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9 marksStructure and Roles of Nucleic Acids

CAPE Biology Unit 1 · May/June 2026 · Paper 2 · Question 2(c)(ii)

Figure 4 shows a normal template DNA gene and three mutation sites (X, Y, Z). Table 4 lists mRNA codons and their corresponding amino acids or stop signals.

Explain how EACH mutation shown in Figure 4 (Mutation X, Mutation Y, and Mutation Z) could affect the polypeptide formed during gene expression, using the information given in Table 4.

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Other parts of this question

  1. 2(a)(i)Complete Table 2 by identifying the differences between DNA and RNA regarding sugar component and stability.[4 marks]
  2. 2(a)(ii)State the location of mRNA and DNA in a cell.[2 marks]
  3. 2(a)(iii)Explain how complementary base pairing ensures the accurate replication of DNA.[3 marks]
  4. 2(a)(iv)During transcription, the template strand of DNA contained 34% cytosine and 16% adenine bases. Determine the percentages of Guanine, Uracil, and Thymine in the…[3 marks]
  5. 2(b)(i)On the grid provided on page 11, plot the data provided in Table 3 as a bar graph, with the mutation type on the x-axis.[5 marks]
  6. 2(b)(ii)State THREE possible deductions based on the results of the study shown in Table 3.[3 marks]
  7. 2(c)(i)State ONE role of the template strand of DNA during transcription.[1 mark]

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