Plants植物

I-2 / 002

Roots

Roots are the part of the plant that is in the ground. The roots of the plant hold the plant in the ground. On each root are tiny root hairs. These tiny root hairs grow into the soil. They take in water and minerals. The plant uses water and minerals to make food. Without water and minerals, the plant cannot grow.

Stems

Now look at a plant's stem. Stems are like tiny pipes. Water and minerals can travel through the stem. The stem takes water and minerals to the leaves, where the plant's food is made.

Stems are of many different sizes. The big tree trunk is a stem. The stem of a cabbage plant is so short that you may not see it. Vines are a kind of stem. The tiny tubes in the stem of a celery plant are easy to see.

Leaves

The leaves of green plants have tiny openings in them. To see these openings, you will need the help of a microscope. A microscope makes things look much bigger than they really are.

The tiny openings are important to help the plant grow. Carbon dioxide, a gas from the air, enters the leaf by the openings. Carbon dioxide is given off by people and animals when they breathe.

When plants use carbon dioxide, they give off a gas called oxygen. People and animals need oxygen to live. Some of the water in the plant is given off through the leaves. Carbon dioxide goes into the leaves of the plant through tiny openings like those in this picture.

Food storage parts

You have learned that all green plants make food. You know that the plants use part of the food they make. This food is used to grow new leaves and roots.

What happens to the rest of the food? All extra food is stored somewhere in the plant. Some plants such as lettuces store their extra food in the leaves. Many plants such as beets and carrots store food in their roots. The celery plant stores food in its stem. Corn, beans, and peas store food in their seeds. Still other plants store food in their fruits. Could you say, then, that you had roots, stems, and leaves for dinner?

必背词汇

练 习

1. Draw four plant parts you have eaten this week.

2. Write down the answers in the blanks.

(1) The tiny openings in the leaves of plants take in __________________ .

(2) Plants give off _____________  and a gas called _____________  into the air.

译 文

根

根是指植物长在地下的部分，它让植物得以固定在土壤中。每条根上都长有细小的根毛，这些细小的根毛会向土壤深处生长，它们吸收水分和矿物质。植物通过水和矿物质制造养料，若没有水和矿物质，植物就不能生长。

茎

现在请看植物的茎。茎就像细小的管子。水和矿物质会通过茎来传输。茎把水和矿物质输送给叶子，并在那里制造植物所需的养料。

茎的大小不一，大树的树干是一种茎；卷心菜的茎则很短，你可能看不见；葡萄藤也是一种茎；芹菜茎中细小的管子则很容易看得到。

叶

绿色植物的叶子中有许多细小的孔。透过显微镜，你才能看到这些小孔。显微镜能够使物体看起来比实际大许多。

这些细小的孔对植物的生长非常重要。空气中的二氧化碳通过这些小孔进入叶子。二氧化碳是人和动物呼出的气体。

植物会吸收二氧化碳，然后释放出一种叫氧气的气体。人和动物需要氧气才能存活。植物的一些水分通过叶子释放出来。二氧化碳通过细小的开口进入植物的叶子里，如图所示。

贮藏养料的部位

你们已经知道所有绿色植物都会制造养料，并且利用一部分自己所制造的养料来长出新的叶子和根。

那么剩下的养料怎么办呢？所有剩余的养料都被储存在植物中的某处。某些植物，如莴苣，会把它们多余的养料储存在叶子里。甜菜和胡萝卜这些植物则把养料储存在它们的根部。芹菜会把养料储存在茎部。玉米、豆子和豌豆则把养料储存在它们的种子里。也有别的植物把养料储存在它们的果实里。所以，你是否也用植物的根、茎、叶来当晚餐呢？

练 习

1. 画出本周内你所吃过的四种植物的部位。

2. 请在空格处填写答案。

(1) 植物叶子内的小孔吸入 ______________ 。

(2) 植物释放出 ______________ 和一种叫 ___________ 的气体到空气中。

答 案

2. (1) carbon dioxide (2) some water, oxygen