Problem:

Question 1: a)  A Humans can have a wide variety of skin colors, and yet all humans have approximately the same number of melanocytes. How is this possible?

b) It appears that a combination of selective pressures in evolution have caused these genetic differences in melanin production. One of the main contributing selective factors appears to be exposure to UV radiation. It appears that the evolution of skin color strongly correlates to UV radiation exposure resulting in skin color that is effective, but not too effective in screening out UV radiation. Why would this be important in the evolution of skin color in humans?

Question 2: An aunt nieces and nephews love to play in the cold River when they visit. First the aunt notices their goose-bumps as they run by to jump off the boathouse roof. As they continue their water activities their lips becomes white and then cyanotic. Finally they cannot stand it any longer and they have to get out of the water to warm up. Explain all the effects of the cold water that the nieces and nephews experienced.

Question 3: During the very hot summer months health professionals are particularly concerned about the elderly. In terms of changes in the skin as people age explain why health professionals are concerned.

Could someone help to explain the answer of these questions.