Question

1. In squash, white fruit is dominant over yellow fruit. If a hybrid white-fruited plant pollinates a yellow fruited one, what choice of fruit colors can be predicted among the offspring?

2. Humans ear lobes hang freely due to a dominant gene, while attached lobes are due to recessive genes. A child whose ear lobes are free-hanging has one parent with ears like his, one parent with attached lobes, and one sibling with attached lobes. Write the genotype of all 4 people. Could other genotypes exist in other children in his family?

3.Suppose a large-nosed man married a small-nosed woman, large nose being the dominant trait. One parent of both is known to be small-nosed. What proportion of their children is likey to be small-nosed?

4. Dimples are dominant. A dimpled man and non-dimpled woman have 10 children, all dimpled, we might be tempted to assume that the father has pure set of genes for the dimpled trait. Do we know this? What must child #11 be to determine the father's genotype with certainty? Explain.

Answer 1

1. Given that white fruit is dominant over yellow.
Suppose the allele for white fruit is = Y
and the allele for yellow fruit is = y.
The genotype of hybrid white fruit = Yy
The genotype of yellow fruited plant = yy
Parents = Yy (hybrid white) x yy (yellow)

	Y	y
y	Yy (hybrid white)	yy (yellow)
y	Yy (hybrid white)	yy (yellow)

The phenotype ratio of progeny = 1 hybrid white : 1 yellow