6.1 Reproduction

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Question 31
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In squash plants, the allele for white fruit colour (WWW) is dominant over the allele for yellow fruit colour (www).

A grower crossed a homozygous white-fruited plant (genotype WWWWWW) with a homozygous yellow-fruited plant. All resulting F1F_1F1​ offspring had white fruit.

a.

State the genotype of the homozygous yellow-fruited parent plant.

[1]
b.

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

Male gamete: WMale gamete: wFemale gamete: WWW(i)Female gamete: w(ii)(iii)\begin{array}{c|c|c} & \text{Male gamete: } W & \text{Male gamete: } w \\\hline \text{Female gamete: } W & WW & \text{(i)} \\\hline \text{Female gamete: } w & \text{(ii)} & \text{(iii)} \end{array}Female gamete: WFemale gamete: w​Male gamete: WWW(ii)​Male gamete: w(i)(iii)​​

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

[3]
c.

State the expected ratio of white-fruited plants to yellow-fruited plants in the offspring of this cross in its simplest form.

[1]

6.1 Reproduction Questions

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