Question

In a dihybrid cross a garden pea produces 1024 plants in F2 generation. How
many plants are homozygous for a one character and heterozygous for another
character?
(1) 256
(2) 512
(3) 64
(4) 128​

Answer 1

The correct option for the dihybrid cross is a garden pea that produces 1024 plants in the F2 generation plants that are homozygous for one character and heterozygous for another character (2) 512.

• In the dihybrid cross of garden pea in which two characters are studied simultaneously.
• Round(R), wrinkled(r) and yellow(Y) and green(y) are two types of characters studied.
• The cross of wild type produces F1 generation as RrYy.
• The self cross of F1 progenies will produce four types of genotypes.
• The genotypes of F2 progenies produced are 1:2:1:2:4:2:1:2:1.
• Out of these, 8 are homozygous for one character and heterozygous for another character.
• Genotypes of plants which are homozygous for one character and heterozygous for another character are 2×(RRYy +RrYY+ rrYy+ Rryy) = 8 genotypes.
• And the total genotypes are 16.
• So, several plants in the F2 generation plants that are homozygous for one character and heterozygous for another character = 8×1024/16 = 512 plants.