AP BIOLOGY

Detailed explanation-1: -With eye color, for instance, “B” stands for a brown allele and “b” stands for a blue allele. An organism with two dominant alleles for a trait is said to have a homozygous dominant genotype. Using the eye color example, this genotype is written BB.

Detailed explanation-2: -Purebred-Also called HOMOZYGOUS and consists of gene pairs with genes that are the SAME. Hybrid-Also called HETEROZYGOUS and consists of gene pairs that are DIFFERENT.

Detailed explanation-3: -An individual that contains two different alleles of a gene is heterozygous. A cow that has two alleles for a red coat is homozygous (bb). A bull with two alleles for a black coat is homozygous (BB). A calf that has one allele for red coat color and one allele for black coat color is heterozygous (Bb).

Detailed explanation-4: -In the cross shown in Figure above, you can see that one out of four offspring (25 percent) has the genotype BB, one out of four (25 percent) has the genotype bb, and two out of four (50 percent) have the genotype Bb.