AQA A-level BIOLOGY 7402/2 Paper 2 Mark scheme June 2021

A-level BIOLOGY 7402/2 Paper 2 Mark scheme June 2021 Version: 1.0 Final *216a7402/2/MS* MARK SCHEME − A-LEVEL BIOLOGY − 7402/2 − JUNE 2021 Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant questions, by a panel based on subject teachers. This mark scheme includes any amendments made at the standardisation events which all associates participate within and is the scheme which was used by them within this examination. The standardisation process ensures that the mark scheme covers the students’ responses to questions and that every associate understands and applies it within the same correct way. As preparation for standardisation each associate analyses a number based on students’ scripts. Alternative answers not already covered by the mark scheme are discussed and legislated for. If, after the standardisation process, associates encounter unusual answers which have not been raised they are required to refer these to the Lead Examiner. It must be stressed that a mark scheme is a working document, within many cases further developed and expanded on the basis based on students’ reactions to a particular paper. Assumptions about future mark schemes on the basis based on one year’s document should be avoided; whilst the guiding principles based on assessment remain constant, details will change, depending on the content based on a particular examination paper. Further copies based on this mark scheme are available from Copyright information AQA retains the copyright on all its publications. However, registered schools/colleges for AQA are permitted to copy material from this booklet for their own internal use, with the following important exception: AQA cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third party even for internal use within the centre. Copyright © 2021 AQA and its licensors. All rights reserved. 2 MARK SCHEME − A-LEVEL BIOLOGY − 7402/2 − JUNE 2021 Level based on response marking instructions Level based on response mark schemes are broken down into levels, each based on which has a descriptor. The descriptor for the level shows the average performance for the level. There are marks within each level. Before you apply the mark scheme to a student’s answer read through the answer and annotate it (as instructed) to show the qualities that are being looked for. You can then apply the mark scheme. Step 1 Determine a level Start at the lowest level based on the mark scheme and use it as a ladder to see whether the answer meets the descriptor for that level. The descriptor for the level indicates the different qualities that might be seen within the student’s answer for that level. If it meets the lowest level then go to the next one and decide if it meets this level, and so on, until you have a match between the level descriptor and the answer. With practice and familiarity you will find that for better answers you will be able to quickly skip through the lower levels based on the mark scheme. When assigning a level you should look at the overall quality based on the answer and not look to pick holes within small and specific parts based on the answer where the student has not performed quite as well as the rest. If the answer covers different aspects based on different levels based on the mark scheme you should use a best fit approach for defining the level and then use the variability based on the response to help decide the mark within the level, ie if the response is predominantly level 3 with a small amount based on level 4 material it would be placed within level 3 but be awarded a mark near the top based on the level because based on the level 4 content. Step 2 Determine a mark Once you have assigned a level you need to decide on the mark. The descriptors on how to allocate marks can help with this. The exemplar materials used during standardisation will help. There will be an answer within the standardising materials which will correspond with each level based on the mark scheme. This answer will have been awarded a mark by the Lead Examiner. You can compare the student’s answer with the example to determine if it is the same standard, better or worse than the example. You can then use this to allocate a mark for the answer based on the Lead Examiner’s mark on the example. You may well need to read back through the answer as you apply the mark scheme to clarify points and assure yourself that the level and the mark are appropriate. Indicative content within the mark scheme is provided as a guide for examiners. It is not intended to be exhaustive and you must credit other valid points. Students do not have to cover all based on the points mentioned within the Indicative content to reach the highest level based on the mark scheme. An answer which contains nothing based on relevance to the question must be awarded no marks. 3 MARK SCHEME − A-LEVEL BIOLOGY − 7402/2 − JUNE 2021 Question Marking Guidance Mark Comments 1. Phosphorylation based on glucose using ATP; 2. Oxidation based on triose phosphate to pyruvate; Accept all mark points within diagrams. 3. Net gain based on ATP; 4. NAD reduced; 2. Accept removal based on hydrogen from triose phosphate for oxidation. 01.1 4 max 3. Accept any description that indicates a net gain e.g., 4 produced, 2 used. 4. Accept NADH/NADH2/NAD H + H+ produced. Question Marking Guidance Mark Comments 01.2 1. Less/no reduced NAD/coenzymes OR Fewer/no hydrogens/electrons removed (and passed to electron transfer chain); 2. Oxygen is the final/terminal (electron) acceptor; 2 1. Accept less/no FAD reduced.