O-LevelBiologyEcology & Environment5090/21 · May/June 2017 · Q710 Marks
Fig. 7.1 shows bacteria growing on the surface of a dish containing nutrient jelly. Paper discs, such as M and N, were soaked in solutions of different antibiotics and placed on top of the growing bacteria. A clear area on the jelly indicates that bacteria in that area have been killed. [Figure 7.1]
- (a)Use the information above, and your knowledge of the process of natural selection, to describe and explain the difference in appearance of the jelly surrounding discs M and N.[6]
- (b)Describe how the process of artificial selection differs from that of natural selection. Include reference to the production of one named economically important plant or animal in your answer.[4]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.
- [6] 7(a) M has clear area + N no clear area; (for disc M) reference to (bacteria) killed around M / not killed around N ; gene; mutation; resistant (to antibiotic); (resistant) survive ; (resistant) reproduce ; pass on resistance to next generation / offspring ; (for disc N) antibiotic (solution) not strong / concentrated enough OR incorrect antibiotic (for the bacteria);
- [4] 7(b) named example of (artificially selected) animal / plant; reason named example is economically important ; reference to human / farmer AW ; reference to breed together / cross breed AW ; over several generations / repeated;
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