The accumulation of free oxygen in the atmosphere ____.
A. was a result of the accumulation of a by-product of a type of photosynthesis
B. caused the further spontaneous generation of life
C. provided the opportunity to extract more energy through anaerobic respiration
D. occurred immediately after the earth was formed
E. allowed for DNA to replace RNA as the primary data storage molecule
Answer: A
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Most of the organic sulfur is located in
A. fatty acids and lipids. B. monosaccharides and carbohydrates. C. amino acids and proteins. D. nucleotides and nucleic acids.
After an action potential is triggered, the rapid increase in membrane potential can be attributed to
A. the closing of potassium leak channels. B. the opening of the voltage-gated potassium channels. C. the closing of sodium leak channels. D. the direction reversal of the sodium/potassium pump. E. the opening of voltage-gated sodium channels.
The positive subatomic particle is
a. the neutron. b. the proton. c. the electron. d. both the electron and the proton. e. both the neutron and the electron
Autoclaving is effective for most materials except for
A) proteins. B) enzymes. C) amino acids. D) oils.