6.1 Reproduction

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Question 44
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In mice, the allele for normal pigmented fur (AAA) is dominant over the allele for albino (white) fur (aaa).

A researcher crossed a homozygous normal-pigmented mouse (genotype AAAAAA) with a homozygous albino mouse. All resulting F1F_1F1​ offspring had normal-pigmented fur.

a.

State the genotype of the homozygous albino parent mouse.

[1]
b.

Two of the F1F_1F1​ offspring mice (both with genotype AaAaAa) are crossed. Complete the genetic diagram (Punnett square) below by determining the missing genotypes of the offspring.

Male gamete: AMale gamete: aFemale gamete: AAA(i)Female gamete: a(ii)(iii)\begin{array}{c|c|c} & \text{Male gamete: } A & \text{Male gamete: } a \\\hline \text{Female gamete: } A & AA & \text{(i)} \\\hline \text{Female gamete: } a & \text{(ii)} & \text{(iii)} \end{array}Female gamete: AFemale gamete: a​Male gamete: AAA(ii)​Male gamete: a(i)(iii)​​

Identify the genotypes for (i), (ii), and (iii).

[3]
c.

State the expected ratio of normal-pigmented mice to albino mice in the offspring of this cross in its simplest form.

[1]

6.1 Reproduction Questions

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