Biology 9700 · AS & A Level · Passage of information from parents to offspring
Passage of information from parents to offspring — practice question
In mice, the degree of fur pigmentation is determined by multiple alleles of one gene. The alleles are arranged below in descending dominance, with $C$ being the most dominant:
$C$ = full colour
$C^{ch}$ = chinchilla
$C^{h}$ = himalayan
$C^{p}$ = platinum
$C^{a}$ = albino
(a)[2]
Explain how multiple alleles come into existence.
(b)[6]
Eye colour in mice is determined by two alleles of a single gene, $B/b$:
- allele $B$ codes for black eyes
- allele $b$ codes for red eyes
A mouse with full colour fur and black eyes was mated with a mouse with himalayan fur and black eyes. One of the offspring was albino with red eyes.
Using the symbols above, draw a genetic diagram to show the genotypes and phenotypes of the offspring from this cross.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Mutation in a gene” …