Question

question 7
which of these is a polygenic trait?
abo blood types in humans
color blindness in humans
developing a tan when human skin is exposed to ultraviolet light
skin color in humans

Explanation:

• ABO Blood Types in humans: Controlled by a single gene with multiple alleles (\(I^A\), \(I^B\), \(i\)), so it is a single - gene trait, not polygenic.
• Color blindness in humans: Usually caused by mutations in a single gene (e.g., genes related to cone - cell pigments on the X - chromosome for common types of color blindness), so it is a single - gene trait.
• Developing a tan when human skin is exposed to ultraviolet light: This is an environmental response (induction of melanin production by UV light) rather than a polygenic trait determined mainly by multiple genes.
• Skin color in humans: Influenced by multiple genes (e.g., genes related to melanin synthesis like \(MC1R\) and many others). Different combinations of alleles of these genes contribute to the wide range of skin colors in human populations, which is characteristic of a polygenic trait.

Answer:

Skin color in humans