What is the expected genotypic ratio resulting from a monohybrid cross?

In a monohybrid cross, two organisms that are heterozygous for a single trait are crossed. For example, if we take the alleles for a trait where "A" represents the dominant allele and "a" represents the recessive allele, the parents would both be "Aa".

When these are crossed, the possible combinations of alleles in the offspring can be represented in a Punnett square. The possible genotypes from this cross are:

1. AA (homozygous dominant)

2. Aa (heterozygous)

3. aa (homozygous recessive)

The expected ratio of these genotypes is derived from the combinations produced in the Punnett square:

• 1 AA

• 2 Aa

• 1 aa

Thus, the resulting genotypic ratio is 1:2:1, which reflects the presence of one homozygous dominant, two heterozygous, and one homozygous recessive genotype in the offspring. This ratio is fundamental in understanding inheritance patterns for a single trait in Mendelian genetics.