AP BIOLOGY

Detailed explanation-1: -Individuals who are homozygous dominant (DD) or heterozygous (Dd) are Rh+. Those who are homozygous recessive (dd) are Rh-(i.e., they do not have the key Rh antigens). Clinically, the Rh factor, like ABO factors, can lead to serious medical complications.

Detailed explanation-2: -Therefore, you have a total of two alleles for this gene. Suppose that the GENOTYPE (the genetic makeup for this trait) of Sam is “DD". He is HOMOZYGOUS (has 2 identical alleles for that gene) for the dimples gene. Sally’s genotype is “dd", so she is also considered homozygous.

Detailed explanation-3: -An organism can be either homozygous dominant ( TT ) or homozygous recessive ( tt ). If an organism has two different alleles ( Tt ) for a certain gene, it is known as heterozygous (hetero-means different).

Detailed explanation-4: -dd = dwarf (homozygous recessive) Mendel was smart to use peas, most stocks are completely true-breeding = homozygous. And he made sure they were homozygous before doing crosses.