The Biology of Skin Color

Which of the following statements about melanin is most accurate?

• Melanin is found only in human cells and is not present in other organisms.

• Human skin cells contain only one type of melanin.

• The more eumelanin an individual has in their skin cells, the darker their skin.

• The darker an individual’s skin color, the more likely ultraviolet (UV) radiation will damage the DNA in their cells.

More melanin leads to

• More vitamin C in the body

• Darker skin tones

• Lighter skin tones

• More Vitamin D in the body

There has been a correlation between birth defects and skin color based on what vitamin deficiency?

• Calcium

• iron

• c

• folate

More sunlight leads to

• More folate in the body

• Less folate in the body

• More Vitamin C in the body

• More iron the body

Knowing the area where UV is highest, is there a correlation in skin color and UV exposure?

• Yes

• No

• IDK

• Maybe

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The areas with the highest UV are in red. What country listed has the most amount of UV?

• The United States

• Africa

• Russia

• Canada

Who would you expect to be most at risk for developing the bone disease rickets?

• Children born to mothers with dark skin, living far from the equator

• Adults with dark skin who live close to the equator

• Children born to mothers with light skin, living close to the equator

• Adults with light skin who live close to the equator

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If you travel north from the equator, what generally happens to the intensity of ultraviolet (UV) light?

• The intensity increases

• The intensity decreases.

• The intensity stays the same.

• It is impossible to predict.

Rickets, a disease that affects bone development in children, is caused by vitamin D deficiency. Which of the following groups of people has the

highest

risk of rickets if they do not take vitamin D supplements? Assume that each group spends a lot of time outdoors.

• adults with dark skin who live close to the equator

• children with light skin who live close to the equator

• adults with light skin who live far south of the equator

• children with dark skin who live far north of the equator

People who live in low-UV environments tend to have lighter skin tones. One hypothesis is that, in low-UV environments, the selective pressure for dark skin is low. Instead, there is selective pressure for lighter skin, which absorbs more UV radiation, since UV is needed for vitamin D production. Which of the following statements best supports this hypothesis?

• In general, people with lighter skin tend to have a higher risk of vitamin D deficiency.

• Red hair and light skin are most common among people of northern European descent.

• Indigenous peoples with darker skin who live at high latitudes have diets that consist of foods rich in vitamin D.

• People with lighter skin cannot synthesize enough vitamin D in high-UV environments, such as equatorial Africa.

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