A penis becomes erect because of
a. muscle contractions.
b. blood flow into spongy tissue.
c. hydrostatic pressure.
d. osmosis.
e. a combination of more than one of these
B
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The density of the organisms living at great depths is about:
a. the same as the surrounding density. b. greater than the surrounding density. c. less than the surrounding density.
Earth's larges phosphorus reservoir is _____
a. the atmosphere c. sediments and rocks b. bird droppings d. living organisms
Do the two DNA double helices following DNA replication have the same, or a different, composition?
a. different b. same
Which of the following factors would most likely increase the rate of photosynthesis?
a) decrease in CO2 concentration b) increase in glucose concentration in the cell c) increase in CO2 concentration in the atmosphere