Question

A pea plant producing round seeds is crossed with another pea plant producing wrinkled seeds. In the $F_1$ generation, $50\%$ of the offspring produced wrinkled seeds. Predict the genotype of the parents.

• A. $RR\times rr$
• B. $Rr\times Rr$
• C. $RR\times Rr$
• D. $Rr\times rr$

Answer 1

The correct option is D $Rr\times rr$

Round shape of seeds is dominant over the wrinkled shape of seeds.

Given that $50\%$ of the $F_1$ offspring produced wrinkled seeds.

This implies that $50\%$ of the offspring were homozygous for the recessive allele. The genotype is represented by $rr$.

The genotype of plants with round shaped seeds can be RR or Rr.

1. Consider the cross, $RR\times rr$, all the $F_1$ offspring will produce round seeds.


2. Consider the cross, $Rr\times Rr$, $75\%$ of the offspring will be producing round seeds, while $25\%$ of the offspring will be producing wrinkled seeds.

3. Consider the cross, $RR\times Rr$, all the $F_1$ offspring will produce round seeds.

4. Consider the cross, Rr x rr, $50\%$ of the offspring will be producing round seeds while $50\%$ of the offsprings will be producing wrinkled seeds.


Hence, the genotype of the parents is Rr and rr.