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: -RR x rr. You’ll note that 100% of all offspring are Rr, which is the genotype. Since the genotype for all offspring are the same, and the Rr genotype encodes a pink color, then 100% of the phenotypes will be pink (NOT red-remember that this is incomplete dominance).

Detailed explanation-3: -There are dominant homozygotes (i.e. RR individuals) and recessive homozygotes (i.e. rr individuals). An individual who carries two different alleles (i.e. Rr) is a heterozygote (hetero = different).

Detailed explanation-4: -Finally, the genotype of an organism with two recessive alleles is called homozygous recessive.

Detailed explanation-5: -We know that RR is red and rr is white, since these genotypes are homozygous. Now you must determine if Rr is red, white, or some other phenotype. Codominance means that both phenotypes show simultaneously, so the heterozygote would be both red and white, which is a distinct third phenotype.