When a leafy plant is under attack, it doesn’...

When a leafy plant is under attack, it doesn’t sit quietly. Back in 1983, two scientists. Jack Schultz and Ian Baldwin, reported that young maple trees getting bitten by insects send out a particular smell that neighboring plants can get. These chemicals come from the injured parts of the plant and seem to be an alarm. What the plants pump through the air is a mixture of chemicals known as volatile organic compounds. VOCs for short.

Scientists have found that all kinds of plants give out VOCs when being attacked. It’s a plant’s way of crying out. But is anyone listening? Apparently. Because we can watch the neighbors react.

Some plants pump out smelly chemicals to keep insects away. But others do double duty. They pump out perfumes designed to attract different insects who are natural enemies to the attackers. Once they arrive, the tables are turned. The attacker who was lunching now becomes lunch.

In study after study, it appears that these chemical conversations help the neighbors. The damage is usually more serious on the first plant, but the neighbors, relatively speaking, stay safer because they heard the alarm and knew what to do.

Does this mean that plants talk to each other? Scientists don’t know. Maybe the first plant just made a cry of pain or was sending a message to its own branches, and so, in effect, was talking to itself. Perhaps the neighbors just happened to “overhear” the cry. So information was exchanged, but it wasn’t a true, intentional back and forth.

Charles Darwin, over 150 years ago, imagined a world far busier, noisier and more intimate (亲密的) than the world we can see and hear. Our senses are weak. There’s a whole lot going on.

1.What does a plant do when it is under attack?

A. It sends out certain chemicals.

B. It makes noises.

C. It stands quietly.

D. It gets help from other plants.

2.Scientists find from their studies that plants can 　　　　 .

A. predict natural disasters.

B. help their neighbors when necessary.

C. talk to one another intentionally.

D. protect themselves against insects.

3.What can we infer from the last paragraph?

A. The word is changing faster than ever.

B. The world is more complex than it seems.

C. People have stronger senses than before.

D. People in Darwin’s time were more imaginative.

高二英语阅读理解中等难度题查看答案及解析

Animals can move from place to place, but plants cannot. When an animal is under attack, it can run away or fight back. Plants certainly cannot run away, and they lack teeth and claws. But plants can defend themselves by using both physical and chemical means.

Some plants have their own ways to keep animals away. For example, the leaves of the holly plant have sharp spines(刺) that discourage grass-eating animals. Holly leaves on lower branches have more spines than leaves on upper branches. This is because the lower leaves are easier for most animals to reach.

Some plants , such as the oak trees, have thick and hard leaves that are difficult for animals to eat. Some grasses may contain a sandy material; eating such grasses wears down the animal’s teeth.

Many plants also have chemical defenses. Some plants produce chemicals that taste bitter or cause an unpleasant reaction. Some plants may fight against an attack by increasing the production of these chemicals. When a caterpillar(毛虫)bites a tobacco leaf, the leaf produces a chemical messenger. This messenger sends to the roots the information to produce more nicotine. The higher levels of nicotine discourage the caterpillar.

Many plants depends on both physical and chemical defenses. A certain plant in China , for instance, has prickly(多刺的) leaves, and each prickle contains poisonous venom(毒液). A single experience with this kind of plant will teach an animal to stay away from it in the future.

1.The holly plant has more spines on the lower leaves because most animals ________.

2.To defend themselves , oak trees use ________.

3. How does tobacco protect itself against an attack from a caterpillar?

4.What would be the best title for this passage?

高二英语阅读理解中等难度题查看答案及解析

Animals can move from place to place, but plants cannot. When an animal is under attack, it can run away or fight back. Plants certainly cannot run away, and they lack teeth and claws. But plants can defend themselves by using both physical and chemical means.

Some plants have their own ways to keep animals away. For example, the leaves of the holly plant have sharp spines (刺) that discourage grass-eating animals. Holly leaves on lower branches have more spines than leaves on upper branches. This is because the lower leaves are easier for most animals to reach.

Some plants, such as the oak tree, have thick and hard leaves that are difficult for animals to eat. Some grasses may contain a sandy material; eating such grasses wears down the animal’s teeth.

Many plants also have chemical defenses. Some plants produce chemicals that taste bitter or cause an unpleasant reaction. Some plants may fight against an attack by increasing the production of these chemicals. When a caterpillar (毛虫) bites a tobacco leaf, the leaf produces a chemical messenger. This messenger sends to the roots the information to produce more nicotine. The higher levels of nicotine discourage the caterpillar.

Many plants depend on both physical and chemical defenses. A certain plant in China, for instance, has prickly (多刺的) leaves, and each prickle contains poisonous venom (毒液). A single experience with this kind of plant will teach an animal to stay away from it in the future.

1.The holly plant has more spines on the lower leaves because most animals________.

A．are not tall enough             B．like the lower leaves only

C．are not clever enough           D．can get the lower leaves easily

2.To defend themselves, oak trees use________.

A．chemical means B．physical means

C．bitter chemicals                 D．sandy materials

3.How does tobacco protect itself against an attack from a caterpillar?

A．Its leaves fight against the attack by physical means.

B．Its roots send a messenger to discourage the caterpillar.

C．Its roots increase the production of nicotine when it is attacked.

D．Its leaves produce poisonous sand to drive the caterpillar away.

4.What would be the best title for this passage?

A．Plants and Animals           B．How Plants Defend Themselves

C．Attacks and Defenses       D．How Animals Eat Plant Leaves

高二英语阅读理解中等难度题查看答案及解析

Dodder is an unusual and unwanted plant that attacks other plants. Except for its flowers, the plant looks like spaghetti, a kind of noodles in the shape of long thin pieces that look like string when they are cooked. Its almost leafless, thread-like stems（茎）hang down on top of other plants that dodder needs to stay alive. Dodder does not produce its own food. Instead, it steals food from other plants. It feeds by sucking juices from the plant which is wrapped around, often making its host very weak or even killing it.

Dodder can find other plants by their smell. When a young dodder plant starts growing, it follows the smell of plants it prefers, like tomato plants, potato plants, or other farm crops. Unlike most plants that usually grow in the direction of light or warmth, a dodder plant will grow in the direction of, for example, tomato smell-if a tomato happens to be growing nearby.

However, a young dodder plant must find a host plant quickly. It no longer needs its root once it is attached to the host and wrapped around it. If it cannot catch a smell of a potential host within a few days, it will dry up and disappear-even if there is plenty of water around. Once it finds a host, the young dodder plant will attach itself to it and start growing faster. At that point the dodder plant will drop its root.

Dodder is thus a difficult weed to manage and a real headache for farmers. When it does get out of hand, dodder can greatly reduce a farmer’s harvest or even destroy crops completely. Before sowing their produce, especially farmers in warm parts of the world often check to make sure no unwanted dodder seeds have mixed with their crop seeds. This is a good way to stop dodder plants from making their way to a crop field secretly.

1.Why does the author mention spaghetti in the first paragraph?

A. To analyze the content of some food.

B. To describe tie shape of dodder plants.

C. To explain where the dodder plants come from.

D. To argue that dodder plants can be used.

2.What will happen if a dodder plant starts growing where there are no other plants around?

A. It will die sooner or later.

B. It will grow deep roots.

C. It will attract other plants.

D. It will cover the entire area of soil.

3.What can be inferred from the passage?

A. Dodder does not produce its own food.

B. Dodder can affect farmers’ income.

C. Dodder can only survive in the shade.

D. Dodder only grows in the warm areas.

4.What is the main topic of the passage?

A. A new variety of farm crops.

B. Plants that are harmful to humans.

C. The special abilities of a dangerous plant.

D. Recent improvements in farming methods.

高二英语阅读理解中等难度题查看答案及解析

Look at the car. It is Mr Black’s car. It doesn’t work now. Mr Black is under it. He is repairing it. Mrs Black is near the car. She is helping Mr Black. A girl is in the car. She is Kate, Mr Black’s daughter. Who is the boy in the car? He is Jim, Kate’s brother. It is Saturday today. They don’t work. They want to go to Zhongshan Park. They all look worried.

1.Today is ________.

A. Tuesday            B. Thursday            C. Monday            D. Saturday

2.Mr Black is ________ his car.

A. washing            B. driving            C. repairing        D. cleaning

3.Kate is ________ the car with her brother.

A. beside            B. in                C. under            D. near

4.They are going to a ________.

A. zoo                B. farm                C. factory            D. park

5.What happens to the car?

A. It runs out of gas.

B. It doesn’t work.

C. It was broken in an accident.

D. It is stopped by a policeman.

高二英语阅读理解中等难度题查看答案及解析

Only ______ a human being.

高二英语单项填空中等难度题查看答案及解析

It is a beautiful day here and I am sitting under the big tree at the e________of the1.________

garden. I have just returned from a long bike ride to an old castle. ________seems 2.________

amazing that at my age I am still________(健康) enough to cycle 20 kilometers in 3.________

An afternoon. It’s my b________in two weeks’ time and I’ll be 82 years old! I think4.________

my long and active life must be ________ to(由于) the healthy life I live.         5.

This brings me to the real________(原因) for my letter, my dear grandson.   6.________

Your mother tells me that you started s________some time ago and now you find  7.

it difficult to give it________. Believe me, I know how easy it is to begin smoking  8.________

and how tough to s________. You see, during adolecence                      9.

I a________smoked and became addicted to cigarettes.                           10.

高二英语其他题中等难度题查看答案及解析

Only when it is hungry______ a human being.

A. a lion will attack　　　　　　　　 B. a lion would attack

C. will a lion attack　　　　　　　　 D. would a lion attack

高二英语单项填空中等难度题查看答案及解析

Only when it is hungry ______ a human being.

A. a lion will attack　　 B. a lion should attack

C. will a lion attack　　 D. should a lion attack

高二英语单项填空中等难度题查看答案及解析

— It’s a lovely day, isn’t it?

— Yes. I love　　　　 when the weather is like this. Why don’t we sit outside and have our lunch?

A.this　　　　　 B.that 　　　　 C.it　　　　　 D.one

高二英语单项填空简单题查看答案及解析