Consider the following independent pathways that control the background feather color in parakeets. The dominant A and B alleles specify functional enzymes A and B, respectively. The recessive a and b alleles do not specify any of the corresponding enzyme. Each enzyme completely coverts the colorless compound to a colored compound (yellow or blue), as indicated by an arrow. Mixture of yellow and blue compounds results in a green compound. EnzA Colorless Yellow Enz B Colorless Blue AaBb parakeet, one of whose parents is white (colorless), is crossed to aabb parakeet. If the two genes that control feather color are 10 m.u. apart, what proportion of the progeny would be yellow or blue? Give a numerical value in percentage (%). A certain disease is caused by a dominant mutant allele. (The wild-type allele is recessive. However, the penetrance of the disease is 50%. Two individuals known to be heterozygotes have a child. What is the probability that the child exhibits the disease? O 1/4 O 3/4 O 3/8
