Biology 9700 · AS & A Level · Passage of information from parents to offspring
Passage of information from parents to offspring — practice question
A single autosomal gene that determines fur colour in cats has three alleles:
• allele $C^B$ specifies black fur
• allele $C^{CH}$ specifies chocolate fur
• allele $C^{CM}$ specifies cinnamon (orange-brown) fur.
Allele $C^B$ is dominant over both $C^{CH}$ and $C^{CM}$. Allele $C^{CH}$ is dominant over $C^{CM}$.
(a(i))[1]
State the term used for a gene’s position on a chromosome.
(a(ii))[1]
A cinnamon-coloured cat must be homozygous. Explain the meaning of the term homozygous.
(b)[6]
Two black cats were crossed. Most of their offspring had black fur, while a few had chocolate fur. When they were mature, one of the black offspring was crossed with one of the chocolate offspring. Some of the cats in the second generation had cinnamon fur.
Draw a genetic diagram to show how cats with cinnamon-coloured fur were produced in the second generation.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “gene locus” …