Genotypic ratio of monohybrid cross is

• A. 3:1
• B. 1:2:1
• C. 1:1
• D. 9:3:3:1

The genotypic ratio of a monohybrid cross is determined by the inheritance of a single trait. In this case, the correct answer is B. 1:2:1.

Understanding Monohybrid Crosses

A monohybrid cross involves two parents that differ in one trait. For example, if we consider a trait like flower color, one parent might have purple flowers (PP) and the other white flowers (pp).

Expected Outcomes

When these two parents are crossed, the offspring can have the following genotypes:

• PP (homozygous dominant)
• Pp (heterozygous)
• pp (homozygous recessive)

This results in a genotypic ratio of 1 PP : 2 Pp : 1 pp, which simplifies to 1:2:1.

Other Ratios Explained

To clarify the other options:

• A. 3:1 refers to the phenotypic ratio of a monohybrid cross, not the genotypic ratio.
• C. 1:1 is typical of a test cross between a heterozygous and a homozygous recessive individual.
• D. 9:3:3:1 is the ratio seen in a dihybrid cross involving two traits.

In summary, for a monohybrid cross, the genotypic ratio is indeed 1:2:1.