Answer:
In Zebra mussels the cross that would the greatest number of heterozygous offspring is AA X aa (option A).
Step-by-step 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.