AQA A-levelBIOLOGY7402/2

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Question Marking Guidance Mark Comments 01.1 1. Circular muscle contracts; 2. Radial muscle relaxes; 2 1 and 2. Accept, for one mark ‘both muscles contract’ or ‘both muscles ... relax’ as names of muscles are in Figure 1. Reject muscles constrict. 1. High (visual) acuity; 2. (Each) cone is connected to a single neurone; 2. (Cones send) separate (sets of) impulses to brain; 2. Accept no retinal convergence. 2. Accept ‘bipolar/nerve cell’ for neurone. 01.2 3 3. Accept ‘optic nerve’ for brain. 3. Reject ‘signals’, ‘messages’ for ‘impulses’. 3. Accept ‘action potential’. 01.3 1. Correct answer of 0.6 (%) = 2 marks;; 2. Incorrect answer but shows number sequence 7065 / 7068 / 7069 / (ignore position of decimal point) = 1 mark OR Final answer number sequence has 64 / 65 (ignore preceding zeros, numbers that follow and position of decimal point) = 1 mark OR Final answer is 2.58 / 2.6 (%) = 1 mark OR Final answer of 0.43 (%) = 1 mark; 2 1. Ignore any numbers after 0.6, 2.58, 2.6 and after 0.43. 1. High (visual) sensitivity; 2. Several rods connected to a single neurone; 3. Enough (neuro)transmitter to reach/overcome threshold OR 1. Accept retinal convergence. 01.4 3 2. Accept ‘bipolar/nerve cell’ for neurone 2. Accept 2, ‘many’ or 5 Spatial summation to reach/overcome threshold; more for ‘several’ 3. Reject ‘signals’, ‘messages’ for ‘impulses’. 3. Accept named neurotransmitter. 3. Accept depolarisation, ‘action potential’ or ‘generator potential’ for ‘to reach threshold’. 3. Generator potentials combine to reach threshold/ depolarisation/action potential/generator potential. Question Marking Guidance Mark Comments 02.1 1. Lipid soluble; 2. (Diffuse through) phospholipid (bilayer); 2 1. Ignore ‘not water soluble’ or ‘fat soluble’. 1 and 2. Ignore reference to joining to receptors/channels/carriers but reject passage through protein channels/carriers. 1. Has a (specific) tertiary structure/shape; 1. Accept in context of AR or testosterone. 2. (Structures are) complementary; 1. Ignore 3D. 02.2 2 2. Reject reference to antigen. 2. Reject reference to active site, enzyme, substrate or induced fit. 02.3 1. (AR is) a transcription factor; 2. Binds to DNA/promoter; 3. (Stimulates) RNA polymerase; 2 max 1. Ignore ‘binds to bases’ or ‘binds to gene’. 1 and 2. Reject reference to active site, enzyme, substrate or induced fit. 1. With 16 or fewer than 16 (repeats the association) is significant; 2. With 17 or more than 17 (repeats the association) is not significant; 3. With 16 or fewer than 16 (repeats) there is less than a 5% or less than 0.05 probability of being due to chance OR With 17 or more than 17 (repeats) there is more than a 5% or more than 0.05 probability of being due to chance OR Explanation of a probability value e.g. 0.30 is a 0.30 or 30% probability of being due to chance; 4. With 16 or fewer than 16 (repeats) reject the null hypothesis OR If none of the marks is awarded allow principle mark of (prostate) cancer more likely with 16 or less than 16 (repeats) or (prostate) cancer less likely with 17 or more than 17 (repeats) OR 02.4 3 max Alternative principle mark Correctly links significant/not significant to correct probability value/percentage or to rejecting/accepting the null hypothesis. 1. Reject ‘the results are significant’. 1. Accept ‘difference in results is significant’. 2, 3 and 4. Accept reference to any number of repeats (e.g. 18) between With 17 or more (repeats) accept the null hypothesis; 17 to 20 for 17 or more than 17 (repeats). 3. Accept equivalent responses in terms of 95% or 0.95 probability. Question Marking Guidance Mark Comments 03.1 1. Stirrer distributes heat (energy); 2. Insulation/space/air reduces loss/gain of heat OR Insulation/space/air reduces conduction/convection; 3. Water has high (specific) heat capacity; 2 max 1. Accept stirrer ensures equal/even temperature or prevents build up of ‘hot spots’. 2. Reject vacuum. 03.2 3.28 / 3.3 (kJ g-1) = 2 marks;; Incorrect answer but shows 328 / 33 (ignore any subsequent numbers and decimal point) = 1 mark OR Incorrect answer of 6.56 / 6.6 (kJ g-1) (ignore any subsequent numbers) = 1 mark; 2 1. (Light is) reflected; 2. (Light is) wrong wavelength; 3. (Light) misses chlorophyll/ chloroplasts/photosynthetic tissue; 4. CO2 concentration or temperature is a limiting factor. 1. Light is not absorbed on its own is not enough. 03.3 2 max 2. Accept frequency for wavelength. 2. Accept reference to absorbing specified wavelengths/frequencies. 03.4 1. ATP; 2. Reduced NADP; 2 Accept 1 and 2 in either order. 2. Reject Reduced NAD. 2. Accept NADPH/NADPH2. 03.5 Correct answer of 1.31/1.3 × 108 (ignoring any subsequent numbers after 1.31) = 2 marks;; Incorrect answer but shows 216 = 1 mark 2 [Show More]

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