Question

Which of the following is an example of pleiotropy?

Group of answer choices

a A gene that encodes coat color also encodes weight gain

b Weight gain is encoded by many genes

c The gene that encodes coat color masks the effects of weight gain

d The gene that encodes coat color is sensitive to temperature

Answer 1

Pleiotropy refers to the phenomenon when a single gene can affect other genes (often unrelated). A common example is the disease PKU (phenylketonuria). In this disease, the gene coding for Phenylalanine hydroxylase is deficient. A defect in single gene produces multiple phenotypes that are observed in PKU.

In this question, example that indicates pleiotropy is option d - the gene that encodes coat color is sensitive to temperature.

Option A talks about two phenotype encoded by same gene, option B is same phenotype encoded by multiple genes. Option C is about the gene encoding coat color but masking effects of weight gain. This is epistasis. None of these options explain the effect of single gene on other phenotypes.

Only option D says that gene that encodes coat color is is sensitive to temperature. So encoding the gene for coat color is also resulting in temperature sensitive phenotype.