Energy from sunlight can excite electrons, kicking them out of their orbitals and creating free radicals. Free radicals are highly reactive atoms or molecules that have unpaired electrons and degrade and destroy other compounds in their vicinity
Carotenoids, one of the pigments present in most chloroplasts, can stabilize these free radicals. This suggests that _____.
A) once chloroplasts are destroyed, the free radicals will destroy the cell
B) carotenoids probably have a protective function in the cell
C) free radicals induce the synthesis of carotenoids in chloroplasts
D) carotenoids communicate directly with the immune system of plants
Answer: B
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Refer to the paragraph on Redi's experiments. In both experiments, flies appeared in all of the open jars and only in the open jars. Which one of the following statements is correct?
A) The experiment was inconclusive because Redi used only one kind of meat. B) The experiment was inconclusive because it did not run long enough. C) The experiment supports the hypothesis that spontaneous generation occurs in rotting meat. D) The experiment supports the hypothesis that maggots arise only from eggs laid by adult flies.
Bryophytes, like ferns and certain other tracheophyte plants, require
A. air to reproduce sexually. B. water to reproduce sexually. C. soil to reproduce sexually. D. shade to reproduce sexually. E. sunlight to reproduce sexually.
Huntington disease
a. is inherited as an autosomal dominant condition. b. results in progressive deterioration of the nervous system. c. often does not show any symptoms until after the child-bearing years. d. is caused by an expansion mutation. e. is all of these.
If a region of DNA contained numerous mismatches due to a modifying agent that caused methylation of guanine, which of the following mutagens is most likely the cause?
A. Ionizing energy such as gamma radiation B. A DNA modifier such as an alkylating agent C. A deaminating base such as nitrous oxide D. An intercalating agent such as acridine orange