问题 解答题

某学习小组利用银边天竺葵(叶片边缘部分呈白色)探究阳光与有机物的关系,实验过程如图所示,据图回答下列问题:

( l )将银边天竺葵放在黑暗处一昼夜的目的是______

( 2 )叶片经脱色、漂洗后,滴加碘液,______部分(填字母)变成蓝色.该部分的叶肉细胞中含有______,它是植物进行光合作用的场所.

( 3 )绿色植物通过光合作用,不仅能制造有机物,同时对维持大气中的______平衡具有重要作用.

答案

(1)将银边天竺葵,预先放在黑暗处一昼夜,再将不透光的纸片用回形针夹在绿色部位.然后,把植株放在阳光下照射4~6小时,再剪下此叶片,并用打孔器分别在该叶片的A、B、两个不同部位取下三两个小的叶圆片(如图所示).将叶圆片放入装有酒精的烧杯中,经热水浴脱色.将经过脱色的叶圆片放在清水中漂洗.将经过漂洗的叶圆片放在白纸上,然后用吸管吸取碘液,分别滴在三个叶圆片上冲洗后观察颜色情况.植物在黑暗处植物无法进行光合作用,可以进行呼吸作用消耗植物的淀粉,所以实验前将植株放到黑暗环境中的目的:是消耗掉叶片原有淀粉,排除干扰,防止影响实验.

(2)观察实验现象,在A、B中,见光的B圆片能进行光合作用制造出淀粉,淀粉遇碘变蓝色;不含叶绿体的A圆片也无法进行光合作用,没有变蓝色.说明植物进行光合作用的场所是叶绿体.

(3)绿色植物通过光合作用制造的有机物,不仅满足了自身生长、发育、繁殖的需要,而且为生物圈中的其他生物提供了基本的食物来源、氧气来源、能量来源.绿色植物通过光合作用消耗大气中的二氧化碳,释放氧气(超过了自身对氧的需要),维持生物圈中的二氧化碳和氧气的相对平衡.

故答案为:( l )消耗掉叶片中原有的淀粉

( 2 ) B   叶绿体

( 3 )碳----氧(或二氧化碳-----氧气)

选择题
阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

     If you walk into W. Lloyd Jerome's dental surgery (手术) in Glasgow, you'll see bright paintings and a

fashionable blue couch which patients sit on while he checks their teeth. Jerome says, "That's because they're

frightened."

     1_____ "That's why I don't wear a white coat. I find that's one of the things that people associate with

pain. In fact, my philosophy is that dental treatment should take place in an atmosphere of relaxation, interest

and, above all, enjoyment."

     Which is all highly shocking for anyone who associates dental treatment with pain, or at the very least,

formal, clinical visits. He says, "If people are relaxed, entertained and correctly treated, they will forget such

previous unpleasant experiences."

     Virtual-reality headsets are one of his new relaxation techniques, "2_____ The headsets are used for the

first check-up, where the patient sits on the blue couch and watches an underwear film while I look at their

teeth." Then the headset switches to a special camera, to give the patient a visual tour around their mouth.

     Another key point is that the surgery smells more like a perfume shop than a dentist's. Today there is the

smell of orange."When people walk in, I want them to realize with all their senses that it's not like going to

dentist's. Smell is very important. 3_____"

     Known as Glasgow's most fashionable dentist, Jerome is keen to point out that he takes his work very

seriously. "4_____"

     For example, Jerome uses a special instrument which sprays warm water on the teeth to clean them, rather

than scraping them. "It feels a bit strange, but as long as people are relaxed, it's not painful."

     5_____ "One of the things I found out there was that when you make it easier for the patient, you make it

easier for yourself." He sees his patient-centered attitude as the start of a gradual movement towards less

formality in the conservative British dentistry profession.

     At that moment, a patient arrives. Jerome rushes over, offers him a cup of tea, asks him what video he'd

like to watch and leads him gently towards the chair.

A. Five years ago, Jerome went to the United States to do research.

B. He has tried to create an environment where people are not afraid.

C. The relaxation techniques are important but the quality of the treatment is the most important thing.

D. We were the first practice in Britain to introduce them.

E. Now they look forward to their visits here.

F. That dental smell of surgical spirit can get the heart racing in minutes if you're frightened of dentists.

G. Fifty percent of the population only go to the dentist when they're in pain.