Q. In tomatoes, stem colour and fruit colour are determined by two independently assorting genes. At one gene, purple stem (P) is dominant to green stem (p). At the other gene, yellow fruit (Y) is dominant to red fruit (y). Consider a cross between two tomato plants heterozygous for both these alleles:
a. Specify the genotypes of all gametes that can be made by one of these plants, and in what proportions they will occur. (Note: Give the genotypes of the gametes, not the offspring.)
b. What proportion of the offspring is expected to be heterozygous for both genes?
c. What proportion is expected to have genotype pp YY?
d. What proportion is expected to have green stems?
e. What proportion is expected to have yellow fruit?
f. What proportion is expected to have green stems and red fruit?
g. What proportion is expected to have purple stems and red fruit?
h. If a double heterozygous plant were crossed with a plant that has green stems and red fruit, what offspring phenotypes would be expected and in what proportions?