EVEN BETTER BIOLOGY SUMMARY EBBS 1|Page UNIT 1: CHARACTERISTICS AND CLASSIFICATION OF LIVING ORGANISMS 1.1 CHARACTERISTICS OF LIVING ORGANISMS The characteristics of living organisms are totaled in the acronym “MRS GREN”. 1.2 Movement: An action by an organism or part of an organism causing a change of position or place. Respiration: The chemical reactions in cells that break down nutrient molecules and release energy for metabolism. Sensitivity: The ability to detect and respond to changes in the internal or external environments. Growth: The permanent increase in size and dry mass (by an increase in cell size/cell number) Reproduction: The processes that make more of the same kind of organism. Excretion: The removal of the waste products of metabolism and substances in excess of requirements. Nutrition: The taking in of materials for energy, growth and development. CONCEPT AND USES OF CLASSIFICATION SYSTEMS Classification systems for organisms is used to reflect evolutionary relationships (i.e. shared ancestors) between them. Organisms can be classified into groups by features they share. Classification systems are important because they make it easier to study living organisms and reflect evolutionary relationships. Species: A group of organisms that can reproduce to produce fertile offspring. Binomial System of Naming Species: An internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and species. (e.g. Panthera leo or Homo sapien) Organisms can be classified into groups using the sequences of bases in their DNA. Groups of organisms which share a more recent ancestor (are more closely related) have base sequences in DNA that are more similar than those that share only a distant ancestor. 2|Page 1.3 FEATURES OF ORGANISMS There are five kingdoms of living organisms: Animal, Plant, Fungus, Prokaryote, and Protoctist. Animal Kingdom: Multicellular organisms which eat other living organisms. Plant Kingdom: Multicellular organisms which make their own food by carrying out photosynthesis and their cells have a cellulose cell wall and chlorophyll. Fungi Kingdom: Unicellular or Multicellular organisms which eat other living organisms, and they also eat dead organisms, and they spread by spores in moist dark environments, and their cells have a cell wall. (made of strands called hyphae, they feed by secreting enzymes to digest food by Saprophytic Digestion) Prokaryote Kingdom: Unicellular organisms with no nucleus, mitochondria, chloroplasts, ER in their cells. Circular DNA, plasmids and sometimes flagellum can be found. Protoctist Kingdom: Organisms with a nucleus in their cells. The Animal Kingdom divides into Vertebrates (Animals with a backbone) and Invertebrates (Animals without a backbone) with the most important group in it being Arthropods. Arthropods have segmented bodies, jointed legs and an exoskeleton. Body Covering Limbs Ear Reproduction Extra Details Mammals Fur/Hair 4 Limbs Ears with external flap (pinna) Gives birth Warm-blooded and have mammary glands to produce milk Birds Feathers (and scales on legs) 2 Wings and 2 Legs Holes to ear drums Hard-shelled eggs on land Warm-blooded and have beaks Reptiles Dry Scales 4 Short Limbs (except for snakes) Holes to ear drums Waterproof rubbery eggs on land Cold-blooded Amphibians Moist Naked Skin 4 Limbs Ears on skin surface Jelly-covered eggs in water Cold-blooded and have skin for breathing Fish Moist Scales Fins Lateral Lines to detect vibrations in water Jelly-covered eggs in water Cold-blooded and have gills for breathing VERTE BRATE 3|Page Arthropod Body Division Jointed Legs Antennae Eyes Wings Insect Head, Thorax and Abdomen 3 pairs of legs 1 pair Compound eyes Present Arachnids Cephalothorax and Abdomen 4 pairs of legs (with pedipalps) Absent Many simple eyes Absent Crustaceans Cephalothorax and Abdomen 5 or more pairs of legs 2 pairs Compound eyes Absent Myriapods Head and body with many segments Many pairs of legs 1 pair Simple eyes Absent Elongated Body The Plant Kingdom divides into Ferns and Flowering Plants. Ferns reproduce by spores, and they don’t have pollen, fruits, flowers and seeds, and they need water for fertilization. Flowering Plants reproduce by flowers and seeds, and they don’t need water for fertilization (it is needed for seed germination). Flowering plants are divided into two subclasses: Dicotyledons and Monocotyledons. MONOCOTYLEDON DICOTYLEDON One Cotyledon Two Cotyledons Long and narrow leaves with parallel veins Short and broad leaves with network of veins (treelike) Fibrous roots Tap roots Floral parts in groups of 3 Floral parts in groups of 4s and 5s Viruses, which are non-living organisms, also have defining features like a protein coat (capsid) and genetic material (DNA or RNA), but with no cell membrane, no cytoplasm, no ribosomes. They only do reproduction, no other characteristic of living organism. 4|Page UNIT 2: ORGANIZATION OF THE ORGANISM 2.1 CELL STRUCTURE Vacuole Nucleus Ribosomes Cytoplasm Chloroplasts Cell Membrane Mitochondria Cell Wall Ribosomes Cytoplasm Cell Membrane Cell Wall Circular DNA New cells are produced by division of existing cells. 5|Page Plasmid Organelle Description Function Animal Cell Plant Cell Bacterial Cell Nucleus Contains DNA Carries genetic information (DNA) and controls cell activities. Cytoplasm Jelly-like, made mainly of water Site of chemical reactions Cell Membrane Partially Permeable membrane Controls what goes in and out of the cell Ribosomes Very small (can be present on ER or freely) Synthesis of proteins Mitochondria Very small, and folded to increase surface area to allow more respiration Aerobic Respiration Permanent Vacuole Contains cell sap Carries the food and wastes of the cell (also provides support by turgor pressure) Chloroplasts Contains green pigment, known as chlorophyll Absorbs light for photosynthesis and stores starch Cell Wall Very rigid and hard, made from Cellulose in Plant cells Supports and protects the cell Circular DNA and Plasmids DNA Carries genetic information 6|Page Specialized cells have specific function and are adapted to it, like: Ciliated Cells – Movement of mucus in the trachea and bronchi. Root Hair Cells – Absorption o Has long finger-like projection to increase the surface area to absorb more water. Palisade Mesophyll Cells – Photosynthesis Neurons – Conduction of electrical impulses o It has many mitochondria for energy to transmit impulses. Red Blood Cells – Transport of oxygen o Biconcave shape to increase surface area, to increase oxygen diffusion rate o Has hemoglobin to carry oxygen o No nucleus to provide more space for oxygen Sperm and Egg Cells (Gametes) – Reproduction There are levels of organization of body cells. Cell Tissue Organ Organ System 2.2 Cell: Structural and functional unit of body. (e.g. Palisade Mesophyll Cell, Red Blood Cell) Tissue: A group of cells with similar structures, working together to perform a shared function. (e.g. Xylem Vessel, Muscle) Organ: A group of tissues in a structure, working together to perform a specific function. (e.g. Pancreas, Stomach) Organ System: A group of organs with related functions, working together to perform body functions. (e.g. Circulatory System, Respiratory System) SIZE OF SPECIMENS 𝐼𝑚𝑎𝑔𝑒 𝑠𝑖𝑧𝑒 = 𝐴𝑐𝑡𝑢𝑎𝑙 𝑠𝑖𝑧𝑒 × 𝑀𝑎𝑔𝑛𝑖𝑓𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝐼 = 𝐴𝑀 Millimeters (mm) is the standard unit for magnification and biological specimens. 1𝑚𝑚 = 1000𝜇𝑚 (𝑀𝑖𝑐𝑟𝑜𝑚𝑒𝑡𝑟𝑒) 7|Page UNIT 3: MOVEMENT INTO AND OUT OF CELLS 3.1 DIFFUSION Diffusion: The net movement of particles from a region of their high concentration to a region of their low concentration (down the concentration gradient) as a result of their random movement. The energy for diffusion comes from the kinetic energy of random movement of molecules and ions. Some substances (usually gases and ions/solutes) move into cells through cell membranes by diffusion. Diffusion of gases and solutes is important in living organisms like the exchange of gases in alveoli of CO2 and O2 for respiration and energy, and the exchange of gases in plant leaves for CO 2 and water vapor for photosynthesis. Factors which increase the rate of diffusion: 3.2 Increasing surface area Increasing temperature Increasing concentration gradient (i.e. the difference between the regions of concentration) Decreasing the distance (i.e. the distance between the regions of concentration) OSMOSIS Water is used as a solvent in organisms for digestion, excretion and transport. Water diffuses through a partially permeable membrane by Osmosis. Osmosis: The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane. Water moves into and out of cells through a cell membrane by osmosis. When you add a plant cell to a dilute solution/pure water, water moves into the cell by osmosis (the cell gains water), making the vacuole and cytoplasm get bigger/enlarge, so the cell becomes turgid. The turgor pressure becomes high. When you add a plant cell to a concentrated solution, water moves out of the cell by osmosis (the cell loses water), making the vacuole and cytoplasm get smaller/shrink (the cell shrinks), so the cell becomes flaccid. If a lot of water is lost, the cell membrane/cytoplasm will pull away from the cell wall, causing it to be plasmolyzed. The plant wilts. The turgor pressure becomes low. When you add an animal cell, it will either burst or shrink. Turgor Pressure: The pressure of water inside the cells pressing outwards on the cell wall. 8|Page Plants are supported by Turgor Pressure. 3.3 ACTIVE TRANSPORT Active Transport: The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (against the concentration gradient), using energy from respiration. Active transport is importance because it is a process for movement of ions or molecules across membranes, like ion uptake by root hairs. Protein Carriers in cell membranes carry out active transport by moving molecules/ions. Figure 1 Protein Carriers moving molecules into a cell As Figure 1 shows, they need energy in order to change shape and move the molecules in the cell, the energy comes from respiration. 9|Page UNIT 4: BIOLOGICAL MOLECULES 4.1 BIOLOGICAL MOLECULES There are three main biological molecules in living organisms: Carbohydrates, Fats and Proteins. Carbohydrates are made from Carbon, Hydrogen and Oxygen. Cellulose, Starch and Glycogen are made from Glucose. Carbohydrates are like grapes, bread, potato. Fats are made from Carbon, Hydrogen and Oxygen. Fats and Oils are made from (III) Fatty Acids and (I) Glycerol. Fats are like butter, meat, milk. Proteins are made from Carbon, Hydrogen, Oxygen and Nitrogen. Proteins are made from Amino Acids. Proteins are like meat, egg, beans. Structures that are made from proteins include Enzymes, Insulin, Antibodies, Hemoglobin Biological Molecule Starch Reducing Sugars Reagent Iodine Solution Benedict’s Solution Biuret Solution Ethanol Emulsion (with a few drops of water) DCPIP Positive Blue-Black Brick Red (Orange Yellow Green) Purple/Violet White/Cloudy Emulsion Clear Negative Brownish Yellow Blue Blue Clear Blue Heating in Water Bath? No Yes (Heat at 80 °C) No No No Proteins Fats and Oils Vitamin C The DNA Molecule: The DNA is made up of two long strands coiled together to form a Double Helix. Each strand contains chemicals called Bases. There are only 4 bases: A, T, C and G. Bonds between each pair of bases holds the strands together. The Bases always pair up in the same way where: A always pairs up with T C always pairs up with G 10 | P a g e Strand UNIT 5: ENZYMES 5.1 ENZYMES Catalyst: A substance that increases the rate of a chemical reaction and is not changed by the reaction. Enzymes: Proteins that are involved in all metabolic reactions, where they function as biological catalysts. Enzymes are important in all living organisms because they give the reaction rate necessary to sustain life. Enzymes have an active site (the place which binds with the molecule/substrate) which is complementary (similar) to the shape of a substrate. When the enzyme binds with the substrate, it becomes an Enzyme-Substrate Complex. Then, the substrate gets digested and broken down into its products. The Active site of enzymes is specific where it has a complementary shape to only one type of molecules and does not fit in any else. (Like a lock and key) There are two main factors which affect the rate of enzyme action: Temperature and pH. Enzymes have an optimum temperature and an optimum pH: the temperature and pH at which they work best. When temperature increases, molecules gain more energy, move faster, and more frequent effective collisions. If the temperature is too high, enzyme molecules vibrate too vigorously; the enzyme is denatured, losing active site shape and no longer binding with a substrate. If the temperature is too low, there is not enough kinetic energy for the reaction, so it reacts too slowly to sustain life. If the pH changes too much, it denatures the enzyme, making it no longer fit with the substrate’s active site; changing shape of active site, therefore, no reaction occurs. 11 | P a g e UNIT 6: PLANT NUTRITION 6.1 PHOTOSYNTHESIS Photosynthesis: The process by which plants synthesize carbohydrates from raw materials using energy from light. Word equation of Photosynthesis: 𝐶𝑎𝑟𝑏𝑜𝑛 𝐷𝑖𝑜𝑥𝑖𝑑𝑒 + 𝑊𝑎𝑡𝑒𝑟 → 𝐺𝑙𝑢𝑐𝑜𝑠𝑒 + 𝑂𝑥𝑦𝑔𝑒𝑛 In the presence of light and chlorophyll Balanced chemical equation of Photosynthesis: 6𝐶𝑂2 + 6𝐻2 𝑂 → 𝐶6 𝐻12 𝑂6 + 6𝑂2 Chlorophyll: Green pigment found in chloroplasts. Chlorophyll transfers energy from light into energy in chemicals, for the synthesis of carbohydrates. Use and Storage of Carbohydrates made in Photosynthesis: Starch: Energy store Cellulose: To build cell walls Glucose: Used in respiration to provide energy Sucrose: For transport in the phloem Nectar: To attract insects for pollination Mineral Ion Function/Importance Deficiency Magnesium To make chlorophyll in plants Yellow Leaves Nitrate To make amino acids in plants (for proteins) Poor Growth To investigate the factors of light, CO2, and chlorophyll, we destarch a plant (i.e. leave it in a dark room for 48 hours), then we remove the factor and test for starch after 4-6 hours. For chlorophyll, use a variegated leaf. Factors which increase the rate of photosynthesis: Increasing light intensity Increasing carbon dioxide concentration Increasing temperature LIGHT CO2 Produced Bright Light Dim Light No Light (Dark) Medium Medium Medium O2 Produced (Photosynthesis Rate) High Medium Low Hydrogen Carbonate Indicator Purple/Violet (Alkaline) Red/Orange Yellow (Acidic) (Respiration Rate) 12 | P a g e At some point, the factors which increase the rate of photosynthesis become limiting factors and thus, do not increase the rate of photosynthesis anymore. Temperature at some point causes the denaturing of the enzymes causing the rate of photosynthesis to decrease, not increase. 6.2 LEAF STRUCTURE Most leaves have a large surface area and are thin. - The large surface area causes the leaf to be exposed to more sunlight and more CO 2 so more photosynthesis and gas exchange. The thin layers allow the sunlight to reach all cells and allows the CO2 to diffuse in and the O2 and the Water Vapor to diffuse out. Structure Adaptation for Photosynthesis Cuticle Waxy waterproof layer to reduce water loss and transparent to allow light to pass through for photosynthesis Upper and Lower Epidermis Transparent layer of cells which protects the inner cells of the leaf and is transparent to allow light to pass through for photosynthesis Palisade Mesophyll Contains many chloroplasts to do photosynthesis Spongy Mesophyll Contains some chloroplasts for photosynthesis, has air spaces for gas exchange Guard cells and Stomata Opens and closes pore of stomata to let CO2 in and O2 and water vapor out. (Guard cells have some chloroplasts for photosynthesis) Vascular Bundle (Xylem and Phloem) 13 | P a g e Xylem transports water and minerals from the roots to the leaf for photosynthesis (upwards only). Phloem transports sucrose and amino acids to give energy/food to all parts of the plant (upwards and downwards). UNIT 7: HUMAN NUTRITION 7.1-5 DIET Balanced Diet: A diet containing all nutrients in correct proportions according to age, gender and activity. Importance of Carbohydrates: Production of energy by respiration Energy is stored in plants as starch but stored in animals/humans as glycogen. Carbohydrates can be found in all sugary items (grapes, fruits, chocolate etc.), all starchy items (bread, rice, pasta etc.), and potatoes. Importance of Proteins: Growth and tissue repair Production of hormones and enzymes Source of energy in case of starvation Proteins can be found in meat items (chicken, beef, fish, eggs etc.) and leguminous plants (beans, lentils etc.) Importance of Fats and Oils/Lipids: Production of energy Heat insulating layer for organs to reduce heat loss Protection of vital organs Lipids can be found in meat and animal items (beef, milk, cheese butter, eggs etc.) and in plant oil items (maize, palm oil etc.) Importance of Fibers/Roughages: Stimulates peristalsis, preventing constipating Reduces the risk of colon cancer Fibers can be found in all plant foods (because they are mostly found in cellulose) Importance of Water: Transport Digestion and Excretion Solvent Photosynthesis and Seed germination Importance of Vitamin C: Helps wounds to heal Keeps blood vessels, skin, and gum healthy Deficiency of Vitamin C causes Scurvy, this causes: Swollen and bleeding gums Delayed healing of wounds and skin ulcers 14 | P a g e Vitamin C can be found in citrus fruits (oranges, tangerines, lemons etc.) and fresh vegetables. Importance of Vitamin D: Helps absorption of Calcium and its deposition in bones and teeth. Deficiency of Vitamin D causes Rickets, this causes: Soft bones Bowed legs Vitamin D can be found in U.V. light, fish, butter, eggs and oil. Importance of Iron: Formation of Hemoglobin in Red Blood Cells Deficiency of Iron causes Anemia easily gets tired/fatigued. Iron can be found in red meat, liver, eggs, and dark green leafy vegetables. Importance of Calcium: Formation of bones and teeth Blood clotting Deficiency of Calcium causes Rickets. Calcium can be found in milk products and many fruits and vegetables. 7.2-5 DIGESTIVE SYSTEM - Alimentary Canal: Mouth, esophagus, stomach, small intestine (duodenum and ileum), large intestine (colon, rectum and anus) - Associated Organs: Salivary glands, pancreas, liver, gall bladder Important Definitions: Ingestion: The taking of substances (e.g. food and drink) into the body. Digestion: The breakdown of food. Absorption: The movement of nutrients from the intestines into the blood. Assimilation: Uptake and use of nutrients by cells, becoming a part of the cells. Egestion: The removal of undigested food from the body as feces. 15 | P a g e Physical Digestion: The breakdown of food into smaller pieces without chemical change to the food molecules. - Physical Digestion increases the surface area of food for the action of enzymes in Chemical Digestion. Teeth: Types of Teeth: Incisors: Chisel shaped, sharp for cutting and biting food Canines: Pointed and sharp for cutting and tearing food Premolars: Broad/Large for grinding and crushing food Molars: Very broad and large for grinding and crushing food Function of Teeth: Physical digestion of food, thus increasing the surface area of food for the work of enzymes and to be easily swallowed. The Human Tooth contains: o Enamel: Non-Living layer made of calcium which can be dissolved by acids (formed after bacteria respiration), is present in the crown only. o Dentine: Living layer made of calcium, found in both the crown and the root. o Pulp: Contains nerves for sensation and blood vessels for food & oxygen, is present in the center of the tooth. o Cement: Collagen fibers which attach the tooth to the jawbone. Teeth are embedded in (jaw) bone and gum. 16 | P a g e Chemical Digestion: The breakdown of large insoluble molecules into small soluble molecules (that can be absorbed). The role of Chemical Digestion is producing small soluble molecules that can be absorbed. Enzymes (does Chemical Digestion): Starch Digestion: Amylase: Breaks down Starch → Maltose (Simple Reducing Sugars) o Secreted in the Mouth by Salivary Glands (neutral) and Small Intestines by Pancreas (alkaline) Maltase: Breaks down Maltose → Glucose on the membranes of the epithelium lining the small intestine o Secreted in the Small Intestines by the Intestines (alkaline) Protein Digestion: This is done by Proteases: Breaks down Protein → Amino Acids Pepsin: Breaks down Protein in the acidic conditions of the Stomach Trypsin: Breaks down Protein in the alkaline conditions of the Small Intestine by the Pancreas Fats and Oil Digestion: Lipase: Breaks down Fats and Oils → 3 fatty acids and 1 glycerol molecules o Secreted in the Small Intestine by the Pancreas and by the Small Intestine Functions of the Digestive System: Mouth: Does Ingestion o o Has Teeth which does Physical Digestion Has Salivary Glands which produces Saliva that contains Amylase which does Chemical Digestion Esophagus: Transports food to stomach from pharynx/mouth by peristalsis, which is the rhythmic contractions and relaxations of the muscles. Stomach: o o o Does Physical Digestion by churning movement of food Does Chemical Digestion by producing Pepsin in Gastric Juice which breaks down Proteins into Amino Acids in the acidic conditions of the stomach Produces Hydrochloric (Stomach) Acid (HCl) which: Kills harmful microorganisms in food Provides an Acidic pH for optimum enzyme (pepsin) activity Small Intestine: o Where all nutrients are absorbed by Absorption 17 | P a g e o Pancreas: Produces Pancreatic juice which contains: o o o o Where most water is absorbed Trypsin to break down proteins into amino acids Lipase to break down fats into fatty acids and glycerol Amylase to break down starch into maltose Maltase to break down maltose into glucose Liver: o o Produces Bile Juice Stores excess glucose as Glycogen Gall Bladder: Stores Bile juice Bile Juice: An Alkaline mixture that: o o Neutralizes the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme activity. Emulsifies fats and oils to increase the surface area for Chemical Digestion Colon (Large Intestine): Absorbs some water and salts Rectum (Large Intestine): Stores undigested food as feces Anus (Large Intestine): Does Egestion Villi and Microvilli: The walls of the small intestine are folded into many villi, increasing the surface area for absorption. Adaptations for Absorption: Has many microvilli which increase the surface area for diffusion and active transport. Contains Carrier Proteins for active transport (Absorption) Contains Mitochondria to provide energy. Thin Epithelium Lining which is one cell thick to increase diffusion rate Lacteal: Absorbs fatty acids and glycerol. Blood Capillary: Absorbs food and amino acids, with the blood vessels going to the Hepatic Portal Vein to the liver, to breakdown harmful substances like drugs and alcohol. 18 | P a g e UNIT 8: TRANSPORT IN PLANTS 8.1 XYLEM AND PHLOEM Function of Xylem: Transport of Water and Mineral ions Support Structure of Xylem Vessels: Thick walls (for Support) made of Lignin (Non-Living material, which is waterproof, so no water leaks out). No Cell Contents (Non-Living) Cells joined end-to-end with no cross walls to form a long and continuous tube (for transportation of water so it passes easily with no resistance) Function of Phloem: Transport of Sucrose and Amino Acids Leaf Cross-Section Blue is Xylem Red is Phloem Stem Cross-Section Root (Cortex) Cross-Section 8.2 WATER UPTAKE Function of Root Hair Cell: Absorption of Water and Mineral Ions The large surface area of root hairs increases the uptake of water and mineral ions Pathway of Water in a plant: Root Hair Cell → Root Cortex Cell → Xylem → Mesophyll Cells 19 | P a g e 8.3 TRANSPIRATION Transpiration: Loss of Water Vapor from leaves by the evaporation of water from the surfaces of the mesophyll cells into the air spaces, then the diffusion of water vapor through the stomata. Water vapor loss is due to the large internal surface area provided by the interconnected air spaces between mesophyll cells as well as the size and number of stomata. The Mechanism by which Water moves upwards in the Xylem: The transpiration pull that draws up a column of water molecules, held together by forces of attraction between water molecules, known as Cohesion forces, due to the differences in pressure, Factors which affect Transpiration Rate: Humidity o Low humidity increases the concentration gradient between the atmosphere and the leaf, which increases the transpiration. o As humidity increases, rate of transpiration decreases Wind Speed o As wind speed increases, the water vapor is removed from the leaf faster, maintaining the concentration gradient for diffusion, so the transpiration rate increases. o As wind speed increases, rate of transpiration increases Temperature o As temperature increases, the kinetic energy of water molecules increases, which makes it evaporate and diffuse faster, so the rate of transpiration increases. o As temperature increases, rate of transpiration increases Wilting occurs because: - Lack of water (Water loss is more than water uptake) Plant cells become flaccid (no longer turgid) No more turgor pressure, so cells do not provide support If more water is lost, cells become plasmolyzed - Stomata closes. Less surface area exposed to sunlight. Decreasing of water loss and transpiration. Advantages of Wilting: 8.4 TRANSLOCATION Translocation: The movement of sucrose and amino acids in the phloem from sources to sinks. Sources: Parts of a plant that releases sucrose or amino acids Sinks: Parts of a plant that use or store sucrose or amino acids Some parts of a plant may act as a source and as a sink at different times, for example: During Growing Season (Spring), Sucrose is transported from a source in the photosynthesizing leaves to a sink in the roots. During Winter Season, Sucrose is transported from a source in the roots to a sink in the leaves. 20 | P a g e UNIT 9: TRANSPORT IN ANIMALS 9.1 CIRCULATORY SYSTEMS Circulatory System: A system of blood vessels with a pump and valves to ensure one-way flow of blood. Single Circulation of a Fish: Where the blood passes through the heart only once in every complete circuit of the body. 𝐻𝑒𝑎𝑟𝑡 → 𝐺𝑖𝑙𝑙𝑠 → 𝐵𝑜𝑑𝑦 Double Circulation of a Mammal: Where the blood passes through the heart twice in every complete circuit of the body. 𝐻𝑒𝑎𝑟𝑡 → 𝐵𝑜𝑑𝑦 → 𝐻𝑒𝑎𝑟𝑡 → 𝐿𝑢𝑛𝑔𝑠 Advantages of Double Circulation: Maintains high blood pressure for blood to reach the body. Faster, more efficient transport Allows more time for gas exchange Prevents damage to lungs Allows lower pressure to lungs Allows animals to have high metabolic rates and enough supply of oxygen and nutrients. Prevents mixing of deoxygenated and oxygenated blood. 9.2 HEART Ventricles are thicker than the Atria, because: Ventricles pump blood to the lungs/whole body. This is a long distance which requires high blood pressure. So, it needs thicker walls. Atria pump blood to the Ventricles. This is a short distance which requires lower blood pressure. So, it does not need thick walls. Left Ventricle is thicker than the Right Ventricle, because: The Left Ventricle pumps blood to the whole body. This is a long distance which requires higher blood pressure. So, it needs thicker walls. 21 | P a g e The Right Ventricle pumps blood to the lungs. This is a shorter distance which requires less blood pressure. So, it has thinner walls than the Left Ventricle. Function of Septum: Separates the oxygenated blood from the deoxygenated blood. There is deoxygenated blood in the right ventricle/atrium. There is oxygenated blood in the left ventricle/atrium. Functioning of the Heart: 1) Deoxygenated blood enters the right atrium via the vena cava from the body. 2) The right atrium contracts and the right ventricle relaxes. 3) The Tricuspid (Atrioventricular) valve opens. 4) Deoxygenated blood enters the right ventricle. 5) The right ventricle contracts. 6) The semi-lunar valve opens. 7) The Deoxygenated blood enters the lungs via the pulmonary artery from the heart. 8) Gas Exchange occurs. 9) CO2 diffuses out of capillaries into alveoli. 10) O2 diffuses from alveoli into capillaries. 11) Blood is oxygenated. 12) Oxygenated blood enters the heart at left atrium via pulmonary veins from the lungs. 13) The left atrium contracts and the left ventricle relaxes. 14) The Bicuspid (Atrioventricular) valve opens. 15) Oxygenated blood enters the left ventricle. 16) The left ventricle contracts. 17) Semi-lunar valves open. 18) The Oxygenated blood is pumped out of the heart to the rest of the body via the aorta. 19) Gas exchange occurs. 20) O2 diffuses from the capillaries to cells. 21) CO2 diffuses from the cells to capillaries. 22) Blood is deoxygenated. 23) The Deoxygenated blood returns to the right atrium from the body via vena cava Event Atria Contract Ventricles Contract Atria and Ventricles Relax 22 | P a g e Atrioventricular Valves Open Semilunar Valves Closed Closed Open Open Closed The activity of the heart may be monitored by: ECG Pulse rate Listening to the sound of valves closing Physical Exercise increases heart rate, because: Muscle Contract (Exercise) requires more energy from respiration. Increases respiration requires demand for more oxygen to the muscles and removal of carbon dioxide at the lungs. Heart pumps faster (done by the pacemaker) to provide more oxygen to the muscles and to remove more carbon dioxide at the lungs. So, the heart rate increases. Coronary Artery: Supplies the cardiac (heart) muscle with blood (which contains food and oxygen) Coronary Heart Disease (CHD): A disease caused by the blockage of coronary arteries. Possible risk factors of CHD: - Diet (Too much saturated Fats) Lack of exercise Stress Smoking Genetic Predisposition Age Gender Reducing the risk of CHD, by: - Eating a healthy balanced diet (With less saturated fats) Regular Exercise Stop Smoking 9.3 BLOOD VESSELS Name Arteries Veins Capillaries Function Carry blood away from the heart Carry blood to the heart Exchange of materials/substances to tissues Blood Pressure High Very Low Low Thick to withstand high blood pressure (nearest to the heart) Thick layer of elastic tissue to stretch due to the changing pressure Thin to withstand low blood pressure (farthest from the heart) Very thin (One Cell thick) walls for short diffusion distance (Faster diffusion) Relative Thickness of Walls Thick layer of muscular tissue to change pressure Diameter of the Lumen Narrow Lumen to maintain high blood pressure Large Lumen to maintain low blood pressure Very Narrow Lumen Presence of Valves Absent Present to prevent back-flow of blood (Due to the low blood pressure) Absent 23 | P a g e Image Main Blood Vessels: Heart: o To: Vena Cava and Pulmonary Vein o From: Aorta and Pulmonary Artery Lungs: o To: Pulmonary Artery (Most CO2 , Least O2) o From: Pulmonary Vein (Least CO2 , Most O2) Kidney: o To: Renal Artery (Most Urea) o From: Renal Vein (Least Urea) Liver: o o 24 | P a g e To: Hepatic Artery, Hepatic Portal Vein From: Hepatic Vein 9.4 BLOOD Components of Blood: Red Blood Cells (RBC) White Blood Cells (WBC) Platelets Plasma Red Blood Cells: Function: Transport Oxygen o Is Bioconcave (More surface area to carry more oxygen) o No Nucleus (To carry more oxygen) o Has Haemoglobin (which binds with oxygen to create oxyhaemoglobin) White Blood Cells: There are two types of WBCs: Phagocytes: o Function: Engulfing Pathogens by Phagocytosis Has a lobed nucleus (Segmented) Lymphocytes: o Function: Antibody production Plasma: Function: Transport of blood cells, ions, nutrients, urea, hormones, and carbon dioxide o Jelly-like substance which surrounds the blood cells. Platelets: Function: Blood Clotting o Which converts the soluble fibrinogen into insoluble fibrin to form a mesh (to trap blood so it does not leave the vessel). o Formation of a scab Role of Blood Clotting: o Prevents blood loss. o Prevents entry of pathogens. 25 | P a g e UNIT 10: DISEASES AND IMMUNITY 10.1 DISEASES AND IMMUNIT Y Pathogen: A disease-causing organism Transmissible Disease: A disease in which the pathogen can be passed from one host to another. A pathogen is transmitted: By Direct Contact, like blood and other bodily fluids. By Indirect Contact, like contaminated surfaces, food, animals, and air. Body Defenses against Pathogens: Physical Barriers: Like the Skin and Hairs in the nose Chemical Barriers: Like the Mucus and Stomach (HCl) acid White blood cells Controlling the spread of disease: Hygienic Food Preparation: o o o o Good cooking. Keep food away from insects/pests. Keep food in fridge. Never cough or sneeze over food. Good Personal Hygiene: o o o Shower regularly using shampoo. Brush your teeth. Use soap. Waste Disposal: Collected in landfill sites. Sewage Treatment Clean Water Supply Removal of Pests Vaccination: By providing Herd Immunity o o o Large amounts of the population are vaccinated and are immune to the pathogen. The disease cannot spread (Because few people can be infected). People who cannot be vaccinated are protected against the disease. Active Immunity: Defense against a pathogen by antibody production in the body Each pathogen has its own Antigen, which have specific shapes. Antibodies: Proteins that bind to antigens leading to: - Direct destruction of pathogens (or) Marking of pathogens for destruction by phagocytes (phagocytosis) Specific antibodies have complementary shapes which fit specific antigens. 26 | P a g e Active Immunity is gained after: - An infection Vaccination The Process of Vaccination: 1) 2) 3) Weakened pathogens or their antigens are put into the body. The antigens stimulate an immune response by lymphocytes which produce antibodies. Memory Cells are produced that give long-term immunity. Passive Immunity: A short-term defense against a pathogen by antibodies acquired from another individual: Across the Placenta In Breast Milk Memory Cells are not produced in Passive Immunity, so it is a short-term defense. Importance of breastfeeding in the development of passive immunity in infants: Reduces the risk of disease, because mothers give antibodies to the infant, since they have not yet developed their own antibodies as they have not been exposed to as many pathogens. Cholera: A disease caused by a bacterium which is transmitted in contaminated water. Cholera bacterium produces a toxin. The toxin causes secretion of chloride ions into the small intestine. This causes osmotic movement of water into the gut (osmosis). This causes (symptoms): (treated by Oral Rehydration Therapy) o Diarrhea o Dehydration o Loss of ions from the blood 27 | P a g e CHAPTER 11: GAS EXCHANGE IN HUMANS 11.1 GAS EXCHANGE IN HUMA NS Features of Gas Exchange Surfaces (Alveoli) in Humans: Large Surface Area (to increase rate of diffusion) Thin Surface (to decrease diffusion distance, to increase rate of diffusion) Good Blood Supply (by capillaries to maintain steep diffusion gradient) Good Ventilation with Air (by capillaries to maintain steep diffusion gradient) Function of Cartilage in the Trachea: Supports the trachea. Keeps the trachea (the airways) open and prevents it from collapsing. Allows air into the lungs. 28 | P a g e Breathing in (Inspiration): Internal intercostal muscles relax. External intercostal muscles contract. Ribs are raised upwards and outwards. Diaphragm flattens. (Contracts) Volume inside the thorax (Lungs) increases. Pressure inside the thorax (Lungs) decreases. Air flows in the lungs (alveoli) down a pressure gradient o High Pressure (Atmosphere) → Low Pressure (Lungs) Breathing out (Expiration): Internal intercostal muscles contract. External intercostal muscles relax. Ribs are lowered downwards and inwards. Diaphragm curves upwards. (Relaxes) Volume inside the thorax (Lungs) decreases. Pressure inside the thorax (Lungs) increases. Air flows out of the lungs (alveoli) down a pressure gradient o High Pressure (Lungs) → Low Pressure (Atmosphere) Composition of Inspired Air: 78% of Nitrogen 21% of Oxygen 0.04% of Carbon Dioxide Variable Water Vapor Composition of Expired Air: 78% of Nitrogen 16% of Oxygen 4% of Carbon Dioxide Saturated (High) Water Vapor To test for Carbon Dioxide, use limewater. It turns milky/cloudy if positive and is colorless if negative. Why is the percentage of Nitrogen inspired is the same as the expired? The body does not absorb nitrogen from the air, since the cells do not need nitrogen. All nitrogen that is taken is released again. Why is the percentage of Oxygen less expired than the inspired air? Because some oxygen is absorbed by the body (needed for respiration, taken by diffusion into RBCs through Alveoli) Why is the percentage of Carbon Dioxide more expired than the inspired air? Because carbon dioxide is produced from respiration and is removed from the body 29 | P a g e Why is water vapor saturated (high) in expired air? Because water is produced in respiration with high temperature Effects of Physical Activity on the body: Increased Breathing Rate Increased Depth of Breathing Increased Heart Rate The link between Physical Activity and Depth/Rate of breathing: Physical activity increases the rate of aerobic respiration because muscles require more energy for contraction. Concentration of Carbon Dioxide increases, so pH decreases (Carbon Dioxide is Acidic) The pH decrease is detected by the brain. This triggers an increase in the rate and depth of breathing, to remove Carbon Dioxide faster and to get more oxygen. Goblet Cells (Found in the Trachea and Bronchi): Produces mucus which traps pathogens and particles. Ciliated Cells (Cilia): Beats the mucus up to the throat to be swallowed. 30 | P a g e CHAPTER 12: RESPIRATION 12.1 RESPIRATION Uses of Energy in Living Organisms: Muscle contraction Protein synthesis Cell division Active transport Growth The passage of nerve impulses The maintenance of a constant body temperature (Remember that Energy is always released [not produced/made due to the Law of Conservation of Energy]) Effect of Temperature on Respiration in Yeast: 12.2 AEROBIC RESPIRATION Aerobic Respiration: The chemical reaction in cells that use oxygen to break down nutrient molecules to release energy. 𝐺𝑙𝑢𝑐𝑜𝑠𝑒 + 𝑂𝑥𝑦𝑔𝑒𝑛 → 𝐶𝑎𝑟𝑏𝑜𝑛 𝐷𝑖𝑜𝑥𝑖𝑑𝑒 + 𝑊𝑎𝑡𝑒𝑟 𝐶6 𝐻12 𝑂6 + 6𝑂2 → 6𝐶𝑂2 + 6𝐻2 𝑂 12.3 ANAEROBIC RESPIRATIO N Anaerobic Respiration: The chemical reaction in cells that break down nutrient molecules to release energy without using oxygen. Anaerobic Respiration releases much less energy per glucose molecule than aerobic respiration. Anaerobic Respiration in Yeast: 𝐺𝑙𝑢𝑐𝑜𝑠𝑒 → 𝐴𝑙𝑐𝑜ℎ𝑜𝑙 + 𝐶𝑎𝑟𝑏𝑜𝑛 𝐷𝑖𝑜𝑥𝑖𝑑𝑒 𝐶6 𝐻12 𝑂6 → 2𝐶2 𝐻5 𝑂𝐻 + 2𝐶𝑂2 31 | P a g e Anaerobic Respiration in Muscles during Vigorous Exercise: 𝐺𝑙𝑢𝑐𝑜𝑠𝑒 → 𝐿𝑎𝑐𝑡𝑖𝑐 𝐴𝑐𝑖𝑑 Lactic acid builds up in muscles and blood during vigorous exercise, causing an Oxygen Debt. Oxygen Debt is removed by: 1) Continuation of fast heart rate to transport lactic acid in the blood from the muscles to the liver. 2) Continuation of deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid. 3) Aerobic respiration of lactic acid in the liver 32 | P a g e CHAPTER 13: EXCRETION IN HUMANS 13.1 EXCRETION IN HUMANS The Lungs excrete carbon dioxide. The Kidneys excrete urea and excess water and ions. Urea is formed in the liver using excess amino acids by Deamination. Deamination: The removal of the nitrogen-containing part of amino acids to form urea. Excretion is important because it removes the toxic urea which is harmful to the body in large amounts. The role of the Liver: The assimilation of amino acids by converting them to proteins. The structure and function of a nephron and its associated blood vessels: a) b) c) The role of the Glomerulus: Filtration from the blood of water, glucose, urea, and ions. a. The filtrate is collected in Bowman’s Capsule. The role of the Nephron Tubule: Reabsorption of all the glucose, some of the ions and most of the water back into the blood (osmoregulation). The formation of Urine: Containing urea, excess water, and excess ions 33 | P a g e CHAPTER 14: COORDINATION AND RESPONSE 14.1 COORDINATION AND RES PONSE Electrical impulses travel along neurons. The Mammalian Nervous System consists of: - The Central Nervous System (CNS): The brain and the spinal cord. The Peripheral Nervous System (PNS): The nerves outside of the brain and the spinal cord. Role of the Nervous System: Coordination and regulation of body functions Types of Neurons: A simple Reflex Arc is the pathway of nerve impulses which goes like this: - Receptor (Place of Sensation) → Sensory Neuron (PNS) → Relay Neuron (CNS in the Spinal Cord) → Motor Neuron (PNS) → Effector (Like Muscles and Glands) Reflex Action: A means of automatically and rapidly integrating and coordinating stimuli with the responses of the effectors (muscles and glands) Synapse: A junction between two neurons. Function: Ensure that impulses travel in one direction only The events which occur at a synapse: 1) 2) 3) 4) An impulse stimulates the release of neurotransmitter molecules from vesicles into the synaptic gap. (by the Vesicle movement and fusion with the membrane) The neurotransmitter molecules diffuse across the gap. Neurotransmitter molecules bind with the complementary receptor proteins on the next neuron. An impulse is then stimulated in the next neuron. 34 | P a g e Nervous System 14.2 Responds quickly Short time Impulses travel to specific muscles/glands More energy required Endocrine System Responds slowly Longer Lasting Hormones can have multiple target organs to respond (as they travel throughout the body) Less energy required SENSE ORGANS Sense Organs: Groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals. Structure Function/Importance Iris Controls how much light enters the pupil Cornea Refracts Light Lens Focuses light on the retina Retina Contains light receptors, some sensitive to light of different colors Optic Nerve Carries impulses to the brain Blind Spot Contains no light receptors Fovea Contains only cones (highest number of cones) with no rods. Giving the sharpest vision 35 | P a g e In Bright Light: Pupil constricts, to avoid too much light entering the eye which may damage the retina. In Dim Light: Pupil dilates to allow more light to enter the eye, to get a clearer image. Near Objects Accommodation Far Objects Accommodation Ciliary muscles contract Ciliary muscles relax Suspensory Ligaments loosen Suspensory Ligaments stretch / tighten Lens becomes more convex Lens becomes less convex Greater refraction of light Less Refraction of light Types of Light Receptors: Rods: Light receptors that detect light. Detect dim light and give a greyscale/black and white image. o Found anywhere on the retina except for the blind spot and fovea. Cones: Light receptors that detect light. Detects bright light and colors and give colored image. o Found anywhere on the retina, with the highest concentration being on the fovea, except for the blind spot. 14.3 HORMONES Hormone: Chemical substance, produced by a gland, and carried by the blood, which alters the activity of one or more specific target organs. Pancreas secretes Insulin and Glucagon. Testes secretes Testosterone. Ovaries secretes Estrogen. Adrenal Glands secrete Adrenaline. Adrenaline is secreted in ‘fight or flight’ situations, and its effects are: Increased breathing rate (to provide more oxygen to the muscles and remove carbon dioxide). Increased pupil diameter (to allow more light in the eye). Increased heart rate (to provide more oxygen to the muscles, to release more energy and remove carbon dioxide). Increased blood glucose concentration (by breaking down stored glycogen in the liver). 36 | P a g e 14.4 HOMEOSTASIS Homeostasis: The maintenance of a constant internal environment. Negative Feedback: Internal conditions must be maintained between set limits, if these limits are exceeded, then negative feedback mechanisms work to correct the change and restore the internal environment to the optimum. Control of Blood Glucose Concentration: If increase in blood glucose concentration (due to a meal containing carbohydrates) is detected by the pancreas, it releases Insulin, which causes the liver to decrease blood glucose concentration. o Liver increases uptake of glucose from blood, and stores them as glycogen, or breaks them down. If decrease in blood glucose concentration (due to fasting or high activity) is detected by receptors in the pancreas, it releases Glucagon , which causes the liver to increase blood glucose concentration. o Liver decreases uptake of glucose from the blood, and breaks down glycogen to glucose, releasing it into the blood. Type 1 Diabetes: When the body is no longer able to secrete insulin. Symptoms: Glucose in urine, fatigue, weight loss. Treatment: Taking Insulin injections (and controlled diet), regular exercise, eating less fats and carbohydrates, monitoring blood glucose concentration Control of Constant Internal Body Temperature: The temperature is regulated by the hypothalamus in the brain, which contains thermoreceptors. If the temperature changes from the optimum 37°𝐶, a response is triggered to return it to the optimum. High body temperature: Sweat glands secrete sweat, evaporates from skin surface, leading to cooling effect. Hair erector muscles relax, to prevent air layer insulation, to increase heat loss. Vasodilation of skin arterioles and constriction of shunt vessels, to force the blood to move near the skin surface capillaries to increase heat loss. Low body temperature: Sweat glands stop secreting sweat. Hair erector muscles contract, which traps a layer of air above the skin, to insulate the skin surface, decreasing the heat loss. Shivering, which is involuntary contraction of muscles, causing heat to be released, due to increased rate of respiration. 37 | P a g e Vasoconstriction of skin arterioles and dilation of shunt vessels, to bypass/prevent reaching the skin surface capillaries, taking a deeper route which prevents heat loss. 14.5 TROPIC RESPONSE S Gravitropism: A response in which parts of a plant grow towards or away from gravity. Phototropism: A response in which parts of a plant grow towards or away from the direction of the light source. Both are examples of Chemical Plant Growth. Auxins: Auxins are made in the shoot tip. Auxins diffuse through the plant from the shoot tip to the shady side (in case of light) or to the lower side (in case of gravity). Auxins stimulate cell elongation (by making cell walls easier to stretch). CHAPTER 15: DRUGS Drug: Any substance taken into the body that modifies or affects chemical reactions in the body. Antibiotics are used for treatment of bacterial infections (by preventing their cell wall formation). Some bacteria are resistant to antibiotics which reduces the effectiveness of antibiotics. o That is why antibiotics should only be used when essential, because bacteria will not gain resistance and evolve/mutate against it, giving rise to resistant bacteria like MRSA. Antibiotics kill bacteria, but not viruses (because viruses have no cell walls, and are non-living) 38 | P a g e CHAPTER 16: REPRODUCTION 16.1 ASEXUAL REPRODUCTION Asexual Reproduction: A process resulting in the production of genetically identical offspring from one parent. Examples: o Binary Fission in Bacteria o Spores formed in fungi at the end of hyphae o Tuber formation in potatoes Advantages of Asexual Reproduction Disadvantages of Asexual Reproduction Only one parent is needed, no mate is needed. No genetic variation, so organisms are unable to adapt to changes in environment (like disease) Large number of offspring are produced. No natural selection, no evolution Faster and less energy needed Disease is more likely to affect the whole population Good characteristics are preserved, because offspring are genetically identical. Overpopulation 16.2 SEXUAL REPRODUCTION Sexual Reproduction: A process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other. Nuclei of Gametes are Haploid (contains half-number of chromosomes) Nucleus of a Zygote are Diploid (contains full number of chromosomes) Fertilization: The fusion of the nuclei of gametes. Advantages of Sexual Reproduction Disadvantages of Sexual Reproduction Allows genetic variation and diversity Requires two parents Allows adaptation, natural selection and evolution Few numbers of offspring are produced Increases chance of survival Slower Different combination of alleles Wastage of Gametes 39 | P a g e 16.3 SEXUAL REPRODUCTION IN PLANTS Structure Function Sepal Protects flowers as buds Petal Colorful petals to attract insects for pollination. Stamen Male reproduction part/organ Filament Carries/Holds the Anther Anther Produces pollen grains (male gametes) for pollination Carpel Female reproduction part/organ Style Carries/Holds the Stigma, helps in fertilization, where pollen tubes travel to deliver male gametes to the ovule Stigma Sticky, catches pollen grains for fertilization Ovary Produces ovules, which contain the female gametes Ovule Contains female gametes. Where fertilization occurs. 40 | P a g e Insect-Pollinated Flower - Colorful petals with scents Nectar Anther inside the flower, short filament Stigma inside the flower Spiky and sticky pollen to stick to insects Pollen grains are bigger and fewer than windpollinated Wind-Pollinated Flower - Not colorful, not scented petals (or none) No nectar Anthers outside of the flower Large feathery stigma outside of the flower Non-sticky pollen, light, small, produces in large quantities to increase the chances of pollination Pollination: The transfer of pollen grains from an anther to a stigma. Self-Pollination: The transfer of pollen grains from the anther of a flower to the stigma of the same flower, or a different flower on the same plant. Cross Pollination: The transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species. Self-Pollination Cross Pollination Less Variation More Variation Organisms have less capacity to respond to changes in the environment, cannot adapt. Organisms have more capacity to respond to changes in the environment and adapt. More reliable, because there is no reliance on pollinators Less reliable, because there is reliance on pollinators Fertilization occurs in plants, when a pollen nucleus fuses with a nucleus in an ovule. 1. 2. 3. 4. 5. 6. Pollen grains are caught in a stigma. Pollen grains germinate a pollen tube. Pollen tube secretes enzymes to digest the style and grows down, penetrating the micropyle. Male nucleus passes down in the pollen tube and enters the ovary. Male nucleus fuses with the female nucleus, forming a diploid zygote, by fertilization. Ovary forms a fruit, and ovules form seeds. Conditions of germination of seeds: Water: for activating enzymes, solvent and transport. Oxygen: for aerobic respiration to provide energy for growth. Suitable Temperature: for optimum temperature of enzymes. 41 | P a g e 16.4 SEXUAL REPRODUCTION IN HUMANS Fertilization: The fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell). Male Reproductive System: Structure Function Testes Produces sperm (male gametes) and testosterone Scrotum Carries the testis, outside of the body where the temperature is lower than the body, to be suitable for sperm production. Sperm Duct Passes sperm by peristalsis to the urethra. Secretes the alkaline fluid which: Prostate Gland - contains sugars for sperm nutrition to provide energy. To neutralize the acidity of urine. Urethra Allows the passage of urine and semen (alkaline fluid + sperm) Penis Delivers semen to the female reproductive system, by insertion into the vagina during sexual intercourse. Adaptive Features of Sperm: Flagellum/Tail: For swimming movement to reach the egg cell in the oviduct for fertilization. Mitochondria: Site of aerobic respiration, to release more energy for movement. Acrosome: Produces enzymes to dissolve the jelly coat surrounding the egg cell. 42 | P a g e Female Reproductive System: Structure Ovary Oviduct Function Produces Ova (female gametes), Estrogen and Progesterone Passes Ova to the Uterus by Cilia and peristalsis. Site of Fertilization Muscular bag, where the embryo develops during pregnancy. Uterus Site of implantation. Muscular walls to push the fetus during birth Cervix Muscular ring, it closes the lower part of the uterus. It dilates during birth to allow the passage of the baby. Vagina Where sperms are deposited during sexual intercourse by the penis. Allows the passage of the baby during birth. Adaptive Features of Egg Cells: Energy Store: Contains nutrients and food for the growth of the zygote. Jelly Coat: Hardens after fertilization to prevent the entry of more than one sperm. Property Sperm Cell Egg Cell Size Small Large relatively Structure Nucleus, Mitochondria, Flagellum Cell with Jelly Coat Motility Swims by flagellum Immobile Numbers Millions produced Once a month after puberty 43 | P a g e Fertilization and Implantation: 1. 2. 3. 4. Sperm reaches the egg cell in the oviduct, secreting enzymes, digesting the jelly coat. Fertilization occurs, where the sperm nucleus fuses with the egg cell nucleus, forming a diploid zygote. Zygote forms an embryo by dividing by mitosis into a ball of cells. The embryo implants into the lining of the uterus, and implantation occurs. Structure Umbilical Cord Placenta Function Transports dissolved nutrients, gases and excretory products between the blood of the mother and the blood of the fetus. Site of exchange of dissolved nutrients, gases and excretory products between the mother’s blood and the fetus’ blood. Barrier to prevent entry of pathogens and toxins. Amniotic Sac Produces amniotic fluid Protects the fetus Amniotic Fluid Maintains the temperature of the fetus Allows movement of fetus Prevents infections Some pathogens and toxins can pass across the placenta and affect the fetus. The Mother’s blood and the Fetus’ blood don’t mix, because: Mother’s blood pressure is too high for the fetus’ blood vessels. Mother’s blood and the fetus’ blood may be different blood groups, causing agglutination. 44 | P a g e 16.5 SEXUAL HORMONES IN HUMANS Secondary Sexual Characteristics: In Males (by Testosterone) Enlargement of testis and penis Growth of hair on face and body Broadening of shoulders Deepening of voice Development of muscles in the body Growth of Pubic Hair Growth spurt In Females (by Estrogen) Enlargement of breasts and hips Enlargement of uterus and vagina Beginning of menstruation Deposition of fats Growth of pubic hair Growth spurt Menstrual Cycle: The menstrual cycle occurs every 28 days. On Days 1-5, the uterus lining breaks down as blood from the vagina, causing menstruation, if fertilization does not occur. On Day 14, ovulation occurs where the ovum egg is released. On Day 21-24, the uterus lining is thickest. Estrogen and Progesterone are secreted by the Ovaries during the menstrual cycle. Estrogen and Progesterone are secreted by the Placenta during pregnancy. Hormones in the Menstrual Cycle: 1. 2. Uterus Lining breaks down, causing menstruation, and falling as blood. On Day 7, the Pituitary Gland in the brain secretes FSH (Follicle Stimulating Hormone) a. FSH stimulates the growth of the follicle (holds the ova) 3. Follicle secretes Estrogen a. Estrogen inhibits (decreases) FSH. b. Estrogen rebuilds and repairs the uterus lining. c. Estrogen stimulates production of LH 4. 5. On Day 14, Estrogen is at the maximum. Pituitary Gland secretes LH (Luteinizing Hormone) a. LH stimulates ovulation on Day 14 b. LH triggers production of Progestrone 6. 7. Formation of Corpus Luteum Progesterone is secreted a. Progesterone inhibits LH b. Progesterone maintains the thickness of the uterus lining 8. If Fertilization Occurs: a. More progesterone produced, maintaining the uterus lining for implantation 9. If Fertilization does not occur: a. Corpus Luteum breaks down b. Progesterone decreases c. Uterus Lining Breaks down once again 45 | P a g e 16.6 SEXUALLY TRANSMITTED INFECTIONS Sexually Transmitted Infection (STI): An infection transmitted through sexual contact. HIV (Human Immunodeficiency Virus): is a pathogen that causes an STI (AIDS acquired Immune Deficiency Syndrome) Methods of Transmission of HIV: Sexual Intercourse, mixing of semen and vaginal fluids. Blood Contact, during transfusion of blood. Sharing needles From mother to fetus, by placenta or during breast feeding How the spread of STIs is controlled: Using condoms or femidoms Avoid having more than one sexual partner Don’t share needles Increasing awareness Screening blood before transfusion 46 | P a g e 17 INHERITENCE 17.1 CHROMOSOMES, GENES AND PROTEINS Chromosomes: are made of DNA, which contains genetic information in the form of genes. Genes: A length of DNA that codes for a protein. Allele: An alternative form / version of a gene. Sequence of Bases in a gene determine the sequence of amino acids used to make a specific protein. Different sequences of amino acids give different shapes to protein molecules. DNA controls cell functions by controlling the production of proteins, like enzymes, membrane carriers and receptors for neurotransmitters. How a Protein is made: 1. 2. 3. 4. 5. 6. The gene coding for the protein remains in the nucleus. Messenger RNA (mRNA) is a copy of the gene. mRNA molecules are made in the nucleus, they move to the cytoplasm. mRNA passes through Ribosomes. The Ribosomes assemble amino acids into protein molecules. The specific sequence of amino acids is determined by the sequence of bases in the mRNA. Most body cells in an organism contains the same genes, but many genes are not expressed because the cell only makes the specific proteins it needs. Haploid Nucleus: A nucleus containing a single set of chromosomes. Diploid Nucleus: A nucleus containing two sets of chromosomes. There is a pair of each type of chromosome in a diploid nucleus. In humans, there are 23 pairs. 17.2 MITOSIS Mitosis: Nuclear division giving rise to genetically identical cells. Present in growth, repair of damaged tissues, replacement of cells and asexual reproduction. The exact replication of chromosomes occurs before mitosis. During mitosis, the copies of chromosomes separate, maintaining the chromosome number in each daughter cell. Stem Cells: Unspecialized cells that divide by mitosis to produce daughter cells that can become specialized for specific functions. 17.3 MEIOSIS Meiosis: Reduction division in which the chromosome number is halved from diploid to haploid, resulting in genetically different cells. Meiosis is involved in the production of gametes. 47 | P a g e 17.4 MONOHYBRID INHERITANCE Inheritance: The transmission of genetic information from generation to generation. Genotype: The genetic make-up of an organism in terms of the alleles present. Phenotype: The observable features of an organism. Homozygous: Having two identical alleles of a particular gene. o Pure breeding is when two homozygous individuals breed together. Heterozygous: Having two different alleles of a particular gene. o No heterozygous individual does pure breeding. Dominant Allele: An allele that is expressed if present in the genotype. Recessive Allele: An allele that is only expressed when there is no dominant allele of the gene present in the genotype. Examples: Two heterozygous parents: o Genotypes: 𝑇𝑡 × 𝑇𝑡 o Gametes: 𝑇 𝑡 𝑇 𝑡 o Offspring Genotypes: 𝑇𝑇 𝑇𝑡 𝑇𝑡 𝑡𝑡 o Offspring Phenotypes: Tall, Dwarf o Ratio: 3∶1 o Percentage: 75% 𝑇𝑎𝑙𝑙 ∶ 25% 𝐷𝑤𝑎𝑟𝑓 Heterozygous and homozygous recessive parents: o Genotypes: 𝑋𝑌 × 𝑋𝑋 o Gametes: 𝑋 𝑌 𝑋 𝑋 o Offspring Genotypes: 𝑋𝑋 𝑋𝑋 𝑋𝑌 𝑋𝑌 o Offspring Phenotypes: Female, Male o Ratio: 1∶1 o Percentage: 50% 𝐹𝑒𝑚𝑎𝑙𝑒 ∶ 50% 𝑀𝑎𝑙𝑒 Homozygous dominant and homozygous recessive parents: o Genotypes: 𝐵𝐵 × 𝑏𝑏 o Gametes: 𝐵 𝐵 𝑏 𝑏 o Offspring Genotypes: 𝐵𝑏 𝐵𝑏 𝐵𝑏 𝐵𝑏 o Offspring Phenotypes: Brown Eyes o Ratio: 1∶0 o Percentage: 100% 𝐵𝑟𝑜𝑤𝑛 𝐸𝑦𝑒𝑠 ∶ 0% 𝐵𝑙𝑢𝑒 𝐸𝑦𝑒𝑠 Test Cross: To determine the genotype of an unknown dominant individual (TT or Tt), breed them with a homozygous recessive individual (tt). If all offspring are dominant, then the unknown genotype is TT. If half offspring are dominant, while other half are recessive, them the unknown genotype is Tt. 48 | P a g e Codominance: A situation in which both alleles in heterozygous organisms contribute to the phenotype, (thus resulting in intermediate phenotypes of a heterozygous individual). For example: Blood Groups (Alleles being 𝐼 𝐴 𝐼 𝑂 /𝐼 𝐼 𝐵 ) Blood Group A is 𝐼 𝐴 𝐼 𝐴 and 𝐼 𝐴 𝐼 𝑂 Blood Group B is 𝐼 𝐵 𝐼 𝐵 and 𝐼 𝐵 𝐼 𝑂 Blood Group AB is 𝐼 𝐴 𝐼 𝐵 Blood Group O is 𝐼 𝑂 𝐼 𝑂 Sex-Linked Characteristic: A feature in which the gene responsible is located on a sex chromosome and that this makes the characteristic more common in one sex than in the other. These genes are present only on the X chromosome, so there are only female carriers of the gene. For example: Red-Green color blindness o o o o 49 | P a g e Genotypes: 𝑋𝐶 𝑌 × 𝑋𝐶 𝑋𝑐 𝐶 Gametes: 𝑋 𝑌 𝑋𝐶 𝑋𝑐 Offspring Genotypes: 𝑋 𝐶 𝑋 𝐶 𝑋 𝐶 𝑋 𝑐 𝑋𝐶 𝑌 𝑋𝑐𝑌 Offspring Phenotypes: Normal Female, Female Carrier (Normal) Normal Male, Colorblind Male 18 VARIATION AND SELECTION 18.1 VARIATION Variation: Differences between individuals of the same species. Sources of Variation in Populations: Mutation, Meiosis, Random Mating, Random Fertilization Continuous Variation Discontinuous Variation Range of phenotypes between two extremes. A limited number of phenotypes with no intermediates. For example: Body Length, Body Mass For example: ABO Blood Groups, Seed shape in Peas, Seed Color in Peas Caused by: Both genes and the environment Caused by: Genes only Gene Mutation: A random change in the base sequences of DNA. Mutation is the way in which new alleles are formed. Ionizing Radiation and some chemicals increase the rate of mutation. 18.2 ADAPTIVE FEATURES Adaptive Features: An inherited feature that helps an organism to survive and reproduce in its environment. Xerophytes Hydrophytes Plants adapted to live in extremely dry environments. Plants adapted to live in extremely wet environments. Thick Cuticle to reduce water loss. Deep and Wide Roots to spread it absorb more water when raining. Small Leaves/Leaves with small surface area to reduce water loss. Rolled Leaves with sunken stomata in pits to reduce water loss. Hair in stomata to increase humidity to decrease transpiration. Swollen stems and leaves to store water. Thin Cuticle because there is no need to reduce water loss. Small Roots for anchorage/to be stable, and there is no need for water absorption through leaves. Large air spaces in leaves so that leaves can float, and more surface exposed to sunlight for photosynthesis. Stomata on upper surface to absorb carbon dioxide and for gas exchange. 18.3 SELECTION Adaptation: The process, resulting from natural selection, by which populations become more suited to their environment over many generations. Fitness: Probability of an organism surviving and reproducing in its environment. 50 | P a g e Natural Selection: 1) 2) 3) 4) 5) 6) Genetic variation within populations Production of many offspring Struggle for survival, with competition for resources A greater chance of reproduction by individuals that are better adapted to the environment than others. These individuals pass on their alleles to the next generation. This is done over many generations. Example of Natural Selection: 1) 2) 3) 4) 5) 6) 7) Some bacteria are not killed due to incomplete antibiotic treatment. A random mutation in the bacterial DNA caused resistance against an antibiotic. Variation among bacterial population Resistant bacteria have a higher chance of surviving, reproducing and passing the resistant alleles to offsprings and undergo natural selection. Frequency of resistant bacteria increases. Many non-resistant bacteria die and their frequency decreases. Bacteria evolve to a new resistant strain. Selective Breeding: 1) 2) 3) 4) Selection by humans of individuals with desirable features. Crossing/Breeding these individuals to produce the next generation. Selection of offspring showing the desirable features. Repeat this process over many generations. Selective Breeding by Artificial Selection is done to improve crop plants and domesticated animals. Natural Selection Artificial Selection Caused by the environment naturally Caused by humans Slow process Faster process More Variation, random breeding Less Variation, not random breeding Results in the development of populations with features better adapted to their environment. Results in development of populations with features that are useful to humans. 51 | P a g e 19 ORGANISMS AND THEIR ENVIRONMENT 19.1 ENERGY FLOW The Sun is the principal source of energy input to biological systems. The Energy Flow through living organisms: Light energy from the sun, absorbed by plants → Converted to chemical energy in organisms by photosynthesis → Transferred to the environment 19.2 FOOD CHAIN AND FOOD WEBS Food Chain: The transfer of energy from one organism to the next, beginning with a producer. Food Web: A network of interconnected food chains Producer: An organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis. Consumer: An organism that gets its energy by feeding on other organisms. o Consumers can be primary (the 1st after the producer), secondary, tertiary or quaternary. Herbivore: An animal that gets its energy by eating plants. Carnivore: An animal that gets its energy by eating other animals. Decomposer: An organism that gets its energy from dead or waste organic material. o Decomposers such as bacteria and fungi secrete enzymes to digest the waste material, then absorbing it. o This process is faster, during high humidity and high temperature, due to increased activity of enzymes. o Decomposers are responsible for recycling elements and adding minerals to the soil, and they help avoid accumulation of dead and waste material. Trophic Level: The position of an organism in a food chain, food web or ecological pyramid. Pyramid of Numbers: It shows the number of organisms in each trophic level, the wider the box, the greater number of organisms there are. Pyramid of Biomass: It shows the total biomass (dry mass) of organisms in each trophic level. Why is a pyramid of biomass better than a pyramid of numbers? o In a pyramid of numbers, one large individual is shown the same way as a very tiny individual. o Biomass indicates how much food there is available. o Biomass is an indicator of the energy available. o A pyramid of biomass is pyramid shaped, while a pyramid of numbers may be sometimes inverted. Pyramid of Energy: It show the amount of energy available in each trophic level. Advantages: o It shows the actual energy transfer between trophic levels. o It is more accurate. o Time is taken into account. o One gram of biomass of one species may be different from one gram of biomass of another species. 52 | P a g e Food chains usually have fewer than five trophic levels, because: Energy is lost between each trophic level. Insufficient energy to support more than five trophic levels. Not all of the organisms are eaten/digested. Some energy is lost as heat energy during respiration and during digestion. Why the transfer of energy from one trophic level to another is often not efficient? Because only about 10% of the energy is transferred from one trophic level to another. Most of the energy is lost to the surroundings by egestion, respiration, movement and homeostasis. It is more energy efficient for humans to eat crop plants than to eat livestock that have been fed on crop plants, because the humans become primary consumers, which decreases the energy loss as the shorter the food chain, the less the energy loss. 19.3 NUTRIENT CYCLES Carbon Cycle: Nitrogen Cycle: Two ways that Nitrogen gas in the air can be converted into a usable form are: o Nitrogen fixing bacteria convert N2 gas into ammonium compounds, which can then be converted to usable nitrates o Nitrogen fixing bacteria can be free-living in the soil or can live within the root nodules of some plants Lightning can split the bond between the two N atoms, turning them into nitrous oxides like N2O and NO2 that dissolve in rainwater and leach into the soil Plants absorb nitrogen from the soil in the form of nitrates and use it to build proteins Animals eat the plants and get the nitrogen they need from the plant proteins Waste (urine and feces) from animals sends nitrogen back into the soil in the form of ammonium compounds 53 | P a g e The bodies of dead plants and animals decay and all the proteins inside them are broken down into ammonium compounds by decomposers The plants can’t absorb ammonium compounds, so nitrifying bacteria convert the ammonium compounds to nitrites and then to nitrates, which can then be absorbed by plants – and so the cycle goes on Denitrifying bacteria take nitrates out of the soil and convert them back into N2 gas o This process reduces soil fertility and is bad for plant growth o Denitrifying bacteria are anaerobic so aerating the soil, e.g. by reducing waterlogging and turning over the soil during ploughing, can reduce the rate of denitrification 19.4 POPULATIONS Population: A group of organisms of one species, living in the same area, at the same time. Community: All the populations of different species in one ecosystem. Ecosystem: A unit containing the community of organisms and their environment, interacting together. Factors affecting rate of population growth: Food supply increases, rate of population growth increases. Competition increases, rate of population growth decreases. Predation increases, rate of population growth decreases. Disease increases, rate of population growth decreases. 54 | P a g e Sigmoid Curve: 1) Lag Phase: Population increases slowly, because organisms are still adapting to the new environment. a. 𝑩𝒊𝒓𝒕𝒉 𝑹𝒂𝒕𝒆 > 𝑫𝒆𝒂𝒕𝒉 𝑹𝒂𝒕𝒆 2) Log/Exponential Phase: Population increases rapidly, because there are no limiting factors (i.e. available food, no predators, no diseases) a. 𝑩𝒊𝒓𝒕𝒉 𝑹𝒂𝒕𝒆 > 𝑫𝒆𝒂𝒕𝒉 𝑹𝒂𝒕𝒆 3) Stationary Phase: Population remains constant a. 𝑩𝒊𝒓𝒕𝒉 𝑹𝒂𝒕𝒆 = 𝑫𝒆𝒂𝒕𝒉 𝑹𝒂𝒕𝒆 4) Death Phase: Population decreases, because of limiting factors like food supply, predators, disease, introduction of foreign invasive species, or accumulation of wastes. a. 𝑩𝒊𝒓𝒕𝒉 𝑹𝒂𝒕𝒆 < 𝑫𝒆𝒂𝒕𝒉 𝑹𝒂𝒕𝒆 55 | P a g e 20 HUMAN INFLUENCES ON ECOSYSTEMS 20.1 FOOD SUPPLY Humans have increased food production, by: Agriculture machinery to use larger areas of land and improve efficiency Chemical fertilizers to improve yields Insecticides to improve quality and yield Herbicides to reduce competition with weeds Selective breeding to improve production by crop plants and livestock Advantages of Large-Scale Monocultures of crop plants: Easier to manage More efficient Promotes technological advancements Offers higher earnings Disadvantages of Large-Scale Monocultures of crop plants: Requires more use of fertilizers Requires more use of pesticides o Leading to increased pesticide resistance Requires more water Pollution Increased soil erosion Lack of biodiversity Deforestation / Loss of habitat Less land available for food crops Advantages for Intensive livestock production: More economical Uses less space More food produced More efficient Easier to manage / monitor Protects from predators Disadvantages for Intensive livestock production: Loss of biodiversity Habitat Destruction Increased risk of disease Pollution Increased greenhouse gases 56 | P a g e 20.2 HABITAT DESTRUCTION Biodiversity: The number of different species that live in an area. Reasons for habitat destruction: Increased area for housing, crop plant production and livestock production. Extraction of natural resources. Freshwater and marine pollution. Humans can have a negative impact on habitats, by altering food webs and food chains. Undesirable effects of habitat destruction: Reduction of biodiversity Extinction Loss of soil Flooding Increased carbon dioxide in the environment (leading to global warming, pollution, greenhouse gases etc.) 20.3 POLLUTION Effects (and reasons to treat the effects) of untreated sewage on aquatic ecosystems: (Prevents the) Spread of disease Can cause bacterial infections Makes water (un)safe to drink Contaminates/Kills fish we eat (Removes harmful organisms/pathogens) Effects of excess chemical fertilizers on aquatic ecosystems: Water pollution Soil degradation Harm to wildlife Eutrophication Process of Eutrophication of Water: Increased availability of nitrate and other ions. Increased growth of producers. Increased decomposition after death of producers. Increased aerobic respiration of decomposers. Reduction in dissolved oxygen. Death of organisms requiring dissolved oxygen in water. Effects of Carbon Dioxide/Methane on the environment: Carbon Dioxide is a pollutant Carbon Dioxide causes an enhanced greenhouse effect and global warming. Climate change Rising Sea levels More extreme weather events Habitat Destruction Extinction of Species 57 | P a g e Effects of Plastic in an aquatic/terrestrial environment: Plastic causes entanglement/suffocation/limb damage/choking Plastic cannot be digested because it’s non-biodegradable, so it causes starvation. It is toxic/poisonous. Blocks out sunlight so reduces photosynthesis. Disrupts food chains. Bioaccumulates Organisms die. Benefits of increased pest resistance in genes: Less pesticides used. Less pollution. Less contamination of food with pesticides. Increased biodiversity Less damage to crop quality/yield Less spread of plant disease 20.4 CONSERVATION Sustainable Resource: A resource which is produced as rapidly as it is removed from the environment, so it does not run out. For example: Forests and Fish stocks Forests are conserved using: Education Protected Areas Quotas Replanting Fish stocks are conserved using: Education Protected Areas Quotas Mesh Size Closed Seasons Controlled Net types Monitoring Factors which cause extinction: Overhunting Overharvesting Climate change / Global warming Introduction of new predators Habitat destruction Disease Lack of food Lack of mates Natural Disaster 58 | P a g e How endangered species can be conserved: Monitoring and Protecting species and habitats Education Captive Breeding Programs Seed Banks Reasons for Conservation Programs: Maintaining or Increasing biodiversity Reducing Extinction Protecting Vulnerable ecosystems Maintaining ecosystem functions (like Nutrient cycling and Resource provision, including food, drugs, fuel and genes) Techniques used in Captive Breeding Programs: Artificial Insemination (AI): where sperm from a male is inserted into the reproductive tract (vagina) of a female, using a syringe. o This allows for sperm to be transported around the world, reducing the need to transport animals. 1. 2. 3. 4. 5. Collect semen from male, which is chosen from different breeding programs to maximize genetic variation. Sperm is screened and frozen. The female is given drugs to induce ovulation. Semen is placed in vagina. Semen is inserted at appropriate time for ovulation. In Vitro Fertilization (IVF): where sperm is used to fertilize egg cells in the lab, where the zygote is implanted into a female for development. o This allows gametes with known alleles to be used, ensuring the next generation is genetically diverse. If a species’ population size decreases, causes reduced genetic variation, so species are more susceptible to environmental changes, the species has less adaptation to the environment, which has a greater risk of extinction. 59 | P a g e 21 BIOTECHNOLOGY AND GENETIC MODIFICATION 21.1 BIOTECHNOLOGY AND GENETIC MODIFICAT ION Bacteria are useful in biotechnology and genetic modification: Rapid reproduction rate Ability to make complex molecules Few ethical concerns over their manipulation and growth They possess plasmids (which is an ideal way of transferring DNA) 21.2 BIOTECHNOLOGY Anaerobic Respiration in Yeast is used: 𝐺𝑙𝑢𝑐𝑜𝑠𝑒 → 𝐸𝑡ℎ𝑎𝑛𝑜𝑙 + 𝐶𝑎𝑟𝑏𝑜𝑛 𝐷𝑖𝑜𝑥𝑖𝑑𝑒 For the production of ethanol for biofuels. For bread-making. o Carbon Dioxide makes dough rise. Pectinase is an enzyme which digests pectin in plant cells. Used in Fruit-Juice production o Larger volume of juice produced o Has a clear appearance, not a cloudy one Biological Washing Powders contain enzymes that breakdown insoluble stains to soluble stains, that can be washed down by water. Some are modified to withstand high temperatures, so that enzymes are not denatured. Lactase is used to produce lactose-free milk for people diagnosed with lactose intolerance. By breaking down lactose in milk → galactose and glucose (Test strips are used to determine the presence of glucose in milk) 60 | P a g e Fermenters: Functions: Water Jacket: To avoid overheating of the fermenter, which may cause enzymes to denature. Paddles/Stirrers: To distribute the temperature and prevent solids from settling. Sometimes Acids and Alkalis are used to provide the optimum pH. Fermenters provide the optimum conditions for the production of useful products, like the Antibiotic Penicillin, the food and nutritious Mycoprotein, and the hormone Insulin. Condition Why and how it is controlled Aseptic precautions Fermenter is cleaned by steam to kill microorganisms and prevent chemical contamination, which ensures only the desired microorganisms can grow Nutrients Nutrients are needed for use in respiration to release energy for growth and reproduction of the microorganisms Optimum temperature Temperature is monitored using probes and maintained using a water jacket. This ensures an optimum environment for enzymes to increase enzyme activity and prevent denaturation Optimum pH pH is monitored using a probe to check it is at the optimum value for the microorganism being grown. The pH can be adjusted using acids and alkalis Oxygenation Oxygen is required for aerobic respiration to take place Agitation Stirring paddles are used to ensure temperature, pH, nutrients, and oxygen are all distributed evenly throughout the fermenter Waste The contents are filtered to remove waste created by the microorganisms 61 | P a g e 21.3 GENETIC MODIFICATION Genetic Modification: Changing the genetic material of an organism by removing, changing or inserting individual genes. Examples of Genetic Modification: The insertion of human genes into bacteria to produce human proteins. The insertion of genes into crop plants to confer resistance to herbicides. The insertion of genes into crop plants to confer resistance to insect pests. The insertion of genes into crop plants to improve nutritional qualities. Genetic Modification using bacterial production of a human protein: 1) 2) 3) 4) 5) 6) Isolation of the DNA making up a human gene using restriction enzymes, forming sticky ends. Cutting of bacterial plasmid DNA with the same restriction enzymes, forming complementary sticky ends. Insertion of human DNA into bacterial plasmid DNA using DNA ligase to form a recombinant plasmid. Insertion of recombinant plasmids into bacteria. Multiplication of bacteria containing recombinant plasmids. Expression in bacteria of the human gene to make the human protein. Advantages of Genetically Modifying Crops (like Soya, Maize and Rice): Less use of insecticides and fertilizers. Improved quality of crops. Higher crop yield. Disadvantages of Genetically Modifying Crops (like Soya, Maize and Rice): Loss of biodiversity More expensive Weeds produced that are resistant to herbicides. New gene may have unknown harmful long-term effects. 62 | P a g e Extras: When mentioning vasodilation/vasoconstriction, mention the volume of blood flow to the capillaries to the skin. When talking about enzymes, mention successful collisions, the relationship between temperature, rate and kinetic energy, denaturation at high temperatures, active site, complementary. For bacteria and other micro-organisms, the reason for their death can be changes in pH, temperature, build-up of toxins/wastes, overcrowding or virus attack. Any wrapping reduces heat loss, even if it be aluminum foil. Shaking is needed for Fat test. Any cutting/fruits, probably have chopping, so you should cut on a hard surface and away from body. For placenta, just write transfer of everything (nutrients, excretory products etc.) by diffusion For amniotic fluid: o Provides support o Protects fetus from shock o Maintains temperature o Allows movement of fetus o Maintains osmotic balance When asked, how is something transported? Say, which vessel it enters through (usually capillaries for absorption), then, the plasma , then the vessel it enters (perhaps the hepatic portal vein) Mycoprotein and Pencillin are produced by Fungi. Insulin is produced in fermenters, by genetically modified bacteria (recombinant DNA, and human proteins) Meiosis causes mutation (reduction and nuclear division) When asked how vaccination works, mention active immunity, what lymphocytes do, and the rest of the charade. When speaking about cholera, get into the specifics of osmosis (i.e. water potential gradient, partially permeable membrane etc.) When asked why all the males are colorblind/sex-linked (i.e. anything that is absolutely on all males, and is about sex-linked characteristics), then answer that there is only one X chromosome in a male, and it needs only one recessive chromosome, to be colorblind/sex-linked. The temperature needs to be controlled, in a fermenter, to ensure high yield, and because respiration produces heat (and then just speak about enzymes, denaturation and reaction rate etc.) When asked to explain why a medicine is better/supplement is better, just say the function of the vitamins/nutrients involved. (; −; ) When talking about carrier proteins, jump to active transport and describe it. Describe fully a graph (do not show weakness in War) Insulin promotes cellular respiration. (wow, such a good guy) Type-1 Diabetes is fixed by insulin injections, regular exercise, not eating too much carbohydrates/ a controlled diet, and monitoring the blood glucose concentration. When counting individuals with genes, remember that AB contains A and also contains B, so counting individuals with only one A includes AB (don’t be an idiot) Good blood supply and a lacteal is also a way villi are adapted to their function. If something is implied, say it outright! 63 | P a g e
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