The ___________ controls the amount of food that moves back up the esophagus.
A) duodenum
B) cardiac sphincter
C) gastric mucosa
D) pyloric sphincter
Answer: B) cardiac sphincter
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The condition that develops on a previously damaged heart valve is called
A. an aneurysm. B. acute bacterial endocarditis. C. myocarditis. D. subacute bacterial endocarditis.
Why does it take more than a week before a mosquito just infected with yellow fever virus can transmit the disease?
A. The virus must replicate in the gut of the mosquito before it can reach high enough numbers for transmission to a new human. B. Mosquitoes only feed once a week, which limits their ability to transmit the disease rapidly. C. Yellow fever is caused by a protozoan. It must develop from the sporozoite form into the mature form to become infectious, and this takes time. D. The virus multiplies in the gut of the mosquito, but then needs to migrate to the proboscis (biting nose) of the animal in order to infect a new human being after a new bite. This migration takes time
Each gene mutates at a characteristic frequency
Indicate whether this statement is true or false.
What does the mesoderm have to do with the designation of a true coelom?
A. The mesoderm gives rise to the fluid found within the coelom. B. The mesoderm gives rise to the lining of the coelom. C. The mesoderm gives rise to the outer covering of the coelom. D. The mesoderm gives rise to the structure of the coelom wall. E. The mesoderm has nothing to do with the coelom.