AQA A LEVEL BIOLOGY PAPER 3 2021

AQA A LEVEL BIOLOGY PAPER 3 2021 Please write clearly in block capitals. Centre number Surname Forename(s) Candidate signature Candidate number I declare this is my own work. A-level BIOLOGY Paper 3 Materials For this paper you must have:  a ruler with millimetre measurements  a scientific calculator. Instructions Time allowed: 2 hours For Examiner’s Use Question Mark 1 2  Use black ink or black ball-point pen.  Fill within the boxes at the top based on this page.  Answer all questions within Section A.  Answer one question from Section B.  You must answer the questions within the spaces provided. Do not write outside the box around each page or on blank pages.  If you need extra space for your answer(s), use the lined pages at the end based on this book. Write the question number against your answer(s).  Show all your working.  Do all rough work within this book. Cross through any work you do not want to be marked. Information  The marks for the questions are shown within brackets.  The maximum mark for this paper is 78. 3 4 5 6 7 TOTAL *JUN2174023D0 ow1 nloa* : 7402/3 2 *02* IB/H/Jun21/7402/3 Section A Answer all questions within this section. You are advised to spend no more than 1 hour and 15 minutes on this section. Do not write outside the box In one species based on squirrel, Sciurus carolinensis, fur colour is controlled by one gene, G B with two codominant alleles. C represents the allele for grey fur colour, and C represents the allele for black fur colour. Table 1 shows the three possible phenotypes. Table 1 Genotype Phenotype G G C C Grey fur G B C C Brown-black fur B B C C Black fur . 1 In a population based on 34 S. carolinensis, 2 had black fur. Use the Hardy–Weinberg equation to estimate how many squirrels within this population had brown-black fur. Show your working. [2 marks]