AP BIOLOGY

Detailed explanation-1: -Only individuals with an aa genotype will express a recessive trait; therefore, offspring must receive one recessive allele from each parent to exhibit a recessive trait.

Detailed explanation-2: -Background: The DD genotype gene is a linkage marker for an etiologic mutation at or near the angiotensin-converting enzyme gene and has been associated with increased risk for the development of coronary artery disease, left ventricular hypertrophy and left ventricular dilation after myocardial infarction.

Detailed explanation-3: -Because of random fertilization between the gametes (there is only one possibility in this example), the genotype of the offspring(s) is “Dd” and the phenotype must be “Dimpled".

Detailed explanation-4: -DD is homozygous dominant, Dd is heterozygous and dd is homozygous recessive. They cannot be heterozygous because the dominant allele will be shown so they will have dimples.

Detailed explanation-5: -Finally, the genotype of an organism with two recessive alleles is called homozygous recessive.