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  3. According to the passage, the five well-known plant hormones are not useful in c

According to the passage, the five well-known plant hormones are not useful in c

游客2024-01-13  36
问题 According to the passage, the five well-known plant hormones are not useful in controlling the growth of crops because______ [br] The passage suggests that the place of hypothalamic hormones in the hormonal hierarchies of animals is similar to the place of which of the following in plants?
选项 A、Plant cell walls
B、The complement of genes in each plant cell
C、A subset of a plant cell’s gene complement
D、The five major hormones
E、The oligosaccharins
答案 D
解析 The best answer is D. According to the passage, “The pleiotropy of the five well-studies plant hormones is somewhat analogous to that of certain hormones in animals” (lines 24-26). The example given involves certain hypothalamic hormones that “stimulate the anterior lobe of the pituitary gland to synthesize and release many different hormones, one of which stimulates the release of hormones from the adrenal cortex” (lines 27-30). These hormones in turn “have specific effects on target organs all over the body” (line 31). This “hierarchy of hormones,” as the author calls it, “may also exist in plants” (line 35), where the five pleiotropic hormones may “function by activating the enzymes that release … more specific chemical messengers” (lines 39-41). Thus, hypothalamic hormones in animals and the five major hormones in plants occupy a similar place in the respective organisms” hormonal hierarchy.
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