Question

A mutation that affects more than one type of phenotype is known as
a. Pleiotropic mutation
b. Multiple mutation
c. Polygenic mutation
d. Monogenic mutation

Answer 1

Hint: Mutations are defined as the sudden and heritable change in the gene or chromosome in the cells of the body. It includes only those changes that alter the chemical structure of the gene at the molecular level.

Complete answer:
> Pleiotropic mutation
Pleiotropy is the phenomenon in which a single gene influences more than one phenotypic trait. However, it may be that one gene may cause evidently well marked expression of some phenotype trait than the others with the less evident phenotype. Most genes have multiple effects and are called pleiotropic genes.
Any mutation in a gene showing pleiotropy is called pleiotropic mutation.

> Multiple mutation
Mutations that affect multiple genes in the cells of the body are called multiple mutations. The various types of cancers in the human body are associated with multiple mutations.

> Polygenic mutation
Though both heredity and environment contribute to the production of grades of phenotypes, continuous variation is often due to the additive effects of two or more genes for the trait. These are called polygenic traits and the genes involved are called polygenic genes.
For example, human skin color can grade from black to white with all intermediate shades and so the human height also exhibits a gradation from short to tall forms. So both these are examples of polygenic traits.
The mutation in the genes showing polygenic inheritance is called a polygenic mutation.

> Monogenic mutation
The mutation in a single gene in every cell of the body is called a monogenic mutation.

Hence, the correct answer is option (A).

Note: The organisms living in this world, are the products of the hundreds of thousands of years of this process of selecting favorable mutations and they are well adapted for the particular environment in which they live.