Question

We all enjoy the beautiful show of colours as leaves change each autumn. But did you ever wonder how and why this happens?

Leaves are nature’s food factories. Plants take water from the ground through their roots and take carbon dioxide (二氧化碳) from the air. Plants use sunlight to turn water and carbon dioxide into glucose (葡萄糖). Glucose is a kind of sugar, which plants use as food for energy and growing.

The way plants turn water and carbon dioxide into sugar is called photosynthesis that means “ putting together with light”. A chemical called chlorophyll helps photosynthesis. It gives plants their green colour. As summer ends and autumn comes, the days get shorter and shorter, and trees “know” to begin getting ready for winter.

During winter, there is not enough light or water for photosynthesis. Trees rest during this time and live on the food they store during the summer. They begin to shut down their food-making factories.

As the green chlorophyll disappears from the leaves, we begin to see yellow and orange leaves. Small amounts of these colours have been in the leaves all along. We just can’t see them in the summer, because they are covered up by the green chlorophyll.

The bright reds and purples we see in leaves are made mostly in autumn. In some trees, like maples (楓樹), glucose is caught in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn turn this glucose into a red colour. The brown colour of trees like oaks (橡樹) is made from waste left in the leaves.

It is the mixture of all these things that makes the beautiful colours we enjoy during autumn.

1.The word “chlorophyll” in the third paragraph means _______ in Chinese.

A．葉綠素           B．氧氣             C．胡蘿卜素         D．蛋白質(zhì)

2.The leaves of the trees in autumn turn yellow because of the short of _____.

A．water and carbon dioxide

B．glucose and energy

C．sunlight and water

D．sunlight and carbon dioxide

3.The way that _______________________ is called Photosynthesis .

A．plants change water and carbon dioxide into sugar

B．plants turn water and carbon dioxide into sugar with the help of sunlight

C．plants use glucose as food for energy and growing

D．chlorophyll is a great help

4.Which of the following is NOT true?

A．When autumn and winter come, the days get shorter and shorter.

B．During winter trees rest and live on the food they store during the summer.

C．During winter small amounts of yellow and orange colours are kept in the leaves all the time.

D．Trees begin to stop making food in summer.

5.This passage tells us __________________.

A．a(chǎn)ll the plants can grow well with the strong sunlight

B．there are all kinds of plants on the earth

C．a(chǎn)ll the colours of the leaves aren’t made from chlorophyll

D．maples and oaks have the same reason as other trees for the change of colours

 

Answer 1

【答案】

1.A

2.C

3.B

4.D

5.C

【解析】

試題分析：這篇短文主要介紹了樹葉顏色變化的原理，以及樹葉在植物生長發(fā)育中的作用。

1.聯(lián)系下文It gives plants their green colour它給指物提供了綠色�？芍�這個單詞與綠色有關(guān)，故選A。

2.根據(jù)短文第四五段描述，可知樹葉在秋天變黃主要是因為缺少光照和水分，故選C。

3.根據(jù)第三段The way plants turn water and carbon dioxide into sugar is called photosynthesis 描述，可知選B。

4.根據(jù)短文第四段描述，可知植物在秋天停止制造食物，故選D。

5.根據(jù)最后一段It is the mixture of all these things that makes the beautiful colours we enjoy during autumn. 及上文描述，可知并不是植物所有的顏色都是來自于葉綠素，故選C。

考點：關(guān)于樹葉顏色的說明文閱讀

點評：本文中長句較多，一時很難讀懂句子含義，注意多讀幾遍，不要強求非得理解一詞一句的含義，能把握文章大意就行。然后帶著問題閱讀短文，一般就能順利找出答題依據(jù)。對于不能直接找到根據(jù)的問題注意聯(lián)系上下文，根據(jù)短文中心總結(jié)出正確答案。