Which of the following is used to describe the openings to the hearts in animals with open circulatory systems?
a. atria
b. ostia
c. septa
d. ventricles
b. ostia
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Why did scientists originally believe that proteins, rather than DNA, were the molecules that directed protein synthesis?
A. Proteins were the more complex molecules in which genetic information could be stored. B. Proteins were more likely to have catalytic properties for synthesis reactions. C. At the time, more was known about the structure of proteins than that of DNA. D. Proteins were the same types of molecules as those that were being synthesized.
The type of relationship between nitrogen fixing bacteria and the roots of various plants is ________
a. commensalistic b. parasitic c. None of these d. predatory e. mutually beneficial
When you are scared or cold and turn pale it is because the ________ in your skin are constricting.
A. arteries B. veins C. capillaries D. venules E. arterioles
Antoni van Leeuwenhoek was the first person in history to
A) use a magnifying glass. B) develop a taxonomic system. C) view microorganisms and record these observations. D) disprove spontaneous generation. E) use the germ theory of disease.