Toward the end of the Proterozoic eon, multicellular animals emerged. The first animals were
A. Invertebrates.
B. Fish.
C. Chordates.
D. Reptiles.
E. Tetrapods.
Answer: A
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Which of the following is NOT true regarding ATP synthases?
A. They require proton motive force to make ATP. B. The proton flow is outward during ATP synthesis. C. They span the inner membrane of mitochondria. D. The subunits of ATP synthase undergo conformational changes during ATP production.
During wine-making, yeast cells obtain energy by fermenting sugar. Alcohol and CO2 are products of this process. When alcohol content reaches a certain level, the yeast cells can no longer survive. The limiting factor to yeast growth in this example is the
A. availability of raw materials. B. availability of energy. C. production of waste products. D. interactions with other organisms.
The synthesis of a growing strand of DNA is carried out by adding nucleotides to which end of an existing strand?
A. 3' B. 1' C. 2' D. 5'
Which of the following is NOT an example of symbiosis?
A. bacteria in the human colon B. tapeworm in the human intestine C. tuberculosis in the human lung D. protozoa in termites E. microbes crossing the placenta to the fetus