问题
问答题 简答题
什么叫光周期反应？
答案
参考答案：
植物对于日照长度的反应称为光周期反应（在特定时期开花）。分为长日照植物（短夜植物），只有在日照长于其临界日长度时才成花（每种植物成花都有一个极限日长度，称为临界日长度或临界光周期）、.短日照植物（长夜植物）：只有日照短于临界日长度时才成花和中日性植物：植物成花不受日长度影响。
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什么叫光周期反应？
参考答案：
植物对于日照长度的反应称为光周期反应（在特定时期开花）。分为长日照植物（短夜植物），只有在日照长于其临界日长度时才成花（每种植物成花都有一个极限日长度，称为临界日长度或临界光周期）、.短日照植物（长夜植物）：只有日照短于临界日长度时才成花和中日性植物：植物成花不受日长度影响。
| When you first drift off into slumber, your eyes will roll about a bit, your temperature will drop slightly, your muscles will relax, and your breathing will become quite regular. Your brain waves slow down a bit, with the alpha rhythm predominating for the first few minutes. This is the first stage of sleep. For the next 30 minutes or so, you will drift down through Stage 2 and Stage 3. The lower your stage of sleep, the slower your brain waves will be. About 40-60 minutes after you lose consciousness, you will reach the last stage. Your brain waves will show the delta rhythm. You may think that you stay at this deep stage all the rest of the night, but that turns out not to be the case. About 80 minutes after you fall into slumber, your activity cycle will increase slightly. The delta rhythm will disappear, to be replaced by the activity pattern of brain waves. Your eyes will begin to dart around under your closed eyelids. This period of Rapid Eye Movements lasts for 8-15 minutes and is called REM sleep. During both light and deep sleep, the muscles in your body are relaxed but capable of movement. As you slip into REM sleep, a very odd thing occurs -- most of the voluntary muscles in your body become paralyzed. Although your brain shows very rapid bursts of neural activity during REM sleep, your body is incapable of moving. REM sleep is accompanied by extensive muscular inhibition. |
In this passage, the word "paralyzed" means unable to______.
A．move
B．think
C．work
D．speak