Which of these diseases affects the body's largest organ, is caused by exposure to environmental stimulus, and is noninfectious?
a) flu
b) aids
c) skin cancer
d) parkinson's disease

How is the carbon cycle related to global warming ?

Describe the two types of vascular tissue

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.