Question

Start with the P generation with the following genotypes (AA x aa). Based on classical Mendelian inheritance, how will a cross between two homozygous parents, one dominant and one recessive, influence future generations?

A) The F1 generation will show an even split between the dominant phenotype and the recessive phenotype.

B) The F1 generation will all show the dominant trait and future crosses will continue to produce genotypes expressing the dominant trait.

C) Although the F1 generation will all show the dominant trait, the offspring will all be heterozygous and increase chances of future variation.

D) The F1 generation will show a mix of the dominant phenotype and recessive phenotype and over generations the recessive trait will increase in number.

Answer 1

The answer is C. The dominant trait will be present in all cells in a Punnet Square, meaning the dominant trait will be shown in the entire F1 generation, but if an offspring from the F1 generation mates with a parent with only recessive traits (aa), it will create one offspring in the F2 generation that will have the recessive trait showing. Ex: F1: Aa - other parent: aa.