There are 127 offspring from a cross of AaBb x AaBb. If Mendelian ratios are followed, how many offspring would you expect to have recessive phenotypes for both traits?

eight (8)

Explanation:

A phenotypic ratio of 9:3:3:1 is predicted from a cross of AaBb x AaBb (i.e., in a dihybrid cross). In this case, the expected phenotypic ratio is equal to:

A_B_ (9:3:3:1) =71.43 >> 71 both dominant phenotypes

aaB_ (9:3:3:1) = 23.81 >> 24 one dominant phenotype

A_bb (9:3:3:1) = 23.81 >> 24 one dominant phenotype

aabb (9:3:3:1) = 7.93 >> 8 both recessive phenotypes

Expected phenotipic ratio (9:3:3:1) = 71 + 24 + 24 + 8 = 127

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".