AQA A LEVEL BIOLOGY Paper 3 MS 2021.

AQA A LEVEL BIOLOGY Paper 3 MS 2021. MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2021 Question Marking Guidance Mark Comments 1. Answer based on 12/13 = 2 marks;; 2. 0.36(48)/0.365/0.37 = 1 mark OR 01.1 36(.48)/36.5/37% = 1 mark OR 2 For 1 mark accept q 2 = 6%/5.9%/5.88% q 2 = 0.06/0.059/0.0588 = 1 mark OR or q = 0.2/0.24/0.243 = 1 mark; Question Marking Guidance Mark Comments 01.2 0.71 1 Question Marking Guidance Mark Comments 01.3 Second box ticked/answer key: B: The mutation that caused black fur happened within a common ancestor based on S. carolinensis and other closely related species. 1 Question Marking Guidance Mark Comments 01.4 1. 2.55% = 2 marks;; 2. 2.61% = 1 mark (question misread ie 8/306x100) OR Evidence based on dividing by 314 or 942 = 1 markOR Answers not given to three significant figures = 1 mark; 2 5 Downloaded by: nurse001 | Distribution of this document is illegal S - The Marketplace to Buy and Sell your Study Material MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2021 Question Marking Guidance Mark Comments 01.5 1. Mutation/lack based on glutamic acid leads to (permanent) activation based on the receptor/protein; 2. (Because) the receptor/protein does not require the binding/leaving based on αMSH (to become activated); 3. ASIP (might) not (be) able to bind to the receptor/protein; 4. (Only) the dark pigment is produced.