2021TrialShort answer

Q30 (b)

2 marks

Question

The data below examines the changes in allele frequencies at a single locus with two alleles B and b in two very large populations of rabbits due to natural selection. It is known that a variety of genetic traits affect the survivability of rabbits in the wild, as well as in breeding populations. One such trait is furless rabbits (naked bunnies). This trait was first discovered in England by W.E. Castle in 1933. The furless rabbit is rarely found in the wild because the cold English winters are a selective pressure against it. The dominant allele for normal fur is represented by B and the recessive allele for no fur is represented by b.

Account for the shape of the graph. Support your answer with reference to the information provided.

Uncropped source page 26 for question 30.b; requires human review and cropping — Reviewed visual · source page 26

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Solution

Marking Criteria	Marks
Accounts for the shape of the graph<br>Reference of the information provided	2
Any ONE of the above<br>OR Some relevant information	1

Sample answer: Population Y has stabilized at generation 50. Stabilization indicates that only allele b is found in the gene pool. This is potentially due to environmental pressure selecting for b allele.
whereas in population x frequency of allele b is going down as it is being selected against, possibly due to cold. It stops at 0.1. Where it is in heterozygous rabbits and masked by the dominant rabbits having fur.

Supplied marking guidance · human reviewed

Compare this with your working, not only your final sentence.

Syllabus alignment

Module 6 · Genetic Change

MutationEvaluate effects of mutation, gene flow and genetic drift on population gene pools.

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