Question

"Which mode of inheritance produces heterozygotes with phenotypes that differ from either homozygote but typically more closely resembles one homozygous phenotype than the other?"

Answer 1

Which mode of inheritance produces heterozygotes with phenotypes that differ from either homozygote but typically more closely resembles one homozygous phenotype than the other?"

A) complete dominance

B) incomplete dominance

C) codominance

D) epistasis

E) incomplete penetrance

Answer:

B) incomplete dominance

Explanation:

Incomplete dominance occurs when the dominant allele of a gene is not able to mask the expression of the recessive allele completely. This results in the expression of a phenotype in the heterozygous genotypes that differ from both homozygous genotypes. However, the phenotype of the heterozygote is closer to one of the homozygous genotypes.

For example, the petal color in four o'clock plant is controlled by a gene with two alleles R and r. Here, the "R" allele can not produce enough pigment in heterozygous conditions to completely mask the expression of the "r" allele and the phenotype of the "Rr" plant is "pink". On the other hand, the phenotype of "RR" plant is red while that of the "rr" plant is "white".