It may seem easy to say that plants and animals are different. Any child can tell the difference between  a tree and a dog. But those differences are far deeper than just what they look like. The cells (細(xì)胞) that plants are made up of are different. In other words, the cell wall of plants has something special.

First of all, it's important to find that not all plant cells have a cell wall. Besides, there are many differences of a cell wall based on the kinds of plant. The following is meant to be what a plant cell wall is  like.
The cell wall of a plant is on the outside of the cell membrane (膜). It is usually hard and cannot be bent easily, but the degree of flexibility (韌性) of the cell wall is different. It is based on the special use that the cell has in keeping the plant alive. Cells that make up the trunk of a tree are clearly less flexible than  cells on a leaf.
Cell walls act in many ways. They serve to protect the plant. They provide support, as well as help in the movement of chemicals and wastes into and out of the cell.  More importantly, they control the water  that goes in and out.  Plants must have good water controlling systems (系統(tǒng)), allowing them to keep water during dry seasons, and get rid of unnecessary water. Plants can't walk around to find water, so  being able to control water is very important.
So there you have it , what a plant cell wall is. Of course, there are many other things that are not talked about here. Knowing more about plant cell wails requires further study and research.
小題1:From the first two paragraphs we can find that _____.
A．a(chǎn)ll plants have a ceil wall
B．plant cells and animal cells are the same
C．different kinds of plant have different cell walls
D．there are no differences between the cells of a tree and a dog
小題2:The underlined word "bent" in the passage is the closest in meaning to _____.
A．變形的B．防水的C．太陽灼傷的D．表皮破損的
小題3:Cells in the trunk of a tree are _____ those on a leaf.
A．a(chǎn)s flexible asB．not so flexible as
C．more important thanD．less important than
小題4:What is the most important use of a plant cell wall?
A．To protect the plant.B．To provide support.
C．To move chemicals and wastes.D．To control the water.

小題1:C
小題2:D
小題3:B
小題4:D

試題解析:本文大意：也許很容易說植物與動物不同，任一孩子能講出一棵樹和一只狗的區(qū)別。但那些區(qū)別遠(yuǎn)比它們看上去的要深。 組成植物的細(xì)胞是不同的，換句話說，植物的細(xì)胞壁有特殊的東西。 首先不是所有的植物有細(xì)胞壁，另外，基于植物的種類細(xì)胞壁有很多不同。細(xì)胞壁在細(xì)胞膜的外面。通常堅(jiān)硬不易破損，但柔韌性的程度不一樣。細(xì)胞壁也多種方法工作來保護(hù)植物。更重要的是，控制水的出入。
小題1:細(xì)節(jié)理解題。根據(jù) there are many differences of a cell wall based on the kinds of plant. 基于植物的種類細(xì)胞壁有很多不同，可知答案選C
小題2:推理判斷題。根據(jù)It is usually hard通常堅(jiān)硬 ，可知答案選D
小題3:細(xì)節(jié)理解題。根據(jù)Cells that make up the trunk of a tree are clearly less flexible than  cells on a leaf.組成樹干的細(xì)胞很明顯沒有樹葉的細(xì)胞柔韌，可知答案選B
小題4:細(xì)節(jié)理解題。根據(jù) More importantly, they control the water  that goes in and out.更重要的是，控制水的出入 ，可知答案選D
練習(xí)冊系列答案
相關(guān)習(xí)題

科目：初中英語 來源：不詳 題型：閱讀理解

Little Smart or Xiaolingtong is becoming more and more popular in China. But you can use it only in your city. If you go to another city, it will have no use. It looks like a mobile phone, but the service(服務(wù) )is quite cheap. We only need to pay about 20 yuan a month for the line and about 0.1 yuan each minute for the talk. What’s more, you don’t have to pay any money when someone else calls you.
But little Smart is not really so smart. Users often complain about( 抱怨) its bad voice. “ I can’t make or get a phone call when I am on a bus,” a person in Hangzhou said. Scientists are trying their best to make Little Smart smarter. And the latest Little Smart even has a color screen.
小題1:Little Smart is popular because__________________.
A．the service of it is very cheap
B．it’s very expensive
C．it’s very smart
D．it’s very useful in another city
小題2:You can use your Litter Smart_____________.
A．in some citiesB．in any cityC．only in the busesD．only in your city
小題3:The latest Little Smart______________.
A．has good soundsB．has a colour screen( 屏幕)
C．has a bad voiceD．is not smarter
小題4:If someone calls you by your Little Smart, you should pay____.
A．20 yaunB．0.1 yuanC．0.1 youan a minuteD．nothing

查看答案和解析>>

科目：初中英語 來源：不詳 題型：完形填空

The little boy entered the house，unhappy．His mother was making cakes in the kitchen．She smiled as she turned around, but       when she saw his face, “Tyler,      happened? Is everything okay?”
“Nothing is okay, Mom.” said the boy, “Today in our science lesson, Mrs Green was talking about the        ．She said that the whole world is getting dirtier and that many animals and plants are        ．She wants us to think of something we can do to help them．I thought all the way home．But there is nothing I can do to make a difference.”
“ Let me tell you a story,” the mother said after thinking for a while. “One morning a man was walking down a beach，there he saw        dying starfish covering the beach，they were pushed up by the waves and it was too far up for them to make their way back by themselves. The man shook his head as he walked along. ‘What a pity! So many starfish will die on the beach.’ The man felt very        for those starfish．He went on walking and just at that time he was         to find a boy in front who was throwing the starfish back into the sea as        as he could．‘How silly you are! My son,’ the man said, ‘there are so many starfish, can you throw all of them back?’ The boy didn’t stop but kept throwing. ‘Though I can’t help them all, I can help this one，and this one, and this one.’ said the boy. Thinking for a moment, the man        to help return the starfish to their home. He smiled and said to himself ‘Sometimes the biggest lesson in life comes from the        person.’”
小題1:
A．shouted B．stoppedC．a(chǎn)skedD．cried
小題2:
A．whoB．whatC．whereD．when
小題3:
A．a(chǎn)irB．landC．waterD．environment
小題4:
A．dyingB．deathC．deadD．die
小題5:
A．two thousandsB．thousands ofC．thousandD．two thousands of
小題6:
A．happyB．a(chǎn)ngryC．sorryD．tired
小題7:
A．a(chǎn)fraidB．surprisedC．sadD．happy
小題8:
A．slowB．soonC．fastD．far
小題9:
A．beganB．continuedC．forgotD．remembered
小題10:
A．happiestB．smallestC．kindestD．smartest

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

One morning, Wu Li discovered that her classroom had changed. She found that the desks were no longer in rows(排), but pushed together to make eight bigger desks. She was too excited about it for the first two days and she couldn’t listen to the teachers carefully. But soon she and her classmates got used to this new classroom arrangement (安排). “Now our class is quieter,” said Wu. “What’s more, we can come up with our own ideas and learn more through discussion. It’s a better way to study.”
Li Yu liked it, too. He said, “Group members first discuss, and then show ourselves in front of the whole class. It makes us believe in ourselves.” It was part of a reform (改革) at Li’s school—Baita Secondary School. The school made this reform because they wanted to provide students with easier ways to study and more chances to discuss. “Our school hopes it can improve students’ abilities (能力) to study by themselves and work in groups,” said Zhang Yong, the principal of the school.
However, the reform has demanded (要求) more from teachers. Now they have only about 15 minutes to give the lesson which should be taught in 45 minutes before. It is difficult to teach in such a short time. The teachers have to find better ways to teach more effectively.
“The reform demands more, but I’m sure it is helpful,” added Mr Zhang.
小題1:After the new classroom arrangement it was easier for Wu Li and her classmates to ______ in class.
A．discuss with each otherB．sit in the classroom
C．push desks togetherD．teach a lesson
小題2:The school made the reform to provide students with _______ to study.
A．noisier classesB．easier waysC．more seatsD．fewer chances
小題3:The Chinese meaning of the word “effectively” in this passage is _________.
A．簡單地B．明確地C．有效地D．認(rèn)真地
小題4:The teachers __________ after the reform.
A．have to find better ways to teach
B．find it easier to teach
C．spend 45 minutes explaining to the students
D．a(chǎn)re happy to explain for only 15 minutes
小題5:The best title of this passage may be “________”.
A．Students’ FriendshipB．Teachers’ Hope
C．Discussion in ClassD．New Look in Class

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

The weather is getting gotter. You are thirsty after playing basketball or riding home from School. A cold drink may be just the thing. But be careful of what you are drinking. Something that looks cool may not be good for our health. There are plenty of "energy drinks" on the market. Most of
them have beautiful colors and cool names. The lists on them tell you they are helpful to your health. Sounds great!
But after a careful check you may find that most energy drinks have lots of caffeine (咖啡因) in them. These drinks are especially aimed at young people, students, busy people and sports players. Makers sometimes say their drinks make you better at sports and can keep you awake. But be careful not to drink too much.
Caffeine makes your heart beat fast. Because of this, the International Olympic Committee has limited( 限制) its use. Caffeine in most energy drinks is at least as strong as that in a cup of coffee or tea. Possible health dangers have something to do with energy drinks. Just one box of energy drink can make you nervous, have difficulty sleeping and can even cause heart problems. Scientists say that teenagers should be discouraged from taking drinks with a lot of caffeine in them.
小題1:Many people like drinking energy drinks because of the following EXCEPT that ________.
A．they have beautiful colors and cool names
B．they have lots of caffeine
C．they can keep them awake and better at sports
D．they are said to be helpful to health
小題2:The main reason for people not to drink too much energy drinks is that they may cause _____.
A．heart problemsB．nervousnessC．sleeping difficultyD．possible health dangers
小題3:Which of the following can take the place of the underlined word “discouraged”
A．encouragedB．stoppedC．helpedD．disliked
小題4:From the passage we can know that _________.
A．a(chǎn)dvertisements are important in getting people to buy energy drinks
B．energy drinks are helpful to teenagers' study
C．sports players need to drink a lot of energy drinks
D．energy drinks are especially aimed at teenagers
小題5:The best title of the passage is ________.
A．Engergy Drinks Are UsefulB．Energy Drinks Help Teengagers
C．Energy Drinks--- Be carefulD．Energy Drinks---Good for Health

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

IMPROVE ON SLEEP
Good health needs good sleep. Going to bed before you’re tired. Not eating or reading in bed. Go to bed at the same time before midnight and get up at the same time. Your body likes routine (常規(guī)) for a good night’s sleep.
STAY FREE OF FLU

Brush your teeth twice daily and visit the dentist at least once a year. The mouth is a mirror of disease. The oral examination is not only for the health of teeth, but the whole body. For more of it, please visit www. mydr. com. au.
FIT FOR LIFE
Studies have shown that many diseases have something to do with less or no physical (身體) activity. Try to do it for 30 minutes a day, 5 days or more a week. For more information, please call HealthLine at 1800 438 2000。
小題1:If you want to get a good sleep, you’d better _______.
A．go to bed after you’re tired
B．go to sleep at midnight
C．follow the bedtime routine
D．eat something or read in bed
小題2:To prevent from catching a cold or flu, it’s good for you _______.
A．to clean your fingers often
B．to brush your teeth twice daily
C．to get up early every morning
D．to wash all parts of your hands
小題3:You should visit the dentist at least once a year, because _______.
A．the oral examination is necessary
B．you don’t often brush your teeth
C．some diseases may be in the mirror
D．you don’t have a good night’s sleep
小題4:Studies have shown that many diseases have something to do with______.
A．having no oral examination
B．washing hands with cold water
C．sleeping too late sometimes
D．doing little physical activity
小題5:When you want to learn more about the flu, you can _______.
A．visit www. mydr. com. au
B．call HealthLine at 1800 848 1313
C．visit the dentist in your place
D．call HealthLine at 1800 438 2000

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

Here is an interview with a painter. Read and choose the best.
Reporter:Mr Shum, you were one of Taiwan’s most outstanding youths last year. Why was that?
Mr Shum:Well, I can tell you that there are two reasons.First, I am a painter. Second, and more important reason is I am handicapped﹙殘疾的﹚。I have no arms and only one leg.
Reporter:Well, how do you paint then if you’ve got no arms? Do you use your foot?
Mr Shum:Hah! For some handicapped people, it’s true and they are able to use their feet.No,I use my mouth. I put my paintbrush or my crayons or pencils or whatever I am using in my mouth. I hold it firmly in my teeth and paint or draw like that. It was a little strange for me at first, but it quickly became very easy.
Reporter:I know you feel that you are first a painter and only secondly that you are a disablbed person, but can we talk first about your handicap?
Mr Shum:Well,in fact I think of myself firstly as a person, secondly as a painter and thirdly as someone with a physical handicap. Can I say that I am not happy with the word “handicapped”?
I am a popular painter because my paintings are good, not because they were painted by a handicapped person. “handicapped”means you can’t do anything. It is difficult for me to do some things like getting dressed.
Reporter: Were you born with your handicap?
Mr Shum:No. An accident happened to me when I was 15 years old.After that I became depressed﹙沮喪﹚and even tried to end my life, but my mother was always there for me.
小題1:Mr Shum is a painter who has no ____.
A．mouthB．teethC．feetD．a(chǎn)rms
小題2:Mr Shum thinks himself first as ____.
A．a(chǎn) personB．a(chǎn) painterC．a(chǎn) hitD．a(chǎn) star
小題3:He doesn’t like the word“handicapped”because it suggests ______.
A．he can do anything
B．there are some things he can’t do
C．there are somethings he can do very well
D．he doesn’t want others to look him down
小題4:What does the underlined word“firmly”in this passage mean?
A．緊緊地B．隨意地C．緩緩地D．輕輕地
小題5:What can we learn from Mr Shum’s story?
A．Comfort in living by painting
B．Pleasure of living with a brave mother
C．Help gives people happiness.
D．What really matters is how you face it.

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

  There are many ways to keep healthy. Different people have different ways. Lisa's father thinks riding a bike is the best way because he likes to go to work by bike. And their home isn't far from his bank. Lisa thinks running is better than riding, so she runs every day. However, her mother thinks it's boring. She loves walking to work. Lisa's sister likes flying kites. She goes to fly kites once a week. Lisa's brother thinks playing ping-pong is a good way to keep healthy. He plays it every morning.
小題1: _____ likes riding a bike to work.
A．Lisa's motherB．Lisa's fatherC．Lisa's brotherD．Lisa's sister
小題2: Lisa's father works in a _____
A．bankB．school C．police stationD．store
小題3:Lisa's sister likes______
A．fishingB．flying kitesC．swimmingD．playing basketball
小題4:Lisa runs_______
A. once a week   B. every week      C every day     D. three times a day
小題5:The best title(題目 ) is______.
A Different Ways to Keep Healthy    
B. Different People, Different Likes
C. How to Eat Healthily             
D. How Often do You Exercise

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解



How much sleep do we need? We are all different. Some people need only three hours of sleep a night. Others need ten hours of sleep a night. Most Americans sleep an average (平均) of seven to eight hours a night. After the age of fifty, the average sleeping time goes down to 6.5 hours a night.
Most people have a bad night when they can’t fall asleep (入睡). The name of this problem is called insomnia.
This isn’t a new problem. Many famous people in history had insomnia, too. Some of these people had special ideas to make them sleep. Benjamin Franklin, the famous inventor, had four beds. He moved(移動) from one to another to fall asleep. King Louis XI V (國王路易十四) of France had four hundred and thirteen beds and hoped to fall asleep in one of them. Mark Twain, the famous American writer, had a different way. He lay on his side across the end of his bed.
小題1:After the age of fifty, the average sleep hours are_______ a night.
A．3 hoursB．7or 8 hoursC．6.5 hoursD．10 hours
小題2:Which of the following is TRUE?
A．King Louis XI V was an American.
B．Many famous people in history had a bad night when they couldn't fall asleep.
C．Benjamin Franklin was a famous writer.
D．Most young Americans sleep for an average of 6.5 hours a night.
小題3:Why did King Louis XI V of France have more than four hundred beds?
A．Because he hoped to fall asleep.
B．Because he was a famous inventor.
C．Because he had a lot of money.
D．Because he liked to lie on his side across the end of his bed.
小題4:What does the word insomnia mean (意思) in Paragraph (段落) 2?
A．too many bedsB．sleep wellC．can’t sleep wellD．problems
小題5:What’s Paragraph (段落) 1 talking about?
A．The history of sleep.B．How much sleep do we need?
C．The story of famous people.D．Why can’t we sleep?

查看答案和解析>>

同步練習(xí)冊答案