问题
选择题
科学家用显微技术除去变形虫的细胞核，发现其新陈代谢减弱，运动停止；当重新植入细胞核后，发现其生命活动又恢复到正常状态。这说明[ ]
A．细胞核是细胞代谢活动的控制中心
B．细胞核是遗传物质的储存和复制场所
C．细胞核是细胞遗传特性的控制中心
D．人工去核的细胞一般不能存活很长时间
答案
答案：A
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科学家用显微技术除去变形虫的细胞核，发现其新陈代谢减弱，运动停止；当重新植入细胞核后，发现其生命活动又恢复到正常状态。这说明[ ]
A．细胞核是细胞代谢活动的控制中心
B．细胞核是遗传物质的储存和复制场所
C．细胞核是细胞遗传特性的控制中心
D．人工去核的细胞一般不能存活很长时间
答案：A
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| For most students, the time of exams is very stressful and difficult. Some students find the exam time is so bad that they become ill, because they are afraid of failing, and they are afraid of letting their parents and families down. If exams are really making you ill or worried, don't hide your feelings. Talk to someone about it. If he or she doesn't help you, ask someone else. Here are some top tips given by educational psychologists (教育心理学家): (1) Ask a teacher about how to revise and about exam skills-how to work when you are in an exam. (2) Take a short rest during your time of work and revision. If your mind is tired, it will not remember well. (3) Revise at the time when you know you will work at your best. (4) Get enough sleep, and eat healthy food. (5) If you feel bad, talk to someone about your worries. But don't be too relaxed! Some stress over exams makes you work hard for them. (6) If it upsets you to talk to your friends about an exam when it is finished, don't do it! In fact, don't even think about the exam you have finished. What is done has been done. You cannot change what you have written ! (7) If you are studying in the evening, don't go straight to bed afterwards. Your mind will still be "going round and round" ——thinking too much. Do something else, maybe walk or get exercise. Choose something that will relax you, and make you think of other things. | ||||||||||||
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