Question

Two genes of a flower, one controlling blue (B) versus white (b) petals and the other controlling round (R) versus oval (r) stamens, are linked and are 10 map units apart. You cross a homozygous blue oval plant with a homozygous white round plant. The resulting F1 progeny are crossed with homozygous white oval plants, and 1,000 offspring plants are obtained. How many plants of each of the four phenotypes do you expect?

Answer 1

If we cross a homozygous blue oval plant with a homozygous white round plant

P: BBrr  x  bbRR

The resulting F1 progeny:

F1: BbRr

If we cross BbRr with bbrr

F2: 1/4 blue round plants (250 plants) ¼ blue oval plants (250 plants)  ¼ white round  plants (250 plants) and ¼ white oval plants (250 plants).