Why do they say human DNA is so similar?
Select one:
a. we travel a lot
b. it is not advantageous to be different
c. we are a young species

Select the correct answer from each drop-down menu proteins are

Which of the following types of pollution is most responsible for large numbers of deaths worldwide because of unsafe drinking water? (a) nutrient pollution (b) thermal pollution (c) pathogen pollution (d) sediment pollution

Substances that can pass through cell membranes by diffusion include a. na ions. b. proteins c. glucose. d. oxygen.