The driving force for heart contraction is
a. contraction of the atria.
b. contraction of the ventricles.
c. closing of the AV valves.
d. opening of the AV valves.
e. closing of the aortic valve
B
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Antigenic variation in Neisseria gonorrhoeae is due to:
A. gene conversion. B. mating-type switch. C. aneuploidy. D. homing endonucleases. E. transformation.
During stressful situations, epinephrine initiates ____
a. dilation of blood vessels to the skin b. dilation of blood vessels to the heart c. constriction of blood vessels to the brain d. a decrease in metabolic rate e. a decrease in blood glucose levels
Which of the following is NOT a mode of transfer of an infectious disease?
a. direct contact b. indirect contact c. inhaling the pathogen d. contact with a transmitting agent e. retro-contact
The principle of nuclear equivalence states that:a
developing cells become specialized to carry out specific functions. b. developing cells follow particular differentiation pathways. c. there is no loss of genetic information through determination or differentiation. d. differential gene expression is responsible for variation among cells. e. nuclear changes can take place during the entire life of an individual.