Question

What phenotypic ratios are likely to occur in crosses when dealing with two completely dominant, independently segregating gene pairs, when both parents are heterozygous?

Answer 1

When both parents are heterozygous for two completely dominant, independently segregating gene pairs, a phenotypic ratio of 3:1 is likely to occur in the offspring.

Step-by-step explanation:

When dealing with two completely dominant, independently segregating gene pairs in a cross where both parents are heterozygous, we would expect a phenotypic ratio of 3:1. This means that for every 4 offspring, 3 will exhibit the dominant phenotype and 1 will exhibit the recessive phenotype.

For example, if we consider seed color in pea plants (yellow being dominant and green being recessive), and both parents are heterozygous (Yy), we would expect approximately 3 offspring with yellow seeds for every 1 offspring with green seeds.

It's important to note that these ratios are based on probability and large sample sizes, so individual crosses may not always produce the exact expected ratio.