What is indicated by the fact that NOT all eukaryotic cells contain both mitochondria and chloroplasts?
a. Endosymbiosis did not occur at all.
b. Endosymbiosis occurred only in the evolution of mitochondria.
c. Endosymbiosis did not occur in stages.
d. Endosymbiosis occurred in stages.
Ans: d. Endosymbiosis occurred in stages.
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The type of movement of molecules that is specific and passive, and which becomes saturated if all of the protein carriers are in use is
A. exocytosis. B. facilitated diffusion. C. active transport. D. endocytosis. E. osmosis.
Which of the following statements concerning the peripheral nervous system is false?
a. Spinal nerves lead to and from the spinal cord. b. There are 31 pairs of spinal nerves. c. Cranial nerves lead from the brain directly to the spinal cord. d. Some nerves carry only sensory information. e. Some nerves are both sensory and motor.
In the experimental evaluation of a new drug, what is the purpose of a placebo?
a. A placebo increases the sample size. b. A placebo prevents errors in recording of the data. c. A placebo removes the bias of the physician in charge of the experiment. d. A placebo removes the potential psychological bias of the patient in the study. e. A placebo prevents sampling errors from compromising the results of the experiment
Which of the following statements is NOT true concerning enzymatic activity?
a. Each enzyme has a preferred pH at which the enzyme reaction rate is highest. b. Above a certain temperature, an enzyme will become denatured. c. As the temperature increases, most enzymatic reactions will still proceed at the same rate. d. Enzymatic reactions proceed quite rapidly. e. Enzyme activity increases as substrate concentration increases until the maximum rate is achieved.