Question

Occasionally, a single gene may express more than one effect. The phenomenon is called:

• A. multiple allelism
  
• B. pleiotropy
  
• C. mosaicism
  
• D. polygeny

Answer 1

The correct option is B pleiotropy


Multiple allelism

Multiple alleles are more than two different forms of a gene. Examples include the ABO blood group system. The I gene has three different forms like I${}^A$ , I${}^B$ and I${}^O$, which determine the surface antigens of RBCs.

Mosaicism

Mosaicism is a condition in which cells with different genetic composition are present in the same organism.

Pleiotropy

Pleiotropy is a genetic condition when a single gene influences two or more distinct phenotypic characteristics or traits, i.e., a single gene influences multiple traits.

Polygeny

Polygeny is a type of inheritance when the phenotype of a trait is influenced by more than one gene.

Final answer
c. pleiotropy