Question

Suppose that in plants, smooth seeds (S) are dominant to wrinkle seeds (s) and tall plants (T) are dominant to short plants (t). A tall plant with smooth seeds was backcrossed to a parent that was short and wrinkle. What proportion of the progeny is expected to be heterozygous for tall and smooth?

Answer 1

Answer:

1/4

Explanation:

According to the given information, the dominant plant is back-crossed with a homozygous recessive parent. Therefore, the dominant plant is heterozygous for both genes.  

The genotype of the tall plant with smooth seeds would be = TtSs

And the genotype of the dwarf parent with wrinkled seeds = ttss

A cross between TtSs x ttss gives heterozygous tall plants with smooth seeds (TtSs) in 1/4 ratio.