Why would someone need to have an artificial pacemaker installed in his or her heart tissue?
A) The heart valves are not directing blood flow through the chambers properly.
B) The AV node is not sending signals to the ventricles.
C) The SA node is not functioning properly to generate action potential at the proper intervals.
D) The Purkinje fibers are not distributing the signal properly.
C
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Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter, a nonhalophilic mannitol fermenter, and a halophilic mannitol nonfermenter. Thus, the medium is acting as a ________ medium.
A. differential B. selective C. selective and differential D. neither selective nor differential
The closest living relatives of birds are
a. mammals. b. snakes and lizards. c. turtles. d. crocodiles. e. amphibians.
Protists contain all of the following forms of life EXCEPT
A. protozoa. B. fungi. C. algae. D. slime molds.
Some protist cell surfaces have ________, including silica or calcium carbonate.
What will be an ideal response?