Question

In pea plants, the long stem trait 'S' is dominant and the short stem trait 's' is recessive. Two pea plants were crossed, producing seeds that yielded 165 long stem plants and 54 short stem plants. The genotypes of the parent plants that was most likely is?

• A. Ss and SS
• B. Ss and Ss
• C. ss and ss
• D. SS and ss

Answer 1

The correct option is B Ss and Ss

The ratio of long stem plants to short stem plants among the progeny is 165:54 which means it has a ratio of 3:1. This ratio is possible if the parents are heterozygous in nature (Ss) which after the cross will produce homozygous tall (SS), heterozygous tall (Ss), and homozygous dwarf (ss) offspring.

As the heterozygous offspring expresses the dominant allele, they will also be tall.

Gametes	S	s
S	SS	Ss
s	Ss	ss

So, the correct option is B.