A short RNA chain is synthesized as the first nucleotides in a new DNA strand by the enzyme ____ to provide a ____
for DNA elongation.
a. topoisomerase; 3¢ hydroxyl group
b. primase; 3¢ hydroxyl group
c. primase; 5¢ hydroxyl group
d. DNA polymerase; 5¢ phosphate group
e. DNA polymerase; 3¢ hydroxyl group
ANSWER: b
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Which habitat type in the figure above makes available the most new tissue to consumers?
A) tropical wet forest B) open ocean C) algal beds and reefs D) wetlands
Methanotrophs affect global temperature. This is because:
A. Methanotrophs metabolize methane, thereby reducing the amount of methane in the atmosphere. Since methane is one of the greenhouse gases whose accumulation causes a rise in global temperature, its reduction by methanotrophs helps prevent global warming. B. Methanotrophs convert methane to carbon dioxide and increase the amount of carbon dioxide in the atmosphere. Since carbon dioxide is one of the greenhouse gases whose accumulation causes a rise in global temperature, its production by methanotrophs contributes to global warming. C. Methanotrophs convert carbon dioxide to methane and increase the amount of methane in the atmosphere. Since methane is one of the greenhouse gases whose accumulation causes a rise in global temperature, its production by methanotrophs contributes to global warming. D. Methanotrophs convert methane to carbon dioxide, thereby decreasing the amount of methane in the environment but increasing the amount of carbon dioxide there. Since both methane and carbon dioxide are greenhouse gases whose accumulation causes a rise in global temperature, the decrease in one cancels the increase in the other and methanotrophs have no net effect on global warming. E. Methanotrophs combine carbon dioxide and methane to form petroleum and in this way take both methane and carbon dioxide out of the atmosphere. Since both methane and carbon dioxide are greenhouse gases whose accumulation causes a rise in global temperature, the decrease in both helps prevent global warming.
The molecule shown above is the purine ____
a. thymine b. adenine c. uracil d. guanine e. cytosine
What two locations can be a target for DNS poisoning? (Choose all that apply.)
A. local host table B. external DNS server C. local database table D. directory server "