(a)[2]
Explain the meaning of a sex-linked gene.
(b)[4]
With B as the allele for black coat and O as the allele for orange coat, complete the genetic diagram below.
(c)[2]
Explain why a male cat cannot have a tortoiseshell coat.
Biology 9700 · AS & A Level · Passage of information from parents to offspring
Passage of information from parents to offspring — practice question
In cats, coat colour is controlled by a sex-linked gene with two alleles that determine black and orange. If black cats are crossed with orange cats, every female offspring is tortoiseshell (black and orange patches), while every male offspring has the same colour as the mother.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A sex-linked gene is located on the X chromosome, not on the Y chromosome.” …
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