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3.2 DNA and protein synthesis

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Question 2
F

Scientists measured the percentage of each base in DNA from three organisms.

The Table shows their results.

Table

OrganismPercentage of APercentage of TPercentage of CPercentage of G
human30302020
wheat27X2323
yeast3131Y19
a.

Give the values of X and Y.

[2]
b.

Explain why the percentage of A in DNA is always the same as the percentage of T.

[2]
c.

Name the type of bond that joins the two bases in a base pair.

[1]
d.

A sample of DNA from a bacterium contains 18% G.

Calculate the percentage of A in this sample.

[2]
Markscheme

3.2 DNA and protein synthesis Questions

  1. GCSE
  2. /Biology
  3. /3.2 DNA and protein synthesis

44 exam-style questions on Edexcel GCSE Biology 3.2 DNA and protein synthesis, covering 3.2.1 DNA structure as a polymer, 3.2.2 Genome and gene definitions, 3.2.3 Extracting DNA from fruit, 3.2.4 Base order determines protein shape, 3.2.5 Stages of protein synthesis, 3.2.6 Non-coding DNA variants affecting phenotype, and 3.2.7 Coding DNA variants affecting phenotype. Each one has a worked solution and a mark scheme showing where the marks go.

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