BIO305 Exam 2
Instructions:
• Answer using a different font (e.g., red font) so that your answers can be distinguished from the
question.
• Use FULL SENTENCES in your answers, with proper spelling, grammar, punctuation, and
sentence structure. Points will be docked for improper writing style. This is a writing-enhanced
course.
• Species Latin (scientific) names MUST follow proper notation or else points will be docked.
• Everything must be in your own words. Plagiarized work will receive a grade of 0 and the
incident will be reported to the Academic Conduct Committee and remain on file in the Office of
the Provost. Plagiarizing more than once will result in an F in the course, with the possibility of
additional sanctions.
• The maximum number of points awarded for each answer is listed for each question.
• Your responses will overwrite the responses from your previous attempt at this exam. If you
leave blank any questions, your grade from your original attempt will hold. It is possible for your
grade to decrease if you score lower on your second attempt than on your original submitted
attempt.
1. As discussed in class, dark skin color in humans is thought to have been an adaptation in areas
with high levels of solar radiation because the melanin that makes skin dark prevents UV
radiation from damaging folate (involved in neural development) in the bloodstream.
Alternatively, light skin color in humans is thought to have been an adaptation in areas with low
levels of solar radiation because it allows for sufficient UV radiation to produce vitamin D within
the human body. Melanin also protects against skin cancer from UV radiation.
Why is it thought that the need for vitamins (folate and vitamin D) played a stronger role in the
evolution of skin color than did the protective effects of melanin against skin cancer? (4 points)
Folate and vitamin D play a stronger role in the evolution of skin color. Humans are exposed to
UV radiation regardless of their location on the planet and the chance of developing skin cancer
is a possibility for every human, even though skin cancer is less prevalent in people with darks
complexions. Deficiencies in folate and vitamin D is more detrimental to a population rather than
skin cancer which occur in a person’s peak reproductive years. Folate and vitamin D are strong
driving forces for the evolution of skin because it reduces offspring fitness and affect a person
overall health through their immune system and fertility. UV radiation destroy folate which is
essential for embryonic development and sperm health which may cause complications for
infertility in women. Vitamin D deficiency can cause rickets in children and osteomalacia in
adults.
2. Skin color can be measured as albedo (or reflectance), a value ranging from 0 to 1, with low
values representing dark coloration and high values representing light coloration. The
