What is the outcome of crossing two heterozygous individuals (Aa x Aa) in a monohybrid cross?

In a monohybrid cross involving two heterozygous individuals (Aa x Aa), the expected outcome is based on the principles of Mendelian genetics. When you set up this cross, you can create a Punnett square to visualize the potential genetic outcomes.

The alleles from each parent can combine in the following ways:

• From one parent, you can have either the dominant allele (A) or the recessive allele (a).

• From the other parent, the combinations remain the same (A or a).

The possible combinations from the cross would be:

• AA (homozygous dominant)

• Aa (heterozygous)

• Aa (heterozygous)

• aa (homozygous recessive)

Counting these combinations, you find:

• 1 AA (homozygous dominant)

• 2 Aa (heterozygous)

• 1 aa (homozygous recessive)

This gives a genotype ratio of 1:2:1, but in terms of phenotype, since both AA and Aa express the dominant phenotype, 3 out of 4 offspring (75%) will display the dominant phenotype. Only 1 out of 4 offspring (25%) will display the recessive phenotype