Question

Using a Punnett square, work out the distribution of an autosomal phenotypic feature in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.

Hint:

In a cross between a homozygous dominant female and a heterozygous male, 50% of the offspring will be heterozygous and 50% will be homozygous dominant, all exhibiting the dominant trait.

Answer 1

Punnett Square: Autosomal Phenotypic Distribution 

In this scenario, we are crossing a homozygous dominant female (AA) with a heterozygous male (Aa) for a single locus.

Punnett Square:

	A (from female)	A (from female)
A (from male)	AA	AA
a (from male)	Aa	Aa

Genotypic Distribution:

• 50% AA (homozygous dominant)
• 50% Aa (heterozygous)

Phenotypic Distribution:

Since both AA and Aa genotypes express the dominant phenotype, 100% of the offspring will exhibit the dominant trait.