The phenomenon in which a single gene can exhibit multiple phenotypic expression is called:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Pleiotropy
Pleiotropy is the effect of one gene on more than one trait. Such a gene is called a pleiotropic gene. Usually the gene acts on a metabolic pathway, and that affects several traits. In humans, the mutated gene for phenylketonuria is an example. A change in the enzyme phenylalanine hydroxylase causes mental retardation, reduced hair and skin pigmentation.
(1) Apomixis — Incorrect. It is the formation of seeds without fertilisation, seen in some angiosperms, mostly grasses.
(2) Pleiotropy — Correct. One gene shows multiple phenotypic expression.
(3) Polyembryony — Incorrect. It means that a seed carries more than one embryo, as in orange and mango.
(4) Polygenic inheritance — Incorrect. This is the opposite of pleiotropy. Many genes together control one trait, as in human skin colour and height.
Note: A similar question was also asked in CUET (UG) 2025 on 26-05-2025 (Slot 2), and in CUET (UG) 2023 on 13-06-2023 (Slot 3).
NCERT Extract:
Pleiotropy –
