Bio 110 Exam 3 Questions With Complete Solutions

A gene that affects the expression of a second gene is an example of __________________. a) pleiotropy b) codominance c) epistasis d) polygenic inheritance e) incomplete dominance correct answer: c) epistasis __________ is an example of a character that is controlled by more than one gene (a quantitative character) and demonstrates a continuum of phenotypes. a) Pleiotropy b) Polygenic inheritance c) Epistasis d) Codominance e) Incomplete dominance correct answer: b) Polygenic inheritance The gene controlling ear color in an organism known as a gizmo has two alleles that exhibit incomplete dominance: CR, which codes for red ears; and CY, which codes for yellow ears. Individuals that are homozygous for the CR allele have red ears, whereas the heterozygous genotype produces orange ears. Those that are homozygous for the CY allele have yellow ears. If two individuals with orange ears are crossed, what ratio of phenotypes should be expected in the offspring? a) 9:3:1, red:yellow:orange ears b) 3:1, red:yellow ears c) 1:2:1, red:orange:yellow ears d) 1:2:1, red:yellow:orange ears e) 1:3, red:yellow ears correct answer: c) 1:2:1, red:orange:yellow ears Mice with the genotypes BBCc and bbcc are crossed. The alleles for brown coat (b) and no pigment (c) are recessive, and black coat (B) is dominant. What color of mice would NOT be produced by this mating? a) brown b) white c) black correct answer: a) brown An individual that is heterozygous for an allele and that exhibits a phenotype intermediate between that of the two homozygous alternatives is an example of _____. a) polygenic inheritance b) pleiotropy c) codominance