Zebra mussels have the following genotypes and phenotypes. Which cross would the greatest number of heterozygous offspring. A) AA x aa C) AA x Aa or D) aa x Aa

In Zebra mussels the cross that would the greatest number of heterozygous offspring is AA X aa (option A).

Explanation:

For a specific trait the cross that provides the greatest amount of heterozygous offspring is that of two pure lines, dominant and recessive. In this case, AA x aa will have a 100% probability of heterozygous (Aa) offspring, as can be seen in a Punnett chart:

Alelles A A

a Aa Aa

a Aa Aa

AA X Aa will only have a 50% chance of heterozygous offspring, as will the cross aa X Aa.

- AA X Aa

Alelles A A

A AA AA

a Aa Aa

- Aa X aa

Alelles A a

a Aa aa

a Aa aa

A heterozygous genotype results in two different alleles being found in one gene, which determines a specific trait, where the dominant characteristic is expressed in the phenotype.