The iris of the human eye can have many colors, including brown, blue, green, and hazel. How does polygenic inheritance explain why many iris colors are possible

The color of the iris is the example of polygenic inheritance.

Explanation:

Polygenic inheritance can be defined as the inheritance in which one trait is controlled by the two or more than two genes. The color of the skin, color of iris, weight and height are polygenic traits. The color of the iris is the polygenic trait the number of genes responsible for this are unknown but these genes are responsible for the synthesis of melanin pigment imparting color to the iris. OCA2 and HERC2 are the chief genes present on chromosome 15 responsible for this trait. Dark brown and black eyes are expected to have more amount of melanin as compared to the green and hazel eyes.

the national environmental policy act (nepa) is a united states environmental law that promotes the enhancement of the environment and established the president's council on environmental quality (ceq). the law was enacted on january 1, 1970. to date, more than 100 nations around the world have enacted national environmental policies modeled after nepa.