AQA Biology A2 Level

#separator:tab #html:true State the 3 products of the light- dependent reaction.Reduced NADP, ATP & O<sub>2 </sub> Where does the light independent reaction occur?In the stroma Where does the light dependent reaction occur?In the thylakoids State the products of the light independent reaction [2]Sugars (e.g glucose) and organic molecules. Explain photoionisation and chemiosmosis. [3]"1. Photoionisation of chlorophyll a (PS II) causes an e<sup>- </sup> to become <font color=""#ff0000"">excited.</font><div><font color=""#ff0000""><br></font></div><div>2. The e<sup>- </sup><sub> </sub>travels DOWN the ETC and <font color=""#ff0000"">loses energy as it goes down</font> (energy is used to pump H<sup>+ </sup>across the thylakoid membrane)</div><div><br></div><div>3. <font color=""#ff0000"">H<sup>+ </sup>diffuses out of the thylakoid membrane through ATP synthase, which provides energy for an ADP + Pi molecule to form ATP</font> (chemiosmosis= movement of ions across a semi perm-membrane, down their electro chemical gradient)</div>" Explain how reduced NADP is formed. [3]"1. Photoactivation of chlorophyll a (PS II) causes <font color=""#ff0000"">photolysis</font>:<div><br><div>H<sub>2</sub>O molecule to be split into hydrogen ions, electrons and an Oxygen molecule<div><div><br></div><div>2. Oxygen diffuses out of the chloroplast via the stomata</div><div><br></div><div>3. <font color=""#ff0000"">H<sup>+ </sup>reduces NADP</font><sup><font color=""#ff0000"">+</font> </sup> to produce reduced NADP (aka NADPH).</div></div></div></div>" Name 2 alternative respiratory substrates.<ul><li>Lipids</li><li>Proteins</li></ul> Explain how proteins enter the Krebs Cycle. [3]<div><ul><li>hydrolysed into AminoA</li><li>deamination</li><li>enters pathway at diff. points depending on number of carbons (3Cs converted to pruvate, 4+5Cs conveted to KCycle intermediates)</li></ul></div> Suggest why genetically identical twins often show slight differences in their appearance MS [1]Environmental factors during pregnancy. (E.g nutrient supply) Define evolution.Change in allele frequency in a population over time. Explain how natural selection causes evolution [This concept can be applied to any exam Q]"1. <font color=""#ff453a"">Variation</font> within a population due to <font color=""#ff453a"">mutation</font><div><br></div><div><span style=""caret-color: rgb(255, 69, 58);"">2. <font color=""#ff453a"">Selection Pressure</font> (e.g. predation, climate disease , competition) => struggle for survival</span></div><div><span style=""caret-color: rgb(255, 69, 58);""><br></span></div><div><span style=""caret-color: rgb(255, 69, 58);"">3. Some organisms have alleles that are more favourable to the selection pressure</span></div><div><span style=""caret-color: rgb(255, 69, 58);""><br></span></div><div><span style=""caret-color: rgb(255, 69, 58);"">4. These organisms are <font color=""#ff453a"">more likely to survive and reproduce</font>, producing more offspring and <font color=""#ff453a"">passing on their favourable alleles to the next gen. </font><u style="""">(differential reproductive success)</u></span></div><div><span style=""caret-color: rgb(255, 69, 58);""><br></span></div><div><span style=""caret-color: rgb(255, 69, 58);"">5. <font color=""#ff453a"">Allele frequencies</font> in gene pool <font color=""#ff453a"">change over many generations</font></span></div>" Explain the effects of directional selection."- Selective pressures / environment favour individuals favourable allele combination <font color=""#ff453a"">one direction from the mean.</font><div><br></div><div>- <font color=""#ff453a"">Mean shifts</font> in direction of favourable allele / phenotype</div><div><br></div>" Explain the main effects of stabilising selection. [3]"- Selective pressures favour the mean/ <font color=""#ff453a"">acts against the 2 extremes of a characteristic.</font><div><span style=""caret-color: rgb(255, 69, 58);"">- Individuals with extreme phenotypes less likely to survive <font color=""#ff453a"">(standard deviation gets smaller over time)</font></span><br></div><div><span style=""caret-color: rgb(255, 69, 58);"">- <font color=""#ff453a"">Mean stays the same</font></span></div><div><span style=""caret-color: rgb(255, 69, 58);"">- e.g human birth weight</span></div>" Explain the effects of disruptive selection."- Selection against the <font color=""#ff453a"">mean</font><div><span style=""caret-color: rgb(255, 69, 58);"">- Population becomes phenotypically divided - favours both extremes</span></div><div><span style=""caret-color: rgb(255, 69, 58);"">- Could result in <font color=""#ff453a"">2 separate species</font></span></div><div><span style=""caret-color: rgb(255, 69, 58);"">E.g Californian salamander</span></div>" Describe and explain differences in sensitivity to light between rods and cones. [5]"<font color=""#ff0000"">Rods are more sensitive to light</font><div><div>- They are connected in groups to one bipolar neurone</div></div><div>- Spatial summation</div><div>- Stimulation of each individual rod cell is insufficent, however, because they are connected in groups the threshold is more likely to be exceeded to generate an action potential.</div><div><span style=""color: rgb(255, 0, 0);""><br></span></div><div><span style=""color: rgb(255, 0, 0);"">Cones are less sensitive to light</span><br></div><div>- One cone joins to one neurone</div><div>- No spatial summation</div><div>- Threshold not reached during exposure to low levels of light </div><div><img src=""Compare-Rod-Cells-and-Cone-Cells.jpg""><br></div>" Describe and explain the differences in visual acuity between rod and cone cells."<div><div><font color=""#ff0000"">Rods give lower visual acuity:</font></div><div>- Rods connected in groups to one bipolar neurone</div><div>- Spatial summation</div><div>- Many neurones generate ONE action potential, regardless of the no. of neurones stimulated.</div><div>- Therefore they cannot distinguish between separate sources of light</div><div><br></div></div><font color=""#ff0000""><div><font color=""#ff0000""><br></font></div>Cones give a higher visual acuity:</font><div>- One cone joins to one neurone</div><div>- <font color=""#ff0000"">If 2 adjacent cones are stimulated, the brain recieves 2 separate impulses</font></div><div>- Therefore it can distinguish between <font color=""#ff0000"">2 separate sources</font> of light.</div><div><br></div><div><br></div><div><img src=""Compare-Rod-Cells-and-Cone-Cells.jpg""><br></div>" Describe and explain the differences between sensitivity to colour between rods and cones."<div><div><font color=""#ff0000""><br>Rods allow monochromatic vision</font></div><div>- One type of pigment (rodhopsin)</div></div><font color=""#ff0000""><div><br></div>Cones allow trichromatic vision</font><div>- 3 types of cones </div><div>- Different optical pigments (opsins) that absorb different wavelengths (red, green and blue)</div><div>- Stimulation of different combinations of cones give a range of colour perception.</div><div><br></div><div><br></div><div><br></div><div><img src=""Compare-Rod-Cells-and-Cone-Cells.jpg""><br></div>" Where are cone cells located in the eye?Concentrated at the fovea.<div><br></div><div>They need bright light to be stimulated</div> Where are rod cells located in the eye?In the periphery of the retina<div><br></div><div>Pigment are broken down by low intensity light.</div> The cardiac muscle is myogenic. What does myogenic mean?Can contract / relax without receiving electrical impulses from nerves. Where are baroreceptors and chemoreceptors located?In the aorta and carotid arteries What are baroreceptors stimulated by?High / low blood pressure. Which part of the brain modifies heart rate?Medulla oblongata. Which centre of the medulla oblongata increase heart rate?The one linked to the SA node by the sympathetic nervous system. Which centre of the medulla oblongata decreases heart rate?The one that is linked to the SA Node by the parasympathetic nervous system. What are chemoreceptors stimulated by?High / low pH. (High CO<sub>2</sub> conc. lowers blood pH) What are the 5 stages of a response to a stimulus?1. Stimulus<div>2. Receptor</div><div>3. Co-ordinator</div><div>4. Effector</div><div>5. Response.</div> What is kinesis? [3]"<ul><li>Non-directional <b><font color=""#ff1f0f"">random </font></b>response <span style=""color: var(--field-fg); background: var(--field-bg);"">to a non-directional stimulus. </span></li><li><span style=""color: var(--field-fg); background: var(--field-bg);"">The more unpleasant the stimulus, the faster the <b>rate of turning </b>seen in the animal's movement. </span></li><li>Animal is hence more likely to find favourable conditions</li></ul>" What is a tropism?"Growth of part of a plant in response to directional stimulus.<div><br></div><div>They can be positive <font color=""#ff0000"">(growth toward a stimulus)</font></div><div><br></div><div>or negative <font color=""#ff0000"">(grow away from stimulus)</font></div>" What is the difference between how IAA works in plant shoot and roots?"In shoots:<div>IAA<font color=""#ff0000""> promotes</font> cell elongation.</div><div><br></div><div>In roots:</div><div>IAA <font color=""#ff0000"">inihibits</font> cell elongation.</div>" Define population.A group of organisms of the same species, occupying a particular space at a particular time that can potentially interbreed.  Define Community.All the populations of different species living in the same habitat at the same time. What are biotic conditions?Living features of an ecosystem<div><br></div><div>e.g predation, disease, food supply.</div> What is a plagioclimax?When human activities prevent succesion and stop a climax community forming.<div><br></div><div>It is usually used for the conservation of a species (as it prevents them being out competed by a new environment)</div> Explain how a resting potential is established. [5]"<img src=""sodium-potassium-pump-crash-course-v2.gif""><div><ul><li>Na<sup>+</sup>-K<sup>+</sup> pump ATrans <font color=""#ff0000"">3 Na out axon & and 2 K into axon</font></li><li>e<sup>-</sup>tro chem. gradient created</li><li>Neurone membrane <font color=""#ff0000"">more permeable to K<sup>+</sup></font> (open K<sup>+</sup> channels) than Na<sup>+  </sup>(closed channels)</li><li>K<sup>+</sup> move out of axon by facilitated diffusion</li><li>Inside of axon more neg relatively to outside = resting potential</li></ul></div>" Draw and label the structure of a synapse."<img src=""synaptic+transmission.png"">" Draw and label the structure of a neuromuscular junction"<img src=""262-neuromuscular-junction.png"">" Compare transmission across cholinergic synapses compared to neuromuscular junctions MS [5]"<ul><li>neurone to neurone vs neurone to muscle;</li><li><font color=""#ff0000"">action potential in neurone vs no action potential in muscle / sarcolemma;</font></li><li><font color=""#ff0000"">no summation in muscle;</font></li><li>muscle response always excitatory (never inhibitory);</li><li><u>some </u>neuromuscular junctions have different neurotransmitters (noradrenaline as opposed to acetylcholine);</li></ul>" Explain why synapses result in unidirectional nerve impulses. [2]- Neurotransmitter only made in pre-synaptic neurone<div>- Neuro receptors are only on post-synaptic membrane</div> Explain spatial summation of synapses. [3]"- Many presynaptic neurones share the same postsynaptic neurone<div><div>- Collectively release <b>sufficient neurotransmitters </b>to cause <b>sufficient depolarisation </b></div><div>- To reach threshold + trigger AP</div><div><br></div><div><br></div><div><img src=""summation_med.jpeg""><br></div></div>" Explain temporal summation of synapses. Explain why this is important. [3]"<ul><li>1 presynaptic neurone releases neurotransmitter many times over a short period</li><li>Sufficient neurotransmitter to reach threshold to trigger an AP</li><li>Important as low freq APs release insufficient amounts of neurotransmitter to exceed threshold in postsynaptic neurone. Summation allows AP to generate by build up of neurotransmitter.</li></ul><div><img src=""summation_med.jpeg""><font color=""#ff0000""><br></font></div>" Explain inhibition by inihibitory synapses. [3]"<div><ul><li><b><u>Inhibitory neurotransmitters hyperpolarise the postsynaptic membrane.</u></b></li><li>K<sup style="""">+</sup> channels open- K<sup style="""">+</sup> diff out</li><li>Cl<sup>-</sup> open - Cl<sup>-</sup> diff in (makes neurone v.neg compared to outside)</li><li>(inhibits the formation of APs)</li><li>Cannot be depolarised</li><li>Reduces effect of sodium ions entering <b>so much less likely to reach threshold</b></li></ul></div>" Why is skeletal muscle incompressible?So the muscle can transmit force to bone Describe the roles of calcium ions and ATP in the contraction of a myofibril. [7]"<div>1. Ca<sup>2+</sup> diffuse into myofibrils from sarcoplasmic reticulum</div><div><br></div><div>2. Ca<sup>2+</sup>cause movement of tropomyosin</div><div><font color=""#ff0000"">(causes exposure of the binding sites on the actin)</font><br></div><div><br></div><div>4. Myosin heads attach to binding sites on actin</div><div><br></div><div>5. Hydrolysis of ATP on myosin heads causes them to bend;</div><div><br></div><div>6. The bending causing pulling actin molecules;</div><div><br></div><div>7. Attachment of a new ATP molecule to each myosin head causes myosin heads to detach from actin sites</div><div><br></div><div><img src=""AfraidRashFowl-max-1mb.gif""><br></div>" Describe the role of myosin in myofibril contraction [3]<ul><li>Myosin head binds to actin and pulls actin past</li><li>Myosin detaches from actin and resets.</li><li>Using ATP</li></ul> What happens to the H zone, I band, A band and Z lines during muscle contraction? [4]"H zone = shorter<div><br></div><div>I band = shorter</div><div><br></div><div>A band = same</div><div><br></div><div>Z discs = closer together</div><div><img src=""1606648542278.jpg""><br></div>" Explain the importance of maintaining a stable core temperature. [3]"<ul><li>Enzymes work at an <font color=""#ff0000"">optimum </font>temperature</li><li>Too low > not enough K.E > fewer successful collisions</li><li>Too high > enzymes denatures as H bonds in 3<sup>o</sup> break > A.S changes shape + no longer complementary to substrate > fewer e-s complexes</li></ul><div><br></div>" Explain the importance of maintaining stable blood pH [2]- Enzymes working at an optimum pH<div>- Too low/high enzymes denature as ionic bonds in 3<sup>o</sup> > A.S changes shape so no longer complementary to substrate > fewer successful collisions and e-s complexes.</div> Explain the importance of maintaining a stable blood glucose concentration. Consider too high and too low."<font color=""#ff0000"">Too low (hypoglyceamia)</font><div>- Not enough gluc. for respiration so less ATP prod.</div><div>- Atrans cant happen.</div><div><br></div><div><font color=""#ff0000"">Too high (hyperglyceamia)</font></div><div>- Blood has low water potential (+ increased solute)</div><div>- Water lost from tissue to blood via osmosis</div><div>- Kidneys can't absorb all glucose > more water lost in uring causing dehydration.</div>" Expain the concept of negative feedback. [2]<ul><li>Receptors detect levels are too low / high; (effectors respond to counteract change)</li><li>Restores levels to original point; (e.g body temp regulation)</li></ul> Explain the concept of positive feedback. [2]"- Amplifies change from normal level<div>- Advantage- rapidly activate something (e.g blood clots)</div><div><font color=""#ff0000"">- NOT INVOLVED IN HOMEOSTASIS</font></div>" State why homeostasis involves multiple negative feedback mechanisms. [3]"<ul><li><font color=""#ff0000"">Greater degree of control</font> over changes in internal environment</li><li>Controls departures in different directions from original state</li><li>Faster response</li></ul>" State 2 factors that affect blood glucose concentration."Eating a meal = increases bldgluc conc. <div><font color=""#ff0000"">(glucose absorbed from intenstine to blood)</font><br><div><br></div><div>Exercise / fasting = decrases bldgluc conc.</div></div><div><font color=""#ff0000"">(incr. rate of respiration of glucose)</font></div>" When and where is insulin secreted?"When <font color=""#ff0000"">blood glucose conc. is too high</font><div><br></div><div>Secreted from <font color=""#ff0000"">beta cells in islets of Langerhans</font> in pancreas<br></div>" When and where is glucagon secreted?"Alpha cells in islets of Langerhans in pancreas<div><br></div><div>Secreted when <font color=""#ff0000"">bldgluc conc. is LOW</font></div>" When and how is adrenaline secreted?"Secreted by <font color=""#ff0000"">adrenal glands</font> when bldgluc conc. is low / stressed<div><br></div><div><br></div>" How do adrenaline and glucagon demonstrate a secondary messenger model?They're the first messengers.<div>They cause glycogenolysis to occur inside the cells even though they bind to receptors on the outside of the cell.</div> State 2 things unspecialised cells are capable of."- <font color=""#ff0000"">Self renewal</font> (can divide to replace themselves)<div><br></div><div>- <font color=""#ff0000"">Specialisation / differentiation</font> (can develop into other types of cell)</div>" Explain how stem cells specialise. [4]1. Stimulus (e.g chemical)<div><br></div><div>2. Causes selective activation of genes (e.g muscle cells gene coding for actin and myosin need to be acitvated)</div><div><br></div><div>3. mRNA only transcribed from active genes => translated on ribosomes = proteins</div><div><br></div><div>4. These proteins modify cell permanently and determine cell structure / function</div> State 3 ways stem cells are used in medicine."<ul><li><font color=""#ff0000"">Regrow </font>damaged tissues in accidents or by disease e.g B cells in the pancreas in type 1 diabetes</li><li>Drug testing (used to grow artificial tissues)</li><li>Developmental biology research (provides insight into embryo development)</li></ul>" Explain how iPS are produced [3]"- Produced from <font color=""#ff0000"">adult somatic cells</font><div><br></div><div>- Specific <font color=""#ff0000"">protein transcription factors</font> associated with pluripotency put into cells, causing cells to express genes associated with pluripotency</div><div><br></div><div>- Cells <font color=""#ff0000"">cultured</font></div>" State 2 advantages of using iPS(induced pluripotent stem) in medical treatment.- No immune rejection as can be made using patient's own cells<div><br></div><div>- Overcome some ethical issues with using embryonic stem cells (no embryo destroyed)</div> Explain how transcription factors work [4]"- Transcription factors are <font color=""#ff0000"">proteins</font><div><br></div><div>- TF moves from <font color=""#ff0000"">cytoplasm => nucleus</font></div><div><br></div><div>- Bind to specific DNA base on <font color=""#ff0000"">promotor region</font></div><div><br></div><div>- Stimulate or Inhibit the <font color=""#ff0000"">transcription of mRNA</font> of target gene by helping or preventing binding of RNA polymerase</div>" Explain the role of oestrogen in initiating transcription. [5]"<ul><li>Oestrogen (steroid hormone) can diff across the PL bilayer as its lipid soluble</li><li>In cytoplasm, oestrogen binds to a receptor of an inactive transcription factor, <font color=""#ff0000"">forms hormone receptor complex.</font></li><li>Inactive transcription factor changes shape, <font color=""#ff0000"">resulting in an active TF.</font></li><li>TF diff from cytoplasm => nucleus and binds to specific DNA base seq on <font color=""#ff0000"">promotor region</font></li><li><font color=""#ff0000"">Stimulates transcription of genes by helping RNA Polymerase bind</font>.</li></ul>" What is a nucleosome? How do they affect transcription?DNA wrapped around histone proteins.<div><br></div><div>How closely the DNA and HP are packed together affects transcription.</div> Explain how increased Methylation of DNA can cause epigenetic changes and its effects. [3]<ul><li>Methyl groups added to cytosine bases in DNA</li><li>Nucleosomes pack more tightly together, preventing transcription factors binding (genes not transcribed)</li><li>It is reversible.</li></ul> Explain how decreased acetylation of associated histones causes epigenetic changes and its effects [3]<ul><li>Decreased acetylation of associated histones increases +ve charge of histones</li><li>Histones bind DNA (-ve charged) more tightly, preventing transcription factors binding; genes are not transcribed</li><li>Reversible.</li></ul> Recall how epigenetics is relevant to the development and treatment of cancer. [3]<ul><li>Epigenetic changes that increase the expression of an oncogene or that silence a tumor suppressor gene, can lead to tumour development</li><li>Tests can be used to see if a patient has abnormal levels of methyl or acetyl- early indicator of cancer</li><li>Could be manipulated to treat cancer (e.g drugs preventing histone acetylation / DNA methylation)</li></ul> What is miRNA?"- Formed as hair-pin bends of RNA but processed into <font color=""#ff0000"">single strands</font> 22-26 nucleotides long, both become incorporated into a protein-based RISC<div><br></div><div>(RNA-induced silencing complex)</div><div><br></div><div><img src=""meltzer-micro-rna-picture.jpg""><br></div>" What is siRNA?"- Formed as double-stranded molecules 21-25 basep long, <font color=""#ff0000"">one strand</font> incorperated into a protein-based RISC<div><br></div><div>(RNA-induced silencing complex)<br></div><div><br></div><div><br></div>" What are the main characteristics of benign tumors? [5]<ul><li>Grow slowly</li><li>Well differentiated</li><li>Normal, regular nuclei</li><li>Well defined borders (cells stick together to a particular tissue)</li><li>Easy to treat, can be normally removed by surgery</li></ul> What are the main characteristics of malignant tumors [5]<ul><li>Grow rapidly</li><li>Cells become unspecialised</li><li>Irregular, darker nuclei</li><li>Irregular / poorly defined borders</li><li>Removed by radiotherapy / chemo</li></ul> What is the normal function of a tumor suppressor gene? [3]<ul><li>Codes for proteins involved in control of cell division</li><li>Stopping the cell cycle</li><li>Involved in apoptosis of damaged/abnormal cells<br></li></ul> Describe 2 ways in which tumour suppressor genes can be affected that can lead to cancer [2]<ul><li>Mutation alters amino acid sequence and 3<sup>o</sup> structure of protein</li><li>Increased methylation prevents transcription</li></ul><div><br></div> What is the normal function of proto-oncogenes? [2]<ul><li>Code for proteins involved in control of cell division</li><li>Mainly stimulating cell division</li></ul> Describe ways proto-oncogenes can become involved in the development of tumors? [2]"<ul><li>Mutation could turn it into a permanently activated oncogene (causes uncontrolled cell division)</li><li>Decreased methylation / incr. acetylation causes <font color=""#ff0000"">excess transcription</font></li></ul>" What is the role of increased oestrogen concentration in the development of some breast cancers? How can this be minimised? [2]"- Increased conc. in areas such as adipose tissues in breasts causes uncontrolled cell division<div><br></div><div>Growth of cancer is minimised with drugs blocking the action of oestrogen in breasts</div><div><font color=""#ff0000"">(e.g Tamoxifen prevents oestrogen binding to OBP)</font></div>" What are benefits of genome sequencing becoming automated? [2]<ul><li>Cost effective </li><li>Can be done on a large scale</li></ul> Why is determining the genome of simpler organisms good for the development of vaccines? [2]<ul><li>Allows assignment of the proteins to each gene (easy because there's less non coding DNA)</li><li>This allows you to identify antigens on the surfaces of viruses / pathogenic bacteria</li></ul> Why can't the genome of a complex organism be easily translated into it's proteome? [2]<ul><li>Non coding DNA is present</li><li>Regulatory genes  are present</li></ul> <div>State and describe the three main types of neurone</div><ul><li><strong>Sensory</strong> neurones carry impulses from <strong>receptors</strong> to the <strong>CNS</strong> (brain or spinal cord)</li><li><strong>Relay</strong> (intermediate) neurones are found entirely within the CNS and <strong>connect</strong> <strong>sensory</strong> and <strong>motor</strong> neurones</li><li><strong>Motor</strong> neurones carry impulses from the <strong>CNS</strong> to <strong>effectors</strong> (muscles or glands)</li></ul> Describe the structure of a Myelinated Motor Neurone [5]"<ul><li>long fibre known as an <b>axon</b></li><li>axon is insulated by a fatty sheath called <b>myelin sheath</b></li><li>small, uninsulated sections along its length called <b>Nodes of Ranvier</b></li><li>myelin is made by specialised cells known as <b>Schwann Cells; </b>these cells wrap themselves around the axon along its length</li><li><b>cell bodies </b>contain a <b>nucleus </b>and many extensions called dendrites</li></ul><div><br></div><div><img src=""A-neurone.png""><br></div>" What is meant by 'resting potential'?<div>In a resting axon, the inside of the axon always has a slightly negative electrical potential compared to outside the axon. </div> Define ecosystem"the community of biotic and abiotic factors of an area and their interactions. It is said to be <b>dynamic</b> <br><br> Copyright © StemUp 2023 | All Rights Reserved " State 5 features of an ecosystem"<ul><li>Dynamic</li><li>Can range in size from very small to very large</li><li>Can range in complexity (e.g a desert is relatively smple, a tropical rainforest is very complex)</li><li>Self-contained</li><li>Flow of energy and nutirents within it </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why are ecosystems described as 'dynamic'?"<div>o   Populations constantly rise and fall<b></b></div> <div>o   Any small change can have a large effect<b></b></div> <div>o   Biotic and abiotic factors may alter the condition of the ecosystem<b></b></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What 4 factors affect population size and distribution?"<ul><li>Interspecific Competition</li><li>Intraspecific Competition</li><li>Predation</li><li>Abiotic Factors </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is interspecific competition?<div><br></div><div>What occurs when,</div><div><ul><li>two species are similarly well-adapted to the environment</li><li>one species is better adapted than the other</li></ul></div>"<ul><li>Competition for the <b>same resources </b>between individuals from different species</li></ul><div><br></div><div><b><u>Case 1 - Species are similarly well - adapted</u></b></div><div><ul><li>Both populations are limited, as each species has access to fewer resources and thus has less chance of survival and reproduction </li></ul><div><b><u>Case 2 - One species is better adapted than the other</u></b></div></div><div><ul><li>Leads to a decrease in population size of one of the species, and an increase in the population size of the other</li><li>This is because the latter species will out-compete the other for resources and thus has a greater chance of surviving and reproducing</li><li>An example is red vs grey squirrels, red squirrels can eat a wider range of food, are larger and store greater amount sof fat over the winter months, hence survive more often. </li></ul><div><br></div></div><div><img src=""Interspecific-competition-grey-and-red-squirrels.png""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is intraspecific competition? What is eventually reached as a result? Use grey squirrels as an example. "<ul><li>This is competition for the <strong>same resources</strong> between individuals from the <strong>same </strong>species</li><li>For example:</li><ul><li>When resources are plentiful, the population of grey squirrels increases</li><li>As the population increases, however, there are more individuals competing for these resources (e.g. food and shelter)</li><li>At some point, the resources become limiting and the population can no longer grow in size – the carrying capacity has been reached</li></ul></ul><div><br></div><div><img src=""Intraspecific-competition-grey-squirrels.png""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe a predator-prey cycle in 3 steps"<ul><li><div>Prey is eaten by predator, resulting in predator population increasing and prey population decreasing<br></div></li><li><div><div>Fewer prey means increased competition for food, hence the predator population decreases<b></b></div></div></li><li><div><div>Fewer predators means more prey survives, cycle begins again <b></b></div></div></li></ul><img src=""7.4.3-Carrying-Capacity.png""><br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by 'carrying capacity'?"The maximum stable population size of a species that an ecosystem can support<div><br></div><div><img src=""paste-736e56ecec4ff91de2fc6da1a39f4c8b002db6f2.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define the term 'niche'"The role that an organism plays in a ecosystem, which is governed by adaptations to abiotic and biotic conditions  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the competitive exclusion principle?"<ul><li>A niche can only be occuped by one species, meaning that every individual species has its own unique niche</li><li><b>Competition for food / named resource;</b></li><li>If two species had identical nichces, one would go extinct</li><li>The better adapted outcompetes the other species</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What causes interspecific competition?"Overlap between the niches of different species  <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why is sampling carried out?"To select a sample which is representative of the population <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 5 key factors to consider when carrying out an ecological study?"<ul><li>Large sample size</li><li>Removing bias</li><li>Seasonal differences</li><li>Choosing appropriate samples</li><li>Conclusions shown </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Sampling can either be {{c1::random}} or {{c1::systematic}} Describe, in detail, how and why we use random sampling in an ecological study"<b><u>How:</u></b><div><ul><li>Two numbered axis are laid out over the sample area</li><li>RNG provides co-ordinates for area to study</li><li>With each area, every part has an equal chance of being chosen</li></ul><div><br></div></div><div><u style=""font-weight: bold;"">Why:</u><br><ul style=""""><li style="""">Eliminates bias</li></ul><div><br></div></div><div><br></div><div><img src=""paste-201aa24a1e43744953affac065a7315e2793eb76.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is systematic sampling different to random sampling?"<ul><li>A similar grid is used, however samples are taken at regular intervals.</li><li>Usually used to investigate environmental gradient. </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How can we increase the reliability of data used in an ecological study? MS [6]"<ul><li>Increase repeats</li><li>Calculate running mean</li><li>When enough quadrats used, graph would level off</li><li>Take enough readings to carry out statistical test</li><li>Test a large number to make sure results are reliable</li><li>Need to be sure work can be carried out in designated time</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why do we use random samples? MS [3]"<ul><li>Avoids bias</li><li>Data representative / Choice of X variable not influencing results</li><li>Allows use of statistical tests </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 ways we can estimate population size?<div><br></div><div>When do we use each?</div>"<div><b><u>For non-motile and slow moving</u></b></div><ul><li>Quadrats (random)</li><li>Transects (systematic) </li></ul><div><br></div><div><b><u>For motile</u></b></div><ul><li>Mark, Release, Recapture</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by distribution of a species?"describes how it is spread throughout the ecosystem <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by abundance?"The number of individuals of that species <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe the two types of quadrats"<ul><li>Frame Quadrats (place randomly, count number)</li><li>Point Quadrat (drop pins randomly, count number of species it touches)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 2 ways we can record data on species using quadrats?"<ul><li>Percentage Cover</li><li>Species Frequency</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " <br>What are the advantages/disadvantages of using Species Frequency when measuring with quadrats?"<div><span style=""color: rgb(0, 176, 80);"">Advantages:</span></div> <div>·         Quick to carry out</div> <div>·         Useful for species that are hard to count (e.g. grass)</div> <div><span style=""color: red;"">Disadvantages:</span></div> <div>·         Doesn’t provide detailed info on distribution of a species</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the advantages/disadvantages of using % cover when investigating with quadrats?"<div><span style=""color: rgb(0, 176, 80);"">Advantages:</span></div> <div>·         Useful for species that are hard to count (e.g. grass)</div> <div>·         Useful for species that are very abundant in area</div> <div>·         Don’t need to count individual plants</div> <div><span style=""color: red;"">Disadvantages:</span></div> <div>·         Not useful in areas where organisms occur in overlapping layers (becomes difficult to estimate an exact amount)</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe a method of random sampling via quadrats MS [3]"<ul><li>Set up grid system with coordinates</li><li>Place <b>a large number of quadrats</b> at coordinates selected at <b>random</b></li><li>Count number of / estimate percentage cover of specise</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 types of transect and how are they used?"<div><u><b>3 types </b><span style=""color: rgb(0, 176, 80);""></span></u></div><div><u><b><br></b></u></div><div><u><b><br></b></u></div> <div>o   <b>Line Transect</b></div> <div>§  Run a tape measure between two points</div> <div>§  Record all species that touch the tape</div><div><br></div><div>o   <b><span style=""color: rgb(0, 112, 192);"">Belt Transect</span></b></div> <div><span style=""color: rgb(0, 112, 192);"">§  </span><span style=""color: rgb(0, 112, 192);"">Use quadrats along the length of the transect</span></div><div><br></div><div>o   <b>Interrupted Transect</b></div> <div>§  Use quadrats at fixed intervals along the length of the transect</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div><b>‘’</b>Describe how you would investigate the distribution of x from one side of an ecosystem to the other’’ MS [3]</div>""<div>·         Transect from one side of the ecosystem to the other</div> <div>·         Place quadrats at regular intervals along the line</div> <div>·         Count the % cover of the plant in quadrats</div><div><br></div><div><br></div><div><img src=""paste-a1ea0c66295cb377a45f44cf6c5827369385bc60.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why are belt transects used in a non-uniform ecosystem?"To investigate the effect of changing physical conditions on species distribution <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div>Why is more difficult to study animals and insects as opposed to plants?</div>""<div>·         Mobile</div> <div>·         Stay hidden from the investigator</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe the Mark-Capture-Rerelease Method [5]"<div>1.      Capture a known sample and mark them (without causing harm)</div> <div>2.      Release back into the community</div> <div>3.      Allow time for re-integration, the community is then revisited and a given number of individuals is caught again</div> <div>4.      The number of marked individuals is counted</div> <div>5.      Population size is calculated via the <span style=""color:red"">equation</span></div><div><span style=""color:red""><br></span></div><div><span style=""color:red""><br></span></div><div><img src=""paste-d226e4d8307ba413d63629bd55bf09573a04d9e1.jpg""><span style=""color:red""><br></span></div><div><span style=""color:red""><br></span></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 4 issues surrounding the Mark-Capture-Rerelease method?"<div><div>·         Deciding in a large area how many individuals to capture and recapture</div> <div>·         Ensuring to mark them in a harmless way</div> <div>·         Ensure to mark in a way that stays til the second collection</div> <div>·         Deciding time for re-integration</div></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the assumptions we make when using the M.C.R method? MS  [6]"<div><br></div><div><ul><li>No immigration / emigration</li><li>Few births / deaths (no losses to predation)</li><li>Proportion of marked / unmarked in both samples is the same as proportion in the habitat</li><li>Marked individuals evenly distribute themselves within the population</li><li>Markings aren't lost</li><li>Markings do not affect survival</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'succession'"The change over time in the species that occupy a particular area  <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why would a bare, barren rock not be habituated by organisms?"<ul><li>Exposed</li><li>No Soil</li><li>Absorbs + Reflects Heat</li><li>Dry</li><li>No Nutrients</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe the steps in primary succession. MS [6]"<ul><li>Colonisation occurs by a pioneer species</li><li>Pioneer species causes a change in environment e.g more food / nutrients / stabilises</li><li>Enables other species to colonise <b>once there is a change</b></li><li>Change (increase) in species diversity / biodiversity</li><li>Stability increases, environment is less hostile</li><li>Climax community is reached</li></ul><div><br></div><div><img src=""paste-a0852d6e32322ff19574d8c69b66d73f571370ae.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What 5 things happen as a result of primary succession?"<ul><li>Abiotic environment becomes less hostile</li><li>Greater number/variety of habitats and niches</li><li>Biodiversity increases</li><li>More complex food webs emerge</li><li>Increased biomass</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the role of pioneer species? MS [6]"<ul><li>Stabilize environment</li><li>Soil development / increase humus</li><li>Change soil pH</li><li>Hold more water</li><li>Release more nutrients / increase N content</li><li>Provide shelter</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by 'climax community'?"<ul><li>The final stage in succession</li><li>Community in equilibrium with environment</li><li>Community is stable</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 key features of a climax community?"<ul><li>Populations are stable around the carrying capacity</li><li>Abiotic factors constant</li><li>Same species present / stable community</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are two types of succession and what's the difference?"<div><ul><li><b>Primary</b> succession occurs when plants grow in newly formed/exposed land and is gradually colonised.</li><li><b>Secondary</b> succession occurs when plants grow where there has previously been a population. These will have been destroyed e.g by fire</li></ul><div><br></div></div><div><br></div><div><img src=""paste-451f64583f3b3aa752c1ae6e9e03f8f95033ce72.jpg""><br></div><div><br></div><div><img src=""paste-ba72a212df1ab4b535c6f9ad1929bebfd506938d.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Draw a table that summaries the differences between the two types of succession. [5]"<img src=""paste-685dd685751d63d22b28ff6bca96a066f2757d36.jpg""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What do we need to know about animal succession?"<ul><li>Animal species present depend on the plant species found in the area</li><li><div>For example, mosses and grasses provide food and habitats for insects and worms. These can then support secondary consumers. </div></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is deflected succession?"<div>A community that remains stable on because human activity prevents succession from running its course</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe 5 ways in which deflected succession can be caused MS [5]"<ul><li>Grazing</li><li>Burning</li><li>Mowing</li><li>Selective Herbicide</li><li>Exposure to Wind</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div>At each stage of succession, certain species may be recognized {{c1::which change the environment so that it becomes more suitable for other species with different adaptations}}. The new species may {{c2::change the environment in such a way that it becomes less suitable for the previous species}}</div>" "<div>SL: Conservation of habitats frequently involves the {{c1::management of succession}}. </div>" Why may management of succession bring about benefits?"<div><ul><li>Maximising the growth of trees</li><li>Maximising the diversity of the habitat</li><li>Maximising the look of the countryside</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'conservation of habitats'"The management of the natural resources to enable future generations to maximize their use  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What does conservation of habitats involve?"<ul><li>Maintaining ecosystems</li><li>Maininting biodiveristy</li><li>Management of existing resources</li><li>Ensuring damaged resources can be obtained again as well</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe how management of succession is used for Grouse"<ul><li>Regular burning of grouse moors</li><li>Encourages new growth of heather shoots</li><li>Perfect habitat for grouse</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 4 main reasons for conserving habitats?"<img src=""paste-8601402067408ea6943f82a8889445bcfed281b6.jpg""><div><ul><li>Economical - large genetical pool in organisms which coudl ead to the development of valuable resources in the future</li><li>Ethical - respecting living things that co-exist with us on Earth</li><li>Aesthetic Reasons</li><li>Cultural - people turn to nature for inspiration</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div>Many species that previously existed on earth no longer do. Explain why in terms of succession and habitats.</div>""<div><ul><li>Habitats have changed or completely disappeared as a result of succession. </li><li>Some have been out competed by other species, mostly the dominant species in a community. </li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " <div>How could we prevent species from dying out due to succession?</div>"<div><ul><li>Through the management of succession.</li><li>We can ensure that changes to habitats are minimal and that they only occur when needed.</li><li> Ensuring that any organisms displaced by change are placed into a suitable environment. <b> </b></li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe how the conservation of species can be achieved through managing succession"<div><ul><li>Climax communities do not contain all the species that existed in its earlier stages</li><li>Maintaining habitats at different stages of succession can <u>keep these species present</u>, by preventing change to the next stage                                            </li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " An example of managing succession is Dormouse Conservation. Recall this."<ul><li>They feed on nuts + berries, found in coppiced forest lands such as hazel + oak</li><li>Numbers are in decline due to loss of habitat</li><li>Coppicing helps to maintain a stable environment</li><li>Halts the natural succession of scrubland + bramble into mature forest</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Grassland management is an example of conservation. Recall this."<ul><li>Much of the higher ground in the UK is moorland. </li><li>Vegetation growth rate slows significantly due to heather burning and sheep grazing</li><li>Burning maintains plant vigour and removes unwanted vegetation</li><li>Prevents climax community from being reached as the young tree saplings are destroyed => stopping progression into deciduous woodland</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is sustainable foresty? Give two examples."<div>These are techniques that employ a variety of removal and replacement methods that provide timber while reducing the impact of timber removal on the environment.<b><u></u></b></div><div><br></div><div><br></div><div><b><u>Coppicing:</u></b></div><div><ul><li>Trees coppiced</li><li>Stems grow from stump</li><li>Stems provide wood from the stump</li></ul><div><b><u>Selection Logging</u></b></div></div><div><ul><li>Trees selected for removla based on height, girth</li><li>Felled individually and directed to fall to minimise damage</li><li>Forest managed to ensure continued growth of young seedlings + provide balance of tree ages</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div>Describe how the percentage cover of heather plants on an area of moorland may be measured. MS [3]</div>""<div>1.     Use of quadrats; </div> <div>2.     randomly placed; </div> <div>3.     Estimate percentage of area shaded/covered by heather; </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How can microscopic plants lead to the development of an ecosystem? MS [13]"<div><div>1.     Pioneer species colonise area; </div> <div>2.     Microscopic plants at start</div> <div>3.     Can survive in hostile environment;</div> <div>4.     Death/decomposition</div> <div>5.     Change in abiotic conditions / <b>less hostile</b>/more stable / more habitats / niches; </div> <div>6.     By absorbing water / <b> adding humus</b></div> <div>7.     New species move into/colonise changed environment;</div> <div>8.     Increase in number / diversity of species / plants / animals;</div> <div>9.     New plants more successful than pioneer as can grow faster;</div> <div>10.   Conditions change to favour new species</div> <div>11.   New species outcompete old species; </div> <div>12.   So change in community over time, so increase in diversity;</div></div><div>13. Stability increases over time / less hostile enviromment leads to climax community</div><div><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " When using M.C.R method of estimating population sizes, why may there be inaccuracies? MS [5]"<ul><li>Sample too small</li><li>Too short a time to mix evenly;</li><li>Birth/death;</li><li>Immigration/emigration;</li><li>Marking method affected behaviour</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Given this data, describe the relationship between a predator and its prey. MS [6]"<div>1.     () year cycles;</div> <div>2.     predator peaks after prey;</div> <div>3.     prey increase due to low numbers of predators / available food;</div> <div>4.     more food for predators so numbers increase;</div> <div>5.     increased predation reduces number of prey;</div> <div>6.     number of predators decreases due to lack of food / starvation</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " <div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div><div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div> Why can the mechanism that brings about characteristics be described as <b>enzymatic?</b>"<ul><li>All genes code for enzymes</li><li>Enzymes involved in biochemical pathway</li><li>Leads to characteristic in an organism </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'genotype'"The genetic constitution of an organism  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a 'modification'?"When the phenotype is NOT affected by the genotype, hence the characteristic hasn't been inherited.  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a karyotype?"An individuals collection of chromosomes <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'dominant allele'"Allele of the heterozygote that expresses itself in the phenotype  <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'recessive allele'"Allele of the heterozygote that is not expressed in the phenotype  <br><br> Copyright © StemUp 2023 | All Rights Reserved " If the allele on both loci = different, characteristic is..."Heterozygous <br><br> Copyright © StemUp 2023 | All Rights Reserved " If allele on both loci = same, characteristic is..."homozygous <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a monohybrid cross?"<ul><li>Investigation into one characteristic</li><li>Shows what the offspring genotypes could be</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the name given to the respective generations of a Monohybrid Cross?"<ul><li>First Gen = First Filial = F<sub>1</sub> </li><li>Second Gen = Second Filial = F<sub>2</sub> </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " State the steps taken to draw a monohybrid cross to work out phenotypic ratio [5]"<ul><li>Choose one letter to represent dominant / recessive</li><li>Work out the parental genotypes and gametes they might produce</li><li>Draw a Punnet Square</li><li>Look at phenotypes in F1 generation (write clearly)</li><li>Decide ratio of phenotypes </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by 'pure breeding'?"Repeatedly breeding the dominant phenotype with other organisms of the dominant phenotype. This will create homozyogus dominant plants.  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a dyhbrid cross?"<ul><li>A cross involving two genes that control <b><u>two different characteristics</u></b></li><li>Unliked genes are found on <b>different chromosomes</b></li><li>Separated by random assortment during meiosis</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How could you determine if an organism with a dominant phenotype is heterozygous or homozygous?"<ul><li>Cross organism with double recessive type</li><li>If homozygous -> all offspring will have dominant phenotype</li><li>If heterozygous -> at least one will have recessive phenotype </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the typical ratio expected in a dybrid cross if the two original parents were heterozygous?"9:3:3:1 <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'co-dominance'"This is when both alleles are expressed in the phenotype <br><br> Copyright © StemUp 2023 | All Rights Reserved " How do we draw co-dominance crosses?"<ul><li>We no longer use Capital Letters since alleles are equally dominant</li><li>We instead choose a letter to represent the gene, and a superscripted letter to represent the allele</li></ul><div><img src=""paste-501cb0858d8b7b5c31801ac0d79c792befe4623d.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe how Co-Dominance is demonstrated by Sickle-Cell Anameia"<ul><li>Sickle Cell is caused by a gene that directions synthesis for haemoglobin</li><li>New protein causes a change in red blood cell, causing C shaped cell</li><li>Inhibits oxygen carrying capacity</li><li>Gene for Normal Hb = A</li><li>Gene for Sickle Hb = S</li><li>Genotype for Normal Cell: Hb<sup>A</sup>Hb<sup>A</sup></li><li>Genotype for Sickle Cell: Hb<sup>S</sup>Hb<sup>S</sup></li><li>A heterozygous mix, Hb<sup>A</sup>Hb<sup>S</sup> creates individuals with sickle cell trait. Express both types of cell. </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why may be it advantageous for individuals to have sickle cell trait? (Hb<sup>A</sup>Hb<sup>S</sup>)"<ul><li>Gives an individual resistance to malaria</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how the inheritance of human blood groups is an example of 'multiple alleles'"<ul><li>The gene has moer than 2 alleles</li><li>3 alleles associated with the 'I' gene</li><li>IA IB IO</li><li>Leads to diff. antigents being produced on membranes of RBCs</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " State the various phenotypes and genotypes of human blood groups."<img src=""paste-d297b628c513c7c4f60b1eab04c5e4f9cb36f382.jpg""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What antigens are produced by the multiple alleles for human blood type?"<ul><li>Allele IA leads to the production ofantigen A.</li><li>Allele IB leads to the production ofantigen B.</li><li>Allele IO leads to the production of <b>neither</b>.</li></ul><div><img src=""BloodTypes_ABO.png""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How could you work out if somebody is I<sup>B</sup>I<sup>O</sup> and not I<sup>B</sup>I<sup>B</sup>"<ul><li>If one of their natural children is blood gorup O, both parents must've given IO</li><li>If their natural mother/father is blood group A, they must have passed on I<sup>O</sup>, otherwise the individual would be I<sup>A</sup>I<sup>B</sup></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by a 'dominance hierarchy'?"<ul><li>If there are multiple alleles for a gene, more than 3, some alleles are <b>more dominant </b>to others</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<img src=""Chromosomes-showing-gene-and-loci.png"" width=""389"">" What is epistasis?"When the allele of a gene affects or masks the expression of another in the phenotype  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two types of linkage in genetics?"<ul><li>Sex linkage</li><li>Autosomal Linkage</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant for genes to be linked? MS [1]"<div><div>1.     (Genes / loci) on same chromosome;</div></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " <div>What is a sex linked gene? MS [1]</div>"<div>1.     Gene located on X/Y/ one sex chromosome </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div>Why can we use cats for experimentation? MS [3]</div>""<ul><li>Mammals, so similar physiological reactions as humans</li><li>Can use lots of thems</li><li>Small enough to keep in a lab </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " <div>Why do small populations have lots of genetic disease? MS [5]</div>"<div>●      Small founder population/ common ancestor;</div> <div>●      Genetic isolation, small gene pool;</div> <div>●      Inbreeding;</div> <div>●      Reproduction occurs before symptoms apparent;</div> <div>●      So no selective disadvantage;</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two divisions of the nervous system?"<ul><li>Central Nervous System - (brain and spinal cord)</li><li>Peripheral Nervous System - (pairs of nerves that originate from either brain or spianl cord)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is ganglia?"<ul><li>structure containing many nerve cell bodies, typically linked by synapses.</li><li>well defined area of grey matter</li><li>present in spinal cord</li><li>relay neurone present within it</li></ul><div><img src=""Autonomic-ganglia-1024x576.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Sensory, motor neurones and sense organs all belong to _____"The peripheral nervous system  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the Spinal Cord? [3]"<ul><li>Column of nervous tissue</li><li>Runs along the back inside the vertebral column (for protection)</li><li>Emerging at intervals are pairs of nerves </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the difference between a somatic neuron and a visceral neuron?"<ul><li>somatic = from/to the senses</li><li>visceral - from/to the organs </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a sense organ?"A part of the body containing receptors  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a stimulus?"A detectable change in the internal/external environment  <br><br> Copyright © StemUp 2023 | All Rights Reserved " In the motor nervous sytem, what are the two divisions?"<ul><li>Somatic (voluntary) nervous system - carries nerve impulses to body muscles</li><li>Autonomic (involuntary) nervous system - carries nerve impulses to glands / cardiac muscles / skeletal muscles </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Draw a flowchart from a stimulus being detected to a response."<img src=""Response-to-Change-Robin.png""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " The cell body of a neurone contains large amounts of RER, ribosomes and mitochondria. Explain why. MS [4]"<ul><li>RER to package neurotransmitters</li><li>Ribosomes to synthesise neurotrasmitters/proteins involve</li><li>Proteins for the development of new neurones</li><li>Mitochondria for ATP involved in polypeptide synthesis </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the functions of Schwann Cells? [4]"<ul><li>surrounds the axon for insulation</li><li>carries out phagocytosis</li><li>involved in nerve regeneration</li><li>wrap themselves around axon to build up myelin sheath</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain why reflex actions are so important MS [6]"<ul><li>Automatic / involuntary adjustments to change in enviroment</li><li>Prevents injury </li><li>Role in homeostasis</li><li>Posture / Balance</li><li>Obtaining food / finding mate</li><li>Escape from predators </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " State two features of simple reflexes"<ul><li>Rapid</li><li>Do not have to be learnt</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a secondary nervous response?"<ul><li>Relay neurone has synpase with OTHER relay neurones</li><li>Transmits impulses to sensory areas</li><li>Allows a slower, secondary response in addition to the reflex</li><li>e.g saying ouch after you pick up a hot pan</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Give ways in which hormonal coordination differs from nervous coordination MS [5]"<ul><li>chemical (not electrical)</li><li>slower (to take effect / transmission)</li><li>longer-lasting</li><li>delivered by blood (not nerves)</li><li>broader targetting</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'nerve impulse'"self-propagating wave of electrical activity that travels down the axon membrane <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain why energy is required in the maintenance of the resting potential in an axon. [2] MS"ATP / energy required by ion pumps<br><br>To move Na+ and K+ against concentration gradient <br><br> Copyright © StemUp 2023 | All Rights Reserved " Sodium and potassium ions can only cross the axon membrane through proteins. Explain<br>why. [2] MS"can not pass through phospholipid bilayer;<br><br>because water soluble / not lipid soluble / charged / hydrophilic / hydrated; <br><br> Copyright © StemUp 2023 | All Rights Reserved " Proteins A and B differ from each other. Explain why different<br>proteins are required for the diffusion of different ions through the<br>membrane. MS [2]"<ul><li>each protein has specific tertiary structure</li><li>because ions have different sizes and shapes </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe a simple reflex arc MS [3]"<ul><li>receptor to sensory, relay, moton neuron to effector (two synapses)</li><li>only to spinal cord, no brain, hence no thinking</li><li>fast and involuntary, prevents injury, escape from predators</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the stages by which an action potential is generated"1. Stimulus<div>2. Depolarisation</div><div>3. Repolarisation</div><div>4. Hyperpolarisation</div><div>5. Refractory Period</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Generation of AP: Stimulus"<ul><li>Neurone CSM excited</li><li>Na+ V.G channels open</li><li>CSM more permeable to Na+</li><li>Na+ diffuse down <b>e.c gradient</b> into neurone</li><li>Inside of neurones become less -ve</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Generation of AP: Depolarisation"<ul><li>Threshold reached</li><li>Many more Na+ channels open</li><li>More Sodium Ions diffuse in (+ve feedback)</li><li>Potenetial rises rapidly </li><li>P.D peaks around +40mV</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Generation of AP: Repolarisation"<ul><li>At 40mV</li><li>Na+ V.G channels <b><u>close</u></b></li><li>All K+ V.G channels <b><u>open</u></b></li><li>K+ diffuse down conc. gradient <b>out </b>of the axon</li><li>Inside of membrane becomes more negative again</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Generation of AP: Hyperpolarisation"<ul><li>K+ ions channels slow to close</li><li>Overshoot of K+</li><li>Too many diffuse out</li><li>P.D becomes <b>more -ve </b>than R.P</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Generation of AP: Refractory Period"<ul><li>Ion channels reset</li><li>NaK pump returns membrane to R.P</li><li>Another AP cannot be generated in this time</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the importance of the refractory period? MS [3]"RP: When no further action potential can be generated<div><br></div><div>- Limits the frequency of impulse transmission</div><div>- Ensure action potentials are <b>discrete </b>(no overlap)</div><div>- Ensures action potentials can travel in one direction</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""cbb394fa3d364a80ae0e79d7dd9ec29d-ao-1-Q.svg""></div> <div id=""io-original""><img src=""215-action-potential-voltage-time-graph.png""></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""cbb394fa3d364a80ae0e79d7dd9ec29d-ao-1-A.svg""></div> <div id=""io-original""><img src=""215-action-potential-voltage-time-graph.png""></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); 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original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""cbb394fa3d364a80ae0e79d7dd9ec29d-ao-8-A.svg""></div> <div id=""io-original""><img src=""215-action-potential-voltage-time-graph.png""></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the 'all or nothing' principle? [3]"<ul><li>AP only occurs when membrane is depolarised to a certain threshold (-55mV)</li><li>If this is not reached, AP will not be triggered</li><li>A bigger stimulus won't cause a bigger AP, AP is just fired more frequently </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div>A myelinated axon conducts impulses faster than a non-myelinated axon. Explain this difference. MS [3]</div>""<div>1.     (In myelinated) action potential / depolarisation only at node(s) of Ranvier; </div> <div>2.     (In myelinated, nerve impulse) jumps from node to node / saltatory; </div> <div>3.     (In myelinated) action potential / impulse does not travel along whole length; </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " <div>How can axons conduct faster? MS [7]</div>"<div>1.     Myelinated;</div> <div>2.     So saltatory conduction;</div> <div>3.     Larger diameter;</div> <div>4.     So less resistance to flow of ions; </div><div>5.     Higher temperature (up to 40<sup>o</sup>C);</div><div>6.      Ions diffuse faster since more Ke; </div><div>7.      Faster r8 of respiration, more ATP for ATrans</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What the consequences of a myelin sheath being broken down?"<ul><li>Less/no saltatory conduction</li><li>More depolarisation over length of membranes </li><li>Slower impulse transmission</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is an AP propagated along an unmyelinated neurone? (in terms of region A and B, adjacent parts of a neurone)"<ul><li>Influx of Na+ in region A</li><li>Localised current</li><li>Result in Na+ V.G.C opening in region B</li><li>Na+ diffuse into region B</li><li>K+ ion channels open in Region A (repolarisation)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " In a myelinated neurone, {{c1::nerve impulses jump from node to node}}. This is called {{c2::saltatory conduction}}.  <div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div><div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div> Two properties of myelin? [2]"<ul><li>Lipid</li><li>Electrical Insulator</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What do we mean when we say a neurone membrane is polarised / depolarised?"<ul><li>Polarised = more -ve on inside</li><li>Depolariesd = more +ve on inside</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why are males more likely to develop a sex-linked disorder?"<ul><li>X longer than Y</li><li>No homologous Y area for most of X</li><li>Hence males only require 1 copy of a recessive allele for expression on the phenotype </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is Haemophilia?"<ul><li>Sex-linked disease</li><li>Blood clots slowly as clotting factors aren't coded for</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why do males always inherit a sex-linked condition from their mother?"<ul><li>Males are XY</li><li>They inherit X chromosome from their mother </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How do you interpret pedigree charts?"<ul><li>▢ = male<br></li><li>O = female</li><li>shading = sufferer</li><li>dot = carrier</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How can you identify, from a pedigree chart, that a disease is recessive?"<ul><li>Unaffected parents givinsg rise to affected individual</li><li>Parents are heterozygous</li><li>Only possible with recessive</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " <br>How can you identify that a disease is sex-linked from a pedigree chart?"<ul><li>Only/primarily males in pedigree affected</li><li>Generations are skipped </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is autosomal linkage?"<ul><li>Autosome = non-sex chromosome</li><li>Genes present on same autosome</li><li>Inherited together</li></ul><div><br></div><div><img src=""paste-53b0e318f366f0ceebdc042aba6c526f9e22ec7c.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " X and Y chromosomes do not form a typical bivalent during meiosis. Explain why MS [2]"<ul><li>X and Y chromosomes different sizes / shapes</li><li>Most of length not homologous / unable to line up</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " The closer the loci of genes on an autosome, {{c1::the more closely linked they are}} because {{c1::they are less likely to be separated during crossing over}} In autosomal linkage, how do the genotypes of the offspring compare to the parents? When may this not be the case?"<ul><li>Most offspring will have the same genotype and phenotype as parents</li><li>Unless alleles are separated during crossing over</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'gene pool'"All the alleles of all genes in a population <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'allele frequency'"The number of times an allele occurs within a gene pool <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 5 assumptions for the Hardy-Weinberg equations?"<ul><li>No mutations or selection</li><li>Isolated and large population</li><li>Random mating<br></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the Hardy-Weinberg equations and how do we use these in calculations?"<ul><li>If the phenotype of a trait in a population is determined by a single gene with only two alleles (we will use <strong>B / b </strong>as examples throughout this section<strong>)</strong>, then the population will consist of individuals with three possible genotypes:<ul><li><strong>Homozygous</strong> dominant <strong>(BB)</strong></li><li><strong>Heterozygous (Bb)</strong></li><li>Homozygous recessive (<strong>bb)</strong></li></ul></li><li>When using the Hardy-Weinberg equations the <strong>frequency of a genotype</strong> is represented as a <strong>proportion</strong> of the population<ul><li>For example, the <strong>BB</strong> genotype could be 0.40</li><li>Whole population = 1</li></ul></li><li>The letter <strong><em>p</em></strong> represents the frequency of the dominant allele (<strong>B)</strong></li><li>The letter <strong><em>q</em></strong> represents the frequency of the recessive allele (<strong>b)</strong></li><li>As there are only two alleles at a single gene locus for this phenotypic trait in the population:</li></ul><div style=""text-align: center;""><strong><em>p + q</em> = 1</strong></div><ul><li><div style=""text-align: left;"">The chance of an individual being homozygous dominant is <strong><em>p</em><sup>2</sup></strong></div><ul><li>In this instance, the offspring would inherit dominant alleles from both parents ( <strong><em>p </em></strong>x<strong><em> p </em></strong>=<strong><em> p</em></strong><sup>2</sup><em> )</em></li></ul></li><li>The chance of an individual being heterozygous is <strong>2<em>pq</em></strong><ul><li>Offspring could inherit a dominant allele from the father and a recessive allele from the mother (<strong><em> p</em></strong> x <strong><em>q</em></strong> ) <strong>or </strong>offspring could inherit a dominant allele from the mother and a recessive allele from the father (<strong><em> p</em></strong> x <strong><em>q</em></strong> ) = 2<strong><em>pq</em></strong></li></ul></li><li>The chance of an individual being homozygous recessive is<strong> <em>q</em><sup>2</sup></strong><ul><li>In this instance, the offspring would inherit recessive alleles from both parents ( <strong><em>q </em></strong>x<em><strong> q</strong> </em>=<strong><em> q</em></strong><sup>2</sup><em> )</em></li></ul></li><li>As these are all the possible genotypes of individuals in the population the following equation can be constructed:</li></ul><div style=""text-align: center;""><strong><em>p</em><sup>2</sup> + <em>q</em><sup>2</sup> + 2<em>pq</em> = 1</strong></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the Hardy-Weinberg <b>principle</b>? (not the equations)"<div>There is an equilibrium between allele frequencies, and there is no change in this between generations. </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why would increasing the temperature above 40 degrees decrease the rate of propagation of an electrical impulse?"Proteins Denature <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe the processes that occur at a cholinergic synapse. MS [8]"1. (impulse causes) calcium ions / Ca++ to enter synaptic knob;<br>2. synaptic vesicles move to / fuse with (presynaptic) membrane;<br>3. acetylcholine (released);<br>4. (acetylcholine) diffuses across synaptic cleft / synapse;<br>5. binds with receptors on (postsynaptic) membrane;<br>6. sodium ions / Na+ enter (postsynaptic) neurone;<br>7. depolarisation of (postsynaptic) membrane;<br>8. if above threshold nerve impulse / action potential produced <br><br> Copyright © StemUp 2023 | All Rights Reserved " What happens to acetylcholine after it has triggered an AP in the post-synaptic membrane? [3] "<ul><li>Acetylcholinesterase breaks down acetylcholine in the cleft (into acetate + choline)</li><li>These diffuse back into pre-synaptic membrane<br></li><li>ATP resynthesises + stores back into vesicles (assisted by SER) </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 5 types of drugs that affect synaptic transmission?"<ul><li><b>Agonist</b>; binds to receptor, produces functional response</li><li><b>Antagonist</b>; prevents agonist from binding to receptor</li><li><b>Enzyme </b>Inhibition; inhibits enzymes that break down NT</li><li><b>Stimulating </b>NT; more receptors activated<br></li><li><b>Inhibiting </b>NT; less receptors activated</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Species exist as {{c1::one or more populations}} Explain the processes by which stabilising selection occurs MS [6]"<ul><li>Unchanging conditions of environment</li><li>Variation between individuals due to mutation</li><li>Extreme phenotypes selected against / less likely to survive + reproduce</li><li>Small variation in allele frequency</li><li><u>Mean </u>value is unaltered / <u>range </u>is reduced</li><li>Repeats over many generations</li><li>Increasing proportion of populations become well adapted to the environment</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why may there be a time lag between the prevalence of an allele and the introduction of a selection pressure? MS [3]"<ul><li>Initially, only some individuals have a favourable mutation</li><li>Differential reproductive success; Individuals with favourable allele will have offspring</li><li>Takes many generations for mutation to become the most common allele</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 sources of genetic variation?"<ul><li>Mutation (primary source)</li><li>Meiosis</li><li>Random fertilisation</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why do individuals within a population show a wide range of variation in phenotype? [2]"<ul><li>Genetic factors</li><li>Environmental factors </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Give 3 examples of selection pressure during natural selection."<ul><li>Predation</li><li>Disease</li><li>Competition</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the effect of differential reproductive success on allele frequencies?"Frequency of <u>favourable </u>alleles increases<br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how allopatric speciation occurs MS [6]"<ul><li>Geographical isolation</li><li>Separate genes pools / no interbreeding or gene flow</li><li>Variation due to mutation</li><li>Different selection pressures / habitats</li><li>Differential reproductive success </li><li>Leads to a change in allele frequency</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how sympatric speciation occurs MS [6]"<ul><li>Occurs in the same habitat</li><li>Mutation causes variation (link to specific phenotype)</li><li>Reproductive isolation</li><li>Different alleles passed on</li><li>Disruptive selection occurs</li><li>Eventually different species formed - cannot interbreed to produce fertile offspring</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " SL: What does reproductive separation of two populations lead to? [3] "<ul><li>Accumulation of genetic differences</li><li>Leads to an inability of members of the populations to interbreed and produce fertile offspring</li><li>New species arise - sympatric speciation </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe the concept of genetic drift. [3]"<div><ul><li>Random changes in alele frequency in a gene pool</li><li>Effect is much more drastic in small populations</li><li>Driven forward by chance, not selection</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two types of genetic drift?"<ul><li>Founder Effect</li><li>Bottleneck Effect</li></ul><div><br></div><div><br></div><div><img src=""paste-6715001c9c2fbf0fc9a3c5924a0ec327e996d0f8.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the founder effect? [3]<div><br></div><div>Give 2 examples. </div>"<ul><li>small group of individuals break off to form a smaller colony</li><li>founding individuals may not represent the full genetic diversity</li><li>evolve in different direction if they are subjected to <b>diff. selection pressures </b>and if the population is <b>missing alleles </b></li></ul><div><br></div><div>EXAMPLES:</div><div><ul><li>Blue Fugates (blue skin)</li><li>The Amish People (recessive conditions)</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a genetic bottleneck? [4] <div><br></div><div>Give two examples. </div>"<ul><li>A sharp reduction in the size of a population</li><li>Produce smaller pop. with reduced genetic diversity.</li><li>In subsequent generations, diversity remains lower.</li><li>Slowly increases with time thanks to random mutations. </li></ul><div>EXAMPLES:</div><div>1. Environmental events (floods, fires)</div><div>2. Human activities (hunting, habitat destruction)</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe what occurs in the light-independent reaction / Calvin Cycle. MS [7]"1. Carbon dioxide combines with ribulose bisphosphate / RuBP; <font color=""#ff0000"">5C + 1C</font><br>2. Produces two glycerate (3-)phosphate / GP; <font color=""#ff0000"">2 x 3C</font><br>3. GP reduced to triose phosphate / TP; <font color=""#ff0000"">2 x 3C</font><br>4. Using reduced NADP; (provides H)<br>5. Using energy from ATP;<br>6. Some triose phosphate converted to glucose / hexose / other useful organic substnaces<div>7. Some triose phosphate is used to generate RuBP in the Calvin Cycle</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe what occurs during the light-dependent reaction MS [7]"1. Chlorophyll absorbs light energy;<br>2. Excites electrons / electrons removed (from chlorophyll);<br>3. Electrons move along carriers / electron transport chain releasing energy;<div><br><div><i>3b. Energy used to pump H+ across thylakoid membrane; H+ diffuses out through ATP synthase, providing energy for ATP synthesis</i></div><div><i><br></i>4. Energy used to join ADP and Pi to form ATP;<br>5. Photolysis of water produces protons, electrons and oxygen;<br>6. NADP reduced by electrons / electrons and protons / hydrogen;</div></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What enzyme catalyses the reaction of RuBP to form 2GP?"Rubisco <br><br> Copyright © StemUp 2023 | All Rights Reserved " What does the Pacinian corpuscle illustrate? [2] "<ul><li>receptors respond only to <b>specific stimuli</b></li><li>stimulation of a receptor leads to establishment of a GeneratorPotential </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how applying pressure ot the Pacinian Corpuscle leads to the generation of an AP. [5]"<ul><li>Pressure causes membrane / lamellae to become <font color=""#ff0000"">distorted </font>/ stretched;</li><li><font color=""#ff0000"">Stretched-mediated</font> Na+ ion channels open</li><li>Na+ ions diffuse into the neurone; <font color=""#ff0000"">depolarising </font>the membrane and producing a GP</li><li>Greater pressure causes <font color=""#ff0000"">more </font>channels to open / more Na+ to enter <br></li><li>GP creates AP if <font color=""#ff0000"">threshold </font>reached</li><br></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Where are Pacinian Corpuscles present? [2]"<ul><li>abundant deep in the skin</li><li>occur in joints, ligaments and tendons i.e fingers, feet soles, external genatalia </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Sketch and label the structure of the Pacinian Corpuscle: "<img src=""Structure-of-Pacinian-corpuscle.png""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Draw a diagram to <b>contrast </b>the differences in neural pathways of rod and cone cells. "<img src=""Connection-of-rods-and-cones.png""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " The heart controls and coordinates the regular contraction of the atria and the ventricles. Describe how. MS [7] "1. SAN initiates heartbeat / acts as a pacemaker / myogenic;<br>2. SAN sends wave of electrical activity across atria causing atrial<br>contraction;<div>3. Non-conducting tissue prevents immediate contraction of ventricles / prevents<br>impulses reaching the ventricles;<br>4. AVN delays (electrical activity / impulses);<br>5. (Allowing) atria to empty before ventricles contract / ventricles to fill before they<br>contract;<br>6. (AVN) sends wave of electrical activity / impulses down Bundle of His / Purkyne<br>fibres;<br>7. Causes ventricles to contract from base up / ventricular systole;</div><div><img src=""a3gkASD.gif""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What does SAN stand for?"sinoatrial node <br><br> Copyright © StemUp 2023 | All Rights Reserved " What does AVN stand for?"atrioventricular node <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two branches of the autonomic nervous system and their functions?"1. Parasympathetic; inhibits effectors<div>2. Sympathetic; stimulates effectors</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the carotid arteries?"arteries that serve the brain <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how chemoreceptors respond to a low pH / high CO<sub>2</sub> blood conc. [5]"1. Chemoreceptors (in carotid arteries / aorta) detect rise in CO<sub>2</sub> / acidity / fall in pH<div>2. Increases frequency of impulses to cardiac centre / medulla oblongata</div><div>3. Increases frequency of impulses to the SAN via the <font color=""#ff0000"">sympathetic nervous system</font></div><div>4. <font color=""#ff0000"">Noradrenaline </font>is secreted at synapse between sympathetic neurone + SAN; (stimulates SAN)</div><div>5. Increases rate of electrical wave production by the SAN; increases heart rate</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how chemoreceptors detect a rise in blood pH / low CO<sub>2</sub> blood conc. [5]"1. Chemoreceptors (in carotid arteries / aorta) detect fall in CO<sub>2</sub> / rise in pH<div>2. Increases frequency of impulses to cardiac centre / medulla oblongata</div><div>3. Increases frequency of impulses to the SAN via the <font color=""#ff0000"">parasympathetic nervous system</font></div><div>4. <font color=""#ff0000"">Acetylcholine </font>is secreted at synapse between parasympathetic neurone + SAN; (stimulates SAN)</div><div>5. Decreased rate of electrical wave by the SAN; lowers heart rate</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How does an increased heart rate lead to a decrease in the blood conc. of CO<sub>2</sub> ?"<ul><li>Increased blood flow</li><li>More CO<sub>2</sub> removed by the lungs</li><li>Conc. returns to normal </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how baroreceptors detect and respond to a rise in blood pressure. [5] "1. Baroreceptors detect rise in blood pressure<div>2. Increases the frequency of impulses to the cardiac centre / medulla</div><div>3. Increases the frequency of impulses to the SAN via the <font color=""#ff0000"">parasympathetic </font>nervous system </div><div>4. Acetylcholine is released at the synapse between the para neurone and the SAN</div><div>5. <font color=""#ff0000"">Decreases </font>the rate of production of electrical waves by the SAN; therefore decreases heart rate </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how baroreceptors detect and respond to a fall in blood pressure. [5] "1. Baroreceptors detect fall in blood pressure<div>2. Increases the frequency of impulses to the cardiac centre / medulla</div><div>3. Increases the frequency of impulses to the SAN via the <font color=""#ff0000"">sympathetic </font>nervous system </div><div>4. Noradrenaline is released at the synapse between the sympathetic neurone and the SAN</div><div>5. <font color=""#ff0000"">Increases </font>rate of production of electrical waves by the SAN; therefore increases heart rate </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'limiting factor'."At any given moment, rate of a physiological process is limited by the factor that is at its least favourable value <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 5 key limiting factors of photosynthesis?"1. Light intensity<div>2. Temperature</div><div>3. Avaliability of water</div><div>4. Avaliability of chlorophyll</div><div>5. Avaliability of CO<sub>2</sub></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by 'compensation point'?"<ul><li>No net exchange of gases</li><li>Rate of photosynthesis is equal to the rate of respiration </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How does the effect of <b>temperature </b>provide evidence for the light independent reaction?"<ul><li>A purely photochemical reaction won't be affected by temperature</li><li>Photosynthesis <b>is </b>affected by temperature; its not a purely light based reaction</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the percentage of CO<sub>2</sub> in the atmosphere?"0.04% <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the optimum concentration of CO<sub>2</sub> required for photosynthesis?"0.1% <br><br> Copyright © StemUp 2023 | All Rights Reserved " T/F: Plants do not respire during the day. Explain your answer. "<ul><li>FALSE.</li><li>Plants respire ALL the time; to produce ATP. </li><li>Respiration is often masked by photosynthesis; which produces oxygen faster than respiration takes it up. Hence, the effects of respiration aren't always apparent until night when photosynthesis stops. </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why do photosynthesis and respiration have different <b>optimum </b>temperatures?"<ul><li>Catalysed by <b>different enzymes</b><br></li><li>Different <b>optimums</b></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain why the rate of the LIR decreases at low temperatures. MS [3] "<ul><li>Enzymes involved</li><li>Slower rate of enzyme at lower temperatures</li><li>Less kinetic energy / fewer collisions</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why are glasshouses used in agriculture? [3]"<ul><li>Better yield</li><li>Crops can be grown out of season</li><li>Grow plants in regions they would not occur naturally </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How are glasshouses used in agriculture?"Optimum conditions for plant growth are maintained<br><div><ul><li>Optimum temperature</li><li>Water loss controlled</li><li>Humidity monitored</li><li>Specific wavelengths of light used </li></ul><div>With these limiting factors controlled, higher levels of photosynthesis means more carbs are produced. Produce energy for faster growth and fruit formation. </div></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how light intensity / <b>wavelength </b>affects the rate of photosynthesis. [4]"<b>INTENSITY:</b><div><ul><li>More energy for photoionisation in the L.D.R; hence faster rate of photosynthesis</li><li>If low, LDR is slower. ATP and NADPH not produced, hence conversion of GP into TP will be slower. GP will rise (still being made) and TP + RUBP will fall (used to make GP) </li></ul><div><b>WAVELENGTH:</b></div><ul><li>Light needs to be at a particular <b>wavelength </b>(leaves look green because they reflect green light - they absorb blue + red)</li><li><b>Different pigments absorb </b><b>different wavelengths </b></li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how temperature affects the rate of photosynthesis. [3]"<ul><li>Calvin Cycle is controlled by enzymes (e.g rubisco)</li><li>At low temperatures, slower reactions as enzyme works more slowly</li><li><b>Levels of RuBP, GP and TP will fall </b></li><li>Increasing temp. increases rate up to optimum; beyond optimum, rate decreases.</li><li>High temp can cause stomata to close (stress response): less CO<sub>2, </sub>less Calvin Cycle</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why is photosynthesis slow in green light? MS [3]"<ul><li>Less absorption of light / more reflection of (green) light;</li><li>Due to the green colour of chlorophyll;</li><li>Light required for light dependent reaction / photolysis;</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why is it important for plants to produce ATP in respiration as well as photosynthesis? MS [6]"<ul><li>ATP required for Active Trans</li><li>ATP required for synthesis of macromolecules</li><li>Plants use more ATP than produced in photosynthesis</li><li>No ATP production in the dark</li><li>Some tissues unable to photosynthesise</li><li>ATP cannot be moved from cell to cell</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div>How do rod cells enable us to see in conditions of low light intensity? MS [4]</div>""<div>1.     Several rod cells to each neuron/convergence;</div> <div>2.     Principle of additive effect of light striking several rod cells/(<b>spatial</b>) summation; </div> <div>3.     Exceeds threshold;</div> <div>4.     Individual generator potentials do not exceed threshold;</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " <div>How does spatial summation work? MS [3]</div>"<ul><li>Impulses from two neurones;</li><li>Causes sufficient depolarisation</li><li>To reach threshold</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How do cone cells enable us to distinguish between objects close together? MS [2]"<ul><li>Each cone connected to a single neuron;</li><li>Brain receives information from each cone individually</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why is dry mass an approximate measure? MS [2]"<div>●      Dry mass measures / determines increase in biological / organic material;<br></div> <div>●      Water content varies;</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How do you measure dry mass? MS [2] "<div>●      Record mass and reheat</div><div>●      Until constant mass recorded</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What factors must be considered when evaluating a study? [10]"<ul><li>Number of times the study was carried out - sufficient times?</li><li>Sample size - too big/small</li><li>Control experiment - done/not done</li><li>Period of time - long/short</li><li>Carried out in animals/culture - representative of humans?</li><li>Shown as % changes - comparable if so</li><li>Sampling bias - chosen randomly?</li><li>Double blind test / placebo</li><li>Statistical test - results may not be significant</li><li>Patients lying - over/under exaggerate</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " In general, what variables must be controlled in a <b>human </b>study?"<ul><li>Age</li><li>Lifestyle</li><li>Ethinicity</li><li>Exercies</li><li>Smoking</li><li>Diet</li><li>Weight</li><li>Medical History</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " In general, what variables must be controlled in a <b>plant </b>study?"<ul><li>Species</li><li>Height</li><li>Number of leaves</li><li>Number of stomata</li><li>Leaf SA<br></li><li>Light Intensity</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how CO<sub>2</sub> levels affects the rate of photosynthesis. [2] "<ul><li>When its low, conversion of RuBP to GP is <font color=""#ff0000"">slow </font>(there’s less CO2 to combine with RuBP to make GP)</li><li>The level of RuBP will rise (still being made) and levels of GP and TP will fall (used to make RuBP)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Suggest how water stress could affect the rate of photosynthesis in a plant."<ul><li>Plants don't have enough water - stomata will close to save the little water that they have</li><li>Less CO<sub>2</sub> will enter</li><li>Slower rate of Calvin Cycle (less CO2 to combine with RuBP)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " SL:  Organisms {{c1::increase their chance of surviva}}l by {{c2::responding to changes in their environment. }} <div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div><div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div> Describe innate behaviour. [3] "<ul><li>Inherited</li><li>(often) automatic</li><li>May be involved in finding mates, food, suitable conditions etc. </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define 'Taxis'. "A <u>directional </u>movement response where the animal moves towards the stimulus or away from the stimulus. The response direction is determined by the direction of the stimulus.  <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how IAA results in gravitropism in roots: [6]"<ul><li>Cells in root tip produce IAA; transported along the root by <b><font color=""#ff1f0f"">diffusion</font></b></li><li>IAA initially transported to all sides</li><li>Gravity causes IAA to move from upper side <font color=""#ff1f0f""><b>to lower side</b></font></li><li>Higher [IAA] on lower side</li><li>IAA inhibits elongation of root cells; lower side <font color=""#ff1f0f""><b>elongates / grows less</b></font></li><li>Root bends downwards to the force of gravity</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how IAA causes phototropism in the shoots. [6]"<ul><li>Cells in shoot tip produce IAA; transported down the shoot by <font color=""#ff1f0f"">diffusion</font></li><li>Initially transported <font color=""#ff1f0f"">evenly </font>throughout all regions</li><li>Light causes movement of IAA to from light side to <font color=""#ff1f0f"">shaded side</font></li><li>Greater [IAA] in shaded side</li><li>IAA causes elongation of shoot cells</li><li>Shaded side elongates faster; tip bends <font color=""#ff1f0f"">towards the light </font></li></ul><div><img src=""n8mCp7m.gif""><font color=""#ff1f0f""><br></font></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the role of specific growth factors in flowering plants?"They move from growing regions to other tissues, where they regulate growth in response to directional stimuli.  <br><br> Copyright © StemUp 2023 | All Rights Reserved " Compare and contrast taxis and tropisms. MS [2] "<div>1.     Similarity − directional response (to a stimulus) / movement towards / away from a stimulus; </div> <div>2.     Difference − taxis (whole) organism moves and tropism a growth (response).</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define receptor. "<div style=""text-align: left;"">a transducer which transforms the energy of the stimulus into another form of</div><div style=""text-align: left;"">energy which will lead to the organism responding to this. They are specific.</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 4 stages of aerobic respiration?"<ul><li>Glycolysis</li><li>Link Reaction</li><li>Krebs Cycle</li><li>Oxidative Phosphorylation / ETC </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Where does glycolysis occur?"cytoplasm <br><br> Copyright © StemUp 2023 | All Rights Reserved " What type of process is glycolysis?"anaerobic (no O<sub>2</sub> required) <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the steps of glycolysis and draw the diagram. MS [6]"<div>1.     Glucose phosphorylated by ATP to give ADP and glucose phosphate;</div> <div>2.     ATP adds another phosphate to form hexose bisphosphate;</div> <div>3.     Split into 2 triose phosphates;</div> <div>4.     Each triose phosphate oxidised to pyruvate;</div> <div>5.     NAD forms reduced NAD (NADH) by accepting H; 1 per TP</div><div>6.     2 ATP formed per TP molecule (4 ATP total)</div><div><br></div><div style=""text-align: center;""><img src=""The_process_of_Glycolysis_(source_https---www.s-cool.co.uk-a-level-biology-respiration-revise-it-glycolysis_).gif""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the net products of glycolysis per glucose molecule?"<ul><li>2x ATP (2 used, 4 produced = 2 net gain)</li><li>2x NADH</li><li>2x Pyruvate </li></ul><div><div><br></div></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the steps in the link reaction. Draw a diagram.  [5] "<ul><li>oxidation of pyruvate; forms acetate</li><li>decarboxylation of pyruvate, CO<sub>2</sub> released</li><li>NAD reduced to form NADH</li><li>addition of CoEnzyme A to acetate</li><li>to form acetyl coenzyme A</li></ul><div style=""text-align: center;""><img src=""paste-a2f7f9c585cb1d4b66dd3f2e5b8ad99831fc5f24.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Where does the link reaction occur?"mitochondrial matrix <br><br> Copyright © StemUp 2023 | All Rights Reserved " How does pyruvate get from the cytoplasm to the mitochondrial matrix?"active transport <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the products of the link reaction per glucose molecule?"<ul><li>2 acetyl coenzyme A</li><li>2 CO<sub>2</sub> </li><li>2 NADH</li></ul><div>Remember that each glucose molecule forms 2 pyruvate molecules. Hence the link reaction occurs twice per glucose molecule. </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a co-enzyme? "<ul><li>Molecule that aids the functions of enzymes</li><li>by transferring a chemical group between molecules</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 co-enzymes in respiration and their functions?"<ul><li>NAD (tranfser H) </li><li>FAD (transfer H)</li><li>CoA (tranfsers acetate)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Compare the number of carbons in an acetate molecule and pyruvate molecule."Pyruvate = 3C<div><br></div><div>Acetate = 2C</div><div><br>One C lost during carboxylation</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the steps in the Kreb's Cycle. Sketch a diagram. MS [6]"<div>1.     Acetyl CoA combines with 4C to form 6C, releases CoA</div> <div>2.     6C converted to 5C </div> <div>3.     decarboxylation and hydrogen removed by NAD to produce reduced NAD;</div> <div>4.     5C converted to 4C</div> <div>5.     decarboxylation and hydrogen removed by NAD/FAD to produce reduced NAD/FAD;</div> <div>6.     ATP produced through substrate level phosphorylation</div><div><br></div><div><img src=""The-Krebs-Cycle_1.png""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the products of the Kreb's Cycle per glucose molecule?"Cycle turns <b>twice </b>for each glucose molecule (remember 2x Acetyl Coenzyme A mols per glucose!)<div><br></div><div><ul><li>6x reduced NAD</li><li>2x reduced FAD</li><li>2x ATP</li><li>4x CO<sub>2</sub></li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall what occurs during the ETC / Oxidative Phosphorlyation. MS [8]"<ul><li>Electrons released from reduced NAD / FAD;</li><li>Electrons pass along carriers / through ETC</li><li>Releasing energy;</li><li>Energy used to actively transport protons into intermembrane space;</li><li>Establishes electrochemical gradient</li><li>H+ move by f.diffusion through ATP synthase back into matrix</li><li>Resulting in the formation of ATP: ADP + Pi --> ATP </li><li>O<sub>2</sub> is the final electron acceptor / H+, e- and O<sub>2</sub> form H<sub>2</sub>O</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how lipids can be used an alternative respiratory substrate. [2]"<ul><li>hydrolysed to glycerol and FattyA</li><li>glycerol phosphorlyated > triose phosphate</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why do lipids release 2x the energy contained in carbohydrates when used in respo?"make 2C fragments of carbohydrates and many H+ ions<br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Where does the ETC take place?"the inner membrane of the mitochondria, along the cristae <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the source of e- in the ETC?"<ul><li>H atoms carried by co-enzymes (FADH and NADH)</li><li>they're oxidised, release H: H -> H+ + e- </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall what happens to <b>pyruvate </b>in anaerobic conditions and explain why this is advantageous to <b>humans. </b>MS [5]<div><br></div><div><br></div>"<div>1.     Reduced to lactate;</div> <div>2.     Using reduced NAD;</div> <div>3.     Regenerates NAD;</div> <div>4.     NAD can be reused to allow glycolysis to continue; </div> <div>5.     Can still release energy/form ATP when oxygen in short supply;</div><div><br></div><div><br></div><div><img src=""Lactate-Fermentation.png""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two pathways for anaerobic respiration?"<ul><li>ethanol fermentation (plants)</li><li>lactate fermentation (humans)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the ethanol fermentation pathway for Anaerobic Respiration. [3]"<ul><li>Pyruvate is decarboxylated to ethanal</li><li>Ethanal reduced to ethanol by enzyme alcohol dehydrogenase</li><li>NADH transfers its H to ethanal, which is a H acceptor</li></ul><img src=""Ethanol-Fermentation.png""><br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What two things can happen to lactate after is it produced?"<ul><li>Oxidised back to <b>pyruvate </b>- enters Link</li><li>Converted into <b>glycogen </b>for storage in the liver</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why do animals breath deeper and faster after exercise? [3]"<ul><li>Anaerobic respiration during exercise</li><li>Produces lactate, which is toxic / causes muscle fatigue </li><li>Oxidation of lactate back to pyruvate needs extra oxygen - <b>oxygen debt</b></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how aerobic respiration stops functioning in the absence of oxygen."<ul><li>No <b>final acceptor of electrons </b>in ETC</li><li>ETC stops functioning</li><li>No more ATP via OxPhosp</li><li>NADH, FADH not oxidised by electron carrier (e- arent moving along)</li><li>No oxidised NAD+/FAD+ avaliable for Kreb's </li><li>Kreb's stops</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why is less ATP produced in anaerobic respiration? [3]"<ul><li>No ETC / OxPhospho</li><li>which produces majority of ATP</li><li>Only <b>glycolysis </b>occurs (net 2ATP per glucose)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the importance of the regenerated molecule in the lactate/ethanol fermentation pathways? [2]"<ul><li>NAD+ is regenerated</li><li>Used in further glycolysis</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain why an athlete's ATP is provided by anaerobic rather than aerobic respiration. MS [2]"<ul><li>high respiration rate / energy demand is high</li><li>insufficient oxygen in muscles to aerobically respire</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain why athletes will breath heavily after a race. [2]"<ul><li>lactate oxidised into pyruvate (repay oxygen debt)</li><li>by <u>aerobic </u>respiration</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the compounds in the Kreb's cycle?"6C = Citrate<div>5C = Intermediate</div><div>4C = Oxaloacetate </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe the piece of apparatus used to measure the rate of respiration. "<ul><li>Using a respirometer</li><li>Removal of O<sub>2</sub> in the tube reduced volume and pressure</li><li>Fluid moves toward the organism</li></ul> <img src=""PB_measuring-rate-of-metabolism-respirometer2-500.jpg""><br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the purpose of soda lime in a respirometer?"<ul><li>Absorbs CO<sub>2</sub> </li><li>Ensures movement is only due to the intake of O<sub>2</sub> </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Muscles act in {{c1::antagonistic pairs}} against an {{c1::incompressible skeleton}} Recall how muscles work in antagonistic pairs. [5]<br>"<ul><li>Muscles can only pull</li><li>They work in opposing pairs (e.g hamstring + quads / biceps + triceps)</li><li>Contracting muscle = agonist</li><li>Relaxing muscle = antagonist</li><li>Muscle contracting becomes 'shorter' </li></ul><div><br></div><div><img src=""paste-8ebb0ad10c7edbc4ea796d20e85ef83732ebf81f.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how muscles help maintain posture. MS [5]"<ul><li>Antagonistic muscles / opposing pairs;</li><li>Working across joints;</li><li>Both contract to keep joint / the body at a certain angle / upright;</li><li>Isometric contraction;</li><li>Only a few fibres contract to avoid fatigue / slow muscle fibres used; <br></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are muscles?"effector organs which respond to nervous stimulation by contracting <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are muscle cells more commonly known as?"myocytes (cells that make up muscle tissue) <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 types of muscle cell and where are they found?"<ul><li>cardiac - found only in the heart</li><li>skeletal - found in walls of gut / blood vessels</li><li>smooth - attached to our bones, under voluntary control </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " (OFF SPEC) What are the adaptations of cardiac myocytes? [4]"<ul><li>Myogenic</li><li>Branched (faster signal propagation)</li><li>Intercalated discs (cells not connected)</li><li>More mitochondria (reliant on aerobic respo)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Contrast ligaments vs tendons."<ul><li>Ligaments = connect bone to bone</li><li>Tendons = connect bone to muscle</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a sarcomere?"the basic unit of muscle contraction in a myofibril (which is in a muscle cell) <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the divisions of a skeletal muscle. "<ul><li>Muscle Tissue - Bundles of Muscle Fibre - Single Muscle Fibre - Myofibrils - Sarcomere (basic unit)</li></ul><div><img src=""paste-614bb9768288fa34b931b9570b368c62944396b8.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<img src=""paste-e243b9afaac73122cf45e79fdd042ec0e8fa2cfd.jpg"">""<img src=""paste-51fded89817a2fa976774c876d2c6668278e63fd.jpg""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the structure of skeletal muscles. [4]"<ul><li>Skeletal muscles made up of many fibres called <font color=""#ff0000"">myofibrils</font>; which are divided into contractual units called <font color=""#ff0000"">sarcomeres</font></li><li>Muscle fibres fused together + <font color=""#ff0000"">share nuclei</font> and cytoplasm (<font color=""#ff0000"">sarcoplasm</font>)</li><li>Myosin + actin filaments <font color=""#ff0000"">overlap</font>, strenghtening the muscle</li><li>Sarcoplasm contains <font color=""#ff0000"">sarcoplasmic reticulum</font> + mithcondria</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the difference between myofibrils and sarcomeres?"<ul><li>Myofibrils = contracting units of muscles</li><li>Sarcomeres = repeating units of the myofibril</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Sketch a rough sarcomere. "<div><br></div><div><img src=""paste-849dba1d2fd17a9e75ba66edabe304211b4fd684.jpg""><br><br></div><div><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<img src=""paste-650024379727bd1dd61a22db253e3ac8f3db8f14.jpg"">""<img src=""paste-7258b4c3763a8a247ed591c5fed456e467e13bca.jpg""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two types of muscle fibres?"<ul><li>Slow twitch</li><li>Fast twitch</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How does the function of slow twitch fibres differ from fast twitch fibres? [3] "<ul><li>ST contract more slowly; FT contract rapidly</li><li>ST provide less powerful contractions; FT powerfully contract</li><li>ST contract over longer periods of time = endurance work; FT adapted for intense exercise<br></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the adaptations of ST muscle fibres. [3]"<ul><li>Large myoglobin store (stores oxygen)</li><li>Rich supply of blood vessels (aerobic respiration)</li><li>Numerous mitochondria </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the adaptations of FT muscle fibres. [4]"<ul><li>Thicker, more numerous myofilaments</li><li>Higher [Glycogen]</li><li>Higher [Enzyme] involved in AnRes, provides ATP rapidly</li><li>Stores phosphocreatine</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<div>What is the role of phosphocreatine (PC) in providing energy during muscle contraction? MS [2]</div>""<div>1.     provides phosphate;</div> <div>2.     To make ATP (ADP + CP → ATP + C ); </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Where would you find ST muscle fibres? Why?"<ul><li>lower legs</li><li>muscle in the back</li></ul><div>helps you to stand / hold posture for long periods of time</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall what is meant by Respiratory Quotient. What information can we deduce from it?"RQ = Volume of CO<sub>2</sub> produced / Volume of O<sub>2</sub> absorbed<div><br></div><div>If:</div><div><ul><li>RQ > 1 implies mainly anaerobic respiration</li><li>RQ = 1 implies aerobic respo of glucose</li><li>RQ < 1 implies aerobic respo of another substrate (e.g lipids / proteins)</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain why, in terms of respiration, a trained organism would be able to exercise for a longer period of time than an untrained one. MS [3]"<ul><li>(adaptations e.g more dehydrogenase means..) More ATP produced</li><li>Anaerobic respiration delayed</li><li>Less lactic acid (which would cause muscle fatigue) </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-1-Q.svg""></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg""></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-1-A.svg""></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg""></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); 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original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-2-A.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg""></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-3-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-3-A.svg""></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-4-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg""></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-4-A.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg""></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-5-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg""></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-5-A.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg""></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-6-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""b2b8fc1aa5c44c77a995a8d990b9cb1a-ao-6-A.svg""></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-1-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-1-A.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-2-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-2-A.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-3-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-3-A.svg""></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-4-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-4-A.svg""></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-5-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-5-A.svg""></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-6-Q.svg"" /></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""59da03aa97054caf9593f1b3c909f061-ao-6-A.svg""></div> <div id=""io-original""><img src=""paste-8b29ae6c02acba9727cdb36a47f77dc76fadf4e3.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Use the string analogy to explain the organisation of a muscle fibre."<ul><li>Myofibrils (threads) make up a single muscle fibre (string)</li><li>These single muscle fibres group to make a bundle of muscle fibres (small rope)</li><li>Bundles of muscle fibre further grouped into muscle tissue (large rope)</li></ul><div><img src=""paste-a48682eb42a4f241f5025291b9a2d6252446b075.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why have the separate cells of muscles fused together to form fibres?"<ul><li>If individual cells joined end-to-end; junction would be a point of weakness</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How are myofibrils arranged within a single muscle fibre?"<ul><li>They are lined up parallel to each other</li><li>in order to give maximum force when contracting </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the sarcoplasm?"cytoplasm shared between muscle fibre cells <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<b><span style=""font-weight: 400;"">What is the role of </span>calcium ions <span style=""font-weight: 400;"">in myofibril contraction? MS [4]</span></b>""<b><div><span style=""font-weight: 400;"">1. Calcium ions diffuse into myofibrils from (sarcoplasmic) reticulum;</span></div><div><span style=""font-weight: 400;"">2. (Calcium ions) cause movement of tropomyosin (on actin);</span></div><div><span style=""font-weight: 400;"">3. (This movement causes) exposure of the binding sites on the actin;</span></div><div><span style=""font-weight: 400;"">4. Myosin heads can now attach to binding sites on actin; (to form an actinomyosin bridge</span></div></b><br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<b><span style=""font-weight: 400;"">What is the role of </span>ATP <span style=""font-weight: 400;"">in myofibril contraction? MS [3]</span></b>""<b><ul><li><b><div><span style=""font-weight: 400;"">Hydrolysis of ATP (on myosin heads) causes myosin heads to bend;</span></div></b></li><li><b><div><span style=""font-weight: 400;"">(Bending) pulling actin molecules; </span>power stroke</div></b></li><li><div><span style=""font-weight: 400;""> Attachment of a new ATP molecule to each myosin head causes myosin heads to detach (from actin sites).; </span>recovery stroke</div></li></ul></b><br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<b><span style=""font-weight: 400;"">What is the role of </span>ATPase <span style=""font-weight: 400;"">in myofibril contraction? MS [3]</span></b>""<b><div><span style=""font-weight: 400;"">1. Splitting/breakdown/hydrolysis of ATP;</span></div><div><span style=""font-weight: 400;"">2. (Muscle) contraction requires energy / ATP;</span></div><div><span style=""font-weight: 400;"">3. Use of ATP by myosin (to bend / detach)</span></div></b><br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the structure of myosin. [2]"made up of two types of protein:<div><ul><li>fibrous protein (the tail)</li><li>globular protein forming two bulbous heads</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What type of protein is actin?"globular <br><br> Copyright © StemUp 2023 | All Rights Reserved " Give an example of where you'd find a high proportion of ST muscle fibres."<ul><li>Calf Muscle</li><li>Contract constantly to maintain the body in an upright position. </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Give an example of where you'd find a high proportion of FT muscle fibres."<ul><li>Muscles that are adapted to high intensity exercise</li><li>Bicep muscles of the upper arm</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall what occurs during muscle relaxation. [4]"<ul><li>Ca<sup>2+</sup> ions move by Atrans back to sarcoplasmic reticulum</li><li>Uses energy from ATP</li><li>Reabsorption of Calcium causes tropomyosin to block actin filament </li><li>Myosin heads no longer able to bind</li></ul><div><br></div><div>NB: MS will likely just say that ''ATP results in the detachment of myosin head from actin'' </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how muscular contraction is stimulated when an AP reaches the end of a motor neurone. [6]"<ul><li>AP arrives at NMJ</li><li>Influx of Ca<sup>2+</sup> and release of acetyl choline (from presynapse)</li><li>Acetylcholine diffuses across cleft; binds to receptor sites on sarcolemma</li><li>Influx of Na+, causes AP in sarcolemma</li><li>Impulse carried through the muscle fibres through <b>T-tubules</b></li><li>Triggers release of Ca<sup>2+</sup> from sarcoplasmic reticulum </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Plants synthesise organic compounds from {{c1::atmospheric or aquatic CO<sub>2</sub>}} "Most of the sugars synthesised by plants are used as {{c1::respiratory substrates}}. The rest are used to make other groups of biological molecules, forming the {{c1::biomass}} of the plant." Biomass is the {{c1::total mass of living material in a specific area at a given time}} "Dry biomass shows the {{c1::chemical energy store in an organism}} and can be measured by the process of {{c2::calorimetry}}" <div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div><div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div> "Gross primary production (GPP) is defined in words as {{c1::the chemical energy stored in plant biomass, in a given area or volume}}" "NPP is defined as {{c1::the chemical energy store in plant biomass after respiratory losses to the environment have been taken into account}}" {{c2::NPP}} = {{c1::GPP - R}} <div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div><div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div> What are the units for GPP, NPP + R?"kJ m<sup>-2</sup> yr<sup>-1</sup> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "<img src=""paste-367f66e7aa8d9a9556986770b2df793e73c74b5e.jpg"">""The NPP is available for {{c1::plant growth and reproduction}}. It is also available for {{c2::consumers in the food chain such as herbivores and decomposers}}." "The NPP is available for {{c1::plant growth and reproduction}}. It is also available for {{c2::consumers in the food chain such as herbivores and decomposers}}.""<img src=""paste-367f66e7aa8d9a9556986770b2df793e73c74b5e.jpg"">" "Net production (N) is {{c1::the total chemical energy consumers store after energy losses to faeces, urine and respiration have been taken away from the chemical energy store of the ingested plant food}}" "Equation for Net Production:    {{c1::N = I - (F + R) <div><br></div><div><br></div><div>Where N is net production, I represents the total chemical energy store in ingested food, F is the energy lost in faeces and urine, and R is energy lost to respiration. All use units (kJ m-2 yr-1)</div>}}" "Primary and secondary productivity is the {{c1::rate of primary or secondary production, respectively}}. It is measured as {{c2::biomass in a given area in a given time e.g. kJ ha–1 year–1}}" <div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div><div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div> "Equation for the percentage efficiency of energy transfer between trophic levels:<div><br></div><div>{{c1::<img src=""paste-d570a5230cd1bb3e74632b39a459e5be456a8b42.jpg"">}}<br></div>" How do farming practises increase efficiency of energy transfer to increase yields? [2]"<ul><li>Reducing respiratory losses in a human food chain e.g reducing the movement / energy expenditure of farm animals</li><li>Simplifying food webs to reduce energy losses to non-human food chains e.g killing weeds + pests using herbicides and insecticides </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " There is a {{c1::finite supply of nutrients}} on Earth, which are recycled within {{c2::natural ecosystems}}. "<br><br> Copyright © StemUp 2023 | All Rights Reserved " Why do organisms need nitrogen?"Source to manufacture:<div><ul><li>nucleic acids</li><li>proteins</li><li>nitrogen-containing compounds</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How do plants take in nitrogen?"nitrate ions in the soil <br><br> Copyright © StemUp 2023 | All Rights Reserved " How do animals obtain most of their nitrogen-containign compounds?"eating + digesting plants <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""3c03e78017554758927ded09464a827b-ao-1-Q.svg""></div> <div id=""io-original""><img src=""paste-3c5a4fa7ee780af6acd7ac935d0393798c63de67.jpg""></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; 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original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""3c03e78017554758927ded09464a827b-ao-6-Q.svg"" /></div> <div id=""io-original""><img src=""paste-3c5a4fa7ee780af6acd7ac935d0393798c63de67.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""3c03e78017554758927ded09464a827b-ao-6-A.svg"" /></div> <div id=""io-original""><img src=""paste-3c5a4fa7ee780af6acd7ac935d0393798c63de67.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""75575e1c86a8424cb7dddfb966fdbec1-oa-1-Q.svg"" /></div> <div id=""io-original""><img src=""paste-3ff996601a4b39d2c21bc5e5ed3bbe656cfc0b60.jpg""></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""75575e1c86a8424cb7dddfb966fdbec1-oa-1-A.svg"" /></div> <div id=""io-original""><img src=""paste-3ff996601a4b39d2c21bc5e5ed3bbe656cfc0b60.jpg""></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""75575e1c86a8424cb7dddfb966fdbec1-oa-2-Q.svg"" /></div> <div id=""io-original""><img src=""paste-3ff996601a4b39d2c21bc5e5ed3bbe656cfc0b60.jpg"" /></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""75575e1c86a8424cb7dddfb966fdbec1-oa-2-A.svg"" /></div> <div id=""io-original""><img src=""paste-3ff996601a4b39d2c21bc5e5ed3bbe656cfc0b60.jpg"" /></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "Recombinant DNA technology involves {{c1::the transfer of fragments of DNA from one organism, or species, to another}}" Why can transferred DNA be translated within cells of the transgenic organism?"genetic code is universal, as are transcription and translation mechanisms <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is recombinant DNA?"<b><span style=""font-weight: 400;"">DNA of two different species / two </span><u>types </u><span style=""font-weight: 400;"">of organisms that has been combined </span></b> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 methods of producing DNA fragments?"<ul><li>conversion of mRNA to cDNA using reverse transcriptase</li><li>using restriction enzymes to cut a fragment containing the desired gene from DNA</li><li>creating the gene in a 'gene machine'</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how reverse transcriptase can be used to isolate a gene. [6]"<ul><li><b><div style=""display: inline !important;""><span style=""font-weight: 400;"">Cells that produce a large amount of mRNA for a required protein are identified</span></div></b></li><li><b><div style=""display: inline !important;""><span style=""font-weight: 400;"">Cells centrifuged to break open + release mRNA</span></div></b></li><li><b><div style=""display: inline !important;""><span style=""font-weight: 400;"">Free DNA nucleotides added to mRNA</span></div></b></li><li><b><div style=""display: inline !important;""><span style=""font-weight: 400;"">cDNA strand formed using reverse transcriptase</span></div></b></li><li><b><div style=""display: inline !important;""><span style=""font-weight: 400;"">Enzyme hydrolyses the mRNA (ribonuclease H)</span></div></b><br></li><li><b><div style=""display: inline !important;""><span style=""font-weight: 400;"">mRNA and cDNA now separated, single strand of cDNA</span></div></b></li><li><b><div style=""display: inline !important;""><span style=""font-weight: 400;"">DNA polymerase then catalyses formation of complementaty strand to the cDNA; producing a double helix of DNA</span></div></b></li></ul><div><img src=""paste-62d6c1f0d75b0564ed8dcbc2ee0861ffdd014cee.jpg""><br></div><br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are endonucleases?"Enzymes produced by bacteria to cut up viral DNA as a defensive measure  <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how restriction endonucleases can be used to produce DNA fragments."<ul><li>Cut DNA at specific sites, about 4-8 base pairs long, called<font color=""#ff0000""><b> recognition sites</b></font></li><li>Recognition sites are usually <font color=""#ff0000""><b>palindromic</b></font></li><li>RE makes staggered cuts will leave exposed bases on either end (sticky ends)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how we use a 'gene machine' to produce DNA fragments."<ul><li>Sequence of bases determined</li><li>Triplets worked out + fed into computer</li><li>Computer designs <b><font color=""#ff0000"">oligonucleotides</font></b>, which are assembled into the desired gene</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Once we have synthesised a gene, how is it amplified <i>in vitro</i>?"PCR (polymerase chain reaction) <br><br> Copyright © StemUp 2023 | All Rights Reserved " Draw a diagram that summarises the nitrogen cycle. "<img src=""paste-3ff996601a4b39d2c21bc5e5ed3bbe656cfc0b60.jpg""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are mycorrhizae?"<ul><li>Certain types of fungi associate with roots of plants</li><li>Increase SA for absorption of water + mineral ions</li></ul><div><br></div><div><img src=""kWO1zcDVYWFQ7L7Phf7PGJXluqw_dKpzFcFXSDGqybvrGYY0xRTnS4VXv61TY86wlU9x9kMPqxsjbK0F54MXHX64aTUzV1qSE-A1UgasiiPVFwRRXjq.png""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 4 stages of the Nitrogen Cycle?"<ul><li>Nitrogen Fixation</li><li>Ammonification</li><li>Nitrification</li><li>Denitrification</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall what occurs during nitrogen fixation. "<ul><li>N<sub>2</sub> converted to N-containing compounds</li><li>by nitrogen-fixing bacteria (either mutalistic or free-living)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the two types of nitrogen-fixing bacteria and their functions."<div><b><u>Free-Living:</u></b></div><div><ul><li>Reduce N<sub>2</sub> into <font color=""#ff0000"">ammonia</font>, which are used to make AA. </li></ul><div><b><u>Mutualistic:</u></b></div></div><div><ul><li>Use N<sub>2</sub> to produce AA. </li><li>Mutualistic: because they obtain Carbohydrates from plants; plants obtain AA from bacteria</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall ammonification. [3]"<ul><li>The production of <font color=""#ff0000"">ammonia </font>from organic N-containing compounds</li><li><font color=""#ff0000"">Saprobiontic micro-organisms</font> feed on <b>faeces </b>+ <b>dead organisms</b></li><li>Releasing <font color=""#ff0000"">ammonia </font>which then form ammonium ions in the soil. </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall Nitrification."<ul><li>Ammonium ions are oxidised to produce to <b>nitrites </b>then oxidised to <b>nitrates <font color=""#ff0000"">(two stage oxidation reaction)</font></b></li><li>by nitrifying bacteria</li></ul><div><br></div><div><img src=""paste-e7d0024677ace952467f1c70e29cdbad1e2bbe60.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall Denitrification."<ul><li>Nitrates are converted back to N<sub>2</sub> gas</li><li>by anaerobic, denitrifying bacteria<br></li><li>Not useful as N<sub>2</sub> cannot be absorbed by plants</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why does waterlogging reduce nitrate content in the soil?"<ul><li>Type of micro-organism changes</li><li><b>Fewer </b>aerobic nitrifying and nitrogen-fixing bacteria</li><li><b>More </b>anaerobic denitrifying bacteria</li><li>Convert nitrates into gaseous nitrogen </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Besides the nitrogen cycle, what are the 2 other ways nitrogen can be fixed?"<ul><li>Lightning (fixes N<sub>2</sub> into nitrogen oxides)</li><li>Artificial fertilisers (haber process)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why is phosphorous essential?"to form DNA, ATP, RNA and Phospholipid Bilayers (in CSM) <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how farming practices increase the productivity of agricultural crops MS [5]"<ul><li>Fertilisers / minerals added to soil</li><li>Nitrate / nitrogen for proteins OR Phosphate / phosphorous for ATP / DNA</li><li>Selective breeding / genetic modification of crops</li><li>Ploughing/aeration allows nitrification / decreases denitrification</li><li>Benefits of crop rotation / increases soil nutrients</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are saprobiontic micro-organisms?"<ul><li>Microorganisms that feed on faeces and dead matter</li><li>Releasing ammonia, which forms ammonium ions in the soil</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe how the action of micro-organisms in the soil produces a source of nitrates for crop plants. MS [7]"<ul><li>Protein / AA / DNA into ammonium compounds / ammonia</li><li>by saprobionts</li><li>Ammonium into nitrite</li><li>Nitrite into nitrate</li><li>by nitrifying bacteria (microorganisms)</li><li>Nitrogen to ammonia</li><li>by nitrogen-fixing bacteria </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Draw the phosphorous cycle. "<img src=""paste-a10bdcbdca780425c97524440742fc2f2f9173cd.jpg""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the steps in the Phosphorous Cycle. "<ul><li>PO<sub>4</sub><sup>3- </sup> released by rocks into the soil due to weathering/erosion</li><li>Plants absorb these phosphate ions</li><li>Animals eat + digest these plants and use these ions to synthesise organic matter</li><li>Excess PO<sub>4</sub><sup>3- </sup> are excreted by animals</li><li>On death, decomposers (some fungi + bacteria) break these animals down releasing PO<sub>4</sub><sup>3- </sup> to water / soil</li><li>PO<sub>4</sub><sup>3- </sup> found in bones/shells, but slow release<br></li><li>Some PO<sub>4</sub><sup>3- </sup> is transported by streams / lakes where they form sedimentary rocks</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why are fertilisers needed?"to replace nitrates + phosphates lost by harvesting plants and removing livestock <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two types of fertilisers?"<ul><li><b>Natural </b>- dead/decaying remains of plants/animals (manure, slurry and bone meal)</li></ul><div><br></div><ul><li><b>Artificial </b>- mined from rocks before being converted into different forms with their composition tailored for specific crops.</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 negative effects of using fertilisers?"<ul><li>Reduced species diversity</li><li>Leaching (polluting waterways)</li><li>Eutrophication</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How does the use of N-containing fertilisers reduce species diversity?"<ul><li>N-rich soil favours rapidly growing species e.g grasses/nettles</li><li>Out-compete other species</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is leaching?"<ul><li>Process by which nutrients are removed from the soil</li><li>Find their way into watercourses (streams, rivers)</li><li>Can have a harmful effect on humans if the lake is a source of drinking water</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the process of eutrophication and how it leads to the death of aquatic organisms. [6]"<ul><li>Mineral ions leached from fertilised fields stimulate rapid growth of algae/plants</li><li>Algae become more densely populated on upper surfaces / <font color=""#ff0000"">algal bloom</font></li><li>Absorbs light / prevents it from reaching plants below</li><li>Plants at the bottom die / unable to photosynthesise</li><li>Saprobiontic bacteria feed on dead plant matter - populations grow</li><li>Bacteria aerobically respire, using up oxygen</li><li>Fish and other aquatic organisms die because there isn't enough dissolved oxygen</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 2 ways in which gene cloning can be carried out?"<ul><li>in vivo - genes inserted into organism that produces copies during normal DNA replication</li><li>in vitro - genes duplicated in a machine using enzymes and rapid temperature changes (e.g PCR)</li></ul><div><br></div><div><img src=""Vyfw8D9Vm1uyG0WZzonRLPvOep5nABNAk3tiENOIjsJpWU7bnTFob_mbTeCZpzCghLZaFkG8KQEqRmBaTDdsRuNONQ.png""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Sticky ends are used in genetic engineering. Explain how. MS [2]"<ul><li>Joining two pieces of DNA;</li><li>By complementary binding/complementary base-pairing;</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why are the same restriction endonucleases used to cut the DNA and the vector?"ensures the sticky ends of the gene + plasmid are <u>complementary </u>to each other  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the promoter region?"<ul><li>sequence within DNA where RNA polymerase binds</li><li>required in order to begin transcription</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the terminator region?"<ul><li>sequence within DNA that causes RNA polymerase to be released and ends transcription</li></ul><div><br></div><div><img src=""paste-0331722c6b52bcc43e3fd8b0c98b1ac5c306abca.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a vector? MS [2]"<ul><li>Carrier of DNA</li><li>into cell / host / other organism</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Describe how PCR is carried out. MS [9]"<ul><li> DNA heated to 90 to 95°C;</li><li> strands separate;</li><li> cooled / to temperature below 70°C </li><li> primers bind;</li><li> nucleotides attach;</li><li> by complementary base pairing;</li><li> temperature 70 - 75°C;</li><li> DNA polymerase joins nucleotides together;</li><li> cycle repeated;</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the role of primers in PCR?"enables replication to start by keeping strands separate <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the 5 stages involved in genetic engineering"1. Isolation: genes isolated<div>2. Insertion: insertion of gene into a vector</div><div>3. Transformation: transfer of DNA into a host</div><div>4. Identification: analysing to see which host cells have taken up gene using gene markers</div><div>5. Growth/cloning: population of host cells rapidly increased</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how a gene is inserted into a plasmid vector."<ul><li>Sticky ends are complementary (since same REnds are used)</li><li>Promoter and terminator regions are added</li><li>DNA ligase forms 2 phosphoidester bonds</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the potential problem with the gene of interest/plasmid having the same sticky ends?"Mismatch - self coiling of plasmid / gene inserted has combined to form new piece of DNA (circularised DNA)<div><br></div><div><img src=""paste-ee828b362f5b3691f2df25cf842e0b347b0fdd94.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two methods of transformation? (insertion of vector into bacteria)"<ul><li>Calcium ions added + heat shock</li><li>Electroporation</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how calcium ions + heat shock are used to insert a vector into a bacteria."<ul><li>Calcium ions added</li><li>Cells heat shocked</li><li>Increases permeability of membrane</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how electroporation is used to insert a vector."<ul><li>DNA negatively charged</li><li>Small electrical field increases permability</li><li>Causes movement of vector into host</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why do only a small % of host cells have the required vector? [2]"<ul><li>Not all plasmids incorporate donor DNA during insertion </li><li>Not all cells incorporate vectors during transformation</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 3 methods of identifying which host cells have taken up the vector?"<ul><li>GFP tagging</li><li>Enzyme marker</li><li>Antibiotic resistance: insertion and disruption</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is GFP tagging used to identify desired host cells?"<ul><li>DNA sequence for GFP inserted into plasmid/donor DNA</li><li>Will light up green</li></ul><div><img src=""paste-782a9c2c0d3663c0963638a2afe1f24eb034c83b.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How are enzyme markers used to identify transgenic host cells?"<ul><li>Sequence for enzyme inserted / disrupted in either plasmid or donor DNA</li><li>E.g lactase is disrupted by insertion of DNA</li><li>Lactase turns colourless substrate blue hence transgenic bacteria will be clear colonies</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is combination gene marking?"<ul><li>GFP / enzyme marker added to both plasmid DNA and Donor DNA</li><li>Allows us to identify hybrid plasmid</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is replica plating?"<ul><li>Technique used to identify transgenic host cell</li><li>Plasmid used contains two antibiotic resistance genes</li><li>One of these is used as the site of <b>insertion </b>and is <b>disrupted</b></li><li>Add both antibiotics to samples of bacteria</li><li>Bacteria w/ recombinant plasmid will be resistant to one, but not the other</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What does NAD stand for?"nicotinamide adenine dinucleotide <br><br> Copyright © StemUp 2023 | All Rights Reserved " Manometer / respirometer: Explain why the apparatus is left for 10 minutes to calibrate MS [3]"1. Equilibrium reached<div>2. Allow for expansion / pressure change in apparatus</div><div>3. Allow for respiration rate to stabilise </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Respirometer / Manometer: Why X temperature used?"1. Optimum temp for normal growth of Y<div>2. Optimum temp for respiratory enzymes </div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Respirometer / Manometer: Explain why fluid moves towards organism."Oxygen taken up<div>CO2 given out is absorbed by KOH</div><div>Pressure decrease in B</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What happens to the length of the A band during muscle contraction?"remains unchanged in length <br><br> Copyright © StemUp 2023 | All Rights Reserved " What happens to the length of the I band during muscle contraction?<div><br></div>"decrease in length <br><br> Copyright © StemUp 2023 | All Rights Reserved " What happens to the length of the H zone during muscle contraction?"decrease in length <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain why the diversity of animal species higher at point B than at A. MS [2]"More niches<div>More food <u>sources</u></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is genetic fingerprinting?"A technique which uses the <b>individuality of DNA </b>molecules to distinguish between organisms or show the relationship between them. Consists of PCR + Gel electrophoresis. <div><br></div><div><br></div><div><img src=""paste-e6079429639114a6e60853a73f9ee8c44f9a132a.jpg"">  <br></div><div><br></div><div><img src=""paste-d1023e2d99c679802729a3178cd843336d86543b.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are VNTRs?"<ul><li>Regions found in the <font color=""#ff0000"">non-coding part of DNA</font></li><li>Contain <font color=""#ff0000"">variable numbers</font> of repeated DNA sequences and vary between diff people</li><li>VNTR may be referred to as 'satellite' or 'mini-satellite' DNA</li></ul><div><img src=""paste-0111eca92330d99b2c5772bdb94872d002b1c2e3.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How are differences between VNTRs detected?"<ul><li>DNA sequences amplified via PCR</li><li>Sample separated by size via gel electrophoresis</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the process of genetic fingerprinting. MS [9]"<ol><li>DNA extracted from sample;</li><li>DNA cut / hydrolysed into segments using restriction endonucleases;</li><li>must leave minisatellites / required core sequences intact;</li><li>DNA fragments separated using electrophoresis;</li><li>detail of process e.g. mixture put into wells on gel and electric current passed through;</li><li>immerse gel in alkaline solution<font color=""#ff0000""> hence two strands of DNA separated</font>;</li><li>Southern blotting / cover with nylon / absorbent paper (to absorb DNA);</li><li><b>radioactive </b>marker / probe added  / complementary to VNTRs;</li><li>(areas with probe) identified using X-ray film / <b>autoradiography</b>;</li></ol><div><br></div><div><font color=""#ff0000"">NB: Allows DNA probes to attach</font></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " The probability of two individuals having the same VNTRs is..."very low unless they're identical twins <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall 4 uses of genetic fingerprinting."<ol><li>Identifying genetic relationships in paternity test</li><li>Matching DNA from a crime scene to suspects</li><li>Diagnosing diseases like Huntington's (based on number of AGC repeats on chromosome 4)</li><li>Prevent undesirable inbreeding in farms or zoos. </li></ol> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a DNA probe?"short, single-stranded length of DNA that is complementary to a known base sequence <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two common forms of DNA probes?"<ul><li>Radioactively labelled probes - made up of nucleotides with isotope P<sup>32</sup> . Identified via X-ray film.</li><li>Fluorescent labelled probes - emit light under certain conditions</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How are DNA probes used to locate specific alleles of genes?"<ol><li>Sequence for mutated allele identified</li><li>Probe made with complementary bases</li><li>Probe is labelled (fluorescent or radioactive) then replicated</li><li>DNA sample obtained</li><li>DNA made single stranded by heating</li><li>Probe added; joins by complementary base pairings. </li><li>Wash to remove unattached probes</li><li>Can now identify using X-ray imaging or UV light</li></ol> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 4 main uses of DNA probes?"<ul><li>Genetic screening for diseases</li><li>Personalised medicine; choosing most effective treatments</li><li>Genetic counselling</li><li>Genetic fingerprinting</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how DNA probes are used in genetic counselling."<ul><li>Look at family history</li><li>If high risk, genetic probes can be used to screen for a disorder</li><li>Advice given to patients on preventative measures / lifestyle </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how DNA probes are used in personalised medicine."<ul><li>Most diseases caused by range of mutations</li><li><font color=""#ff0000"">Different mutations</font> = different mechanisms hence we can tailor treatment to specific mutation</li><li>Some people's genes mean <font color=""#ff0000"">certain drugs are more/less effective</font> (e.g a particular form of enzyme needed)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is gene therapy?"treating genetic disease by providing the sufferer with a corrected copy of their defective gene <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two methods of gene therapy currently used?"1. Somatic cell therapy (body cells)<div>2. Germ line therapy (gametes)</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the 2 methods of delivery in gene therapy? "1. Viral vectors;<div>2. Liposomes</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are liposomes?"Lipid filled vesicles<div>are able to fuse into the CSM to insert a vector into the nucleus</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the drawbacks to somatic cell therapy? [4]"<div><ul><li>Cells need to be successfully reintroduced</li><li>Only directly altered cells are affected </li><li>Does not fix faulty function as original cells still remain.</li><li>Viral vector could mutate and become infectious</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the advantages and disadvantages of germ line therapy. "<div>A;</div><div>Potentially more effective;</div><div>All the cells of a person are easily accessible;</div><div>Possible to prevent inheritance;</div><div><br></div><div>D:</div><div>Safety & Ethical issues</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Why does structure and function vary between somatic cells; even though DNA is identical?"<div><ul><li>Only the relevant genes are active in a given cell at a given time (as a result of cell specialisation). </li><li>The rest are inhibited because their transcription and/or translation is switched off</li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a stem cell?"undifferentiated cell with the potential to become a wide variety of cells. <br><br> Copyright © StemUp 2023 | All Rights Reserved " Besides their ability to differentiate, what is another key ability of stem cells?"able to replicate very rapidly  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is differentiation?"the process by which stem cells divide and become specialised <br><br> Copyright © StemUp 2023 | All Rights Reserved " What's important to note about the division of totipotent cells during development?"They only translate a part of their DNA, resulting in their specialisation.  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are totipotent stem cells?"Stem cells that are able to differentiate into any type of cell <br><br> Copyright © StemUp 2023 | All Rights Reserved " Where are totipotent stem cells found in mammals?"early embryo <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are pluripotent stem cells?"Stem cells that differentiate into almost any type of cell, besides placental cells.  <br><br> Copyright © StemUp 2023 | All Rights Reserved " Where are pluripotent stem cells found?"in the embryo and fetus <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are multipotent stem cells? Give examples."<ul><li>Stem cells that can differentiate into a <font color=""#ff0000"">limited number </font>cell types.</li><li>e.g adult stem cells or placental stem cells</li><li>Used for growth, repair, replacing </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are unipotent stem cells? Give an example. "Stem cells that can differentiate into only a single type of cell<div><br></div><div>e.g cardiomyoblasts can only differentiate into cardiomyocytes</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Evaluate the use of multipotent adult stem cells."A:<div>1. not rejected by the body;</div><div><br></div><div>D:</div><div>1. can become only a few types of cells;</div><div>2. risky/difficult procedure</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Evaluate the use of plancetal/umbilical multipotent stem cells."1. Not rejected by the body<div><br></div><div>2. Can become a few types of cells</div><div>3. Only useful for future patients that have these cells harvested;</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Evaluate the use of totipotent embryonic stem cells."<div>A:</div>1. Can become any cell; advantageous for tissues that do not have adult stem cells e.g nervous system<div><br></div><div>D:</div><div>1. ethical objections;</div><div>2. difficult matching / preventing rejections</div><div>3. rapid division could form tumour</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Totipotent cells occur only for {{c1::a limited time}} in {{c1::early mammalian embryos}}.  Where are multipotent and unipotent stem cells found?"in mature mammals <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are induced pluripotent stem cells?"A type of <b>pluripotent </b>cell that is produced from unipotent stem cells by using protein transcription factors to express pluripotency-associated genes.  <br><br> Copyright © StemUp 2023 | All Rights Reserved " How do we turn specialised cells back into stem cells?"<ul><li>Inducing genes and transcriptional factors within the cell to express themselves</li><li>(i.e turning on genes that were otherwise turned off)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Give 3 examples of changes that occur during cell specialisation."<ul><li>Cell shape</li><li>Number of organelles</li><li>New cell content</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Where do we find stem cells in plants?"<ul><li>Meristem cells in stem / root / shoot</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is plant cloning achieved using stem cells? [1]"<ul><li><b>Cuttings </b>taken from plants (shoot) - grows into genetically identical plants. </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is homeostasis?"The maintenance of constant internal environment within a living organism <br><br> Copyright © StemUp 2023 | All Rights Reserved " What does homeostasis involve in mammals?"Physiological control systems that maintain the internal environment within restricted limits <br><br> Copyright © StemUp 2023 | All Rights Reserved " Via what systems is homeostasis controlled?"<ul> <li>The nervous system</li> <li>The endocrine system</li> <li>A combination of the two</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by the term hormone?"<ul> <li>A chemical secreted by an endocrine gland</li> <li>Travels to all cells in the body in the blood</li> <li>Only affects cells in target tissues</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is heat lost in an organism?"<ul> <li>Breathing, urinating, defecating</li> <li>Mostly lost from the skin: <ul> <li>Evaporation</li> <li>Radiation</li> </ul> </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What vessel governs vasoconstriction and vasodilation?"Shunt vessel <br><br> Copyright © StemUp 2023 | All Rights Reserved " What mechanism returns systems to their normal level?"Negative Feedback <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the different parts of a negative feedback system?"<ul> <li>A <font color=""#ff0000""><strong>receptor</strong> </font>(or sensor) – to <strong>detect</strong> a <strong>stimulus</strong> that is involved with a condition / physiological factor</li> <li>A <strong><font color=""#ff0000"">coordination system</font></strong> (nervous system and endocrine system) – to <strong>transfer information</strong> between different parts of the body</li> <li>An <font color=""#ff0000""><strong>effector</strong> </font>(muscles and glands) – to <strong>carry out a respon</strong></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "Recall how the body responds to a large <span style=""font-weight:600""><font color=""#ff0000"">increase </font></span>in external temperature.""<ol><li>hypothalamus (contains the thermoregulatory centre); </li><li>has receptors which detect temperature increase of blood; </li><li>receives impulses from receptors in skin;</li><li>nerve impulses transmitted (from hypothalamus / brain); </li><li>results in vasodilation / constriction of shunt vessels; </li><li>diversion of blood to skin surface; </li><li>sweating increases heat loss by evaporation;</li><li>no release of thyroxine / adrenaline; </li><li>no release metabolic rate / respiration; </li><li>correct reference to <b>negative feedback mechanisms</b>;</li></ol> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "Recall how childbirth can be used as an example of positive feedback.<br><div><br></div><div><font color=""#ff00ff"">[Outside spec]</font></div><div><font color=""#ff00ff"">Synoptic Links: Hormones, Receptors</font></div>""<ul> <li>Baby head pushed onto cervix</li> <li>Cervix stretches</li> <li>Receptors detect the stretch, send impulses to the brain</li> <li>Oxytocin is secreted</li> <li>Oxytocin = increases in uterine contractions and baby pushed further onto cervix</li> <li>Stretches the cervix more</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define glycogenesis"synthesis of glycogen from glucose <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define glycogenolysis"breakdown of glycogen into glucose <br><br> Copyright © StemUp 2023 | All Rights Reserved " Define lipogenesis"glucose converted into lipids <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the set point for BGC?"~90mg/100cm3 blood <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the Islets of Langerhans and its components."<ul> <li>Islets of Langerhans: tissue that acts as both receptors and endocrine cells </li><ul> <li>α cells = detect low glucose concentration and secrete glucagon</li> <li>β cells = detect high glucose concentration and secrete insulin</li> </ul></ul><img src=""IM01_Islets_of_Langerhans_v04.jpg""><br><ul> </ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the action of insulin in lowering BGC. [7]"<ol><li>insulin binds to <font color=""#ff0000"">specific receptors </font>(on membranes);</li><li>insulin <font color=""#ff0000"">activates </font>carrier proteins / opens channels </li><li>insulin causes more glucose transporters to form via <font color=""#ff0000"">vesicle fusion</font></li><li>insulin increases the <font color=""#ff0000"">permeability </font>of liver / muscle cells / tissues to glucose;</li><li>glucose <font color=""#ff0000"">diffuses </font>into cells</li><li>insulin action activates <font color=""#ff0000"">enzymes </font>involved in glucose conversion to glycogen / glycogenesis;</li><li><font color=""#ff0000"">respiration </font>rate increases to use up more glucose</li></ol><div><br></div><div><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the action of glucagon in increasing BGC."<ol><li>Attaches to specific receptors on the surfaces of liver cells</li><li>Activates enzymes involved in conversion of glycogen to glucose / glycogenolysis</li><li>Activates enzymes involved in conversion of glycerol and amino acids into glucose / gluconeogenesis</li></ol> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is the role of the liver in regulating blood sugar?"Whilst the pancreas produces the hormones, it's in the liver where they have their effects. Three important processes occur:<br><ul><li>Glycogenesis</li><li>Glycogenolysis</li><li>Gluconeogenesis</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the mode of action of adrenaline when BGC is low."<ul><li>Attach to receptors on CSM of a liver cell</li><li>Activates enzymes involved in the conversion of glycogen to glucose (glycogenolysis)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the second messenger model of adrenaline and glucagon action."<ol><li>Adrenaline / glucagon bind to specific receptors on cell membrane</li><li>Activate <font color=""#ff0000"">adenylate cyclase</font></li><li>Converts ATP to <font color=""#ff0000"">Cyclic AMP</font> (CAMP)</li><li>cAMP activates <font color=""#ff0000"">protein kinase A</font></li><li>Protein kinase A activates an enzyme cascade to break down glycogen to glucose (glycogenolysis)</li></ol> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What causes Type I diabetes?"<ul><li>Genetic mutation</li><li>Results in autoimmune response to B-cells in Islets of Langerhans</li><li>Body can't produce as much insulin</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What causes Type II diabetes?"<ul><li>Poor diet / obesity</li><li>Glycoprotein receptors on body cells lose their resonsiveness to insulin</li><li>Cells less responsive to insulin hence less glucose taken up </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is Type I diabetes controlled by insulin?"<div><ul><li>Injection insulin (not taken orally as protein is digested)</li><li>Insulin dosage matched to glucose intake </li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is Type II diabetes controlled by insulin?"<ul><li>Use of drugs which target insulin receptors</li><li>Results in more glucose uptake by cells / tissues </li><li>e.g Metformin</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is Type I diabetes controlled by diet manipulation?"<ul><li>Eating regularly</li><li>Control of carbohydrate intake</li><li>Avoid sudden rise in glucose</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How is Type II diabetes controlled by diet manipulation?"<div><ul><li><div style=""display: inline !important;""><b>Reduced sugar intake / eat foods with low glyceamic index</b></div></li><li><font color=""#ff0000"">(less sugar absorbed into blood)</font></li><li><b>Reduced fat intake </b></li><li><font color=""#ff0000"">(less fat converted to glucose)</font></li><li><b>More (regular) exercise</b></li><li><font color=""#ff0000"">(uses glucose / fats by increasing respiration)</font></li><li><b>Lose weight</b></li><li><font color=""#ff0000"">(increased sensitivity of cells to insulin / increased uptake of glucose by cells)</font></li></ul></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Gene mutations occur {{c1::spontaneously}} during the process of {{c2::DNA replication}}. "<br><br> Copyright © StemUp 2023 | All Rights Reserved " What are mutagenic agents?"Chemical, physical or biological agents that <font color=""#ff0000"">increase the rate of mutation</font>. <div><br></div><div>e.g UV light, ionising radiation, benzopryene</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by an inversion mutation?"A sequence of bases detaches and rejoins in the same position back to front (inverse order)<div><br></div><div><br></div><div><img src=""paste-b755526feba7a7c86d202f4d8e8f8105eca1a05a.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is meant by a duplication mutation?"One or multiple bases are repeated; causing a frameshift. <div><br><div><img src=""paste-078249c9ed1e9702361e2a07d96d6bc2e9411694.jpg""><br></div></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a translocation mutation?"<ul><li>Group of bases become separated on one chromosome</li><li>Inserted into the DNA sequence of a different chromosome</li></ul><div><br></div><div><img src=""paste-e48013f0bf03bbd5ad97cc04c1cf3181281893c7.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the possible results of a mutation on an encoded protein? [3]"<ul><li>Single point mutation; protein remain functional</li><li>Degenerate code; same AA coded for</li><li>Frameshift; all codons / AA downstream from the mutation are changed</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Explain how a mutation can result in a non-functional enzyme. MS [5]"<ol><li>Change in the base sequence of DNA;</li><li>Leads to a change in the amino acid sequence / primary structure;</li><li>Change in position of hydrogen / ionic / disulphide bonds;</li><li>Leads to a change in the tertiary structure / active site (of enzyme)</li><li>Substrate no longer complemenetary / no E-S complexes form. </li></ol> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How can pluripotent stem cells be used to treat medical disorders?"These can replace cells hence can treat disorders like leukaemia and diabetes. <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is a transcription factor?"A protein that controls the transcription of genes by binding to a specific region of DNA.  <br><br> Copyright © StemUp 2023 | All Rights Reserved " What are the two types of transcription factors?<br>"<ul><li>Activators (help RNA polymerase bind)</li><li>Repressors (prevent RNA polymerase binding)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is epigenetics?"changes in DNA that alter the expression of genes without changing the base sequence of DNA itself. It involves the addition of chemical tags onto DNA or histones<br><br>heritable changes in gene function<br> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How does RNAi control gene expression?"by preventing translation <br><br> Copyright © StemUp 2023 | All Rights Reserved " What does siRNA stand for?"small interfering RNA <br><br> Copyright © StemUp 2023 | All Rights Reserved " What do siRNA within RISC do? [3]"<ul><li>Bind to a molecule of mRNA containing a sequence of bases complementary to its own.</li><li><font color=""#ff0000"">mRNA hydrolysed / translation stopped</font></li><li>miRNA expression is deregulated in many human diseases including cancer => this offers opportunities as bio markers and novel therapies</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What does miRNA within RISC do?"<ul><li>Binds to complementary sequence on mRNA</li><li>Prevents the attachment of the mRNA to ribosome</li><li>Prevents translation </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Besides vaccination production, what are possible applications of whole genome sequencing?"phylogeny <br><br> Copyright © StemUp 2023 | All Rights Reserved " Sequencing methods are continuously {{c1::updated}} and have become {{c2::automated}} <div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div><div>The front of this card is blank.<br><a href='https://anki.tenderapp.com/kb/card-appearance/the-front-of-this-card-is-blank'>More information</a></div> Compare and contrast anaerobic respiration in yeast cells vs muscle cells. MS [6]"Similarities:<div>1. ATP formed / used;</div><div>2. Pyruvate formed/reduced;</div><div>3. Reduced NAD;</div><div>4. Glycolysis involved;</div><div><br></div><div>Differences:</div><div>1. Ethanol formed by yeast; lactate formed by muscle cells</div><div>2. CO2 produced by yeast, no CO2 by muscle cells</div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is osmoregulation?"control of water potential of the blood <br><br> Copyright © StemUp 2023 | All Rights Reserved " What 2 functions does the kidney carry out?"<ul><li>Ultrafiltration of blood</li><li>Selective reabsorption of useful substances </li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What 3 [   ]s do the kidneys regulate?"<ul><li><font color=""#ff0000"">Water </font>- cells only function in isotonic solution;required for metabolic reactions</li><li><font color=""#ff0000"">Ions </font>- required for cellular processes and osmotic balance</li><li><font color=""#ff0000"">Urea </font>- toxic product of amino acid breakdown so could damage cells</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " " <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""66a1813ca5b3428e823e47802c693e1c-ao-1-Q.svg"" /></div> <div id=""io-original""><img src=""tmpt25epjnl.png""></div> </div> <div id=""io-footer""></div> <script> // Prevent original image from loading before mask aFade = 50, qFade = 0; 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} if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> "" <div id=""io-header""></div> <div id=""io-wrapper""> <div id=""io-overlay""><img src=""66a1813ca5b3428e823e47802c693e1c-ao-5-A.svg""></div> <div id=""io-original""><img src=""tmpt25epjnl.png""></div> </div> <button id=""io-revl-btn"" onclick=""toggle();"">Toggle Masks</button> <div id=""io-extra-wrapper""> <div id=""io-extra""> </div> </div> <script> // Toggle answer mask on clicking the image var toggle = function() { var amask = document.getElementById('io-overlay'); if (amask.style.display === 'block' || amask.style.display === '') amask.style.display = 'none'; else amask.style.display = 'block' } // Prevent original image from loading before mask aFade = 50, qFade = 0; var mask = document.querySelector('#io-overlay>img'); function loaded() { var original = document.querySelector('#io-original'); original.style.visibility = ""visible""; } if (mask === null || mask.complete) { loaded(); } else { mask.addEventListener('load', loaded); } </script> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What happens at the glomerulus / Bowman's Capsule?"ultrafiltration <br><br> Copyright © StemUp 2023 | All Rights Reserved " What happens at the PCT?"<font color=""#ff0000"">selective </font>reabsorption of glucose/water/ions <br><br> Copyright © StemUp 2023 | All Rights Reserved " What happens at the loop of Henle?"Reabsorption of water/ions for <font color=""#ff0000"">OSMOREGULATION</font> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the constituent parts of the barrier between capillaries and lumen of Bowman's capsule."<ul><li><font color=""#ff0000""><b>Endothelium </b></font>- have narrow gaps so plasma can pass through</li><li><font color=""#ff0000""><b>Basement membrane </b></font>- fine mesh of collagen fibres/glycoproteins which act as a filter</li><li><font color=""#ff0000""><b>Podocytes </b></font>- epithelial cells w/ projections called foot processes. Form gaps. </li></ul><div><br></div><div><img src=""paste-214ffb7a4bdb291f90ba37efb5b7bd8bbeba02cb.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " What is red urine indicative of?"<ul><li>Indicates <font color=""#ff0000"">RBCs </font>in the urine</li><li><font color=""#ff0000"">Ultrafiltration </font>not working due to injury / infection - basement membrane is damaged</li><li><font color=""#ff0000"">Proteins </font>will also be in urine</li></ul><div><img src=""paste-429a5b6e48f552a7a0d1e578244dbc186afd3be4.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the process of ultrafiltration. MS [4]"<ul><li><font color=""#ff0000"">High </font>blood/hydrostatic pressure</li><li>Water/glucose/ions/urea pass out</li><li>Through small gaps/<font color=""#ff0000"">fenestrations </font>in capillary endothelium</li><li>Through <font color=""#ff0000"">basement </font>membrane</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall the process of selective reabsorption that occurs at the PCT. [4]"<ul><li>Na+ <font color=""#ff0000"">Atrans </font>out of cells lining PCT. (ATP needed; mitochondria supply)</li><li>[Na+] lowered; <font color=""#ff0000"">maintaining </font>Na+ conc gradient (lower in the cell than the lumen)</li><li>Na+ diffuse in down conc gradient, <font color=""#ff0000"">co-transporting glucose</font> (or AA, Cl-, other mols..)</li><li>Glucose <font color=""#ff0000"">diffuses </font>from PCT cell into blood </li></ul><div><img src=""paste-1964c427c7eb6d121765129763d511350f6fe968.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How are the PCT cells specialised for reabsorption? [4]"<ul><li>Microvilli <b><font color=""#ff0000"">so </font></b>large SA</li><li>Co-transporter proteins <b><font color=""#ff0000"">for </font></b>transport of AA/Glucose in association with Na+ ions by f.diffusion</li><li>Many channel proteins <b><font color=""#ff0000"">so </font></b>more diffusion</li><li>Many mitochondria <b><font color=""#ff0000"">to </font></b>supply ATP for active transport</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " By what processes does selectively re-absorption occur at the PCT?"<ul><li>Active transport (all AAs, some glucose)</li><li>Facilitated diffusion (some glucose) </li><li>Osmosis (water)</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Sketch and label the functional unit of the kidney."<img src=""paste-415264d84e3cc97fe297db8efd111ef4001e8c14.jpg""> <br><br> Copyright © StemUp 2023 | All Rights Reserved " Recall how the loop of Henle reabsorbs water. MS [8]"<ul><li>In descending limb sodium(ions) <font color=""#ff0000""><b>diffuse </b></font>in;<br></li><li>Descending limb water moves out / <font color=""#ff0000""><b>permeable </b></font>to water;</li><li>In the ascending limb sodium(ions) <b><font color=""#ff0000"">actively </font></b>transported out;</li><li>Ascending limb walls are too thick and hence is <b><font color=""#ff0000"">impermeable </font></b>to <b><font color=""#ff0000"">water</font></b>;</li><li>Low water potential / high concentration of ions in the medulla / tissue fluid;.  </li><li>The longer the loop / the deeper into medulla, the <font color=""#ff0000""><b>lower the water potential</b></font> in medulla / tissue fluid;</li><li>Water leaves collecting duct / DCT;</li><li>By <font color=""#ff0000""><b>osmosis </b></font>/ down water potential gradient</li></ul><div><img src=""paste-df46757b5c375a7c23492f45e6a9d9526380e034.jpg""><br></div><div><img src=""paste-20b458d2e66fde33d0831028a30ac65dbd47dc30.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "Explain the role of the hypothalamus, posterior pituitary gland and ADH in osmoregulation <font color=""#ff0000"">when there is a decrease in water potential in the blood</font>. ""<ul><li>Detected by <font color=""#ff0000"">osmoreceptors </font>in hypothalamus</li><li>Hypothalamus produces <font color=""#ff0000"">ADH </font></li><li>Posterior pituitary gland secretes more ADH into the blood </li><li>ADH travels in blood to kidney and attaches to receptors on DCT / collecting duct</li><li>ADH incr. water permeability of walls of DCT / collecting duct to water</li><li>By causing vesicles with aquaporins to fuse with CSM;</li><li>More water absorbed from DCT / collecting duct by <b>osmosis</b>.</li><li>(Less water lost to urine) smaller vol, more conc. urine.<br></li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "Explain the role of the hypothalamus, posterior pituitary gland and ADH in osmoregulation <font color=""#ff0000"">when there is an increase in water potential in the blood.</font> [5]""<ul><li>Detected by <font color=""#ff0000"">osmoreceptors </font>in hypothalamus</li><li>Hypothalamus produces <font color=""#ff0000"">less </font>ADH</li><li>Posterior pituitary gland secretes less ADH into the blood </li><li>Less ADH travels in blood to kidney and less attach to receptors on DCT / collecting duct</li><li>This decrease water permeability of walls of DCT / collecting duct to </li><li>Less water absorbed from DCT / collecting duct by <b>osmosis</b>.</li><li>(More water lost to urine) larger vol, less conc. urine.</li></ul> <br><br> Copyright © StemUp 2023 | All Rights Reserved " How does ADH work?"<ul><li>Binds to <b><font color=""#ff0000"">specific receptor</font>s </b>on collecting duct wall</li><li>Triggers <font color=""#ff0000"">phosphorylase </font>synthesis in cell</li><li>Phosphorylase causicles vesicles w/ <font color=""#ff0000"">aquaporins </font>to fuse with CSM</li><li>Aquaporins are <font color=""#ff0000"">channel proteins</font> that water pass through, increase water permeability</li></ul><div><br></div><div><img src=""paste-079181d12137c628773ef1750ca8b3a7ea4316df.jpg""><br></div> <br><br> Copyright © StemUp 2023 | All Rights Reserved " "what happens during photoionisation in the light dependant reaction {2} <br><br> ""chlorophyll absorbs light. electrons are lost and go to etc <br><br> <br><br> " "what is the role of chlorophll in photolysis{3} <br><br> ""absorbs light<br>loses electrons<br>accepts electrons from water <br><br> <br><br> " "explain why reducing the light intensity would affect the amount of oxygen released by the seaweeds.  <br><br> ""light intensity would be a limiting factor <br>fewer electrons released from chlorophyll<br>less photolysis of water so less oxygen produced <br><br> <br><br> "

AQA Biology A2 Level

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