Which of the following is true about a spinal reflex? a. it is controlled by the brain. b. it is an involuntary response to a stimulus. c. it is a voluntary contraction of muscles. d. it increases blood flow to muscles.

Marianne is comparing two animals: a fruit fly and a fruit bat. she asks, "do a fruit fly and a fruit bat share a common ancestor in their evolutionary history? " according to evolutionary theory, what is the answer to marianne's question?

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

Which level of taxonomy has the fewest organisms?