A geneticist spent several years studying the inheritance of types of earwax (cerumen) in a large isolated Native American population out in the midwest U.S. The geneticist studied the inheritance of this trait by observing the reproduction of different couples and keeping notes of their phenotypes (dry or sticky earwax) and numbers of offspring.

offspring

Parent phenotypes Number of couples observed Sticky Dry

Sticky x sticky 10 32 6

Sticky x dry 8 21 9

Dry x dry 12 0 42

a. Look at the data for all 3 possible types of parents (both sticky, both dry, and one sticky/one dry). Which phenotype is dominant? Which phenotype is recessive? Explain the thinking that got you to your answer! (Hint: Remember dominant phenotypes have multiple possible genotypes; recessive phenotypes do not)

b. Based on the dominant/recessive allele information you figured out in part a use a letter E/e to represent the earwax gene and show one possible cross of a sticky x dry couple, as well as the genotypes and the phenotypes of the offspring. (There are two possible correct ways to do