Which of the following elements were MOST likely the electron donors and electron acceptors of early microorganisms?

a. NADH / O2
b. NADH / fumarate
c. NO2- / O2
d. H2 / S0


Answer: D

Biology & Microbiology

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If two different species of fish fossils were found in two different layers of sedimentary rock, what might one infer about the specimens?

A. The species in lower layer died first B. They died at the same time C. The species in the higher layer evolved from the species in the lower layer D. The species in the higher layer died first E. The two species are unrelated

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The Bacteria and Archaea are the ONLY domains in which organisms exist that can

A) catalyze the transformation of inorganic nitrogen species for biosynthesis. B) assimilate nitrite. C) conserve energy from the transformation of inorganic nitrogen species. D) catalyze the incorporation of inorganic nitrogen species into biomolecules.

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Serological tests are most often conducted in

A. test tubes. B. flasks. C. microtiter plates. D. graduated cylinders.

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The coordinated beating of the heart is accomplished in part by the presence of ____ in heart muscle tissue that allows

for communication between the cells.

a. tight junctions b. desmosomes c. adherens junctions d. anchoring junctions e. gap junctions

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