Question

A completely-plated stickleback from a marinepopulation was mated to a low-plated sticklebackfrom a freshwater population. The resulting F1hybrids all displayed a completely platedphenotype. When the F1 hybrids were allowed tointerbreed, the resulting F2 generation includedcompletely plated offspring and low-platedoffspring in an approximate 3:1 ratio. Which ofthe following conclusions is best supported by theresults of the breeding experiments?
(A) Phenotypic variation in the F2 generationsuggests that armor morphology iscontrolled by many alleles of a single gene.
(B) The completely-plated phenotype iscontrolled by a dominant allele of asingle gene.
(C) Armor loss is an acquired characteristic thatis affected by one or more environmentalfactors.
(D) Patterns of armor plating in sticklebackpopulations are regulated by sex-specificsignals.

Answer 1

Answer:

This conclusion best supported by the results of the breeding experiment. "The completely-plated phenotype is controlled by a dominant allele of a single gene."

Explanation:

In the given inherent cross, all the F1 offspring stated a "completely plated" phenotype. This resources that this phenotype is dominant. Interbreeding of F1 hybrids attained the "completely plated" and "low plated" progeny in a 3: 1 ratio. This resources that equally these phenotypes are measured by two alleles of a gene. The F1 hybrids remained heterozygous dominant for the characteristic and passed both recessive and dominant alleles of the gene. Separation of these alleles throughout gamete development fashioned 50% alleles with the foremost allele and rest 50% with the retreating allele. The accidental fusion of these gametes gave the F2 progeny in 3 dominant: 1 recessive ratio .