Perhaps the most familiar plant
movement belongs to one species of mimosa called the sensitive plant. Within
seconds, it can lower its leaves and make its tiny leaflets close up like
folding chairs. This movement is thought to be initiated by electrical impulses
remarkably similar to nerve signals in animals. But without the animals’
sophisticated motion machinery, the mimosa has had to be creative in devising a
way to move. For motion, the plant depends on tiny, bulb-shaped organs located at the base of each leaf stalk and leaflet. Called pulvini, these organs hold the plant parts in place. When the mimosa is stimulated—say, by a crawling insect or a sudden change in temperature—an electrical impulse sweeps through the plant. This causes potassium and then water to be shifted from certain cells in the pulvini to others, quickly turning one side of the o A. geographical distribution of plant and animal species B. location and purpose of the pulvini C. appearance of the mimosa D. process that causes movement in the mimosa [单项选择]Which of the following belongs to number prefixes
A. Auto-. B. Mis-. C. Hemi-. D. Pre-. [单项选择]Which of the following group belongs to complementary antonym
[A] Long and short. [B] Good and bad. [C] Present and absent. [D] Husband and wife. [单项选择]Perhaps the most familiar plant movement belongs to one species of mimosa called the sensitive plant. Within seconds, it can lower its leaves and make its tiny leaflets close up like folding chairs. This movement is thought to be initiated by electrical impulses remarkably similar to nerve signals in animals. But without the animals’ sophisticated motion machinery, the mimosa has had to be creative in devising a way to move.
For motion, the plant depends on tiny, bulb-shaped organs located at the base of each leaf stalk and leaflet. Called pulvini, these organs hold the plant parts in place. When the mimosa is stimulated—say, by a crawling insect or a sudden change in temperature—an electrical impulse sweeps through the plant. This causes potassium and then water to be shifted from certain cells in the pulvini to others, quickly turning one side of the organs flaccid. Because the pulvini can no longer support the leaves and leaflets, this shift results in a corresponding change in A. drop off B. become limp C. revolve D. twitch 我来回答: 提交
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