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Biology Question 105 – NEET-UG 2023

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The phenomenon of pleiotropism refers to

Understand different ways genes interact to produce phenotypes.

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Ninja Strategy•Core Definition Recall

Quickly recall the precise definition of pleiotropy as a single gene influencing multiple traits to identify the correct option and eliminate others that describe different genetic phenomena.

Step 1: Define Pleiotropy✦ Active

Pleiotropy is a genetic phenomenon where a single gene influences two or more distinct phenotypic traits. This means one gene has multiple effects on an organism's phenotype.

Step 2: Evaluate the Options○ Expand

Let's examine each option: (1) "presence of several alleles of a single gene controlling a single crossover." This describes multiple allelism and genetic recombination, not pleiotropy. (2) "presence of two alleles, each of the two genes controlling a single trait." This describes polygenic inheritance (multiple genes for one trait), not pleiotropy. (3) "a single gene affecting multiple phenotypic expression." This statement perfectly matches the definition of pleiotropy. (4) "more than two genes affecting a single character." This also describes polygenic inheritance, where multiple genes contribute to a single trait.

💡 Teacher's Secret Hint

Carefully distinguish between pleiotropy (one gene, many traits) and polygenic inheritance (many genes, one trait).

Step 3: Conclusion○ Expand

Based on the definition, option (3) correctly describes the phenomenon of pleiotropism.

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