Plants and animals usually do not live apart, as in many ways they are important

Plants and animals usually do not live apart, as in manyways they are important to each other. Most green plants can make their ownfood. The food of other living things, even the food of meat-eating animals,comes directly or indirectly from green plants. For example, some people eat mutton(羊肉); mutton comes from a goat; the goats eatgrass. These steps, or links, make up what is called a food chain. Withoutgreen plants, all other living things would in time die of starvation.

Plants help animals in other ways too. They furnishhomes and shelter for many animals. Many birds, as you know, build their nestsin trees. Deer and many other animals use bushes for shel­ter. And even mandepends much upon plants for his shelter. Animals repay some of this debt byhelping plants. You may be aware that many insects and some birds do importantwork for plants by pollinating (授粉) them. Youmust have also learned how animals often help plants by spreading seeds.

What is waste material for one of these kinds of lifeis often valuable substance for the other. For example, animals give off carbondioxide gas when they breathe. When plants make food, they absorb this gas fromthe air, using the carbon and releasing some of the oxygen back into the air.The oxygen that is released, then, is again supplied to animals. Thus the cyclecontinues, ani­mals helping plants, and plants helping animals.

All plants and animals have their enemies. Insects eatplants; birds eat insects; other animals kill birds. But here too, animals suchas birds and bats help the plants by destroying harmful in­sects. Many plantsand animals are helpful to some living things but are harmful to others. Thenthere are other rules in nature that act as checks and balances. For example,if there are more animals in a certain area than there is food to support them,some of the animals must mi­grate or starve. In either case, the number ofanimals will be reduced until the balance between animals and the availablefood supply is restored.

These helps and hindrances (障碍) are constantly going on in the plant and animalworld to achieve a balance. As long as one living thing is dependent onanother, whenever the scales are tipped (使倾斜),nature takes steps to balance the scales again.

 (Note: Answer the questions or complete thestatements in NO MORE THAN TEN WORDS.)

1.What does the author mean by saying “Plants andanimals usually do not live apart”?

2.Besides providing food and shelter for animals,plants can also ______ to help animals to live.

3.“Checks and balances” refers to ______ in the worldof animals and plants.

4.What will be the final result if some animalsmigrate or starve for lack of food?

试题答案

【答案】

1.They are important to each other. / They depend oneach other.

2.release oxygen

3.helps and hindrances that are going on

4.Their / Animal number will be reduced until thebalance is restored.

【解析】

试题