Biology 9700 · AS & A Level · Passage of information from parents to offspring
Passage of information from parents to offspring — practice question
In domestic chickens, the sex chromosomes are called W and Z. A male has two Z chromosomes, whereas a female has one W chromosome and one Z chromosome. The gene controlling feather colour lies on an autosome. This gene (C) has two alleles: black ($C^{B}$) and splashed-white ($C^{S}$). If a black-feathered chicken is crossed with a splashed-white chicken, every offspring shows blue feathers. The gene controlling feather pattern is found on the Z chromosome, not on the W chromosome. This gene has two alleles: barred (striped) feathers (A) and non-barred feathers (a).
(a)[2]
State the inheritance type for feather colour and for feather pattern.
(b)[5]
A male chicken with black, non-barred feathers was crossed with a female chicken with splashed-white, barred feathers. Every offspring had blue feathers, but the males were barred and the females were non-barred. Using the symbols given, draw a genetic diagram for this cross.
(c)[3]
Explain how the genotype of a male chicken with blue, barred feathers could be found.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “The answer is codominance.” …