Bacteria(細(xì)菌) are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in micron. One micron is a thousandth of a millimeter; a pinhead is about a millimeter across, Rod-shaped bacteria are usually from two to four microns long, while rounded ones are generally one micron across. Thus, if you magnified a rounded bacterium a thousand times, it would be just the size of a pinhead, while a grown-up human enlarged by the same amount would be over a mile tall.

Even with an ordinary microscope(顯微鏡), you must look closely to see bacteria. Using a magnification of 100 times, one can hardly find bacteria. Nor can one make out anything of their structure(結(jié)構(gòu)), of course. Only by using special colors, can one see that some bacteria have wavy-looking “hairs” called flagella. Others have only one flagellum. The flagella move round a central point, pushing the bacteria through the water. Many bacteria lack flagella and cannot move about by their own power, while others can move along over surface by some little-understood “machinery”.

From the bacterial point of view, the world is a very different place from what it is to humans. To a bacterium, water is as thick as molasses(糖漿) is to us. Bacteria are so small that they are affected by the movements of the chemical molecules(分子) around them. Bacteria under microscopes, even those with no flagella, often jump up and down in the water. This is because they knock with the water molecules and are pushed this way and that.

36. The underlined word magnified means _______________.

A. enlarged                                                      B. widened                  

C. killed                                                          D. caught

37. We know from the passage that _______________ is the smallest.

A. a pinhead                                            B. a rounded bacterium 

C. a microscope                                        D. a rod-shaped bacterium

38. The relationship between a bacterium and its flagella is most nearly like which of the following?

A. A rider jumping on a horse back 

B. A ball being hit by a bet

C. A boat powered by a motor    

D. A door closed by wind

39. Why does the writer compares water to molasses in the third paragraph?

A. To tell us how difficult it is for bacteria to move through water.

B. To suggest that bacteria are fond of different liquids.

C. To show different chemicals are of different structures.

D. To show that bacteria are the best swimmers.

40. Which of the following is the main topic of the passage?

A. The characteristic (特點(diǎn)) of bacteria.      

B. How bacteria reproduce.

C. The various parts of a bacterium’s body    

D. How bacteria cause diseases.            

 

【答案】

 A

 B

 C

 A

 A

【解析】略

 

練習(xí)冊(cè)系列答案
相關(guān)習(xí)題

科目：高中英語(yǔ) 來(lái)源：必修二訓(xùn)練譯林英語(yǔ) 譯林版 題型：050

閱讀理解

　　Milk was one of the main human foods long before history was written．It will probably remain one as long as there are animals that give milk．The old word “milk” came from Sanskrit(梵文), one of the oldest languages known to man．A very old picture of milking, which was drawn five thousand years ago, has been found．

　　In the past, years long ago, people got their milk from their own animals．But in modern times new inventions made the milk industry a big business．In 1851 Gall Borden found a way to take some of the water from milk．This made milk keep longer．Four years later, Louis Pasteur introduced a way to kill the bacteria(細(xì)菌)in milk．Next a special milk bottle was made．This was followed by the invention of machines that could fill bottles with milk．These discoveries had a great effect on the milk industry．They meant that milk could be stored longer．

　　Some people believe that milk drinking will become less popular than it has been．But remember how long milk has been an important food and think of the many ways in which it is useful．It seems safe to say that the milk industry will always be important．

(1)

People began to milk animals ________．

[　　]

A．

five thousand years ago

B．

in the 1850s

C．

before history was written

D．

in recent years

(2)

Sanskrit is a language ________．

[　　]

A．

used by Europeans

B．

recorded in pictures

C．

known to people all over the world

D．

that has a long history

(3)

People did a lot of work to make milk ________．

[　　]

A．

easy to store

B．

easy to drink

C．

thicker

D．

more tasty

(4)

Which of the following is NOT true?

[　　]

A．

A picture of milking was discovered five thousand years ago．

B．

People drink milk as a kind of food．

C．

Many years ago people had to raise animals if they wanted to drink milk．

D．

Louis introduced a way to kill the bacteria in milk in 1855．

(5)

The writer doesn’t agree that ________．

[　　]

A．

milk is useful in many ways

B．

milk has been important to people for thousands of years．

C．

new inventions help people to keep milk much longer．

D．

milk drinking won’t be so popular as it has been

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2012-2013學(xué)年江蘇漣水中學(xué)下學(xué)期期中考試英語(yǔ)卷（帶解析） 題型：閱讀理解

Bad teeth can be painful -- and worse. They can even be deadly. Infections (感染) of the gums (牙齦) and the teeth can cause bacteria (細(xì)菌) to go into the blood system. Those bacteria can increase the chance of a heart attack and worsen the effects of other diseases. And adults are not the only ones at risk.
For example, in 2007, doctors in the Washington area said a boy died when a tooth infection spread to his brain. They said it might have been prevented had he received the dental care (牙齒保健) he needed. He was twelve years old.
Experts at the National Institutes of Health say good dental care starts at birth. Breast milk, they say, is the best food for the healthy development of teeth. Breast milk can help slow the growth of bacteria and acid production in the mouth.
But dentists say a baby's gums and early teeth should be cleaned after each feeding. Use a cloth with a little warm water. Do the same if a baby is fed with a bottle. Experts say if you decide to put your baby to sleep with a bottle, only give the child water.
When baby teeth begin to appear, you can clean them with a wet toothbrush. Dentists say it is important to find soft toothbrushes made especially for babies and to use them very gently.
The use of fluoride (氟化物) to protect teeth is common in many parts of the world. For example, it is often added to drinking water supplies. The fluoride mixes with enamel (琺瑯質(zhì)) , the hard surface on teeth, to help prevent holes from forming.
【小題1】Which of the following can be used as the title of the passage?

A．Concerns for Healthy Teeth of the Young
B．Causes of Teeth Problem
C．Importance of Healthy Teeth of All
D．Solutions to Teeth Problem
【小題2】What's the main idea of paragraph 4 and 5?
A．How to develop babies' teeth.B．How to keep babies' teeth clean
C．Why to protect babies' teethD．Why to keep babies' teeth clean
【小題3】The passage indicates that ______.
A．Enamel is most widely used to protect teeth in the world
B．Breast milk can cure babies' bad teeth
C．Bad teeth may affect the health of adults and the young
D．Babies' teeth should be brushed once per day
【小題4】The writer uses the boy's death as an example to show that ______.
A．not only adults but the young may suffer from teeth problem
B．the doctors should be responsible for the case
C．babies with bad teeth can easily die
D．the boy was not fed with his breast milk

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2012-2013學(xué)年廣西省田陽(yáng)高中高一上學(xué)期11月段考英語(yǔ)試卷（帶解析） 題型：閱讀理解

Norm Pethrick, a 36-year-old man in Australia’s northern city Darwin, was praised on Thursday for jumping onto a crocodile’s back to save his wife Wendy at Litchfield National Park, a popular tourist spot southwest of Darwin, a local newspaper reported.
Ms Pethrick was standing on a river bank Wednesday afternoon when the saltwater crocodile lunged (撲), locking its jaws on both her legs as it tried to drag her underwater.
Norm Pethrick, who with his wife had been collecting water, immediately went to help her. He jumped onto the back, poked (戳) the eyes of the crocodile and finally got his wife free.
Ms Pethrick was later taken to Royal Darwin Hospital for a medical treatment. The doctors said she was suffering eight puncture wounds (傷口) in her right leg, a puncture wound in her left leg and a serious cut to one of her fingers.
“This could have been a fatal and tragic situation,” said the general manager of Royal Darwin Hospital (RDH), Dr Len Notaras, according to a local report.
He said Ms Pethrick was saved by her husband’s “quick and diligent actions”.
Dr Notaras also said she would remain in hospital for three to four days and have an operation to clean the wounds, which are easy to get infected because of bacteria (細(xì)菌) on the teeth of the crocodile.
【小題1】This passage is most likely to be found in _____.

A．a(chǎn) travel guideB．a(chǎn) newspaperC．a(chǎn) textbookD．a(chǎn) novel
【小題2】The crocodile attacked Ms Pethrick when she was ______.
A．standing on the river bank
B．swimming in the river
C．watching the crocodile
D．fishing in the water
【小題3】Which of the following statements is TRUE about Ms Pethrick?
A．Her eyes were badly poked.
B．She had eight wounds altogether.
C．One of her fingers also got hurt.
D．One of the crocodile’s teeth was found in her leg.
【小題4】 According to the passage, Norm Pethrick can be described as following EXCEPT _______.
A．braveB．diligentC．quickD．humorous
【小題5】 Which of the following would be the best title for this passage?
A．A man saves wife’s life from crocodile’s jaws
B．The husband should save the wife
C．A crocodile is not so dangerous as people imagine
D．Human beings can beat crocodiles sometimes

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2012-2013學(xué)年遼寧省協(xié)作體高三領(lǐng)航高考預(yù)測(cè)（十）英語(yǔ)試卷（解析版） 題型：閱讀理解

Scientists have not come close to understanding all the different kinds of life on the planet, but US researcher Craig Venter is already working on creating the first artificial life.

Venter and his researchers made a breakthrough this August. They successfully moved the DNA of one type of bacteria(細(xì)菌) to a yeast(酵母) cell, changed it, then put it into another bacterial cell.

“Bacteria have systems that protect them from foreign DNA,” Venter explained to the BBC. In the experiment, the team managed to block this system.

The experiment was performed on a simple type of bacteria called Mycoplasma mycoides. The team took the bacteria’s genes and put them into a yeast cell.

Putting the DNA in a yeast cell allowed the team to change the genes----in this case, taking out a gene that was not necessary for the bacteria to live.

They then put the gene into a host bacteria cell. The cell went on to divide normally, producing new healthy bacteria.

In January, the team created artificial genes of a new type of bacteria. Their next goal is to put the artificial DNA into a host cell to create a new species, according to a report in Science magazine.

“If we don’t make any errors, I think it should work and we should have the first artificial species by the end of the year,” Venter said in the report.

The first artificial life from is likely to be a simple man-made bacteria, to prove that the technology can work. But that form will be followed by more complex bacteria that turn coal into cleaner natural gas, or algae that can take in carbon dioxide and change it into fuel.

Many scientists think it’s good news to have this artificial life, but others are worried that the technology to create new organisms might end up in the wrong hands, with dangerous results.

1.Craig Venter and his team are working to ______.

A．create a new animal

B．clone a new species

C．produce the first artificial bacteria

D．develop a new system

2.Which of the following is the right order of the experiment?

a. A gene was removed and put into a host bacteria cell.

b. The genes were put into a yeast cell.

c. The cell produced new healthy bacteria.

d. The genes were changed.

e. Some genes were taken out of Mycoplasma mycoides.

A．d-e-a-c-b                              B．e-b-d-a-c

C．a(chǎn)-d-e-c-b                              D．b-e-d-c-a

3.According to the passage, complex artificial bacteria, which will follow the first simple man-made bacteria, are intended to ______.

A．cure deadly diseases

B．prepare the Earth for natural disasters

C．prove that the technology can work

D．improve the earth’s environment

4.We can learn from the passage that ______.

A．Venter and his team are the only scientists trying to create artificial life

B．The experiment was based on research into different kinds of life on Earth

C．A new type of bacteria was created in January

D．All scientists are not in favor of the research

 

查看答案和解析>>

科目：高中英語(yǔ) 來(lái)源：2012-2013學(xué)年山東省高三11月階段性測(cè)試英語(yǔ)試卷（解析版） 題型：閱讀理解

Norm Pethrick, a 36-year-old man in Australia’s northern city Darwin, was praised on Thursday for jumping onto a crocodile’s back to save his wife Wendy at Litchfield National Park, a popular tourist spot southwest of Darwin, a local newspaper reported.

Ms Pethrick was standing on a river bank Wednesday afternoon when the saltwater crocodile lunged (撲), locking its jaws on both her legs as it tried to drag her underwater.

Norm Pethrick, who with his wife had been collecting water, immediately went to help her. He jumped onto the back, poked (戳) the eyes of the crocodile and finally got his wife free.

Ms Pethrick was later taken to Royal Darwin Hospital for a medical treatment. The doctors said she was suffering eight puncture wounds (傷口) in her right leg, a puncture wound in her left leg and a serious cut to one of her fingers.

“This could have been a fatal and tragic situation,” said the general manager of Royal Darwin Hospital (RDH), Dr Len Notaras, according to a local report.

He said Ms Pethrick was saved by her husband’s “quick and diligent actions”.

Dr Notaras also said she would remain in hospital for three to four days and have an operation to clean the wounds, which are easy to get infected because of bacteria (細(xì)菌) on the teeth of the crocodile.

1.This passage is most likely to be found in _____.

A．a(chǎn) travel guide                          B．a(chǎn) newspaper

C．a(chǎn) textbook                             D．a(chǎn) novel

2.The crocodile attacked Ms Pethrick when she was ______.

A．swimming in the river

B．standing on the river bank

C．watching the crocodile

D．fishing in the water

3.Which of the following statements is TRUE about Ms Pethrick?

A．Her eyes were badly poked.

B．She had eight wounds altogether.

C．One of her fingers also got hurt.

D．One of the crocodile’s teeth was found in her leg.

4.According to the passage, Norm Pethrick can be described as following EXCEPT ______.

A．brave                                B．diligent

C．quick                                 D．humorous

5.Which of the following would be the best title for this passage?

A．The husband should save the wife

B．A man saves wife’s life from crocodile’s jaws

C．A crocodile is not so dangerous as people imagine

D．Human beings can beat crocodiles sometimes

 

查看答案和解析>>

同步練習(xí)冊(cè)答案