AQA 2023 a level biology exam

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INTERNATIONAL AS
BIOLOGY (9610)
Unit 2 Biological Systems and Disease


Wednesday 11 January 2023 07:00 GMT Time allowed: 1 hour 30 minutes
Materials For Examiner’s Use
For this paper you must have:
• a ruler with millimetre measurements Question Mark
• a scientific calculator, which you are expected to use where appropriate. 1
2
Instructions
• Use black ink or black ball-point pen. 3
• Fill in the boxes at the top of this page. 4
• Answer all questions. 5
• You must answer the questions in the spaces provided. Do not write
outside the box around each page or on blank pages. 6
• If you need extra space for your answer(s), use the lined pages at the end of 7
this book. Write the question number against your answer(s). 8
• All working must be shown.
• Do all rough work in this book. Cross through any work you do not want TOTAL
to be marked.

Information
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 75.




*JAn23BL0201*
IB/H/Jan23/E14 BL02

, 2
Do not write
outside the
Answer all questions in the spaces provided. box




0 1 Gene mutations are changes in the base sequence of DNA.

Table 1 shows some amino acids and the DNA triplets that code for them.

Table 1

Amino acid DNA triplets

Arg AGA, AGG, CGT, CGC, CGA, CGG

Gly GGT, GGC, GGA, GGG

Leu TTA, TTG, CTT, CTC, CTA, CTG

Ser AGT, AGC, TCT, TCC, TCA, TCG

Trp TGG

Tyr TAT, TAC

Table 2 shows:

• the original DNA base sequence for part of a gene that codes for an enzyme
• the effects of two different mutations on the DNA base sequence of this gene.

Table 2

Original DNA base sequence A G C C G G C T G T A C

Mutation 1 DNA base sequence A G C C G G C T C T A C

Mutation 2 DNA base sequence A G C G G G C T G T A C

Use the information shown in Table 1 and Table 2 to answer the following
questions.

0 1 . 1 Give the sequence of amino acids coded for by the original DNA base sequence.
[1 mark]




*02*
IB/H/Jan23/BL02

, 3
Do not write
outside the
0 1 . 2 Mutation 1 shows that the genetic code is degenerate. box


Explain how.
[2 marks]




0 1 . 3 Explain how mutation 2 may produce a non-functional enzyme.
[3 marks]




6




Turn over for the next question




Turn over ►


*03*
IB/H/Jan23/BL02