterium, ‘present’ These B -lymphocytes the of also these proteins engulf are some insert these antigens known to as antigens they stands for major take complex. There into cells MHC and biology foc us histocompatibility molecules of lived MHC phagocytes 3 of are the class similarly two class II present in I classes and class presentation different proteins. of these these II. of on are antigens cells. There proteins proteins Both is but more page – involved on about 147 . Complement Did you know? Phagocytes, proteins in such the as neutrophils, bloodstream are do not function stimulated by alone. Complement pathogens and by Complement antibodies and act in a cascade fashion to stimulate a range of The responses proteins. including There neutrophils is a engulf phagocytosis. complex bacteria There sequence or attack are of about changes them 20–25 that directly. of system C3, plays a central role. Bacterial and fungal to because of the complement system that activate to rid get antibodies cascade. At the non-specic end activate of defences each as a different cascade, shown in set C3 of enzymes protein Figure is enzymes in attached to helps so antibodies can of bacteria. We act in a without now know activation by Bacteria are removed a the body much faster when separate activated to stimulate complement work 2.2.3. on antibodies it activate from cascade; name. was help compounds other strange complement antibodies. enzymes a proteins called they protein, of these occur The is defence proteins together their and compared antibodies with either own. bacterial bacteria cell walls enzyme cascades Summary q uestions 1 Outline the role of a mast cells, C3 and stimulates and bacterial cell cells to complement proteins mast in antibodies b defence against bacterial release pathogens. walls stimulate activation complement of histamine protein C3 2 attracts Distinguish and between neutrophils macrophages. Active inflammation neutrophils C3 3 from Copy the diagrams phagocytosis digestion makes attaches to forms membrane large capillaries receptors on attack in sheet and intracellular Figure of 2.2.2 on a paper. Annotate complex more phagocytes of blood with the permeable diagram to explain what other happens at each stage. complement 4 proteins phagocytes State by and the bonds proteases and are broken nucleases that destroy are found bacteria Figure 2.2.3 lysis of in lysosomes. bacteria 5 The central role of the complement protein, C3, in defence against a pathogens Outline what happens during inammation. b Non-specific defences Suggest might against viruses how infection of host cells by dengue viruses stimulates the production chemicals including interferon, which is a to an as infection 1 a (see of pages hormone-like interleukin stimulate fever response The that engulf 100–101 for some non-specic ideas). defence against infections. inuenza, It such production infected is of with viral infections. mainly as It is responsible muscle antibodies and and joint the also for produced the pain. during symptoms Interferon T-lymphocytes of also that inuenza dengue fever activates destroy cells and the 6 Describe the action macrophages in of antigen presentation. DENV . 145 2.3 Lymphocytes The Learning outcomes immune groups On completion should be able of this section, of describe the origin of and groups form the differences between and T-cells identify the genes different types are of T-cell a outline lymphocytes the term B -cells type for difference humoral and immune responses. between of to the B -cell in potential its that surface amongst regions has a specicity. cell-mediated (TCR) that structure to BCRs. variation in BCRs molecules cholera bone T-lymphocytes. marrow. T-cells. Both involves receptors. these of the cells. the Stem groups cells of divide cells This Similarly, shaped each gives B -cells antibody differently rearrangement rise have B -cell type of to that receptor T-cell a of go has that they secrete. (BCR) a the huge receptors molecules on the such and as identies Also, and TCRs surface the its T-cells of specicity. do not allows released have to that T-cell different bacteria This recognise microorganisms by a antibodies. lymphocytes invading toxins TCRs secrete that and their cause huge the cell tetanus, diphtheria. thymus S tudy gland foc us B-lymphocytes usually main immune response products, are two lymphocytes originate and process cell variation identical receptor the code of identies of maturation that amount Each dene and are and T-cells) explain B -lymphocytes maturation of potential through as There lymphocytes to B-cells known lymphocytes. and Both lymphocytes the to: maturation (B-cells involves you Origin response and T-lymphocytes abbreviated and T-cells. To save to space B-cells that is mature what we will call them here. immature T-lymphocytes Immunology has many long words T-lymphocytes and many abbreviations. It might be lymphoid tissue, marrow a good idea glossary you of read to make these your own e.g. abbreviations lymph on. mature mature Did you know? to genetic 10 rearrangement million antibodies different and lymphocytes. cell It is leads variants receptors thought and have TCRs and enough BCRs to in recognise blood these Origin and maturation of lymphocytes their any type B -cells of in lymph on that variation and of Figure 2.3.1 cells B- T-lymphocytes B-lymphocytes circulate The nodes as are produced constantly in the bone marrow; they mature and antigen. then leave the throughout bone bone the marrow, marrow body. but all in T-cells go the are into blood to produced the thymus occupy early gland in in lymphoid life the and tissue also chest. leave This the organ Did you know? doubles Sometimes lymphocytes do attack T-cells B- the body’s own cells. Diseases and cause are auto-immune have another category our of list afnity populate involves the and puberty lymphoid death of and tissue. cells that then The have shrinks after maturation cell all the process receptors with are for ‘self ’ killed antigens. because of The this. majority These of cells include all that those mature that of a in the recognise disease on page antigens. This is to ensure 129. destroy 146 to birth diseases ‘self ’ missing from between left T-cells thymus – size with high this in the body ’s own cells. that the immune system does not Module As as lymphocytes CD proteins identify mature, (CD different immature they stands classes lymphocytes of do Lymphocyte CD B-lymphocytes CD20 helper develop for other cluster of lymphocytes not develop receptors cell surface receptors differentiation). as you CD can see receptors CD in Applications of biology known receptors the then 3 table. they are If killed. Function CD4 T-lymphocytes present differentiate antigens respond secrete to to into helper T-cells plasma antigens cytokines cells that presented to by stimulate secrete cells B-cells, antibodies with MHC class II cytotoxic T-cells proteins and non-specic defences cytotoxic CD8 T-lymphocytes regulatory CD4 and CD8 T-lymphocytes CD4 and receptors cells. CD8 receptors (BCRs and Lymphocytes spleen and liver . help TCRs) circulate In so to and respond attack cells attack cancer regulate suppress stabilise the they the MHC between doing, antigens the cells with and specic by cells intracellular transplanted defence with MHC class I proteins parasites tissues system auto-immunity interaction on lymph, into presented infected proteins blood, come to between lymph contact the cell antigen-presenting with nodes, any the pathogens, Did you know? toxins, other antigens. foreign Note that material and phagocytes T-lymphocytes that differentiate might into be these processing different classes Humoral before taking part in an immune response; they do not differentiate about the different classes during or after an immune is strange word to use something so serious and response. potentially from Immune a into responses the life-threatening. use mediaeval of the term medicine to It comes humour refer to in body uids. The specic responses. These presentation rst and time The of that group of involve is the characterised selection When are complementary of a small clone, clones that as of to the have all having of of enters the lymphocytes antigens express receptors immune lymphocytes pathogen numbers they by groups particular only is very a are cells activation system antigens. there TCRs small defence of the the by the body with pathogen. same BCR complementary to for Summary q uestions BCRs or Each 1 TCR. is clonal selection . In order to be effective, many the maturation more to be produced. In clonal expansion the activated Describe by humoral immune response involves the production of antibodies B -cells. Helper against pathogens T-cells may while also they be are involved. in the Antibodies blood, lymph are and very what happens tissues. B-cells pathogens Name They are of limited use in protecting against the different describe as, being cell-mediated protein, they cannot cross cell immune response does not It involves cytotoxic T-cells that are Outline intracellular parasites. These the functions presence involve B -cells within the DENV cell This is host cells proteins surface antigen cytotoxic cells. as when For some of their attach Golgi example, the most pathogens antigens to presentation . T-cells with the MHC vesicles The during class fuse antigen appropriate I is the and Outline the following appear cell and in to in give the the are surface detected by stages important tend processing proteins with B-cell and immune responses: antigen away clonal selection cell and of of receptors proteins. presentation, membranes of T-cell membranes. of against types their functions. cells 5 antibodies. body as intracellular MHC their and T-cells mature. receptors, T-cell defence to effective between 4 The and T-cells. by and within B-cells and mitosis. 3 The origin lymphocytes they divide of of cells potential need sites the 2 antigens State clonal expansion. Golgi exposed at membrane. patrolling 6 Distinguish immune between response mediated the and immune humoral the cell- response. TCR. 147 2.4 The immune response Both Learning outcomes humoral different On completion should be able outline and of this section, of cell-mediated immune responses occur in two slightly ways. Humoral stages cell-mediated you to: the and immune response humoral The humoral The diagram response involves the production of antibodies by B -cells. immune shows the events that happen during a humoral immune responses response. describe antigen what happens presentation, selection, clonal during directly clonal expansion are to many describe destroy how of cytotoxic T-cells outline in infected the role long-term host respond B -cells. cells of memory B -cells immunity. the are skin. These by phagocytic are dengue the rst are the the diagram involvement require to large the interact multiple these because of B -cells helper can T-cells, respond but there T-cells. molecules large with a with polysaccharide many interaction differentiate also to cells be viruses. They are respond interact the Helper infected directly these These This processed Did you know? cells like and within in that to repeated into is BCR receptors sufcient plasma molecules structure. to on on the activate the surface surface the B -cell of to cells. cells each Langerhans parts without responses bacteria. divide antigens two secretion Antigens are and B -cells antibody There B -cell. with BCRs into T-cells They are with CD4 antigen small antigens, BCR taken MHC class TCRs secrete differentiate. protein, to single into II the cell proteins proteins that by and the protein this molecules happens, endocytosis. presented to activate stabilise as When complementary cytokines and such receptors. the the They on the antigen B -cell interaction to antigens are cell bind divide between that the surface. to the and MHC TCR. important APCs. The cells activated within cells. ribosomes Link reticulum. Find an plasma electron cell. There Module how micrograph 1 the in Unit cell synthesis is and one Look in 4. Your help revise 2.2 answer in of at protein aspects and Golgi cells in Most an of the the of genes to packaged clone do not antibodies are the of large both B -cells membrane assembled bodies, each antigen clones Antibody polypeptides Summary annotations many a carefully adapted for then question you is 1. of the Some B -cells form necessary are antibody vesicles become produced molecules to transcribed, make into and in make on to the page as rst form many endoplasmic They by remain to make translated exported but divide that rough mRNA response IgM cells molecules. and active, (see T-cells plasma and are processed exocytosis. memory Other cells presentation of 150). will of cell bacterial pathogen with non-repeating B-cell and molecular polysaccharide biology. in its wall antigen B-cell repeated receptor antigen CD4 B-cell B-cell B-cell differentiating into plasma receptor B-cell cells receptor and in helper T-cell antigen; processes and takes antigen presents it in mitosis MHC activated class II proteins B-cell MHC activated class II T-cell receptor plasma cell B-cell plasma secretion cell of secretion antibodies Figure 2.4.1 148 of antibodies The stages of the humoral immune response Module Cell-mediated Many pathogens immune invade cells, response response host proteins specic and so escaping antibodies. cytotoxic cells are In the the protection provided cell-mediated activated to attack ingested by phagocytes and are partly are presented in MHC class II proteins. and kill digested. Helper seems a complementary proteins again to help the to antigen stabilise bind the to the pathogens that This act T-cells the helper to be T-cells more to secrete effective at cytokines killing the that of clone these of helper cells to T-cells increase also their divides by effect so on body. MHC to what need a is going on ‘failsafe’ complex. to identify them correctly interaction activate pathogens mitosis stimulatory the way for T-cells monitor they that would destroy the within healthy there cells or ignore them. parasitised The a cells. They perfectly macrophages as with otherwise stimulates against enter Their MHC–antigen binding. complicated infected method CD4 very defence inside TCRs foc us system for continually antigens biology by proteins are of immune cells. Pathogens Applications S tudy This complement 3 are cells. more macrophages. Did you know? Cytotoxic T-cells expressing patrol foreign the antigens body. in When their they MCH come class I across an proteins, infected they cell may Some become active. This only happens if the TCR is complementary to lymphocytes antigenic antigen. CD8 proteins help to stabilise the interaction between MHC material protein, antigen and TCR. Once activated by binding, cytotoxic T-cells the surface in the cell of the infected cells and secrete perforins that ‘punch’ so that toxins such as hydrogen peroxide dust can host remove cells die. This replicating seems pathogens, a drastic such as measure DENV or but the it is the only inuenza Examples are pollen mites. Asthma is a grains disease is caused by unnecessary enter . immune The to perfectly holes that membranes is x and to that class harmless. I respond the way responses to such harmless to materials. virus. problem It in is a growing health the Caribbean. macrophage infected by bacteria Summary q uestions infected MHC class body cell 1 Outline the roles of the following cytotoxic T-cell II CD4 terms TCR TCR in immune responses: macrophages, B-cells, helper T-cells, cytotoxic T-cells cytokine 2 Outline the two ways in which activates B-cells mitosis macrophage helper to T-cell class immune I 3 bacteria Outline activated cell T-cell the circulates blood in during other cell-mediated in infected Suggest the advantages The stages of the cell-mediated immune response responses memory 5 body Explain as by one of the strains of the dengue fever virus tends to why during the rst to reinfection infection not only by are the same plasma strain. cells and This is T-cells produced, but also memory cells. active These helper cells do but continue to circulate in the blood and lymph subsequent infection. If they contact the same antigens, some respond presentation. Make until there then they a a labelled plasma cell diagram as seen is a transmission electron will micrograph. Annotate divide and differentiate into active B cells (plasma cells) and active yet more memory cells. ‘Memory ’ is not a very good name for them with have now a rst not much infection, infections. ‘learnt’ larger they Y ou can anything. clone can see of respond the They cells. As are much effect of just there are faster this in the representatives more on of them second Figure 2.5.3 and on than of what before subsequent page the functions of the as structures they your T-cells diagram and B-cells during and in a only pathogens. not of differentiate, means of defending because 6 cytotoxic immune give antigen immunity a against and T-cells long-term and cells the Infection which T-cells responses. disadvantages of Immunological in search 4 of ways cytotoxic immune Figure 2.4.2 humoral responses. the respond memory during CD8 MHC kill respond you have labelled. is the 7 Explain what is meant by immunological memory 151. 149 2.5 Antibodies Antibodies Learning outcomes short). On completion should be able of this section, you Unit levels to: It 1. describe the structure of of helps molecule explain how antibodies particular describe how the antibodies body and knowledge of polypeptides, secondary structure as and they protein which for structure each tertiary are (Ig have structure. formed from from three All four The simplest form of antibody molecule (Ig or class is composed of four polypeptides as you can see in Figure G 2.5.1. IgG molecule act and two is composed identical short of two identical long polypeptides (or polypeptides. to region of the antibody molecule is the region that binds to antigens against – pathogens primary, quaternary immunoglobulins are One defend your from as antigens chains) have recall formed organisation: polypeptides. IgG) Each specic for to are known (IgG) or here proteins an more antibody plasma Proteins antibodies are their the antigen-binding site. If you imagine an IgG the top molecule as Y-shaped, toxins. these In a binding order to different sites bind to are its at the two specic antigen-binding ends at antigen, site. This each is type possible of of the Y . antibody because molecule amino acids has can Link be This is a good opportunity to revise arranged shapes. variable protein structure. To explain how of antibodies is related knowledge protein of you the four structure. Module 1 in Unit S tudy need See to you can molecules to The of 1.8 of see in really since to 2.5. 1, IgG shaped polypeptides do our efcient as in ‘sticks’ highly in the antigen to similar a give vary, to different these the receptor binding contact with of with The the polypeptides molecule site regions bodies. three-dimensional regions active sites are of also called enzymes, sites, in that they have and a specic agent. are ‘t better joined by that it molecule binds. around’ the to exibility antigens antibody which to response some an ‘t’ We the is need many different between complementary antibodies antigens antigen and that in with may antibody, the infection. disulphide so may that be the bonds, two separated but binding by the hinge sites slightly can region gives make different distances. like constant region is the same for all antibodies of the same class. The not polypeptides regions of IgG molecules are all identical, whatever the are specicities shown antigen variable more constant branch. The four the enter The a Y, are neurotransmitter antigen-binding shape The Figure not and complementary different 1. foc us are They to sites to the As sequences binding use levels 1.6 these the shape their function, different regions . hormone structure in Because of the variable regions. These constant regions bind to diagrammatic form receptors, for example There four those on the surfaces of phagocytes. diagram. binding sites are different Class of Number of antibody binding IgA 2 or 4 classes antigen of antibody as shown in the table. Functions sites inhibits prevents adherence of bacteria to host cells hinge region variable mucous bacteria forming membranes, e.g. colonies in the on gut region IgE 2 constant secrete region activates histamine – mast-cells during to infections, light but polypeptide also during unnecessary responses to disulphide chain harmless bond pollen objects (allergic such as dust mites and reactions) heavy polypeptide constant chain IgG receptor binding molecule activates helps complement neutralises causes activates causes macrophages proteins engulf pathogens toxins agglutination of bacteria site IgM Figure 2.5.1 150 2 region 10 complement proteins The structure of an antibody agglutination of bacteria Module Antibodies full a Agglutination antibodies bigger wide of for Immobilisation types of contact Neutralisation have very diphtheria of of toxin viruses on to and biology two or hold more them bacteria together to make the toxins: into cells: of cells the agella are from prevent host and bacteria Examples choleragen to Antibodies bacteria surface Some bind of some moving. and entering effects. and them pathogens of DENV , severe binding Antibodies prevent entry as By of roles. spreading bacteria: to proteins such of Applications phagocytes. proteins with viruses, of surface them of bacteria Prevention the bacteria: prevent targets number 3 cells. being release This bind to making prevents replicated. toxins, botulinum cholera that them which toxin, bacteria. often tetanus toxin, Antibodies that Figure 2.5.2 This computer model shows an antibody attached to an antigen forming an antigen–antibody complex form complexes Breaking has a bacteria: break lower open water and the help to are them walls. body that The uids, are antitoxins combine cytoplasm so water with of other bacteria enters by burst. facilitate ‘mark’ harmless antibodies cell than cells them phagocytosis: for destruction Antibodies by that phagocytes. attach This to is opsonisation Activating systems Antibody that protein: activates Some antibodies complement concentrations in the activate protein, C3 one (see of the page 145). concentration measured. in During the the blood primary of any one immune antigen 0) second to (Day antibody presentation expansion the of antigen. have appropriate then decreases When a to response. the to This place is specic antibody response clone it plasma clonal are molecules of the takes can a 5 10 are differentiate removed antigen in the many into and cells increases identical there selection to a for the clonal plasma to the secondary cells Antibody concentration responses secrete and Summary q uestions of antibody 1 Make of immune an a simple Annotate the describe cells. is the presence response that molecules. secreted will by memory also plasma and antigen. of responsible Notice become second is that cells. established any and by the there This subsequent Antibodies cells for the is a means that a by faster greater that it person infections produced beginning much by other of the is has the as unlikely no clones of of that with B-cells antibody more that 2 molecules any symptoms pathogen are pathogen different will strain of also the show same the same pathogen pattern. will But produce a an your diagram the function of to each part. infection during that why the infection different by the shown specic responded Describe the four organisation of a levels Figure of protein. antibody in these of Explain molecule 2.5. 1 has all four levels. to 3 that diagram molecule. secondary production response labelled antibody labelled It 35 circulation. occurs, more 30 during primary and secondary immune maximum from 25 20 time/days the able 15 be while following plasma are immediately because to the there 20) blood concentration almost happens in because before The presentation B -cell appear antibody increases This appropriate take antibody. as second concentration molecules exposure antigen response Figure 2.5.3 specic the primary 0 The response exposure the (Day ytitnauq cascade complement to fo secondary initial ydobitna bacteria to Lysins potential pathogens make bacterial bacterial Coating to eht ni osmosis open to toxins doolb proteins with Explain how the structure of a an response. antibody is related to its function. HIV 4 and T-cells Explain what is meant by the term specicity as applied to antibodies. HIV infects protein. binds to helper they the often the few fact as burst HIV+ T-cell cell the CD4 T-cells treating at In a types, glycoprotein protein to described open. in the entry page the as As the T-cells gp120) into 132. decreases monitor helper (known gain on This patients count including the the progress of on cell. host number expressing HIV cells of the the the surface infects infection of HIV the produce T-cells. CD4 viruses, Doctors by looking 5 Figure 2.5.3 secondary Explain shows immune the in the of and responses. changes concentration shown primary in the antibody as graph. blood. 151 2.6 Types of immunity So Learning outcomes far body. On completion should be able of this section, we This response you Natural to: active explain the difference have is considered active and the active what immunity , protection immunity immunity happens which always an term, often happens when you when you are antigen involves long happens is when an lasting are given a enters a the immune lifetime. infected. vaccine Articial that contains an between antigen. active and passive immunity It explain the difference is also This natural and artificial is state examples of passive the four and immunity explain in the how cross vaccination control of is passive infectious give the importance by existing and immune Here the by simply body receiving gains antibodies. antibodies into contact with the antigen. from No another immune its mother . or instant passive during Breast occurs are milk when immunity. diphtheria immunity pregnancy; is also rich given who occurs occurs in antibodies People often it IgA are are injected by antibodies a child antibodies. likely antitoxin when when to into have injection is Articial a person to tetanus, as a of In each case, the antitoxin neutralises the toxins released vaccination by programmes come Natural immunity precaution. maintaining not placenta them rabies discuss has occurs. the breastfed used diseases become types response of to immunity . immunity source possible between developing each of the pathogens and prevents the damage that the toxins can new cause. ones globally and in the This Caribbean. table summarises the main points about these four types of immunity. Type of natural immunity Example active a immunity person is measles, immune Advantages infected which by immunity promotes is Disadvantages long term immune an response active vaccination immunity against e.g. natural passive mother (breast passive not symptoms develop; toxin is to in immediate across common colostrum mother milk) against tetanus collected from donations need long term; suffer from immune the and blood protection diseases has had immunity the young hospital. that Read the introduction to the an two very carefully and then run he man The is at injection also graphs be fatal not immediate protection destroyed no to takes time; immediate and an is involved team risk of of in of the a nasty Accident tetanus tetanus injection in the are destroyed as he has antibodies vaccine car and to for accident and Emergency got give soil in him tetanus in in his is produced term; gradually the cells body; produced transferred department wounds. immediate case body; short are memory gradually the cells is antibodies diphtheria short-term; in memory immunity disease, tetanus is antibodies been against e.g. to that or vaccinated specic injected A foc us immediate; response protection no S tudy may time; disease child and antibodies immunity no passed from to placenta articial diseases, measles antibodies immunity immunity infectious takes protection disease articial response he has to decides He is given protection never and been a vaccinated. ruler across right and two note types Summary 152 each of graph from the changes antibody. question 1. left in Now to the answer The in health his workers blood hospital. so The take decide blood results are to check samples shown in that at he has regular Figures enough intervals 2.6.1 and of the while 2.6.2. antibodies he is in Module stinu stinu 25 15 10 of biology 20 15 10 ydobitna ydobitna 5 Applications 25 yrartibra/noitartnecnoc yrartibra/noitartnecnoc 20 3 5 0 0 20 time of Figure 2.6.1 injection 20 time/days time Changes in antibody concentration in the blood Figure 2.6.2 following an injection of antibodies to protect against tetanus V accination offered by vaccinated were against responsible Many case programmes governments of of these polio transmission still exists travellers the of in for the from much ill are had world areas used health very rare was been and important citizens. that Americas polio an their diseases diseases in are to it be and in in is many the 1991 be still of the and common health in are populations in for example 1994 it interrupted. introduced endemic. protection children and deaths. region; and successfully could where to part Infants Changes in antibody concentration in the blood following an injection of a vaccine to protect against tetanus into In But the 2011 was the last declared the Americas there that disease were by 181 Figure 2.6.3 cases of polio in Pakistan and as of 2012 the disease still exists there, A child in the North West in Frontier Province of Pakistan receiving oral neighbouring WHO will follow the countries one day and in announce progress of the parts the of W est Africa. eradication campaign by of It this searching is hoped disease. online that Y ou the polio vaccine as part of the programme to eradicate polio can for ‘polioeradication’. S tudy During eradication vaccination programmes schemes give rise vaccination to herd is used immunity in in two which ways. almost all Find people are immune. People who do not respond to vaccines are out about the chances of them coming into contact with the disease as most people around them have immunity and will not disease. Surveillance identies people who have caught the BCG. You disease; of it spreading all contacts and people in the neighbourhood – this is ring them. Which had infectious do they protect against and are when vaccinated Hib, probably to diseases prevent HepB, have transmit many the DTP, OPV, are MMR, small the following protected vaccines: because foc us Mass should they be given? Use the vaccination information Summary you nd question to help answer 2. Summary q uestions 1 Describe the two and explain the changes in antibody concentration that occur in S tudy You 2 Explain, using examples, how vaccination is used in the control should infectious using infectious by examples, why vaccination is not used to control some diseases. 4 Immunisation 5 Hospitals is the should active or passive. What are the advantages of each Extended and CAREC be exam used countries how this with venomous anti-venom is snakes produced. hold supplies of in your on information answers question. You should to also type? understand in Programme Immunisation. Current any Outline information PAHO, WHO diseases. about Explain, read of provided 3 foc us graphs. anti-venom. should be why up to you date and your family with your vaccinations. 153 2.7 Monoclonal During Learning outcomes a On completion should be able of this antibodies section, range T-cells you dene the of different advantage to: term immune are others an at antigens. selected that response and some attaching antigen-presenting As antibodies to a result, activated. and This many is a produced helping to cells process clones of polyclonal will destroy be B -cells effective pathogenic present and response more the and with the than bacteria. monoclonal Each clone of B -cells produces one type of antibody with a highly specic antibody antigen outline the process by site. which In monoclonal binding antibodies the 1970s, scientists in Cambridge, UK, developed a method for are producing antibodies from single clones of B -cells. The main problem produced that explain the advantages monoclonal diagnosis explain antibodies and the of using in of in B -cell treatment use they kept in pregnancy This antigenic monoclonal anticancer material, each Mabs for blood such as A, (Rhesus). When cells of Mab type A, aggregate B and visible three drops you of to anti-A the into the Mabs red is of example isolated cells) immunising red from blood the a them which small cells animal’s of do not with survive survive and mammal type spleen A. divide in with After and if malignant several fused form hybridoma cells. These were kept in with culture and was isolated Cells were that grown so that produced in culture the the antibodies required where they secreted antibody, divided and (if any) anti-A then could in this produced is eye. added in to to this the single many antibody – monoclonal a monoclonal antibodies on antibody the (Mab market for are used in blood typing. Mabs in diagnosis which Each are many different Mabs for diagnosis and for research. Pregnancy of separate results response types AB+ of added blood clumps, naked blood. What expect blood cell Amongst testing the myeloma rst B -cells fuse D There are as to group those blood to quantities short). to by individual was foc us large are for were cells identied. example, antigens, (known done that solution treatment. be There cells was was The testing then S tudy overcome culture. B -cells myeloma and to tumour culture. weeks, antibodies had tissue would samples of used diagnostic kits test to be kits for done are the gonadotrophin by doctors available presence (hCG), of in that the or at use health Mabs to glycoprotein clinics. give Now instant hormone, home results. human These chorionic urine. and O–? Figure 2.7.2 positive shows and Monoclonal by having proteins changes in the identication specic for used the to are also testing used hormones of various urethritis, pregnancy follow number of a kit works to give both results. antibodies Mabs are how negative the T-cells is FSH fertility and progression sexually which in in the LH. of by the Mabs HIV blood. transmitted caused testing kits. These raised against infections They are infections, pathogen also work by used such as Chlamydia, CD detecting in the non- and gonorrhoea. Figure 2.7.1 A home pregnancy testing Mabs in cancer treatment kit that uses monoclonal antibody raised against the hormone, hCG Mabs can which They be used express are deliver not drugs Rituximab is to target particular only that a located will Mab specic cell by affect that is cells surface Mabs, only used but the to in the antigens also cells treat body. can be For example, located destroyed by those using Mabs, Mabs. which targeted. certain cancers of B -cells. It is ® marketed The Mab receptor surface 154 under a locates protein. of variety of cancerous This plasma is cells. names cells found Its that on mode including express the of MabThera surface action is the of not CD20 B -cells, cell but completely surface not on clear , the but Module hCG binds mobile hCG of in the urine: urine for 5 the pad particles First zone: The bind to a the first mobile Mabs layer of fixed window Figure 2.7.2 should seconds. When that start have that hCG Mabs pad in a up move test stream first second zone zone antibody-latex a with blue Second hCG cross to in a shows present. zone: Antibodies second that up the no cross antibodies sampler. This in that layer of fixed the first is have have been important window, a binding that lead some severity own to the to the of tissues, target B -cells. CD20 death protein, of the rituximab cell. these of sequences diseases, antibodies is of ‘self ’ are to the primary amino the causes Rituximab in have that result is if bind here moved there is correct. a variety is has also secreted as which the multiple of B -cells been immune sclerosis appears system by the embryo of after fertilisation. Later it is used by the placenta. See and to reduce attacks our Module Unit 3 Section 2.4 in the guide for 1. antigens. on in cells, that diagnosis such specicity structure acids such numbers effective antigens due the diseases, Reducing expressing specic This function and indicate hCG line Link auto -immune arthritis. Monoclonal can coloured Pregnancy testing using monoclonal antibodies. If there are two coloured rheumatoid the bound to mobilised to negative secreted treat not antibodies. A shortly to biology sampler hCG changes of urine pad lines then the result is positive. following Applications move. gives is absorbent held the combined antibodies. This indicating be wet, to to Mab 3 of of as the their variable antibodies exist within and treatment CD20 and these as proteins regions, the they on which is a different regions. Summary q uestions 1 Dene 2 Explain why 3 Explain how 4 Make table the term monoclonal antibody Mabs are Mabs are produced used in by a (Mab). process pregnancy that testing involves cell fusion. kits. Figure 2.7.3 a the following 5 Outline 6 Explain 7 Use the the your using to show Mabs: advantages should results anti-A, reasons for knowledge Mabs the of be anti-B using of testing and Mabs using the of in Mabs menstrual blood anti-D (D treating in of is to the types Rhesus Rituximab cancer drug with antigen). cancers. diagnosis cycle different and suggest treatment. how fertility kits used. 155 2.8 Practice Health Answers to 1 a all Explain b why c why does Outline the the give most be found on the common with one to strain regional data infectious dengue fever in and a Describe the b Explain why there diagnosed ways as in c the on of are HIV+ many but do symptoms of the diseases c Discuss factors of 3 HIV d diseases, social, being e such enters T-cells in reverse HIV Suggest similar to problems to treat treat that drugs to treat HIV. to secondary Explain those in why. the [2] table are dengue fever. are likely people to who [2] arise are when living with HIV. as [2] [3] have [3] Candida albicans is a fungus that causes opportunistic infections. The scanning electron micrograph (Figure 2.8. 1) shows a phagocyte engulng a cell of been C. albicans any of the associated with AIDS. [2] control by and of biological the transmission endocytosis. Three transcriptase, to protease, into drugs to make of which smaller integrase, of the are: chromosomes show why prescribed not developed administering transmitted. people who not economic the is are but [4] template HIV Explain incidence HIV. enzymes how influence Antibiotics [3] health the immunology infections, dengue another. tuberculosis. which and accompanying CD. 4 2 questions: [2] protection from collecting of is can disease, year. importance of prevalence malaria, of infection not authorities and dengue fever months Suggest fever and exam-style questions wettest exam-style the is which DNA to host’s used to uses viral RNA incorporate into as a the cells break a polypeptide molecules which inserts proviral DNA to human Figure 2.8.1 DNA. a The table gives information about some of these drugs. Explain briefly invading Drug Enzyme zidovudine inhibited Mode of action reverse occupies active transcriptase site reverse occupies transcriptase site reverse occupies transcriptase other b c Describe how invading cells. Outline how phagocytes microorganisms the such phagocytes recognise as engulf C. albicans. and [2] digest [5] differences between neutrophils and macrophages. tenofovir 5 a Outline in efavirenz the how lymphocytes human protease Severe Combined the (SCID) site occupies and mature body. is a rare [4] Immunodeciency Syndrome inherited T-lymphocytes fail atazanavir originate sites than active [3] active to condition develop in which properly. B- Babies and with active SCID are susceptible to opportunistic infections such site as raltegravir integrase binds ions magnesium needed for active site those caused by die early in b Explain Explain the difference between the mode of zidovudine and People who receive drug efavirenz. treatment for why babies mixture of drugs that act in different HIV drugs 156 the advantage shown in the of table. taking a mix are susceptible to [3] [2] with AIDS are also susceptible to take infections. ways. d Suggest with SCID infections. [4] opportunistic a babies Suggest how infants with SCID may be treated. People b these of c action and treated, infancy. opportunistic a Candida albicans Pneumocystis jiroveci. Unless of the [3] Explain how AIDS differs from SCID. [2] Module 6 Figure 2.8.2 is a diagram of an antibody molecule. 9 Some diseases are 3 Applications classied as both of biology inherited and degenerative. a variable Explain, using ONE example of between these two region The table diseases region shows the between as changes 1985 collected each, the difference categories of disease. and and in death 2000 in published Disease Mortality condition deaths [4] rates for four the Caribbean by CAREC. rates/number of constant per 100 000 population region heart disease diabetes a Name the type of cell that produces antibodies. b State ONE function for 1995 2000 107 .2 109.5 114.0 102.5 36.2 50.0 51.9 65.0 81. 1 81.6 88.5 98.5 19.6 39.8 mellitus the two component HIV/AIDS [1] antibody that are labelled on the 0.2 2.7 parts b the 1990 cancer Figure 2.8.2 of 1985 i Calculate the percentage change in the death diagram. rate for diabetes mellitus between 1985 and [2] 2000. c Explain why part of the antibody molecule ii known as the variable [1] is region. Suggest death 7 T-lymphocytes cell a surface Explain have special T-cell receptors on their signicance of these receptor d [3] Distinguish and between lymphocytes on the responses the rst and of of the same strain of a The table analysed of [6] the increase between shows show diseases in 1985 as how the the and only four Explain to change in the death rate for 2000. types of the gures relative leading [2] [3] disease should importance causes of death be of in each the [2] a Distinguish between the following pairs: bacterial antibody and antigen; humoral and cell-mediated [3] immunity; Describe the mellitus. Caribbean. phagocytes pathogen. d the diabetes repeated 10 infections Account for condition. Name THREE different types of T-cells and outline their roles in defence against pathogens. c rate for HIV/AIDS molecules. b c membranes. the explanations for [3] one example of each of primary and secondary immune the following responses. types of immunity: natural active, articial b natural passive, articial passive. Outline Soon after the rst a pathogen time, antibody the enters blood molecules, the contains each human many produced by body for c different a of roles of mast cells and complement defence. Explain [4] how molecule is the structure related to of an antibody its function. [5] different 11 group the [4] in 8 [6] active, The body produces many different clones of B- and cells. T-lymphocytes. a Distinguish between the terms pathogen and antigen. b Explain a State the b Describe c Outline meaning of the term clone. [1] [2] why the response is a the origin of these clones. [3] polyclonal response. [3] how clones of specic T-lymphocytes develop. c Explain the why blood infection Monoclonal and d much by the antibodies are sooner following same antibodies present a d subsequent pathogen. are produced for [4] in [2] Name the outline cells the that roles of produce antibodies antibodies. and [6] diagnosis treatment. Explain the diagnosis e these Outline advantages and how pregnancy of using antibodies in treatment. monoclonal testing and [3] antibodies cancer are used treatment. in [6] 157 3 Applications 3. 1 Diet and are completion should be able of this section, you the and the encouraged are term eat are dene outline in components of in increasing we healthy. many and The countries as need t people to active results people become satisfy our of ways in neglecting are getting more needs are and and which this we sensible heavier . more neglect overweight. to If exercise, energy is stored as fat in adipose tissue. People who are such the term how malnutrition overweight diets the Caribbean early 1950s state the have obesity links and problem increased are categorised as obese. Obesity is risk since the between diet, food survive. disease. have a we If foc us The and exercise form part denition of discussion health? about We Look health on that Sufcient page you 128 and wrote see needs if just cardiovascular diet. a Many varied our us a energy of and it is associated diseases, variety meet of an emerging with cancers achieve to nutrients nutrients this require balanced to a these people diet bodies of with enough carbohydrates, and an arthritis. this supplies function to that meet without the we our much energy need needs to we conscious and the efciently. diet: fats our and energy requirements. proteins in our food. It This is is provided by recommended back fat does not provide more than 35% of total energy intake, with and fat providing no more than 10% of total energy. Rened the sugars denition provides eat eat saturated disease because of that the eat we components the your countries diabetes, balanced chemicals diet of many Balanced diet thought. S tudy in changed region The at remain keeping diet Did and balanced diet health to than signicantly a diet obvious: more excess list balanced W aistlines to: explain a advice we biology disease Eating Learning outcomes On of (sucrose) should not be more than 10% of the total energy amending intake. to include these two important The eight to ten essential amino acids (EAAs). These are provided by aspects. the protein must be in in our the diet. diet. EAAs cannot Without them, be synthesised proteins are by not our cells and synthesised properly. Essential fatty linolenic acid. membranes. quantities W ater acids We are soluble (EFAs) . They are cannot There needed to E, K. vitamins, Vitamins quantities make NADP S tudy and Minerals, food synthesise a great required more about the roles e.g. , B water many biology and bre. relate that Find you to other have aspects studied. in the water revise body when W ater the roles of Na and and we how get we conserve dehydrated Fibre not 5.4 and is required 6.2 in Module solvent (non-starch helps with prevent either . Only acid and for very small B or , C, and fat soluble vitamins, e.g. A, 2 cannot synthesise such as the required them, in but very need coenzymes small them FAD, to NAD, A. iron as of and part of functions. functioning not and only for iodine. organic These are absorbed compounds. Sodium of the to prevent and They potassium nervous system dehydration temperature polysaccharides) and/or its absorbed. movement constipation. reduce from are our required ions (see are page 122). but also as a regulation. energy It along also intake. is material Instead the gives There a it gut gives by sense is of developing intestinal diseases. from bulk plant to our peristalsis, of ‘fullness’ evidence 2). chances 158 We calcium, proper digested helps (see linoleic of For + K – out + example, these compounds substances, ions variety for reactant, how day. organic coenzyme as these of nutrients, are vital e.g. either of phospholipids foc us for Read each certain two required. 1 D, are make that it food that food, helping after to eating reduces is which the so Module The quantities such as age, women, energy, whether Allowances dietary of gender , that advice they you are nutrients occupation, are and levels pregnant might nd quantities or on water of vary exercise, according climate breastfeeding. packets sufcient for of food most of to factors and, or in Applications of biology Link for Recommended the 3 leaets Daily with You can nd information different food population. more, on the Caribbean groups, website Food and about and of the much the Nutrition Institute. Malnutrition For are many too people poor to a balanced afford diet enough of is impossible the staple for foods economic that reasons provide – energy, they such S tudy as rice, foods, our and bread. particularly Their fresh fruit diet and is unlikely vegetables, to contain that the provide variety the foc us of vitamins and Find out what diseases are categorised minerals we need to protect us from deciency diseases. Even apparently as diarrhoeal diseases well-fed people may have a low intake of a specic nutrient such as and then iron, answer Summary question which foods leads from reduction The to iron-deciency the of different energy nutrition of food intake most anaemia groups. as they are Malnutrition happens populations as when in the not is people eating more suffer Caribbean 2. sufcient than the starvation. has improved Summary q uestions signicantly great since the improvement living standards. malnutrition 1950s. in food This and is Over supply, reected diarrhoeal that period education in the diseases, of about decrease both time of there food in has and been a general 1 childhood which used to Explain the be causes what terms is meant by balanced diet and of malnutrition high rates of infant improvements desperately associated are poor , with and not childhood uniform. with children poverty, many morbidity Parts and of of the adults which and mortality. Caribbean suffering are related are from to These 2 still the poor a Give explain diet. b At the other extreme, unbalanced diets may provide too much two examples deciency diseases Give diseases their two this change in diet in the Caribbean have come the diseases examples not rich meat in energy of dense populations saturated better poverty. and and like fat, food those supply, obesity products provides sugar , manufactured, The dairy far more elsewhere salt and which is convenience in low a epidemic that in good foods is increase energy the is but not the intake people are Partly thing, that than world bre. partly the also has by good. fat, need. eating this result of of diets c is include a variety of fruits and Explain high in about why mortality has by infant in has prevalence become that it is an decreased since region. epidemic now Currently, the about have neglected Discuss in most the Caribbean, important with underlying such increasing the differences cause of death modern Western 25% of adult women in many countries which is is an almost twice emerging and as many as extremely adult men. worrying Obesity and diets. in Explain the eating effects diets on rich in health saturated among fat children between diets are of obese, the vegetables. 4 the and the Caribbean traditional Caribbean Obesity and morbidity 1950s. eating People state causes. childhood 3 to of and diets which Caribbean come diseases of their plenty, causes. energy. diarrhoeal With of and and rened sugar, but low in problem. bre. 5 ‘Nothing better difference as the food whether they you statement or inequalities addressed 6 Outline by the take reduce Figures 3.1.1 and 3.1.2 to the rich eat’. agree not. the and poor Explain with this Suggest in food supply how can be governments. steps governments can illustrates between in that the Caribbean improve diets prevalence of and diet- See how we have grown? In the 1950s and 1960s obesity was rare. Now it is very common. The mismatch between energy input and energy output is related diseases. responsible for the obesity epidemic. 159 3.2 Fats in the Learning outcomes On completion should be able of this section, you diet Fat is are absorbed form describe the diet outline what after of happens it how fat is to fat blood and blood explain plasma. they circulate where are they small molecules that Chylomicrons fatty acids are travel in into composed them the glycerol, reformed particles make and soluble lymph to of in the which fat a in core the the of fat lymph and Also absorbed are then absorbed by the blood where liver . is transported from the intestine and transported in chylomicrons is in Liver cells also make cholesterol, which is transported to cells transferred require it in lipoproteins . These are smaller but similar to organs how atherosclerosis very low There density are several different lipoproteins types (VLDLs) of carry lipoprotein: fat for storage in adipose tissue outline the associated health with risks atherosclerosis low high density take cells These into absorbed occurs intestine epithelial protein chylomicrons. small in that between the into by cholesterol. the in chylomicrons. surrounded to: and digested describe the different cardiovascular types lipoproteins density it to (LDLs) lipoproteins the liver for carry (HDLs) excretion cholesterol remove in the from the cholesterol liver from to tissues tissues and bile. of disease. Y ou need between all of these them. cardiovascular lipoproteins, People with diseases high than so doctors ratios those of with tend to monitor LDLs:HDLs low are the more ratio at risk of ratios. Link To better understand the context Fat is the kidneys section about fat, it would be idea to revise the In lipids from Unit 1. 1 in Unit tissue, heart, for and example around the underneath intestine the skin, (visceral or around abdominal The any site excess of carbohydrate deposition of fat and is protein is important, converted since into people fat with biochemistry See 1.5 abdominal fat (‘beer bellies’) are more at risk of cardiovascular of diseases Module the addition, stored. much of adipose a and good in and of fat). this stored than those with the fat on their hips (‘pear-shaped bodies’). 1. Atherosclerosis Did you know? LDLs penetrate breaks The density of lipoproteins refers or they speed HDLs to in settle a centrifuge. sink, their when spun Put content high simply: LDLs oat! This relative at of is may related lipids. cells’. This walls and of begin 3.2.1). lumen which This endothelium block ow often of atheroma The endothelial result in of found the blood high tissue blood as developing the may less inside be a that lines pressure. arteries. Here form you can see in a all in high children and smooth and less blood in of the able is to clot of it increase artery ow The LDLs forms the plaques or blood in a by of is properly. The plaques, thrombus. an wall Figure roughened through in the arteries (see function ‘foam and plaques width disrupted give form muscle plaques to to surface. When artery with table. are blood as of development the atherosclerosis macrophages atheroma plaques endothelium block and growth healthy can fat by deposited elastic the to is the The it for saturated time, lumen. platelets engulfed material through occurs is promote With become factors which Calcium break results risk high of stimulates drastic also arteries. to thrombosis in the the accumulated Arteries smooth calcium be cholesterol, Macrophages bres. the their atherosclerosis . build-up in to deposit how tears breaks smoking, pressure. young as lack Fatty of exercise, streaks have a diet been seven. deposits vessel walls Link This is an opportunity especially reduced revise how the their structure role in and function delivering blood lumen constricts blood flow Figure 3.2.1 160 to arteries. Think Atherosclerosis pressure will be affected by the build-up of fatty plaques. of to blood vessels, tissues at high Module 3 Applications of biology Cardiovascular diseases These they diseases are of the inuenced heart by and many Cardiovascular Region disease affected hypertension whole coronary heart heart circulatory factors and system there is are no multifactorial one underlying as cause. Symptoms body none (at angina disease least pectoris during – many severe years) chest pain often exercise heart failure to not for pump – weaker blood heart gradually fails efciently Figure 3.2.2 A cross-section of a coronary artery in which an atheroma is myocardial sudden infarction and necessarily severe (heart chest related to attack) pain, – obstructing most of the lumen (× 10) not exercise Link stroke (cerebral brain speech slurred (or no speech at all) face Here infarction) drops, not able to raise an arm (or is another category of disease. both This group of diseases all affect the arms) same Hypertension Hypertension pressure. At is a rst condition there may in be which no the patient symptoms, but has high there is system of the would you classify table? See page body. the How diseases else in the 129. blood a higher risk of Summary q uestions damage occurring atheroma and to the increases artery the walls. chances This of stimulates developing the development angina or of suffering 1 from a stroke or heart attack. High blood pressure is more likely in Dene the disease, who smoke, are overweight, drink and/or salt excessive alcohol, take little terms plaque, eat a high fat high diet. The normal blood atherosclerosis, exercise, hypertension, or cardiovascular people pressure for stroke, coronary a heart disease young adult pressure and a is about above diastolic Coronary 13.3 16.0 kPa pressure kPa systolic increases above the 17.3 and risk kPa is 10.7 of kPa diastolic. cardiovascular considered to be A diastolic 2 problems, very serious. 3 heart disease Outline what the after Explain the The the two coronary aortic coronary these to heart arteries, some heart valve. of has is heart work a branch of disease . there the to arteries Disease If these a from blockage reduction tissue, harder in which to the arteries force base occurs the may blood of the supplying within supply lead to of a the just cardiac branch oxygen death through aorta, the of and the one 4 nutrients tissue. coronary is of The blood pressure increases. Also the cardiac output does arteries not Explain during times of high demand, such as during why (cerebral stroke burst and occurs with their brain and is formed in a cholesterol body; it and b cells is in is the transported with in protein. and Outline the in effects the wall of of a fatty an artery on exercise. of blood. infarction) when leakage nutrients in increase 6 A to fat artery. to the ow Stroke plaque an transported deposit sufciently of combination 5 so how wall happens ingestion. above muscle of diet an into may artery brain die. compensates for or arteries tissue. People the The who in the brain tissue survive functions that brain is strokes they are blocked, starved often have of nd Describe the long-term consequences or accumulating oxygen that lost. 7 a coronary b arteries Find the of fatty in arteries arteries, in the deposits in and brain. risk factors for coronary Did you know? Cardiovascular Caribbean as diseases in many are other the most parts of important the world. cause of death in the heart disease them and and identify preventable and stroke. which which List are are not. 161 3.3 Investigating Learning outcomes completion of this section, be able ways dene and the terms aerobic exercise aerobic fitness describe the of the others effects muscular, or that As of in their the gas or explain effects exchange are how of encouraged now tend to to do maintain less good physical health activity are as diet part of and their the there activities. solitary is a This exercise need may to be include regular an exercise routine participation in as sport part with routines. best type of exercise to carry out provides activity for the heart, cardiovascular immediate exercise system and the gaseous exchange system. This type of systems exercise are home, weekly circulatory and we people exercise The on exercise to: work of you exercise. should effects Aerobic fitness T wo On the on the body tissue is so they weightlifters demands investigated. known within aerobic respire and they the provide as time it oxygen. aerobically, eld make athletes on is exercise their not not bodies is for are for exercise oxygen is provided anaerobically. exercise possible Aerobic as very for the long body ’s term periods not of time. endurance systems and muscle Sprinters, short power to does to respond not The and involve and the Link expenditure everyday Work that of out all occur aerobic of in the the other body at exercise. This opportunity to cardiovascular revise 82 to the is a good aspects physiology. start of Aerobic fitness cardiovascular is assessed you is a per than unit time. explosive measurement and gas exchange tness are harder phosphate about exercise includes walking How to much everything marathon do you do? from run or than so myoglobin running. energy better In terms of tness for exercise. scores of the body ’s systems like the to one ability provide to use oxygen described the to muscles. It here. to take part in an endurance event, such as a 97 . Did you know? brisk far See much from much is with long-distance Aerobic as it changes Imagine pages of life, the (see swim. before. rates page haemoglobin responds dioxide concentration and rate output of transport to oxygen in to this the the start, soon This does more muscle body blood not last The the it for is lungs also long creatine by available either , in so the carbon in the oxygen. per working and stored increase more begin A TP is increase an with to their Oxygen available; stimulates the muscles exhaust becomes blood your increase. anaerobically. provide provide to very blood. respiring breathing increases and the muscle They you respiration 165) in by of When depth The unit cardiac time to tissues. Step tests Y ou can test that Figure Figure 3.3.1 Aerobic steps; you can use investigate to assess 2.7.4 on laboratories to the effect aerobic page 32 assess of shows the exercise on the body by carrying out a tness. the tness apparatus of athletes. used This by exercise shows the physiology sorts of something similar in a step test measurements easiest to recorded work and this or you As it is page Figure 3.3.2 There is no excuse for not taking enough exercise. You can even play tennis with the help of a games console. 162 like by be heart It during this and also at taking with before, blood helps exercise machine by made a – if ngers pressure you say tness your during by can after monitors measure using centre. pulse and It a is over with the treadmill, difcult measurements placed exercise. pressure the It amount an to points of exercise take during is data precise an (see Figure 88). unlikely determining exercise with results investigation on do rowing reliable 3.4.1 can electronically. that bicycle do that that aerobic doing a you have tness step access you test. can to sophisticated investigate the equipment immediate for effects of Module Apparatus: Y ou need may be This a box, able to stair or borrow photograph. Y ou also bench an about aerobic need a 250 mm step like high. Y ou the one in of the timer. is a very aerobic you simple fitness information could modify aerobic or test. Y ou you based the test exercise, 3 can on Applications may age and yourself such as know search to for of biology other others body use shuttle of tests that give mass. Y ou another form of runs. Safety: T ake some exercise continue. Y ou four times. over 40, can Then then it first to walk take is ensure up your not a and pulse good that down for idea it is safe some 15 to Y ou stairs seconds. to continue of breath three If it with or is can takes This If you are numb, dizzy or out then the period use of do the test. Do not carry out any investigation if you sure if the person doing the exercise is free of much find condition that might put them at in are thoroughly rested and then take pulse. Do this three times and can Start with both feet on the take an Step up • Step down and put who both put feet both Practise stepping seconds Carry out to step the up up on the feet and and procedure long it value. time. to achieve fitness? Y ou can an simply the use take the resting step test pulse a fitness programme and see at if any significant not take improvement, it much use exercise. took of a a number student of different who ran on a treadmill in floor. step or exercise on the down The until very it takes you in much the admitted to not exercise each week. The results are table. 2 Measurement have student box. down. you laboratory. floor. shown • also does physiologist taking and how resting average. an • record the recovery necessary during show measurements • to your A resting is aerobic intervals someone you but risk. Procedure: sure the test, return any decreases. T o Make is exercise out. Y ou regular medical time to are to not same rate not improvement do the pulse the How test. also for practised for At rest During During strenuous recovery 4 exercise minutes without taking any rests. 3 When you finish, • Rest for 1 • Rest for another stay minute standing and take tidal up. your pulse for 15 seconds and take your 3.3 1.7 seconds. breathing 45 0.5 volume/dm pulse rate/ again 12 24 18 80.0 30.6 –1 breaths min for 15 seconds. 3 ventilation • Repeat again, so you have three readings of pulse (volume for the 3 minutes after you finished the rate/dm –1 min 6.0 rate of air breathed exercise. in during 1 minute) Results: pulse Multiply each pulse rate by four. Calculate the sum of three pulse rates your (in fitness 70 190 120 minute ). beats min aerobic per the –1 calculate rate/beats Use this figure to systolic score: blood pressure/ 15.0 26.1 21.0 10.0 10.5 10.5 kPa 24 000 ___________________ aerobic fitness score = diastolic total number of blood pressure/ beats kPa Compare your Aerobic score fitness against the score table. Category of fitness S tudy less than 61 61 to 70 average 71 to 80 good 81 to 90 very Look carefully 90 at the physiologist. Make Then each look at measurements sure one that in you turn taken know and see by what what the they all are. has good happened over foc us poor during and after exercise. You can do some excellent simple calculations, for exercise was Summary double question example what it was breathing at rest. rate Now during answer 2. Summary q uestions 1 2 Outline the immediate following systems exchange and a of effects the body: of exercise muscular; on 4 the gaseous the results in physiologist the cardiovascular. Summarise A tness the a table. planned improvement Explain Suggest what the changes you have described in terms physiology of the Outline a tness programme that the student to improve compare different should can be be done made to ensure between the that valid people different tness programmes. Explain how you would monitor aerobic tness could during follow to during student. b 3 investigation of following the an aerobic tness programmes. comparisons b in the investigation. aerobic tness. 163 3.4 Exercise Learning outcomes and Assessing fitness A On completion of this health section, measure absorb should be able of and state VO the meaning of the term max explain tness oxygen. This is the is maximum the max. VO rate at which Exercise the body can physiologists 2 intensity and 2 use to: determine aerobic you how VO max of on volume exercise gradient person is this of the an of oxygen increases. exercise treadmill is by measuring This can treadmill. measured be The with the done oxygen a gas oxygen by uptake increasing the consumption analyser and of the as the speed the results 2 plotted determined explain the term cardiac on a graph max The VO that most is people sophisticated state be how much undertaken exercise to aerobic tness state benecial good in Figure indicator of 3.5.2 the on level page of 166. are ever laboratory going to determine tness. apparatus available for But it is to themselves not an exercise using one the physiologist. should improve maintain that 2 efficiency a like and However, there is a cor relation between max VO and heart rate, so it is 2 possible to use measurements working at their max VO or of at a pulse rate to proportion assess of it. when This is someone important is in 2 the effects of designing exercise on the tness programmes that will improve aerobic tness. See cardiovascular, below. gas exchange, muscular and Cardiac skeletal in efficiency is the ratio between the work done by the left ventricle systems explain how chronic diseases. exercise can pumping blood and the volume of oxygen consumed by cardiac prevent muscle. digital Sit This also is difcult blood-pressure on a chair pressure Place Pump the blood Also Now and up and relax heart cuff the of rate the cuff to monitor for determine, it is 10 just minutes. before release it to to if Be have this access to a technique: prepared to measure blood up. monitor record you use standing blood-pressure and but possible on the the upper systolic and arm. diastolic pressures. record stand Someone with the up heart and good rate. immediately cardiac repeat efciency the should measurements. see an increase in all three measurements: Systolic Heart rate Increases results less is Gaseous are provides Figure 3.4.1 Aerobic exercise can be should than an benecial These diastolic indicate Exercise of and a these serious essential effects some of surface pressure increase on exchange a blood the for by 10 indicate part of three to15 poor problem should beats cardiac with the of per by 10 to 15 mmHg. minute. efciency; decreasing heart. maintaining systems increase the good health. It has a number body. system effects the air and increase in tidal increase in ventilation that exercise diffusion of has oxygen on and the system carbon that dioxide between blood: creative and fun each S tudy is a good idea to know at least increase effects for each – the of volume air of in air each that breath enters the lungs in vital out capacity after taking – the a deep maximum volume of air that is breath increase in reserve volumes – the volume of air breathed in after a system. normal 164 rate volume two three the minute breathed or – foc us It volume breath and the volume breathed out after a normal breath Module These are possible improved thanks uptake of to better oxygen by use of the gaseous diaphragm exchange in and the ribcage. is achieved by increases in the elasticity of the during inspiration to give a larger surface alveoli; area for they is also an increase in the number of capillaries group gas vitamins The maximum rate of oxygen uptake is around achieved more these the These are supplies some of quickly. is muscles system the coenzymes: NAD, not with the that oxygen exercise they has require on the for system aerobic to nicotinic riboavin for the that FAD and to coenzyme A. just consumption you vitamins food respiration: acid for enough exercise; effects needed alveoli. energy Cardiovascular are exchange; pantothenic biology expand acid for there of Did you know? make more Applications alveoli B This 3 and also and increase if you need to or not take consider minerals whether It your in to your take supplements. decrease Resting in heart resting rate is heart one of rate the best indicators of aerobic tness. S tudy increase heart in with stroke each volume – the volume of blood pumped out of foc us the beat Blood-pressure increase in cardiac output – the volume of blood pumped out in in minute, calculated as stroke volume × heart mmHg so three much make during decrease the in the heart exercise resting amount of in more a person systolic work efcient, done and by with so diastolic the the good as rate does aerobic blood not increase tness. pressures – multiply this used increase in cardiac are by some of the effects that exercise has on the system that medical mmHg to kPa, 0. 133. foc us exercise on the also and glucose to provide the energy to generate A TP rest of has the benecial body ligaments, by tendons and for reducing the blood contraction: cholesterol increase used in increase increase there in the size of muscle bres and the gross size of the muscles exercise the convert uses bones; results of system glycogen muscle give unit efciency. strengthen fat, the heart effects These is lowers Aerobic Muscular by profession. To S tudy that rate pressure These monitors each is in in an increase requires of respiratory increase in concentration; total overweight number two mitochondria enzymes in glycogen these decreasing the and and number fat as muscle coenzymes of stored substrates in tissue – blood these must increase if in muscle sources of – aerobic energy pressure hypertension chronic mitochondria for and body mass obese; in those and in with decreasing degenerative those decreasing risk of diseases. respiration formation of Summary q uestions A TP and more creatine capillaries phosphate in muscle – (see page capillary 33) density in muscle increases to 1 improve the supply of oxygen and nutrients, and the removal a Explain what is meant by of VO max. 2 carbon dioxide increase single in and the stores polypeptide afnity for lactate of with oxygen concentrations oxygen at aerobic very haem than oxygen myoglobin as in its bres; prosthetic haemoglobin fall muscle so signicantly. low partial pressures of respiration during strenuous tends myoglobin group. to It keep hold Oxymyoglobin oxygen, so has helps a of it Outline a Explain what cardiac efciency. 2 until b its maintain Outline T o at be of 70% benet, of your subtracting exercise exercise aerobic is age-predicted your should age be from about maximum 220. 142 should If you beats be heart are per undertaken 17, rate, then minute; three which the this is times a week calculated heart rate exercise 4 State the out for at least 20 minutes. This gives exercise at should 50–55% Explain stages max. Exercising at less than this 2 is done longer than 20 it meant may by be of aerobic occur in intensity is acceptable so long regular reduce the aerobic chances of chronic diseases. be of Discuss the benets of exercise your as terms of general wellbeing and it protection for that can developing in VO how is how taking exercise by during 5 carried determined. mitochondria. enough? exercise is exercise. respiration much it assessed. 3 How how a higher releases to is b against disease. minutes. 165 3.5 Practice Social Answers to 1 a all Explain One way mass This to index is and exam-style questions what is meant measure by a obesity exam-style can preventative be found on the balanced diet. is to questions: calculate medicine accompanying CD. [1] the body (BMI). calculated as follows: body mass in kg _______________ BMI = blockage 2 (height The table Body below mass shows the in BMI index m) categories. Category Figure 3.5.1 20 underweight b 20–25 Heart disease Discuss acceptable reduce the is a steps risks major that of cause of ill individuals developing health. can heart take [4] overweight c Explain how benets over 30 obese over 40 very 3 Figure 3.5.2 athlete maximum programme Before they starting each on record as the consumption intensity consumption is of oxygen by increases. The max. the VO 2 their max 2 body the [5] of exercise a VO and of mass. 53.3 4.5 Height/m P 25 M 1.82 Mass/kg 78.2 68 M 1.67 81.0 R 43 F 1.75 53.3 S 57 M 1.78 131.5 T 18 F 1.47 75.3 negyxo Q 46.7 4.0 40.0 3.5 md/ekatpu Gender 3 Age nim 1– Person negyxo exercise club. the someone exercise. mc/ekatpu and a tness shows convince regular 33.3 3.0 26.7 2.5 30.0 2.0 1.5 13.3 1.0 6.7 3 diet join would gk people you taking 1– Five of obese an height to disease. nim 25–30 the 1– below 0 0 0 b i Calculate the ii the BMI for each of the people people with in would the group? reference information you in to Explain each the give to each your person’s of 6 8 10 12 24 26 time/min rest [5] advice 4 in table. What 2 Figure 3.5.2 the answer BMI and a the table. Use the [5] the graph intensity to of describe exercise the on effect the of increasing athlete’s oxygen consumption. c Outline the effects of obesity on the health [4] of individuals. [5] b Explain the advantage of measuring the VO 2 max. 2 Figure 3.5. 1 is a diagram of the heart. There is c blockage in one of the [3] a Describe i Name the artery where the blockage occurred. Explain iii Describe the what treatment 166 [1] how is the likely health benets of is blockage likely given. to was formed. happen if to a low-fat and high-bre diet. [3] has d ii explain arteries. changing a and [3] no [5] Explain the advantages of eating less salt. [2] Module 4 An exercise minutes same physiologist exercise age, on height the and investigated pulse body rate the effects of four men of of 5 6 a the Suggest how exercise so the physiologist that valid designed comparisons the could the cardiac efciency. [2] ii Explain why it is a good indicator of health. Suggest the factors that taking up are likely regular to [2] prevent aerobic exercise. [2] made results. the four biology Dene Explain the steps that health-promotion bodies [4] should Results from of i people from be c between term Applications mass. b a the 3 men are shown in the table. take to encourage more people to taking exercise. d Explain [3] the medical, social and economic –1 People Pulse rate/beats min arguments for encouraging more people to take exercise. At rest Immediately after 7 A 68 [4] exercise A student designed how much exercise aerobic tness B 74 70 105 the Select 62 results higher i show that the immediately Calculate rate for pulse after rate for all four Explain Select the percentage the four increase in the the of 17 year olds. The the student as follows: who do not take exercise on a [4] of an increase in rate during students age, body into pairs, mass and matching them height. member of each pair to carry out the programme. pulse men. advantage the one Train by at swimming a xed several speed so lengths that the of a pulse swimming rate the reaches pulse group men exercise. pool ii a students gender, training b out improve basis. Organise for was to nd to 81 The of necessary investigation 20 regular D investigation was 135 planned C an 98 exercise. approximately 70% of the age-predicted [5] maximum. iii Suggest reasons for the differences in the pulse rates for the four men. Train for 20 minutes on three occasions every [3] week. c i Describe how you would extend the physiologist’s investigation to nd out Measure at effect of resting ii Suggest the regular pulse aerobic exercise on the you results from [3] would this collect extension and to Another man, E, investigation. increased i by joins His E’s the resting after pulse subjects pulse the rate 5 of rate the Explain heart ii the is minutes 45 of immediately health benets of a low and exercise. b a Make i after ii healthy artery show and an a cross-section artery in which plaque has Use the drawings you made to of plaque on the structure one pulse rate the describe pulse rate is advantage rather of than measuring using other resting ways of [1] student on one in selected a regular each people who did not take basis [1] pair followed the training the students [1] were matched for gender, body age and height [1] the students their exercised maximum at pulse approximately 70% rate. [1] the and function walls. Atheroma resting why: only Suggest how the student could analyse the data of this investigation to nd out if [5] there c the [1] collected from artery group [5] c effect whole through developed. have why State of b the an iv atheromatous of programme [3] to Explain mass, a rate investigation: exercise resting rate. drawings this Explain iii 5 pulse determining tness. [1] the resting intervals. recorded. exercise. ii In i [2] 30% Calculate a analyse investigation. d regular men’s rates. how the the increases the risk of blood was a signicant improvement in aerobic clots tness. developing in arteries. Explain the d of blood clotting in a coronary artery. Explain Explain how the risks of why swimming for 20 minutes is better [5] than d [2] consequences weight lifting for improving aerobic developing tness. atherosclerosis can be reduced. [3] [3] e State one muscle. long-term consequence of exercise on [1] 167 3 Applications 4. 1 Drugs of Drugs Learning outcomes body. On completion of this section, be able are This dene the medicinal terms drug and drug which distinguish illegal between legal and The drugs explain they The biology can action links help it the you your study is of the so much term USA S tudy and drugs the pages the should lead of are the the in but by can be as difcult diseases. The based on effects body, which are such cells, as as antibiotics deal with tissues cocaine, central and heroin and/or and the painkillers, These are and two our pathogens and marijuana peripheral non-medicinal nicotine attitudes drug’ many medicinal sold any the that their they legality are of drugs and used. the in legal alcohol. drugs changing are in nervous drugs Both of socially response (ganga), systems. that are these are very acceptable to the harm in that is often used to refer to drugs that are use. In often society. as are over of sale but in as of there the are Illegal severe into drugs Psychoactive and Stimulants, functions to and banned, as on that their and and for are so too small they often Canada. (FDA). to follow Licenses the for circumstances. many supermarkets. of the Administration prescription; painkillers painkillers Some that can be sold in are also for places sale there country Similar they The has where inuence sale licensed; them countries, No that body. regulations and the total yet banned tobacco can have differ minimum are restrictions the and bans be on the tobacco, smoked been countries. with severe from penalties country categorised name improve. on UK. drugs whole offer alcohol. the be the Muslim of vary may UK number tobacco restrictions Penalties drugs the market certain on psychoactive Caribbean are consumption. on many Canada under pharmacies places consumption USA, the USA, available effects over In sale Drug governments on the governments and misuse. are alcohol purchasers. and/or avoid having countries introduced restrictions to in by Food come their at the regional only counter licensed is that permit nicotine well consumption age drugs usually time and are authorities the have that authority Caribbean, the drugs one between types the those licensing Alcohol drugs categorising ways in illegal drugs all Antibiotics foc us Categorising the such the societies: licensing investigate mind on drugs, target psychoactive. used Throughout of at have with ‘recreational but countries chemical, dr ugs , sections as studied. We revision. categories reactions covers: specic many modes drugs; following next few Legal are as chemical drugs a fascinating together have on a few the It brings touch of on is effects. that only inuence do. Legal as or foc us Pharmacology their modify therapeutic societies, illegal, subject few in categorised drug tolerance S tudy or on interact next common many and act psychoactive abuse denition that to: which substances you should biology as suggests, Examples of to for sale, dealing and/or country. follows: cause these mental drugs and/or are physical nicotine, caffeine, Did you know? amphetamines and Drugs once that sold (from are and which now used heroin illegal cocaine are wakefulness. that have is prepared) good examples an Second Their World effects W ar may pilots include used to greater take alertness amphetamines were to help to concentrate, them stay Hallucinogens interesting as awake. do Smokers cause many coffee maintain changes in drinkers that mental on nicotine helps them states caffeine. and the way in which of people drugs cocaine. openly. Opium and and perceive their surroundings. These drugs, such as LSD, ganga mescaline induce dreams going changes in consciousness that users compare to having history. 168 and social or into trances. These experiences can be frightening. Module Depressants nervous from pain pressure, and Drug W e all have inhibitory systems. and may heart opiates These induce rate and (heroin, effects drugs on reduce sleep. They breathing. morphine the central feelings may and act are Applications of biology peripheral anxiety, also Examples and of 3 to provide lower alcohol, relief blood barbiturates codeine). abuse use benets drugs; that they are therapeutic part of drugs our have everyday on experiences. people’s health. Just think Moderate of use the Figure 4.1.1 Injecting heroin is at one extreme of the drug-abuse spectrum. of Smoking a cigarette and drinking a cup of non-therapeutic drugs, such as caffeine and alcohol, often has little impact coffee are at the other extreme. on health. However , palpitations abuse are accepted The to used (mainly of because alcoholic both misuse feelings misuse of to is inadequacy they liver think it these and the the often or drugs disease. describe alcohol) drugs of The use, of with solve drug limited, People ranging misuse mental turmoil. them effects substances however associated help cause terms overuse emotional will can and that of illegal illness often emotional or are or from drug socially substances. with take drugs behavioural S tudy problems, though, which may increased may lead to anxiety be symptomatic mental and illness depression. of such Drug mental as illness. Misuse drug-induced misuse is as of schizophrenia, much foc us drugs, Drug dependence a problem in Alcohol, nicotine and is that faces Caribbean Caribbean countries as it is elsewhere in the world. trafcking from ganga are viewed by many young people as a rite of passage peer preference – wanting to t in with a social group – a driving factor . The fear is that use of so -called soft drugs may use of hard drugs such as crack cocaine and heroin. effects of these hard drugs often results in users becoming and Europe to is should of consider illegal drugs the on Experimental society use Drug lead wider onto societies. South America is another. You often problem through North America adolescence; one hooked. as well as the effects on Long- individuals. term the use of health alcohol and and wealth nicotine, of nations though, than brings the use of far more soft and problems hard for drugs. Drug dependence Often drug it users effect as did same effect. nd when that they after rst a while, took it. a drug They does increase not the have dose the to same regain that Link may be two This happens reasons for because drug tolerance has developed. There this: Read Metabolism of the drug has increased so that its concentration in on body decreases Neurones drug is without produce needed Eventually, it: quite users they to page about drug dependence 175. quickly. more receptors occupy come are more the to them rely on at and the synapses have drug the and so that same feel more of the effect. they cannot live dependent. Summary q uestions 1 Dene the terms drug, drug abuse, drug tolerance 5 Read about drugs: 2 Suggest term 3 Make why some drug misuse a table to health rather show medicinal drugs: the aspirin; professionals than prefer effects of nicotine; alcohol compare the are statins; legal penicillin; psychoactive amphetamines; and effects. barbiturates. and some Discuss are why Present some of a table these to drugs not. Find out the restrictions on sale and consumption of zidovudine and alcohol in several countries across the rituximab. world. 4 the following cocaine; anti-histamines; tobacco (AZT); of heroin; the the following paracetamol; (epinephrine); effects drug abuse 6 adrenaline the marijuana; Distinguish between stimulants, depressants of and Identify these the pros and cons of restricting the sale drugs. hallucinogens. 7 Discuss under whether all drugs should be legalised and sold licence. 169 4.2 The biological The Learning outcomes completion of this drug we call of alcohol is alcohol actually ethanol (C H 2 by On effects section, the fermentation absorbed you in the of sugars. stomach as it When ingested, diffuses readily OH), which is produced 5 it is usually across cell rapidly membranes. –1 should be able Ethanol to: is a good metabolised describe how alcohol describe the in the cells lining vein that drains short-term the liver effects and the energy, the providing stomach, but . 29 kJ g most A little passes is into directly into the the hepatic liver . body and Metabolism of long-term of is portal metabolised in source of alcohol nervous alcohol on system. Alcohol energy is absorbed and pathway is for a and oxidised precursor alcohol is for by liver cells. synthesising shown in Figure It fatty is used acids. as The a source of metabolic 4.2.1. Link liver Compare the metabolic cell CH surface CH 3 blood OH cytosol 2 pathway membrane with what you know about CH respiration. See pages CH 3 20–29. You OH (ethanol) 2 NAD could draw a ow chart to show an ALD outline of the metabolic pathways of reduced NAD NAD respiration and include the one reduced shown in Figure CH NAD CHO (ethanal) 3 4.2. 1. Key ALDH1 ALD alcohol = CH (ethanol COO fatty acids 3 dehydrogenase) CHO CH 3 ALDHI ethanal = CH acetyl COO 3 dehydrogenase ALDH2 coenzyme A (acetate) (cytosol) ALDH2 ethanal = Krebs cycle dehydrogenase (mitochondrion) CO + H 2 Figure 4.2.1 Y ou S tudy can The foc us We gain most metabolism Triglycerides fatty acids, acetate of our of fat, are are that the down then enter split the As quite to into Krebs that Y ou to a a large just a few NAD in of fat to is used starts This more to The a If hours, accumulate liver, as is is used NAD. of to someone there droplets affects those little it in oxidative then which for coenzyme there NAD energy. few problem the as through reduced provide fatty a requires recycled occurs over to is of be this alcohol it cells. It is of Instead, liver that alcohol mitochondria. less drinks. of needs recall quantity fat. cytoplasm oxidation of should result oxidise the form phosphorylation A TP . glucose. broken which groups energy from not see cell. mitochondrion The metabolism of alcohol in the liver reduced each O 2 who generate has is inside a need the people drink drunk less even lot after over a cycle. short period of time Long-term Fatty liver drinking is a – so -called effects of short-term bouts, then the drinkers. alcohol on the effect fat binge on the disappears liver . and If a the liver person cells has days recover . between However , Did you know? people These three conditions of the liver liver who tissue moderate are stages of alcoholic liver you want to nd out more effects of alcohol on the liver a good search term to or stop is a to develop reversible completely. In the hepatitis, effect into cir rhosis, in which brous tissues long replace isolate liver cells now in begins nodules, to which degenerate. do not get Cirrhosis is if in which people term the sufcient this liver blood irreversible, use. will 170 drinking likely This may cells. supply. it The is are about These the their drinking inamed. disease. develop If continue becomes not get worse if someone decides to quit drinking. although it Module The functions plasma absorb amino accumulate ow into a cancer liver tissue. and also of body has drink interactions the which the is an occurs The with the of is a this It on – efcient disorder has – so direct for in myelin in the loss Blood serving the blood cancers alcohol system. many on in the main Figure shows 2.2. 1 that on page alcohol factors that release histamine. is 144, one stimulates of which the mast cells to and on sheaths and it didn’t, and lives it make Link neurones, the effect brain, of Myelin and of the by the neurones reducing long sheaths insulation excitatory effect Over If people’s inhibitions the insulators biology Link See V omiting by of to fatal. several inhibits the have prove arteries done effects It behaviour . of as of secrete Applications system loosen one in nervous proteins. neurone are factor to cells T oxins bleeding. damage the to interactions neurones risk the cells fewer blood. into neurotransmitter glutamate maintenance of internal fewer and may ows depressant, channel of cirrhosis a of the nervous effects It easier . of speed is function These less the destruction of in are blood from much result consequences them reduces Symptoms a inhibitory effects with makes Alcohol as it. much neurotransmitters. This and There the toxins resulting social activity into eventually immediate not social interferes and and develop important inhibitions, disrupted. obstructed cirrhosis. an enhances are albumin, glucose is fulls GABA, as alcohol on the would inuencing liver stomach, may Effects of Alcohol the liver symptom liver people the such acids, in the oesophagus is of proteins, 3 term Schwann in peripheral it and cells. demyelination that provide around PNS). reminding the central nervous See of the and systems page about the some 120 if (CNS you need them. transmission. PNS of leads sensory to polyneuropathy. feeling, particularly in the Did you know? hands and feet, movement. Alcohol In acts numbness, the to brain, inhibit tingling neurones the release and may of a reduction be ADH affected so in by water is the control of dehydration. not There conserved are disorders the kidney. Brain cells are also adversely affected by the low oxygen concentrations of the blood that also occur in people who alcohol-related that involve degeneration and of glucose several by brain tissues and gradual loss of misuse mental functions. alcohol. Alcohol provides nutrients their needs balanced of as in well for diet. alcohol what most on with energy This the are known alcoholic with means liver a drink that and deciencies as drinks. that these nervous of ‘empty People in misuse provides people system, vitamins calories’, who no by having ) B there the of severe severe and are no satisfy constituents compound (especially that alcohol a effects malnutrition minerals. 1 Summary q uestions 1 Make over 2 Explain leads 3 why the the cirrhosis Describe the chart periods to fatty Describe b 4 a ow long the show the effects of alcohol consumption on the liver time. short-term consumption of a large quantity of alcohol liver. appearance and nervous to of c of liver tissue in people who have: a fatty liver, cancer. short-term and long-term effects of alcohol consumption on system. Figure 4.2.2 5 Summarise 6 Explain why such vitamin the long-term health risks of excessive alcohol consumption. Alcohol is a social lubricant, but everyone should know their limits, understand the effect the drug has on as someone B who misuses alcohol may have deciency diseases, them and drink responsibly deciency. 1 171 4.3 The social effects Figure Learning outcomes A On completion of this section, unit be able of shows alcohol is 8 explain the describe term the petty describe the of mass alcohol of in alcohol a variety that of people drinks. metabolise in 1 hour . of alcohol on since its drinking. the rst The world publication British issue recommendations in Government’s 1987 as shown in advice the has about been updated table. behaviour, family crime the throughout unit of alcohol effects interpersonal life, is units to: responsible the grams. Governments alcohol you This should 4.3.1 of and effects vandalism of alcohol Date Units of alcohol on Men Women driving describe the regulations concerning alcohol and in driving 1987 21 units different countries. 1995 3–4 units a day 2012 3–4 units a day, least Some 4 safe 2 people to week. In people not extra week strong 2 the 1995 in days 14 the advice drinking how with the equivalent interpreted know but abstinence interpreted drink dangers alcopop a units a week consumption these many units a day at 2–3 units a day, week least advice of given 21/14 was these a 2–3 changed quantities limits. units of in units to Often alcohol one daily to mean which exceed are but with abstinence drinking limits. day, they they days 1987 in every 2 that it these how was each there are many limits consuming. week session However , is at a as The they do advice cider lager changed again taken moderation, liver , in and in these 2012 can to has get include some short-term worse if alcohol-free effects alcohol is on the drunk days. body, every Alcohol, even especially if the day. 5 2.2 Limits for women concentrations the same are in lower women number of than are units of for higher men than alcohol. because in There men are blood when several alcohol they both reasons drink for this, 1.4 including tissue cocktail wine spirit their has a smaller limited size blood and greater supply, so in proportion women of more body fat. alcohol Adipose remains in alcohol per and the blood rather than entering other tissues. mixer Figure 4.3.1 The units of alcohol in some drinks Blood The alcohol blood alcohol concentration concentration (BAC) is measured in mg of 3 of 100 cm blood. The table shows the effects of increasing BAC on behaviour . S tudy foc us Social On page 129, we dependence the as Many example of two of categories of disease. Should dependence on as included drug an alcohol a disease? What be criteria used to decide whether should alcohol dependent? After you thought answer Question 172 4d on page be is have about these questions, 178. people dominate alcohol classied someone to or an effects of a and social extent live with them. misuse they alcohol Sadly, it. lubricant, that alcohol it It as there is not just becomes can think part are of of their people an else. without become enjoyable incorporated little lives who it ever dependent accompaniment into their way of coming on to life food to such Module Units of alcohol Blood alcohol Effects of alcohol on 3 Applications of biology behaviour concentration/mg Men Women –3 100 cm blood 1½–3 ½–2 20–50 reduced tension, 3–5 2–3 50–80 euphoria, 5–8 3–5 80–120 slurred 8–15 5–10 120–260 loss of signs 16–26 10–15 >26 >15 Alcohol dependence their general are may in colleagues Petty Acts in the People have to responsible misuse take days for coordination, condence motor walking control, in a loss of staggered inhibitions way, slow of voluntary and actions, of of balance, erratic behaviour, aggression coordination, difculty depression loss breathing remaining control upright, centres in the extreme brain, confusion death following: who alcohol off work absenteeism. especially loss of ne in if often as a Repeated relationships neglect result. with absenteeism work damaged. this records is in vandalism show because escalate implicated of and behaviour: occasionally often also Police Often Aggressive work: dismissal, are crime: crime. from involved health Hangovers result is impaired emotion loss of coma, judgment, increase times control of total >400 Absenteeism 260–400 impaired speech, reaction relaxed feeling, that alcohol criminals drink Disagreements into aggressive is often before between a factor drinkers behaviour in committing and petty crimes. may ghts. Alcohol is homicides. are often committed by people who are drunk. Summary q uestions The the effects of inuence alcohol of can alcohol. be just The as bad when withdrawal not drinking symptoms make as life when very under difcult, 1 not only for the drinker , but for his or her immediate family. Explain terms symptoms include irritability, shortness of temper , what are meant by the These shakiness, unit of alcohol and daily insomnia, alcohol limits. sweating, nausea persistent and shakes, a panic high attacks. pulse rate At their and very even worse, there frightening are visual 2 hallucinations. This condition is called delirium tremens. One way Describe the effects interpersonal ‘cure’ it is by downward arguments, this may drinking mental more and aggression, lead to alcohol. physical abuse, family Alcohol spiral: instability breakdown, dependence neglect, and shortage insecurity. homelessness, can of lead to poverty the 3 and long term The annual to the UK destitution. and driving cost of health estimated The Alcohol alcohol on behaviour. a money, In of to in costs of were 2008 crime estimated alcohol misuse services was at £2.7 billion. and disorder at over £7 billion. Effects on the workforce were Alcohol and other drugs are involved in many road accidents. Alcohol has estimated adverse effects on people’s concentration, while at the same time a them The feel more legal limit for someone driving in the USA, UK and the Explain how society so English-speaking Caribbean is b 80 mg 100 cm blood; Explain how (as in most of Europe and the non-English speaking Panama and Guadeloupe and drive in Cuba, those and Martinique) however , have a it zero is 50 mg 100 cm tolerance. It is . are Barbados, illegal to blood who and urine to costs of you would other assess drugs misused compared that with countries. suspect someone test for of drink alcohol. In driving can countries take where samples the –3 80 mg 100 cm cost alcohol. drink 4 Police can Caribbean –3 including alcohol much. in the France billion. in –3 of £6.4 condent. maximum much at making of legal breath, limit is Explain the thinking behind: a daily alcohol limits, and b safe limits for driving. In your –3 blood, the limit in breath is 35 µg 100 cm and in urine is answers explain why the daily –3 107 mg 100 cm limits for women are lower than The of penalties licence to for drink driving offences can be very severe, including loss those for men. drive. 173 4.4 The effects of smoking T obacco Learning outcomes is tabacam. On completion should be able of this section, you an list the chemicals to: main components outline that the the effects of smoking gaseous outline gaseous tar – a exchange the effects of smoking tobacco concentrations T obacco combustion substances the in smoke of the smoke Nicotiana nicotine contains products tobacco of plant, over biological that that 4000 have act as different molecules greatest in effect exchange and cardiovascular systems are: black cardiovascular distinguish in oily as containing that many condense aromatic on the compounds; lining of the it is bronchi nicotine – the drug in tobacco, which is the reason for smoking the leaves system betwen physical carbon monoxide (CO) – a highly toxic product of the incomplete and combustion psychological liquid droplets on high of system dried the leaves on plant. the The dried contains the are leaves. breathed the plant for the smoke from of on tobacco The insecticide tobacco made of compounds in the leaves dependence. carcinogens, smoke When It (see bronchi settles on lead the vulnerable the to smoke trachea into lower the there are also co -carcinogens in tobacco 135). tobacco down that benzpyrene; page inhaled, travels e.g. the sides travels which lungs. of harmful the through branches, Much of bronchi. effects of the like the airways an particulate This is into inverted the part Y , the matter of lungs. into the in the smoke body most smoking. Link The Find videos their of ciliated coordinated are fascinating Remember structures by cell they each surface to see movement. They structures that – cells are one is to watch. intracellular surrounded airways ciliated cells mucous these to the an and throat, to that effective of mucus move where it the is Short-term Gaseous T ar S tudy is an part you distinguish the effects on these gas and carcinogens exchange system; this the mucus, mucus and cells. rather or like onto chemical transmitted the Interspersed Beneath the an beat the in escalator , otherwise a between the epithelium surface. defence through Cilia the against air . are T ogether , dust, Particles stick coordinated up the airways to the removed. smoke system causing inammation monoxide are blood and affect accumulates is cough their not – to bronchi. in cells the and of the epithelium mucous bronchi. T ar glands lining also secrete the tract. inhibits more moved upwards; it just accumulates. the action This is of why remove The the accumulated accumulated mucus mucus, dust provides a and spores suitable nicotine for pathogens to grow. There is plenty of food and it is absorbed and warm. Smokers are often more susceptible to airborne the infections, cardiovascular goblet affect moist into are swallowed response mucus environment carbon that cells. two from and more mechanical covering exchange which so smokers systems. Tar the even epithelium. goblet carefully cilia, between ciliated effects of tobacco irritant, of mucus, sure a foc us As Make by secrete pathogens layer fashion membrane. lined mucus-secreting glands form spores are are such as colds, than non-smokers. system. Cardiovascular system Carbon diffuses monoxide irreversibly with into haemoglobin red to blood form cells where it combines carboxyhaemoglobin . As a result, Link the as Nicotine is a stimulant 168). The sympathetic system part is nervous of system the (see (see much autonomic 91). Nicotine the blood to carry oxygen is signicantly reduced, often by 10%. is rapidly seconds of nervous system glands. 174 as of page nervous page capacity As absorbed, inhaling. a and result It acts and at promoting there are can reach synapses the the secretion increases brain stimulating in of heart in the less adrenaline rate and than 30 sympathetic from blood adrenal pressure. Module Nicotine causing also the capillaries. to cold of This and peripheral stimulates smooth is sympathetic muscle to vasoconstriction, during exercise. vascular The disease, neurones contract and which can innervate blood happens long-term which that reduce effect lead to of ow during this gangrene may Applications of biology arterioles, to our and 3 response be amputation limbs. Smoking also composed therefore factors causes red more than chances of coronary people of an blood difcult promote a blood arteries. already at increase cells. to pump. blood clot the heightens of blood Platelets clotting. because relative makes (thrombus) This risk in This are These the risk of effects in (see the to and release the particularly heart page blood viscous increase arteries, coronary factors of more stimulated two occurring other proportion become disease in 160). Figure 4.4.1 Even the rst cigarette has Passive smoking harmful effects on health; more dangerous T obacco smoke not only has effects on the smoker , it also has effects on is the power of nicotine to become addictive other with people, a smoke smokers smoker . which burning tip and Smoke comes which from from is non-smokers a burning the called lter alike, who cigarette or mouth ‘sidestream’ are in consists end smoke. and the of same mainstream smoke About room 85% from of the Link the smoke Collect from of a burning tobacco cigarette smoke mainstream are smoke. in is a sidestream higher Breathing smoke. Many concentration in cigarette in smoke of the sidestream like this some is than help in give passive of smoking. people you who conditions live as second-hand or work smokers. smoke in with smokers Children their are homes. develop the particularly Their same at lungs risk quit published to smoking. These information nicotine difcult People leaets components it addiction is to about and will aspects how overcome. medical from develop breathing more slowly and Summary q uestions they are at children, increased 33% of risk male of asthma. non-smokers, Researchers and 35% of estimated female that 40% of non-smokers 1 were exposed to second-hand smoke globally in 2004. This exposure Make a ow effects estimated to have caused deaths from asthma and heart and of This represented about 1% of deaths the to show the components of lung tobacco diseases. chart was smoke on the gaseous worldwide. exchange and cardiovascular systems. Drug dependence 2 As we saw on page 169, drug users can develop tolerance. Nicotine Explain in at cholinergic exposure metabolism taking a synapses neurones and drug by make leads because to it interacting more of physical has with these receptors. receptors. dependence . become part of With This Drug their is are not using their drug, they often users change need metabolism. experience which only stop when the user takes physical the drug of the following the healthy functions gaseous exchange of the mucous glands system: cilia, to to keep When and goblet cells. drug Describe the effect of carbon withdrawal monoxide symptoms, roles continued a 3 users the acts again. on the transport of This oxygen. keeps drug headaches, sweating, users ‘hooked’. stomach gain in The pains, weight, withdrawal craving for increased a symptoms smoke, appetite, for anxiety, irritability nicotine are: 4 tiredness, and insomnia. Outline of the the risks to the cardiovascular health system of smoking. Psychological drug. In this there are rituals dependence. are dependence form of is most both a behavioural dependence, surrounding For elements of the people forms drug who of change drug-taking are taking has that dependent, dependence. A – a craving become a reinforce it is gradual for habit; the often 5 the likely that reduction in there the Smoking is WHO be disease. a drug may reduce physical problems, then dependence, it may be but hard if to there ‘kick are the are addicted dependence, such as to nicotine withdrawal wanting a show physical symptoms smoke at certain and and of the what is disease meant and by justify underlying habit’. decision by WHO to call People a disease. psychological compulsive times by self-inicted Explain smoking who a self-inicted the psychological considered use a of to day. patterns of behaviour , 6 Dene the smoking, terms passive physical dependence, psychological dependence. 175 4.5 Chronic smoking-related There Learning outcomes are On completion should be state able the of this you many related diseases explain what is smoking- meant by pulmonary diseases concentrating obstructive conditions to: chronic obstructive section, are on occur chronic emphysema are long-term, pulmonary that that diseases disease in the related or to smoking. chronic, (COPD) bronchi is and diseases a In of collective lungs, this the section, lungs. term used we Chronic for including: bronchitis chronic disease COPD (COPD) COPD describe the the effects of COPD is a signicant cause of ill health; globally the death rate from this on condition is on the epidemic, since increase and this is linked with the smoking lungs explain how lung smoking is the major cause. Asthma of bronchi is another . cancer Bronchitis is the inammation the and other air passages. The develops. rst sign of mornings, mucus to As all air the may to disease of only be day. capable and Chronic bronchitis and the the cold or person Emphysema walls feet, of the elasticity is often a die disease (the break a by leads in down, it. The only the extra becomes protective that way in causes gradually means the wheezing steps and and is the the more epithelial mucus person the lips can clear the the the occur at person may may include appear affected become blue. person seriously acute, infection. structure spaces producing If skin a totally symptoms and may advanced, becoming Other emphysema. of breathlessness well before bronchitis result air disease few which tiny This coughing. to the a severe inammation bronchi lining and the failure, as particularly coughing. time inuenza, alveoli and heart may tissue. coughing, taking the cilia lungs, by The of the scar is the of of incapacitated of a By lining the mucus swelling catches by in usually sputum. loss worsens, the cough, up replaced of a The the accumulates breathless Figure 4.5.1 brings leading passages times is produced. becomes produced the disease which be damaged, tissue the in the larger of the lungs) air lungs changes. gradually spaces. This lose The their means that Withdrawal symptoms and the lung has a smaller surface area for gas exchange. As a result, the cravings make nicotine addiction one of the hardest to give up; this is why it is much better not to start in the rst place affected person oxygen. Blood damage to lung turn the in As result the of to breathe protein alveoli Elastase hard for as breaks people out. responsible for right of this, the more lungs ventricle of the blood uid heart. vessels narrowed side of enlarges, from builds often the right ventricle frequently become blood become for bringing it you breathe down, with making emphysema irritates chemicals secreted that are that by the up leads radicals these in for macrophages attract capable responsible which 176 the in to As the the carry heart to to and to tissues, failure to right side page lead blood of the the to and lungs changes neutrophils of the smoke normally in the neutrophils. digesting damage damage protects and lung seen the alveoli, Proteases, to rise heart. legs and 161). macrophages. tissue in and from in turn Proteases these emphysema. enzyme alveoli which particularly inhibitor , proteases. chemicals Oxidants release elastase, are are enzymes are and for in through pressure particularly (see the These the sufcient can progresses pump causes the gain this blood destroyed. which heart order emphysema that or body in damaged, foc us the recoil out. it is harder Emphysema Smoking Elastin it The veins ankles. S tudy right breathe in deteriorates, make the to replenishment lungs. a the tissue oxygen has vessels free alpha-1-antitrypsin, Module 3 Applications carcinogens in and in biology co-carcinogens tobacco mutations of smoke epithelial cells of the bronchi regulation is uncontrolled a of the cell cell division by mitosis b Figure 4.5.2 a Drawing of a part of a lung from someone with emphysema. b A healthy primary lung drawn to the same scale for comparison. cancer Almost all tumour bronchus tumour Lung – of lung cancer are related to smoking. In addition in the lung cancer , smoking is also a contributory factor to break the off blood such as cancer of the in carcinogens bronchial and genes co -carcinogens epithelial genes code that cells, for unchecked. If control causing the inhibitory a mutated cell in tobacco smoke mutations. cycle proteins. cell and and spread lymph secondary in tumours in mouth. Cells interact become with e.g. DNA and Once survives mitosis lost, and mutate. cells evades liver continue e.g. tissue, lymph nodes cancerous Some to destruction lymphoid organs, Figure 4.5.3 the the to other The of carcinoma other tumours cancers, wall bronchial cells through cases a secondary promoting if cycle disrupted of these The development of a tumour in the lungs divide by Did you know? lymphocytes, bronchial then it can epithelium. grow Blood into a vessels mass and of cells, lymph or tumour , vessels grow within into the the Scientists tumour , supplying it with oxygen and nutrients so that the cells spent unravelling continue may and to take be divide. 20–30 Although years for a this is tumour uncontrolled to be large growth, enough to it is not cause fast. the will tumour , obstruct a and up or bronchial airways blood, primary and/or occurred, it link between and lung cancer. involved epidemiology Research problems and will carcinoma, blood suggest vessels. lung grows within Symptoms cancer as the in the a lung tissue smoker , diagnosis. If it such the as on on page tumour will be treated there more by (see the ow chart), will chemotherapy be secondary difcult to treat and then it may radiotherapy. be tumours in other If parts 178) and animals. To nd about the (see Question work of laboratory out more, Richard work read Doll and cancer removed Peto in the UK, and Oscar by Auerbach surgery has the smoking Richard still time detected. coughing is long It 2 As a can in the USA. metastasis of the body successfully. Summary q uestions 1 State 2 Describe the chronic the diseases differences associated between the with smoking. bronchus of a non-smoker and a smoker. 3 Outline 4 Describe 5 State how emphysema what the happens symptoms of develops. in the lung development cancer and of lung explain the cancer. advantage of early Figure 4.5.4 The message is loud and clear – eat a balanced diet, take regular diagnosis. aerobic exercise and follow sensible advice 6 Outline 7 Discuss the consequences of failure to seek treatment for lung cancer. about smoking, alcohol and other drugs. But are you listening? How effective are the success of anti-smoking measures. health promotion agencies at getting their message across? 177 4.6 Practice exam-style Substance Answers to Most of some 1 these are more all exam-style questions questions about closely Chronic other the are about topics questions bronchitis is a in in can abuse be found on the substance Module Paper 3 to abuse, accompanying CD. but a represent by the age of 70 in each of the different groups. associated b with Suggest groups smoking. a Using the information in Figure 4.6. 1, state the percentage of male British doctors who had died 2. condition questions: i Explain the meaning ii State THREE symptoms of chronic bronchitis.[3] iii Smoking-related categorised as of the diseases social term are diseases chronic. c [1] diseases. Explain at the Molecular cancer. as have Project stating disease, with developed that Immunology Centre but it does advanced production of uncontrolled b Outline c i how Explain d a Explain how lung why people read cancer cancer such the only as c Discuss the that a that [5] polio. of b [2] arise the With light The study sample those of who had never recorded. The each who are smoking started into three those were group after of was smoked, times results effects divided those of different the doctors were and percentage at on male doctors smokers alive the liver. effects of [5] alcohol on the [5] social that consequences may arise from of the violent alcohol abuse. [5] reference to alcohol, between explain physical and the psychological is [3] What meant by a unit of alcohol? [2] ii Explain the advantages of recommending daily c Comment on the fact that some [2] tolerance for drink countries have driving. a [3] [3] long-term 1951. The in the passage d large and alcohol limits and safe limits for driving. if above. A large i zero 2 of immediate dependence. [2] might sentence to system. the difference cannot and changes briey behaviour differs from vaccines measles consumption leads cause developing. the rst Describe nervous patients develops. problems b the of 4 the vaccine regular alcohol reported stimulates proteins the Cuban vaccine lung how on is condition against the of in proliferation. diseases Comment the [2] lung prevent cancer. The vaccine cell prevent for improve antibodies Suggest ii against cannot [2] [2] director Gisela Gonzalez the vaccine [3] different smoking causes death from lung diseases. why. a vaccine the Explain why the evidence from the British Doctors long-term Havana amongst doctors varied. quantities Scientists rates self3 inicted of death Study, as shown in the graph, does not prove that sometimes and why of the shown who heavy doctors study in in a regarded 5 as a were a Explain b State THREE with smokers. who whether alcohol dependence should be disease. [5] in categories: began Figure on Britain Discuss who were was c 4.6. 1. the meaning cirrhosis does Explain services not or in of the which differs from misuse whether dependence 120 ways you should whether term the the drug abuse. liver liver of of a a [3] person person alcohol. think be [2] people treated people by with alcohol national should nd health their own elam treatment. 100 In 2006, the [3] British Virgin Islands joined many other fo fo egatnecrep srotcod hcae evila puorg countries 80 smoking d and in Explain territories public the in the Caribbean in banning places. reasons for banning smoking in public 60 places. 6 40 a [5] Describe gaseous never the short-term exchange effects system of tar (trachea, on the bronchi and smoked lungs). 20 light [4] smoker heavy smoker b Explain how chronic bronchitis. smoking can lead to emphysema and 0 40 50 60 70 age/years Figure 4.6.1 178 80 90 [6] 100 c Describe THREE system. effects of smoking on the blood [5] Module 7 Tobacco smoke benzpyrene, potent a contains and cancer-causing State FOUR carcinogens, such co-carcinogens. Together other as these are e agents. carcinogens. include this form each your of Suggest the [4] of 3 Applications anaemia and of give biology a reason for choices. how health prevalence of [4] authorities could iron-deciency monitor anaemia in the Caribbean. b Outline the stages in the development of cancer. [5] 9 c Explain of the them, why it is important symptoms especially of if cancer they that and people do not are aware with ignore smoke. A variety is [3] Figure 4.6.2 shows global mortality for the of heavy alcohol risk factors for disease in which misuse Explain in what a are the serious good most indicator of associated the of these level of populations. information collect to nd out about the cirrhosis level of you misuse of 2004. alcohol high is disorders of eight would leading alcohol-related drinking. One cirrhosis, a 8 [3] lung in a country. [5] blood b Outline c Explain the social harm done by alcohol. [5] pressure tobacco higher use with high why than the economic simply the alcohol-related costs costs of diseases of alcohol treating like are far people cirrhosis. [5] blood 10 glucose a Explain, using classied as examples, why self-inicted some diseases are diseases. [3] physical b inactivity Discuss related why named diseases alcohol-related should be and classied in smoking- several overweight and different obesity c high cholesterol HIV/AIDS and of dengue fever ii Compare d 8 0 0 0 6 7 0 0 0 0 0 0 4 5 0 0 0 0 (total: in 0 0 3 0 0 1 2 0 0 0 0 0 0 0 0 mortality the ways Explain million) effect two what is meant by the term 11 of Although information in Figure 4.6.2 to which HIV and the transmitted. is a [2] long-term disease, leading causes of ill health and the world sketch graph to in infectious show programme given concentration and legal are controls 3 of the consisting months the on apart of on the blood. the measures should health and that [4] consumption of take early anaemia to reduce the in death. poor are these illegal. some drugs are considered legal and is the the most world and health of illegal. [3] smoke contains Both are nicotine absorbed by and the carbon blood. [5] Describe THREE is women short-term effects of nicotine on common a major and body. [3] risk c the the Caribbean, cocaine burden the disease and health b Iron-deciency throughout Heroin why as monoxide. ill alcohol drugs. Explain Tobacco in a many the formation [5] preventative authorities deciency available for stimulate of vaccine there others of [2] mortality a across the not. discuss: are factor by [1] the the Draw is a vaccination doses tobacco ii caused risk factor for disease. i in are HIV/AIDS are vaccines antibodies. thousands 58.5 There antibody Explain Use why dengue fever diseases. Vaccines Figure 4.6.2 b both use but a are [6] sex dengue fever virus alcohol disease. viruses. i unsafe categories Describe the effects of carbon monoxide on the children. body. Health the by authorities pregnant the half of women disease all estimate and in that maternal that up to the Caribbean it is a factor in one-half are as d affected many The term who as Discuss the being very d reasons for iron-deciency State TWO anaemia other [3] is a categories deciency of disease large heavy is often quantities smoking of applied alcohol. should be to people Discuss classied as abuse. [5] anaemia common. Iron-deciency alcohol abuse drink whether deaths. drug c [3] of disease. that could e Explain the term f Explain the likely children and passive smoking. effects teenagers. of tobacco [2] smoke on [3] 179 Glossary altruism any action which an atherosclerosis process in which fatty A individual abiotic factor chemical any physical another, or environmental factor inuences absorption a that e.g. another’s graph an that in performs for defence material and feeding young amination community spectrum organism group which (–NH ) introduces to systole pump contraction blood autonomic into within the wall of artery atrial reaction amine an develops into nervous the of the atria ventricles system 2 shows the absorption wavelengths such as of light by another, different a acids pigment, cholinergic neurotransmitter; produced transfer in the Krebs ammonia of compound link 2-carbon from formation keto acids; of involuntary amino reaction comprising see acetyl groups does to decomposers excess respiration not anterior cycle production deaminating anaerobic to by motor require pituitary autotroph of as a amino result acids respiration carbon it needs compounds from potential reverse in potential pituitary that secretes across a cell membrane of TSH, LH, part nerve cell (or a muscle carbon hormones, action –70 mV to spectrum activity of a about compound graph process, microorganism +30 mV that such shows the synthetically) growth as produced by diet that sufcient for at of antibody different (or to nutrients, bre wavelengths of following plasma light immunity immunity contact with an antigen by or inhibit species present genetic diversity infection or cells to that is secreted the with rapid onset (active the B-cells) presence different these short duration, e.g. (ADH) species and fever biological pyramid displays numbers made in the released from pituitary antigen nucleotide that organisms, or energy at their different levels in an ecosystem any factor that inuences hypothalamus the involving organisms, posterior such phosphorylated method of by as predation and competition gland blood (ATP) in are found an communities adenosine triphosphate species ecosystems hormone octapeptide neurones dengue the each in of biotic factor and/or area, by trophic disease an within antigen antidiuretic vaccination in the biomass acute disease water (biodiversity) bacteria protein response gained and and produced kill which active provides needs a and photosynthesis, dioxide e.g. biological diversity about the organic FSH antibiotic cell) from make of specic a systems obtains B front energy difference that that balanced diet action to system and nervous organism oxygen gland nervous sympathetic parasympathetic ammonication see synapse acetyl-coenzyme A e.g. deamination chlorophyll acetylcholine the of any macromolecule, pressure force acting on blood e.g. vessels with ribose as the pentose polysaccharide sugar; or protein, that B-lymphocyte universal energy currency in stimulates cells the formation that adhesion force of attraction between type responds to molecules and cellulose antigen cell presentation display by hydrogen antigens bonding within MHC proteins hormone secreted by the and class glands; works with antitoxin the antibody mass nervous type neutralises system index of antibody relative toxic exercise any exercise in which produced by pathogens, e.g. the gaseous exchange system and by that molecules indicator that to of body height capsule in cup-shaped cause tetanus kidney nephron that by surrounds bacteria cell substances structure aerobic antigen plasma that Bowman’s sympathetic a II) mass adrenal into (class I body adrenaline lymphocyte specic of secretes walls a antibodies differentiating water of of a glomerulus to collect and ltrate heart supply oxygen aerobic tness efciency a with to muscle measure which gaseous exchange muscles with of the diphtheria apoplast the heart system tissue and and supply all the tissue; forms other a cell walls in a pathway for substances plant C water travelling Calvin through oxygen plant cycle see light-independent tissues stage aerobic respiration respiration arteriole that type of blood vessel between cancer requires artery oxygen and capillary; disease growth AIDS Acquired of Immunodeciency blood through that involves the determines ow capillaries of a malignant tumour in the by body Syndrome; collection widening of (vasodilation) or capillarity opportunistic infections related constricting to thin HIV articial infection immunity immunity spaces rule neurones by are vaccination or by against of the water pull in of gained gravity all-or-nothing movement (vasoconstriction) injection due to adhesion and surface of tension either stimulated to send impulses or antibodies carbaminohaemoglobin not; they do not have graded atheroma fatty tissue within the formed responses to stimulation of an when carbon dioxide artery combines 180 compound wall with haemoglobin Glossary carbon xation dioxide into incorporating a more carbon clonal carbon of complex T-cells) compound carboxyhaemoglobin formed when combines cells compound carbon clonal monoxide irreversibly of to carbon a by and increase lymphocytes mitosis selection addition compound, dioxide in of carbon e.g. xation photosynthesis in MHC closed class and active have to of ow break down simple bacteria organic inorganic dioxide demyelination cell receptors antigen e.g. decomposers carbon presented from compounds and loss myelinated associated with and fungi that compounds to such as ammonia of myelin sheaths neurones; drinking alcohol in excess proteins II vessels, number produce selection circulation within in (B-cells cells that complementary the to memory lymphocytes with haemoglobin carboxylation dioxide expansion selected of denitrication blood arteries and veins ions to conversion nitrogen gas (N of nitrate ) 2 carcinogen cancer, e.g. ionising cardiac cardiac agent certain the the causes chemicals heart done pumping and during the by blood and one ratio the consumed that immune are left the by response activated in beat between ventricle volume cardiac protons across a host active with of organism simple that type cells an uses chemical and the diffusion autotrophic to x the competitive between species (outer stroma gains its inner) grana that of immune that in any chloroplasts compound that absorbs light synapse acetylcholine released by is the neurotransmitter long-term inammation associated with chronic disease where pre-synaptic bronchitis involving synapse the of same live in (of the all species results each in when one ecological to of the proteins infection; protein C3 any has a central producers organism and/or other atheroma to in heart one or restriction muscle more of by muscle that ADP make ATP to (plural and ATP transfers cristae) large infolding synthase area for stems involve photolysis cytosol the surrounds of have part of the all the phase on in insulin of the heart, ventricles ll with owering two leaves of owers plant cotyledons; with are in net-like 4s or 5s, 3s disease disorder or illness, poor functioning body double or associated part during circulation travels in of of the mind circulation blood drug with broad of through one the the body, heart twice mammals any substance that in taken inuences the abuse body use effect that is illegal drug; of a not a or the that mind legal called see and into process drug intended; often dependence covering leaves that water reduced surface act effects plant drug dependence ETC then to use drug gain of an misuse physical psychological dependence layer and disease slow of enzymes photophosphorylation of to to reduction its and seed parts occurs membrane; non-cellular waxy production a veins; drug in phosphate surface epidermis of cyclic compound mitochondrial provides the has body phosphate by to atria many e.g. coronary large and and non-infectious relaxation the complete heart disease with dead it blood not heterotrophic on caused eats shreds decomposers dicotyledonous non-specic comprising photophosphorylation bronchi; with part system material, resistance diastole competition that or that mellitus disease same animal material area for time neurone smoking disease egests with cuticle cholinergic by water organisms that exclusion respond inner pigment xylem between role crista chloroplasts chloroplast the decaying arteries two and the occupying coronary but from and is that creatine envelope membranes surround that light detritivore consumers reactions chloroplast chronic at all levels) that feeds energy from organism not from chemical found trophic blood ow chemotroph water diabetes community consumer reactions through attraction complement gradient carbon energy of complement of of ATP chemoautotroph force area muscle transport electrochemical synthesis transpiration in niche membrane subsequent facilitated their in in which T-cells enter the by tension molecules response to pathogens that chemiosmosis down caused occur cell-mediated immune response of cohesion–tension transmitted changes efciency work oxygen that radiation cycle within the any body’s type does drug tolerance of not or quantities same that are becomes so that required to part of larger gain the effect ductless NADP drug metabolism gland secretes gland without directly into a the duct blood cytoplasm that organelles E onset and/or circulatory body in long duration system which substances system a uid around cytotoxic T-lymphocyte of the that kills infected host type of T-cell cells ecological transports the efciency consumed body trophic by level the as a the energy organisms in percentage one of the D cirrhosis there is disease of growth of brous associated with the liver drinking in which tissue; alcohol energy deamination in acid to breakdown remove amine of the previous trophic level amino group entering (–NH ) ecological niche the role of a species 2 excess to form climacteric steep increase respiration rate ripening some fruit, of in associated e.g. with bananas a keto acid decarboxylation carbon dioxide compound and ammonia reaction is in which removed from a in a community in the food with other including chain and species its position interactions and the physical environment 181 Glossary ecosystem a community features self-contained named and trophic that interactions effector out or ion it food that by web of or two or heterotroph more point in the energy ow diagram that shows chains in many gradient for compound across G a glial composed cell cell gradient the nervous and protects neurones; some any the to system and (plural glomeruli) knot is stimulates infects T-cells immune in collection opportunistic of these maintaining is AIDS near conditions within a Bowman’s of the kidney; equilibrium the body dynamic capsule nature cortex within of transport the (HIV) increase homeostatic in that and cells the electron cells ineffective homeostasis capillaries in mast virus leading constant of carbohydrates are an glomerulus compounds by as hormone system attraction carrier such local infections; Schwann electrical in of that concentration compounds, histamine obtains carbon inammation ecosystem a that complex secreted an organism carbon from HIV/AIDS gradient charged membrane electron at arrows interrelated food carries stimulated levels; direction the them gland when and organisms hormone electrochemical an physical inuence action or the between muscle an nerve all site of homeostasis involving of continuous chain monitoring and ultraltration electron transport chain regulation (ETC ) glucagon series of compounds that alternately reduced and hormone energy to form a by in pancreas immune immune in conditions response type of that to increase internal islets humoral oxidised Langerhans stimulates transfer secreted are of of blood response in which glucose antibodies proton are secreted; effective concentration against gradient gluconeogenesis emphysema lung disease in are damaged and the of the lungs always synthesis of a population in a glucose, for example place; species only found in a systolic blood blood pressure pressures above 140 liver mmHg and diastolic pressure is glucose above of concentration when a in the present specic cells high glycogen when to decrease in host hypertension decreases of a disease remain acids surface from endemic that glucose outside amino glycogenesis area of which from alveoli formation pathogens stimulated 90 mmHg most of the time by hypothalamus specic part of the brain that insulin controls place glycogenolysis endocrine gland see ductless inner layer of cortex osmoregulation, the vascular tissue in and the to increase the activity of temperature the pituitary blood gland concentration when stems stimulated energy currency idea that is the energy glucagon I ‘currency’ transactions are series of reactions in which by glucose which by one glycolysis molecule, ATP, is converted to pyruvate with immune response changes that occur made transfer in liver roots glucose and in body glucose, for that example surrounds to form including of gland glycogen endodermis breakdown activities of some energy in to ATP; the specic immune system in cells occurs epidemic an outbreak of a in granum ethylene (ethene) plant cytosol a stack stimulates a variety of of thylakoids in site of light-dependent of immunoglobulin photosynthesis to defend against type of protein that using zoos antibodies and immunology gardens to away from their study of the defence H conserve against species ability disease ripening conservation botanical antigens the infectious forms ex situ to immunity a responses stage including fruit response cells hormone chloroplast; that of disease disease natural habitat the place where an organism in situ conservation using protected habitat lives excretion removal from the waste products of substances in as nature reserves various denitions; some of the conserve species in their to natural metabolism best and such body health of areas, excess incorporate physical, mental habitat of and social health; see WHO incidence number of people who requirements denition on page 128 helper T-lymphocyte develop type of T-cell over a a disease certain or are period of diagnosed time F that facultative uses anaerobe oxygen for survive without organism respiration, it in that but avin can anaerobic fatty liver droplets of 182 in liver as a herd result an ecosystem shows ow between with B-cells mechanisms to secrete of uid of drinking the liver; alcohol in from tissues of vaccinating the protection for immunised pathogen is as a large population; those transmission reduced non-specic involving capillaries defence leakage and surrounding of swelling site of infection insulin hormone Langerhans immunity provides that out inammation of proportion alcohol diagram and stimulate excess of fat cells carry inammation associated respiration accumulation chain energy in to to antibodies dinucleotide; involved inside drinking food phagocytosis hepatitis adenine coenzyme cytokines macrophages conditions FAD secretes stimulates in secreted pancreas decrease in by islets of that blood glucose concentration not of a interspecic competition competition for individuals of resources different between species Glossary intraspecic competition for resources between competition individuals of memory that cell lymphocyte remains in (B- circulation or T-cell) after nitrogen xation nitrogen gas conversion (N ) into of ammonia 2 the same immune species antigen; response see to a specic secondary node of immune Ranvier action response gap potentials in myelin occur in where myelinated neurones K metastasis site Krebs cycle stage of of cancer primary in which a is dehydrogenated major with transfer to reduced become type of elswhere in the body NAD, histocompatibility cell surface of proteins reduced used to display antigens photophosphorylation phosphorylation that photolysis which of are energy to and complex; decarboxylated tumour non-cyclic 2-carbon MHC fragment travel from aerobic established respiration cells of reduced water and involves production NADP non-specic defence system to mechanical, FAD cellular and chemical lymphocytes defences and ATP MHC class proteins I on body macrophages present L antigens of and respond to pathogens cells quickly except that B-cells but always in the same way that intracellular O parasites lactate 3-carbon compound that is MHC class II the end product of and respiration in animals and some B-cells that interior of stage reactions present mitochondrial matrix bacteria light-dependent proteins on macrophages obesity body that reaction antigens enzyme-rich mitochondrion; and Krebs suitable for site of cycle of than link in grana light of chloroplasts energy to that monoclonal chemical single antibody specicity antibody secreted by a in ATP and aerobe an of survive reduced NADP of hybridoma stage reactions morbidity occur an organism that survives where there in stroma triose of chloroplasts phosphate using ATP motor sickness neurone transmits or reduced NADP from light- nervous nerve cell person impulses from system to dependent mutualism stage that is two (or together for their in that ineffective system central coating a pathogen with effectors more) species mutual or antibody molecules living to any factor with that the complement limiting factor no oxygen disease illness opsonisation and is cells immune to form that oxygen a infects that than greater organism without opportunistic disease light-independent more is clone only energy 20% BMI respiration obligate anaerobe transfer is height; 30 obligate cannot occur mass anaerobic make it easier to be engulfed by a benet phagocyte shortest supply and myelin therefore layers of cell membrane made oxidation prevents a biological process, such as by Schwann cells as the photosynthesis, proceeding loss oxidative myelinated neurone nerve a surrounded method for population by insulatory layers reaction reaction in respiration myelin size made by Schwann by is converted see in nal stage which ATP chemiosmosis; is occurs inner mitochondrial membranes which to the volume of oxygen N acetyl that coenzyme A; and cells oxygen debt pyruvate electrons of on link of phosphorylation aerobic synthesised determining loss hydrogen cell of index the of neurones any faster Lincoln is insulation for is absorbed after exercise to pyruvate NAD nicotinamide respire adenine lactate and restore oxygen dehydrogenase dinucleotide; lipoprotein particle that coenzyme involved in oxygen decit respiration lipids in the epidermis layer of cells forming nicotinamide lowest layer in a and blood between cell made in the is part of the coenzyme demand for respiration oxygen for during exercise aerobic and in photosynthesis volume the supplied bone natural that the adenine phosphate; leaf involved marrow muscle difference protective dinucleotide lymphocyte in the blood NADP lower concentrations transports immunity immunity gained specic by infection or antibodies transferred P immune system; see B-lymphocyte from mother and T-lymphocyte negative feedback that set maintain point to palisade control mechanism returns a value to its homeostatic cells mesophyll in the upper mesophyll immediately beneath layer tissue the of of a leaf upper M epidermis equilibrium macrophage presents tissue antigens phagocyte and that neutrophil destroys blood pathogens mass ow direction; phloem mast to e.g. direct cell a uid xylem in sap one and part system by of to infection or secreting the non-specic destroys in the present in the increase during infections nitrate nitrifying conversion ions by bacteria Nitrobacter respectively reactions disease continent pathogens; blood pandemic parasite use in of ammonia bacteria Nitrosomonas ammonia their living passive and and nitrite energy-transfer by or and/or inside or whole receiving source, mother e.g. that across obtains a host organism immunity gained antibodies from by across a world protection from on immunity breast present the organism nutrition nitrication to responds damage histamine; defence blood, of sap cell that numbers movement phagocyte injection the another or from placenta and in milk 183 Glossary pathogen a percentage quadrat that particular petiole to a disease-causing cover of stem; phagocyte such as phloem a leaf leaf that in a tissue e.g. of the bone material, viruses which sucrose a transports and amino of factor to e.g. during an by hypothalamus apparatus for rates of leafy twigs water blood into that of to x prevalence immune of the light as a specic antigen it has producer an that forms that is chain the rst making used to of simple the rate apparatus –70 any drug that the difference of order –60 bisphosphate compound (RuBP) that dioxide acceptor is in the the stage of light- photosynthesis in vaccinating contact with a all those person with a specic transmission disease in to the mind immediate risk factor becomes habit-forming the any factor chance rituximab difcult to of increases developing a disease drug to give it drug based on a up monoclonal photosynthesis circulation that so the cravings for area drug- the it potential membrane has of pulmonary of mV prevent are to heterotrophs carbohydrates of cell infected making measure a people there photosynthometer used respiration trophic use drive of energy process that taking synthesis rate ring vaccination a food on to ATP autotrophic psychological dependence energy apparatus the independent effects energy from before source absorption of compounds not energy to drive formation of ATP light transfer potential carbon to between immune that carbon the the organic 5-carbon in ecosystem of organisms ribulose an urine division the rst in to blood living a photosynthesis to photosynthesis an the the time response psychoactive drug light people one to available in of any to form ATP photophosphorylation place at autotrophic uses in in in glomerulus (GP) to appear heat across process to capsule number disease sensory molecules resting a level takes the a species complex blood that glucose to partitioning resources or known organism energy of small in Bowman’s (primary) organism resource cell maximum of starts measure encountered an it respiration use action neurone renal threshold before plants nerve impulses from concentration is measuring by motor different to force the system photoautotroph uptake that that neurone transmits small carbon added e.g. ADP region the in relay that neurone a made response compound, gland an potential a potential pituitary pressure 3-carbon also chemical is action in of in respirometer (PGA) cycle; phosphate increase depolarisation hormone ADH primary which change the from 3-phosphate phosphorylation a and elements for produced glycerate an immediately following control releases with as leads factor, a which (ultraltration) assimilates in Calvin in pressure ltration column acid mechanism potometer sap tube phosphoglyceric compound it positive feedback posterior in and phloem transport attaches engulfs foreign sieve xation a ‘stalk’ sieve tube phloem by that made bacteria plant acids, a cell assimilates, phloem occupied of species part marrow is organism percentage antibody for treatment blood ow (R) by production of of oxygen from photosystem pigments and around a reaction is a chlorophyll a an organism stretch by absorbing blood that gains is forced has into them the heart; pressure points, e.g. on part of 3-carbon at drug tolerance and there are when the of water stem in by osmosis stroma of wrist that that catalyses the is of carbon dioxide glycolysis enzyme has catalyses the link reaction S in withdrawal mitochondrial symptoms the body that developed the compound of into absorption enzyme xation product movement roots be felt a end MabThera by can rubisco pyruvate dehydrogenase metabolism; the chloroplast reliance become pressure following of as arteries its the it of molecule pyruvate as recoil light physical dependence drug and sold back from at energy and root the contraction phototroph lungs centre as which to proteins pulse arranged heart cancer; drug is matrix not Schwann taken myelin cell to glial cell insulate that makes neurones; see glial Q pituitary below gland the anterior endocrine gland hypothalamus; and posterior just see cell quadrat pituitary apparatus composition of a used in analysing secondary pumps community gland diffusion plaque region of an artery where active transport sodium another ions out gradient for substance so cell creating sodium that a and moves into R atheroma has plasmodesma thin developed (plural cytoplasmic plant the plasmodesmata) connection between cells polyclonal many immunity clones of B- response and of or T-cells to an same at 184 all species the at the centre receptor cell energy into travel same the individuals living time in the of the same place the gain a converts molecule a form impulses of of that and hydrogen cannot be (or any of time when stimulated immune same transport response subsequent) memory cells to an encountered selective period the protein system electrons through secondary neurone gain period neurone a photosystem electrical the of a that along refractory a chlorophyll centre of reduction antigen population reaction cell of the specic antigen that by immune has been before reabsorption movement substances from ltrate blood second response back into of the Glossary sensory neurone nerve cell that T transmits the set impulses from central point factor nervous the homeostatic sieve tube part single of a phloem complete e.g. cell sieve of above the number once, a a species defences that a is each mesophyll and process within blood thylakoid by a sent which blood clot vaccine by a a blood vessel within respond response to a tissue above in a chloroplast; is a activated response; also is stacks of granum type of known an see cytotoxic layer a of cells translocation sap leaf; inside sieve of phloem tubes of an infectious disease of infected loss of some a or all to causative uninfected interruption of in an artery an immune articial active varying give different different ventricular a acid shapes sequences to bind organism pathogen, to that e.g. Aedes dengue fever systole ventricles VO antibody antigen-binding antigens and so contraction blood artery element xylem of amino of disease aegypti vessel part that forms enters and cell of the the aorta that forms part of vessel max agent from oxygen maximum person during is rate absorbed at aerobic into which the blood exercise loss of water vapour by blood diffusion from supply by brain transpiration by provide site; a epidermis functions or 2 transfer stroke in mouth containing stimulate region pulmonary movement transmission lower to to transmits immune as T-cell; and involved by immunity vector lymphocyte during e.g. preparation molecule T-lymphocytes of the space procedure vaccine, antigen(s) variable blood enclosing uid- helper T-lymphocytes antigen lower membrane T-lymphocyte that a injection difference impulse vaccination giving hormone potential an thylakoids form of is found cellular that antigens; immediately species system mesophyll the of percentage which different for spongy receptors for when response thrombus lled specic defence different has vessel in chemical by the clot forms body, heart area quadrats that responds which thrombosis one the so neurone in sh unit cell threshold tube of through cell hormone stimulated that forms during species frequency in part circulation travels species density per target physiological equilibrium element circulation blood as a V to system value for maintained receptors supplying aerial parts of plants W the transpiration pull loss of water by brain withdrawal transpiration stroma enzyme-rich interior causes movement symptoms associated water chloroplast; site of the symptoms of of through the xylem with abstinence from by lightdrug-taking cohesion–tension independent stage of photosynthesis transpiration suberin waxy substance that does movement allow water and ions plant between sap in continuous the X xylem phosphate 3-carbon compound cells; forms Casparian xylem that strip of to ow triose between stream not endodermal is an intermediate in plant water cells and Calvin tissue and ions xylem vessel trophic and transports provides support cycle substrate-linked phosphorylation which glycolysis level feeding level in a column of xylem a food vessel phosphorylation elements for transport of chain of ADP to form ATP that occurs in water the tumour active site of an enzyme with a mass of cells that has a plant grown xylem vessel in from association a in one mutated cell that forms substrate dividing element a cell that began a xylem vessel uncontrollably molecule symplast pathway through Z plant U tissues in which substances travel Z-scheme from cell to cell through unmyelinated neurone nerve cell diagram electron ow plasmodesmata is not surrounded by place adjoin; where includes synaptic two pre- neurones and membranes post- and layers upper synaptic cleft cleft gap between two epidermis layer of topmost nitrogenous an or effector systemic heart with formula CO(NH systole heart; lungs, blood from in and contraction atrial ventricular neurone and urea cycle reactions ammonia everywhere the a cell circulation to except between body, back phase systole systole the the of the photosynthesis and a leaf ) 2 that carbon in product convert dioxide into urea ureter from is followed of protective layer excretory 2 neurones represents light-dependent myelin cells forming urea synaptic of in insulatory stage synapse that that muscular tube kidney the to that moves bladder urine by peristalsis by urethra urine muscular tube travels from the through which bladder 185 Index Key terms are in bold biological diversity community (biodiversity) companion 50–61 70S ribosomes 7 , 40 cells 74, 75, 76, 77 25 biological pyramid biotic factors 42–3 48 competition 48 competitive exclusion 48 A blood abiotic factors absorption 48, 59 spectrum acetyl-coenzyme A acetylcholine 91, 82–3, blood 10 94, pressure blood sugar blood vessels 96, 151 85, 88–9, 124, spectrum 121, 151, immunity mass 84–5, 86–7 cooperation 42, 43, 143, 145, 146–7 , 148, 154 coronary creatine index gardens (ATP) 4–5, 46 heart disease phosphate 161 33 166 cristae 57 crop 24, 28 production capsule 113, 114 cuticle 17 6 making 28, 37 , 34 cyclic photophosphorylation 11 13, brewing 35 cytosol 12 47 cytotoxic T-lymphocytes adhesion 44, 48 129 bread 24, 41, 145 152 adenosine triphosphate 23, 40, 144, 56–7 123 Bowman’s 20, consumers 55, 10 botanic acute disease 53, 125 body active conservation 143, 125 149, potential 161 104–5 B-lymphocytes action 114, proteins 26 acetylcholinesterase action 91, complement 147 , 149 71 C ADP 11, 20, 23 adrenaline 91, D 103 Calvin aerobic exercise 162, cycle cancer aerobic tness 9, 12–13, 17 135, 154–5, 177 deamination 110, 111 162–3 capillaries aerobic 5, 165 respiration 20, 22–9, 33, 82, 84–5, 113, 114 decarboxylation 26, 27 36–7 , capillarity 70 decomposers 40, 41, 44, 46, 49 96 carbaminohaemoglobin AIDS 132–3, 136–7 , 168, all-or-nothing rule 20, 158 demyelination 2–3 dengue fever dioxide 2, 3, concentrations acids 12, 46, 46–7 , 34, 107 denitrication 110–11, pituitary antibiotics 168 antibodies 143, 20, 32–5, 36–7 , 96 gland 144, 108 147 , 148, 150–1, antidiuretic hormone (ADH) 103, 12 135, cardiac cycle cardiac efciency 174, 177 cardiovascular 164 cell-mediated presentation 143, antitoxins 146, 151, 85, 91, 66, 147 , cells, 148, 149, 150 152 92, pathway aquaporins 145 67 , 70, 161 immune 116 158–9, disease response 147 , chemiosmosis 4, between 24–5, 102–3 keys 28 DNA 2 7 , double chloroplast envelope chloroplast pigments 7 , 12 drug 84–5, indexes 24, 25, tubules 85, 87 , 89, 7 , 8, 9, 10 74, 160, synapses bronchitis 75, 124–5 168–77 129 systole 102 system 64, 82–97 , 161 E 160 170–1 92 climateric atrioventricular autotrophs glands 129 161 cirrhosis atrial 175 76 circulatory atherosclerosis 169, 169 152 chronic disease atheroma 82 169 10 ductless 64, 135 circulation abuse drugs immunity chronic assimilates 113, 114 cholinergic active (DCTs) 61 132, drug tolerance articial 142–55 136–8 160 chloroplasts arterioles 7 128–9 against drug dependence 82, 6, 116 diversity 2 58 plants convoluted 115, 134 92 160–1 49, statistics distal communication chemotrophs 76 86, defence chemoautotrophs 93 diastole diet 67 49 mellitus dicotyledonous diseases strip 44, diabetes dichotomous 92–3 149 116–17 apoplast carcinogens Casparian 154–5 arteries 145 47 169 detritivores 174 46 anaerobic respiration 82, depressants 158 carboxylation antigens 16–17 12 110 ammonication aorta 30, 14–15, 9, carboxyhaemoglobin ammonia antigen 171 130–1, 46 carbon xation 152, 27 48 amination anterior 26, 122 carbon amino 23, 170–3 carbon altruism dehydrogenation 138 carbohydrates alcohol 96 2, node 8, (AVN) 90–1, respiration rate 106 ecological efciency ecological niches 44–5 92 clonal expansion clonal selection 147 40, 48 46 closed ecosystems 147 circulation 40–5, biodiversity 82 48–9 50–61 B coenzyme A bacteria 142, 144, balanced diet 186 151 158–9 26 effectors cohesion-tension collecting ducts 71 (CDs) 100, 101, electrochemical 113, 115, 116, 117 electron carriers 102 gradient 10 11, 122 Index electron transport 20, 24, embryo banks emphysema energy currency energy ow epidemics 143, HIV/AIDS 132–3, homeostasis hormones 144 2, 4 44 101, morbidity 105 mortality immune hypertension 43, monoclonal equilibrium response 147 , 148–9 20, acids (EAAs) (EFAs) 122 neurones muscle 121 90 N responses 143, 147 , 148–9, NAD 151 106–7 immunity 56–7 in 164–5 situ (Ig) conservation 8, natural 150 21, 9, 22, 23, 10–11, immunity nephron 136 nervous 144 112–13, system 24, 12, 28, 13, 32, 34, 170 17 152 negative feedback 55 incidence of disease inammation 20, NADP 152–3 immunoglobulins 110–15 162–3, 120, I immune (ethene) 28 154–5 138–9 158 34 conservation excretion 158 26, 121 myogenic acids 25, (Mabs) 48 myelinated 116 32 24, 136–8 neurones myelin 100–1, 130 amino motor 28, matrix antibodies data mutualism 125 161 hypothalamus 24–5, mitochondrial 151 102–7 hyperpolarisation 40–1, mitochondria 136–7 , 100–1 homeostatic 130 158 essential fatty exercise histamine humoral 2–3, ex situ 9, 67 energy ethylene 8, 176 endodermis ethanal (ETC) 57 endemic diseases essential chain 28 101, 105, 117 117 120–5, 171 F insulin facultative FAD fats 27 , 20, fatty anaerobes 36 28 158, liver 160–1 103, 104–5, neurones 134 interspecic competition 48 intraspecic competition 48 ions 66, 67 , 70, 96, 121, neutrophils nicotine 174, nitrifying 34–5 nitrogen 120–3, 83, 143, 124, 125, 171 144 174–5 nitrication 122 170 fermentation 102, 47 bacteria 47 46 K bre 158 tness keystone 162–5 food chains food webs 40–1, fruit, ripening kidneys 43 Krebs 41 species 104, cycle 52, 111, 20, 53 112–17 21, 22, nitrogen xation 46–7 nodes of 121 Ranvier non-cyclic 24, 26–7 , 107 28, 32 photophosphorylation non-specic defence nutrients 41, system 11 142–3 158 L G O lactate gas exchange genetic germination glial 30, diversity cells glomerulus 22, 113, 104, glycogen 23, 23, grana guard limiting factors 105 Lincoln 105 27 , link 104–5 105 glycogenolysis glycolysis 20, 22–3, 24, 6–7 , 8–9, stage of Henle obligate anaerobes 12–13 opsonisation 26, 115, 36 36 28, 32 oxidation 9, 132 151 osmoregulation oxidative 116–17 26, 23, 27 47 phosphorylation 20, 28–9, 32 117 oxygen 6 14, 20, 30, 32–3, 36, 94–5, 96–7 , 164–5 176–7 oxygen debt 83, 159 aerobes opportunistic diseases 170–1 113, epidermis lymphocytes lysis 8–9, 24, 160, lungs 71 17 158, obligate oxaloacetate 160 of 10–11, 16–17 20, 105, obesity 60 liver 33, 10 stage of lipoproteins lower 32 index reaction loops 105 21, 7 cells of photosynthesis 114 33 glycogenesis structure light-independent 121 gluconeogenesis glucose 33 photosynthesis 112, 103, 32, light-dependent 56–7 31 120, glucagon leaves, 164–5 51, 20, 143, 146–7 33 oxygen decit 33 23 H P M Haber process haemoglobin 47 94–5, hallucinogens health malnutrition 168 128–9 statistics heart palisade 85, 136–9 86–7 , 90–3, 148, 149, 170 immunity heterotrophs 2 153 159, 64, mast 143, cells cells metastasis MHC 151 hepatitis 147 , 143, mass ow memory 161 helper T-lymphocytes herd macrophages 96–7 I class II minerals 145, 147 , 171 149, 147 , 151 148 149 immunity passive smoking pathogens 49, phagocytes phloem 7 142 passive phloem 6, 138 percentage 149 147 , mesophyll pandemics parasites 144 148, 145, 158 160 78 135 proteins class 144, 6, 142, cover 143, 64, 152 175 144–5, 65, 147 , 149, 151 149 74–9 sieve tubes phosphoglyceric 143, 60 65, acid 74–5, (PGA) 76–7 , 79 12 187 Index phosphorylation 24–5, 27 , 4, 11, 20, 21, rituximab 23, RNA 28–9 photoautotrophs root 2 photophosphorylation photosynthesis 2, photosynthometer photosystems phototrophs 66–7 , rubisco 14–15, 13, 17 10 pull stream triose S 103, cells systems phosphate levels (TP) 40–1, tumours secondary active transport secondary immune 67 , 75, 135, 177 115 banks response 151 57 reabsorption 114–15 ultraltration 122 unmyelinated neurones 120, neurones point 100, sieve tube 101, upper 116 epidermis pituitary gland 103, elements index of 74 diversity 61 urea 110, urea cycle 110–11, 110, 74, 75, 76, 77 , ureter 78–9 111 72–3 sino-atrial 49, pressure ltration (SAN) 90–1, urine 92 tests effects of 117 174–7 114 sources pressure ow node 52 smoking, 76–7 , 74, 75, 76, 78–9 V 78–9 species prevalence of disease 40 136 vaccination diversity immune response 51, 52–3, species density primary 40, 41, 42, 43, 131, 140, species frequency regions 150 60 47 vasoconstriction specic defence 20, 143 60 44 variable 36, 153 58–61 151 vaccines prokaryotes 116 110–11 116 sinks potometers 46, 150, system sperm gradients 5, 20, 24, 29, banks 56–7 vectors tubules 101 76 spongy convoluted 101 143 158 vasodilation proximal 6 123 Simpson’s proteins 121 154 40 positive feedback producers, 114 76 set primary 23, 44 U immunity population predation 12–13, 121 175 sensory posterior 9, 42–3, 116 selective polyclonal 70 64 83 plasmodesma proton 70–1 160 82, 142 70–3 transpiration trophic gland 76–9 transpiration transport seed plasma transpiration 16 Schwann plaques 71 71 12, 74, transmission of disease 2 physical dependence pituitary translocation 132 pressure roots 11 8–17 154–5 130, (PCTs) mesophyll 6, 130 12 113, veins standing crop 82, 84–5 43 114–15 vent step psychoactive drugs tests communities ventricular stimulants psychological dependence 6, elements, xylem 68 70 82 viruses stroke pulse 3 92 168 vessel circulation systole 175 stomata pulmonary 2, 162–3 168 130–1, 132, 135, 142, 151 161 88 vitamins stroma pyramids, ecological 7 , 9, 11, 12 42–3 VO suberin pyruvate 20, 24, 26, 32, 33, 67 max 164 2 34 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your potential Developed guide in will CAPE® exclusively provide Biology, Written by an Biology syllabus information the key ● Engaging the ● ● to the with in and an additional team outcomes activities of examination, easy-to-use enhance Caribbean Examinations support to Council®, maximise your this study performance 2. experienced learning designed you Unit with your that teachers this study double-page from study help the of you and guide and subject , develop the in covers format . syllabus the experts Each all a CAPE® the topic contains such the essential begins range of with features as: analytical skills required for examination Examination tips with essential advice on succeeding in your assessments Did You Know? boxes to expand your knowledge and encourage further study This study choice also questions examiner Biology The guide and feedback, includes sample to build a fully interactive examination skills and answers confidence Caribbean Examinations Thornes subjects at to 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