问题 解答题

英国科学家普里斯特利曾做过如下实验:在甲、乙两个密闭的玻璃容器中,甲容器中放入一只小白鼠,乙容器中放了一盆绿色植物和一只小白鼠,都给予充足的光照,他发现小白鼠在乙容器中比在甲容器中存活的时间长.请根据以上实验现象分析回答:

(1)甲容器中小白鼠很快死亡的原因是______,乙容器中小白鼠比甲容器中小白鼠存活时间长的原因是______.

(2)实验中甲和乙是一组______实验,实验时两个容器中选用的小白鼠应该是______.

(3)如果用黑布将乙容器罩住,那么小白鼠存活的时间比没有罩住时存活的时间要______,因为用黑布罩住的植物不能进行______,但能进行______,说明植物的光合作用需要______.

答案

(1)甲容器中小白鼠很快死亡的原因是小白鼠很快将通过呼吸作用将容器内的氧气消耗干净,因此缺少氧无法呼吸;而乙容器中小白鼠比甲容器中小白鼠存活时间长的原因是此装置置于阳光下,植物能进行光合作用释放出氧气,而老鼠呼吸需要氧气,释放二氧化碳,所以小白鼠和植物在一段较长时间内不会死亡.

(2)装置甲、乙形成了一组以植物为变量的对照实验,目的是验证植物的光合作用产生氧气,乙实验起对照作用.为了对比的更具说明力,因此两容器中的小白鼠应该大小相当、生命活力一样;

(3)如果用黑布将乙容器罩住,因为植物进行光合作用需要光,如果将此装置放在黑暗环境中,植物无法进行光合作用且进行呼吸作用消耗氧,小白鼠因缺氧而无法进行呼吸,不久将死亡.若取出装置中的绿色植物,由于植物也要进行呼吸作用,消耗氧,所以小老鼠存活的时间会变长,死亡的时间会缩短.由此说明植物的光合作用需要光照.

故答案为:(1)缺少氧无法呼吸      植物光合作用释放氧气,供小白鼠正常呼吸利用

(2)对照     大小相当、生命活力一样

(3)短    光合作用    呼吸作用   光照

填空题

Have you had a headache during a test Have you ever been so worried about something that you have a headache or even can’t sleep at night If so, then you know what stress is. Stress is what you feel when you are worried about something. This worry in your mind can make your body feel bad. You may feel angry, sad, scared, or afraid—all of which can give you a stomachache or a headache.
However, there are different kinds of stress. Some kinds of stress are good and others are bad. Good stress might happen when you’re called to answer questions in class or when you have to give a speech. This kind of stress can help you to get things better done. For example, you may do a better job on your test if the stress pushes you to prepare better before the test.
On the other hand, bad stress can happen if stress lasts too long. You may not feel well if your parents are fighting, if a family member is sick, if you’re having problems at school, or if anything else makes you unhappy every day. That kind of stress isn’t going to help you. And it can actually make you sick.
The best way to fight stress is to have a balanced life. Make sure you keep your SELF in mind: Sleep, Exercise, Leisure(休闲), and Food. If you get enough sleep and eat properly, and if you exercise and leave time for fun, you’ll probably feel less stressed.

Title: Face the Stress
Meaning of stressStress is a (68) when you are worried about something.
Possible effectYou may feel uncomfortable in your (69) and body.

Good stress

· It might happen when you have to (70) in public.

· It will be more (71) for you to do the job successfully.

· It makes you (72) better before doing the job.

Different kindsBad stress

· It might happen if your stress (73) too long.

· You may not feel well with the (74) of a family member, problems at school or something else that worries you every day.

· It might stop you from getting your work well done.

How to keep stress (75) 

Have a balanced life.

· Have enough sleep and have (76) food.

· Take exercise and have time to (77) yourself.


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