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  3. When soil is plowed in the spring, pigweed seeds that have been buried in the so

When soil is plowed in the spring, pigweed seeds that have been buried in the so

游客2025-02-25  20
问题 When soil is plowed in the spring, pigweed seeds that have been buried in the soil all winter are churned up to the surface and redeposited just under the surface. The brief exposure of the seeds to sunlight stimulates receptors, which have become highly sensitive to sunlight during the months the seeds were buried in the soil, and the stimulated receptors trigger germination. Without the prolonged darkness, followed by exposure to sunlight, the seeds do not germinate. The statements above, if true, most strongly support which one of the following statements about a field that will be plowed in the spring and in which pigweed seeds have been buried in the soil all winter?
选项 A、Fewer pigweed plants will grow in the field if it is plowed only at night than if it is plowed during the day.
B、Fewer pigweed plants will grow in the field if it is not plowed at all than if it is plowed only at night.
C、Fewer pigweed plants will grow in the field if it is plowed just before sunrise than if it is plowed just after sunset.
D、The pigweed seeds that are churned up to the surface of the soil during the plowing will not germinate unless they are redeposited under the surface of the soil.
E、All of the pigweed seeds that are already on the surface of the soil before the field is plowed will germinate.
答案 A
解析 根据本题的论述可知，离开了太阳光的刺激，藜的种子就不会发芽，因此在夜晚犁的地要比在白天犁的地生长的藜类植物少，即(A)为正确答案；同时推出(C)是错误的；(B)、(D)和(E)都不能从短文中合理地推出。
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