AQA A LEVEL BIOLOGY PAPER 3
2021
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IB/H/Jun21/E14 7402/3
A-level
BIOLOGY
Paper 3
Time allowed: 2 hours
Materials
For this paper you must have:
• a ruler with millimetre measurements
• a scientific calculator.
Instructions
• 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.
*JUN2174023D0ow1nloa*:
For Examiner’s Use
Question Mark
1
2
3
4
5
6
7
TOTAL
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2
*02*
IB/H/Jun21/7402/3
1
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,
with two codominant alleles. C
G represents the allele for grey fur colour, and C
B
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
. 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. [Show Less]