Question

A recessive mutant is one, which is
A. Not expressed
B. Rarely expressed
C. Expressed only in the homozygous state
D. Expressed only in the heterozygous state

Answer 1

Hint: Wild allele is the one which was originally present in the population, is dominant, and usually widespread. the recessive allele is less common and is believed to be formed through mutation of the wild allele.it is therefore also called a mutant allele

Complete answer:Option-A-Not expressed: A recessive allele is known as the mutant allele and it will not be expressed if the other allele is dominant but if the other allele is also recessive or mutant then it can express itself.
Option-B-Rarely expressed: A recessive allele is present in a low number in the population and can only be expressed when present with other recessive alleles but since option c is more accurate that's why it cant be option B.
Option-C-Expressed only in the homozygous state: Recessive allele or mutant allele can only express itself when present with other recessive alleles and this type of combination is known as the homozygous combination(presence of identical allele of a gene on its homologous chromosome). To express a recessive allele is to be present with another recessive allele (HOMOZYGOUS STATE).
Option-D-Expressed only in the heterozygous state: The recessive allele can not express themselves when they are present with another dominant allele (HETEROZYGOUS STATE). As only dominant allele or wild allele can express themselves when present with mutant allele or recessive allele.
So, the correct answer is option C (Expressed only in the homozygous state)

Note: The mutant allele even becomes the wild type if a genetic shift occurs within the population. The mutation of wild-type alleles has a very important role in genetically modified crops and the formation of vaccines for some untreatable diseases such as EBOLA, HIV.