Question

In pea plants, smooth (S) peas are dominant over wrinkled (s) peas in the single gene controlling pea texture. A plant with smooth peas is crossed with a plant with wrinkled peas. Of the progeny, 252 are smooth and 247 are wrinkled. What are the genotypes of the parent plants?

Answer 1

Answer:

Ss and ss

Explanation:

Since the smooth trait (S) is dominant over the wrinkle trait (s), the genotype of the wrinkled pea parent is definitely ss.

Also, some of the progeny had wrinkled pea texture (ss). Each of the 2 wrinkled alleles must have been donated by each of the parent. It thus means that the smooth pea parent is heterozygous for the trait (Ss).

Now, let us look at a cross between the two parents;

  Ss   x   ss

Progeny: Ss, Ss, ss, ss.

Phenotypically, 50% of the progeny are smooth peas while 50% are wrinkled.

Looking at the population of each of the phenotype resulting from the cross. 252:247 is approximately a 50:50 ratio.

Hence, the genotypes of the two parents are Ss and ss.