The Biology of Human Skin Color

What is the most important pigment that determines skin color in humans?

• Tyrosinase

• Keratinocytes

• Melanin

• Hemoglobin

What percentage of the ultraviolet radiation (UVR) can melanin absorb to protect the DNA within skin cells?

• 50%

• 75%

• 90%

• 99.9%

Which cells are primarily responsible for the production of melanin?

• Melanocytes

• Keratinocytes

• Hemocytes

• Erythrocytes

What is the function of melanin in relation to ultraviolet radiation (UVR)?

• It helps to produce Vitamin D.

• It serves as the body's natural sunscreen.

• It increases the absorption of UVR.

• It has no significant function related to UVR.

Why did early human ancestors develop dark skin according to the text?

• To protect against cold climates.

• To produce more Vitamin D.

• To protect against the damaging effects of intense equatorial sunlight.

• To adapt to the migration to northern regions.

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What is the popular theory for the evolution of lighter skin in humans who migrated to areas with less intense sunlight?

• They needed to absorb more UVR to produce Vitamin D.

• They needed to adapt to colder climates.

• They needed to conserve body heat.

• They needed to blend in with the snowy environment.

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What is melanin? Describe the two main types of melanin.

• A type of skin cell; eumelanin and pheomelanin

• A pigment that gives skin its color; eumelanin and keratinocytes

• A pigment that gives skin its color; eumelanin and pheomelanin

• A vitamin necessary for skin health; keratinocytes and melanocytes

Why do people with albinism lack melanin?

• Due to a vitamin D deficiency

• Because of excessive exposure to sunlight

• Owing to a genetic mutation that prevents melanin production

• As a result of a lack of keratinocytes in the skin

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How do melanocytes contribute to skin color?

• They produce keratin which affects skin color

• They absorb sunlight and darken the skin

• They produce melanin which gives skin its color

• They reflect light and protect the skin from UV rays

What causes the difference in pigmentation between people with darker skin and people with lighter skin?

• The amount of keratin in the skin

• The number of melanocytes in the skin

• The type and amount of melanin produced by melanocytes

• The skin's exposure to sunlight only

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