Question

In a dihybrid cross, the recombination frequency is usually:

• A. More than 50%
• B. Less than 50%
• C. Zero
• D. Upto 100%

Answer 1

The correct option is B Less than 50%

• In a dihybrid cross, breeding of two parent organisms possessing different allele pairs in their genotypes is carried out. A typical example is given in the above diagram where a pea plant with yellow round seeds is crossed with another pea plant with green wrinkled seeds. The F1 generation is then self-fertilized to get the F2 generation.
• In the F2 generation, the phenotypic ratio (yellow round: yellow wrinkled: green round: green wrinkled) is 9:3:3:1. Here the recombinants (deviation from parental phenotype) are 3 yellow wrinkled and 3 green round out of 16 progenies, which means the recombination frequency is 37.5%. Hence in a dihybrid cross, recombination frequency is usually less than 50%.