AP BIOLOGY

HEREDITY

THE PEDIGREE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which of the following terms applies to traits, such as human eye color, that are controlled by more than one gene?
A
polygenic
B
mutants
C
carriers
D
homozygous recessive
Explanation: 

Detailed explanation-1: -A polygenic trait is a characteristic, such as height or skin color, that is influenced by two or more genes. Because multiple genes are involved, polygenic traits do not follow the patterns of Mendelian inheritance .

Detailed explanation-2: -In humans, height, skin color, hair color, and eye color are examples of polygenic traits. Type-2 diabetes, coronary heart disease, cancer, and arthritis are also deemed polygenic. However, these conditions are not just genetic since polygenes can be influenced by environmental factors.

Detailed explanation-3: -It was originally thought that eye color was a simple Mendelian trait, meaning it was determined by a single gene, with brown being dominant and blue recessive. It is now clear that eye color is a polygenic trait, meaning it is determined by multiple genes.

Detailed explanation-4: -Three examples of polygenic traits in humans are height, skin colour and eye colour. These traits are governed by multiple genes.

Detailed explanation-5: -Human phenotypes such as hair color, eye color, height, and weight are examples of polygenic traits. Complex diseases (e.g., cardiovascular diseases, Alzheimer’s, and Schizophrenia) also have a polygenic basis. Human hair color is an example of a polygenic trait.

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