a recently married couple are both heterozygous for cystic fibrosis. they would like to have two children. a. what is the probability that their first pregnancy will result in a child with cystic fibrosis

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.