Question

Polygenic Trait means

• A. Several genes influence different traits; genes for a polygenic trait may be scattered along the same chromosome
• B. Several genes influence a trait; genes for a polygenic trait are not scattered along the same chromosome or different chromosomes
• C. Several genes influence different traits; genes for a polygenic trait are not scattered along the same chromosome or on different chromosomes
• D. Several genes influence a trait; genes for a polygenic trait may be scattered along the same chromosome or located on different chromosomes

Hint:

• Polygenic Inheritance A single phenotypic trait is controlled by the additive effects of two or more genes.
• Examples: Human height, skin color, intelligence, crop yield.
• These traits often exhibit continuous variation.
• The contributing genes (polygenes) can be on the same or different chromosomes.
• Contrast with Pleiotropy}, where one gene influences multiple traits.

Answer 1

The Correct Option is D

A polygenic trait (or quantitative trait) is a trait whose phenotype is influenced by multiple genes (polygenes), often in an additive manner. Each gene may contribute a small effect to the overall phenotype. These traits typically show continuous variation (e.g., height, skin color, weight in humans). The genes involved in a polygenic trait:

• Can be located on the same chromosome (they might be linked or assort independently if far apart).
• Can be located on different chromosomes (they will assort independently).

Let's analyze the options: (a) "Several genes influence different traits...": Incorrect. Polygenic inheritance refers to multiple genes influencing a single trait. Pleiotropy is when one gene influences multiple traits. (b) "Several genes influence a trait; genes for a polygenic trait are not scattered along the same chromosome or different chromosomes": The "not scattered" part is restrictive and likely incorrect. The genes can be scattered. (c) "Several genes influence different traits...": Incorrect, as in (a). (d) "Several genes influence a trait; genes for a polygenic trait may be scattered along the same chromosome or located on different chromosomes": Correct. This accurately describes that multiple genes contribute to a single trait, and these genes can be located at various positions in the genome.
Therefore, option (d) is the best description. “Several genes influence a trait; genes for a polygenic trait may be scattered along the same chromosome or located on different chromosomes.”