Which structure prevents blood flowing back into the atria during ventricular contractions?
A. semilunar valves
B. atrioventricular valves
C. sinoatrial node
D. carotid blood shunts
E. foramen ovale
B. atrioventricular valves
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Which of the following is a cellular response to signal transduction?
A. a change in the proteins found in the cytosol B. the release of more signal molecules C. a change in the activity of an enzyme D. All of these answer options are correct.
To cultivate Legionella in the laboratory, a medium supplemented with what ingredient(s) is necessary?
a. L-cysteine and iron b. Blood and cysteine c. Dopa-cysteine d. Nicotinic adenine
During a lecture on adaptive evolution, your instructor is explaining how dark-colored moths were selected for during the Industrial Revolution in England, due to their better camouflage against soot-covered trees and buildings. One of the other students in the class interrupts the lecture to insist that this example does not support the theory of evolution because the genes for both light colored and dark colored moths already existed prior to the Industrial Revolution. What mistake has your classmate made?
a. The genes for dark colored moths were in fact created by natural selection during the Industrial Revolution. b. This example is entirely hypothetical; moths do not fossilize so there is no way to document their phenotypes in the past. c. Natural selection is intended to explain the change in frequency of existing alleles in a population over time. d. Your classmate raises an original point that certainly would not be a waste of the class’s time to argue about yet again.
A substance that can elicit an immune response from a lymphocyte is called a(n) ________
A) defensive protein B) pathogen C) antibody D) antigen