For a pair of genes with alleles: a (dominant) a (recessive) at the first locus; and b (dominant) b (recessive) at the second locus, that operate in a duplicate dominant epistatic manner, what proportion of offspring from a doubly-heterozygous mating are expected to show the recessive phenotype? a. 0.5. b. 1 (it's dominant). c. 15/16. d. 9/16. e. 1/16.

E. 1/16

Explanation:

In a duplicate dominant epistasis, when one locus presents a dominant genotype and the other presents a recessive genotype, the dominant one hides the effective of the recessive gene. Therefore, a recessive phenotype will only be observed when both genes are recessive homozygous (aabb).

Assuming a doubly-heterozygous mating (AaBb x AaBb), the probability that both genes are recessive homozygous is:

1/16 of offspring are expected to show the recessive phenotype.

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs