Question

In dogs, the trait for aggressiveness is recessive and is represented with a. Mild-mannered dogs show the dominant trait, represented by A. Consider the cross of two dogs. What are the chances that these two parents will have an aggressive puppy?

Answer 1

Can't answer that without knowing the genotype of the parents. If the are both AA, chance is zero. If they are both aa, chance is 100. If one is Aa and the other is AA, etc. Got any more info?

Answer 2

There would be two possible cases in for this cross.

Case I: The genotype of the dog with a dominant trait is homozygous dominant, that is, AA.

The genotype of the dog with a recessive trait would be aa.

So, the genotype of all the puppies would be heterozygous dominant, that is, Aa.

Thus, the chances of having an aggressive puppy would be zero.

Case II: The genotype of the dog with a dominant trait is heterozygous dominant, that is, Aa.

The genotype of the dog with a recessive trait would be aa.

So, the genotype of the puppies can either be heterozygous dominant Aa or homozygous recessive aa.

Thus, the chances of having an aggressive puppy would be 50 percent.