Quelpr
4 marksNatural Selection

CAPE Biology Unit 1 · May/June 2019 · Paper 2 · Question 2(a)(iii)

Table 1 shows the relative growth rates of sensitive and resistant strains of S. typhimurium exposed to varying tetracycline concentrations.

Explain how the differences between the growth rates of the bacteria could lead to natural selection.

This question uses a figure or table from the paper — you'll see it when you practise.

The mark scheme is shown once you've answered.

Practise this question

Other parts of this question

  1. 2(a)(i)Plot a line graph on the grid provided showing the relative growth rate (y-axis) vs tetracycline concentration (x-axis) for both the sensitive and resistant…[6 marks]
  2. 2(a)(ii)Outline the effect of antibiotic concentrations of 0.1 ug/ml and 0.7 ug/ml on BOTH bacterial populations.[4 marks]
  3. 2(b)(i)Complete the missing codons in the boxes labelled A and B in Figure 3.[2 marks]
  4. 2(b)(ii)With reference to the mutation in Figure 3, explain how mutation brings about genetic variation at the DNA, protein and cellular level.[6 marks]
  5. 2(c)Discuss the process of natural selection as proposed by Darwin to be the mechanism of evolutionary change.[8 marks]

More practice: the rest of this paper · more Natural Selection questions · all CAPE Biology Unit 1 past papers