Question

the biology of skin color
name eligan
this handout supplements the short film the biology of skin color.

1. true / false. biologists classify specific forms of traits as good or bad. for example, long tails in cats could be classified as good and short tails as bad.
2. explain the reasoning or evidence you used to answer question 1.
3. if you travel north from the equator, what generally happens to the intensity of ultraviolet (uv) light? a. the intensity increases. b. the intensity decreases. c. the intensity stays the same. d. it is impossible to predict.
4. who would you expect to be most at risk for developing the bone disease rickets? a. children born to mothers with dark skin, living far from the equator b. adults with dark skin who live close to the equator c. children born to mothers with light skin, living close to the equator d. adults with light skin who live close to the equator e. anyone who eats a diet that includes a lot of fish
5. explain the reasoning or evidence you used to answer question 4.
6. when dr. nina jablonski describes her discovery of the uv data collected by nasa, a headline is visible that reads, \ozone depletion raising risk of skin cancer, scientist says.\ use this headline and your understanding of what causes skin cancer to infer a beneficial feature of the ozone layer for humans. why would a depleted ozone layer increase the risk of skin cancer?
7. ultraviolet light can cause mutations and other damage within cells, which can hurt an individuals chance of surviving and leaving offspring. some molecules can protect cells from damage by uv. the amount of these molecules is determined by genes. within a population, some individuals make more of these uv - protection molecules than others.

Explanation:

1. Biologists do not classify traits as good or bad in an absolute sense as traits are adaptations to different environments. So the answer to question 1 is False.
2. Traits are evaluated based on their fitness - how well they help an organism survive and reproduce in a particular environment, not as inherently good or bad.
3. As you travel north from the equator, the intensity of ultraviolet (UV) light generally decreases because the sun's rays hit the Earth at a more oblique angle, spreading the energy over a larger area. So the answer to question 3 is b.
4. Children born to mothers with dark skin, living far from the equator are most at risk for rickets. Dark - skinned individuals have more melanin which blocks UV light, and in areas far from the equator where UV light is already less intense, there may not be enough UV to stimulate vitamin D production necessary for calcium absorption and bone health. So the answer to question 4 is a.
5. Rickets is caused by a lack of vitamin D, which is synthesized in the skin upon exposure to UV light. Dark - skinned individuals in low - UV environments have reduced ability to synthesize vitamin D.
6. The ozone layer absorbs most of the sun's harmful UV radiation. A depleted ozone layer allows more UV radiation to reach the Earth's surface. UV radiation is a known mutagen that can damage DNA in skin cells, leading to an increased risk of skin cancer. So a beneficial feature of the ozone layer is that it absorbs UV radiation, protecting humans from excessive UV exposure.
7. This passage describes the concept of natural selection. Individuals with genes that code for more UV - protection molecules are more likely to survive and reproduce in high - UV environments, passing on those genes to the next generation.

Answer:

1. False
2. Traits are not inherently good or bad but are adaptations to environments.
3. b. The intensity decreases.
4. a. Children born to mothers with dark skin, living far from the equator
5. Rickets is due to lack of vitamin D synthesis from insufficient UV exposure in dark - skinned individuals in low - UV areas.
6. The ozone layer absorbs UV radiation. A depleted ozone layer allows more UV to reach Earth, increasing skin cancer risk.
7. Describes natural selection related to UV - protection molecules.