Question

In garden pea plant, when a plant with intermediate sized starch grains is crossed with a plant with small sized starch grains, what is the probability of offsprings with round shaped seeds and large sized starch grains?

• A. $\frac{1}{2}$
• B. $\frac{1}{4}$
• C. $\frac{1}{8}$
• D. 0

Answer 1

The correct option is D 0


Starch synthesis in the seeds of pea plant is an example of pleiotropy. In pleiotropy, one gene influences more than one character. In pea plant, the size of the starch grain and shape of the seed are controlled by a single gene with two alleles B and b. Starch is effectively synthesised BB homozygotes and large starch grains with round shaped seeds are produced. bb homozygotes have lesser efficiency and produce small sized starch grains with wrinkled seeds. The Bb heterozygotes produce intermediate sized starch grains with round shaped seeds.

When plant with intermediate sized starch grains is crossed to a plant with small sized starch grains, the resulting offspring show round shaped seeds with intermediate sized starch grains and wrinkled shaped seeds with small sized starch grains. But no offspring shows round shaped seeds with large starch grains.