Question

1. folate is a b vitamin (vitamin b - 9) that is important in red blood cell formation and for healthy cell growth and function. the nutrient is crucial during early pregnancy to reduce the risk of birth defects of the brain and spine. what happens to the body’s folate supplies with high levels of uv exposure?
2. vitamin d is a necessary vitamin that helps the body absorb calcium to help build bones and keep bones strong and healthy. it may also play important roles in muscle function and the immune system. how is sun exposure related to vitamin d production?
3. early human ancestors were thought to be covered in hair (like chimpanzees), with light skin underneath. this hair protected them from the uv rays. what is believed to have been the cause of the darkening of skin in early hairless humans?

Explanation:

1. High - level UV exposure can break down folate in the body. UV rays can damage folate molecules, reducing the body's folate supplies.
2. Sun exposure is essential for vitamin D production. When the skin is exposed to sunlight (specifically UVB rays), a precursor molecule in the skin is converted into vitamin D3.
3. The darkening of skin in early hairless humans is believed to be an adaptation to protect folate from UV - ray damage. Darker skin contains more melanin which absorbs UV rays, preventing the destruction of folate.

Answer:

1. High levels of UV exposure break down folate, reducing the body's folate supplies.
2. Sun exposure (UVB rays) causes the conversion of a precursor molecule in the skin into vitamin D3, facilitating vitamin D production.
3. The need to protect folate from UV - ray damage is believed to be the cause of skin darkening in early hairless humans as darker skin with more melanin absorbs UV rays.