DNA was not the first informational molecule in evolving cells. What choice best supports this statement?
a. Ribozymes were probably isolated in a vesicle resembling a living cell.
b. Ribozymes act as catalysts for diverse reactions.
c. Self-replicating molecules alone do not constitute life.
d. DNA can replicate only with the help of enzymes, but the code for enzyme construction is found in the DNA.
e. RNA appeared after hundreds of millions of years of prebiotic chemical synthesis
Ans: d. DNA can replicate only with the help of enzymes, but the code for enzyme construction is found in the DNA.
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In the example of the predator/prey web in the grassland community on Bylot Island, a rise in the Snowy Owl population would have what effect on the Snow Goose?
A. The Snow Goose population would rise due to owls preying upon foxes. B. The Snow Goose population would fall due to an increase in the fox population. C. The Snow Goose population would fall due to a lower consumption of grasses. D. The Snow Goose population would rise due to lemming, and subsequently fox, populations declining. E. The Snow Goose population would not be affected at all.
Chemicals that are poisonous to specific cell types are said to be
a. hazardous. b. cytotoxic. c. allelochemicals. d. bioactive.
The most probable cause for the difference in mean stem length between plants in dish A and plants in dish B is which of the following?
(A) Shortening of cells in the stem in response to the lack of light (B) Elongation of seedlings in response to the lack of light (C) Enhancement of stem elongation by light (D) Genetic differences between the seeds
In bacteria the RNA polymerase holoenzyme consists of?
a. a sigma subunit and the core polymerase b. a sigma subunit, the core polymerase, and EF-Tu c. the sigma subunit and a ribosome d. the core polymerase and EF-G