Scientific term for a situation where a single gene can exhibit multiple phenotypic expression is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Pleiotropy
Option (1) Polygenic inheritance — Incorrect. Here one trait is controlled by three or more genes, as in human skin colour. It is the reverse of the situation in the question: many genes, one trait.
Option (2) Pleiotropy — Correct. One gene affects several traits. In phenylketonuria, a mutation in the gene for the enzyme phenylalanine hydroxylase causes mental retardation and less pigment in hair and skin.
Option (3) Co-dominance — Incorrect. In co-dominance both alleles of a gene show fully in the heterozygote. In the ABO blood groups, IAIB gives blood group AB.
Option (4) Phylogeny — Incorrect. Phylogeny is the evolutionary history of a group of organisms. It is not a term about how a gene acts.
Note: A similar question was also asked in CUET (UG) 2026 on 21-05-2026 (Slot 1).
NCERT Extract:
Pleiotropy –
