It may seem easy to say that plants and animals are different. Any child can tell the difference between a tree and a dog. But those differences are far deeper than just what they look like. The cells (细胞) that plants are made up of are different. In other words, the cell wall of plants has something special.
First of all, it's important to find that not all plant cells have a cell wall. Besides, there are many differences of a cell wall based on the kinds of plant. The following is meant to be what a plant cell wall is like.
The cell wall of a plant is on the outside of the cell membrane (膜). It is usually hard and cannot be bent easily, but the degree of flexibility (韧性) of the cell wall is different. It is based on the special use that the cell has in keeping the plant alive. Cells that make up the trunk of a tree are clearly less flexible than cells on a leaf.
Cell walls act in many ways. They serve to protect the plant. They provide support, as well as help in the movement of chemicals and wastes into and out of the cell. More importantly, they control the water that goes in and out. Plants must have good water controlling systems (系统), allowing them to keep water during dry seasons, and get rid of unnecessary water. Plants can't walk around to find water, so being able to control water is very important.
So there you have it , what a plant cell wall is. Of course, there are many other things that are not talked about here. Knowing more about plant cell wails requires further study and research.
小题1:From the first two paragraphs we can find that _____.
A．all plants have a ceil wall
B．plant cells and animal cells are the same
C．different kinds of plant have different cell walls
D．there are no differences between the cells of a tree and a dog小题2:The underlined word "bent" in the passage is the closest in meaning to _____.
A．变形的
B．防水的
C．太阳灼伤的
D．表皮破损的小题3:Cells in the trunk of a tree are _____ those on a leaf.
A．as flexible as
B．not so flexible as
C．more important than
D．less important than小题4:What is the most important use of a plant cell wall?
A．To protect the plant.
B．To provide support.
C．To move chemicals and wastes.
D．To control the water.
小题1:C
小题2:D
小题3:B
小题4:D
试题解析:本文大意：也许很容易说植物与动物不同，任一孩子能讲出一棵树和一只狗的区别。但那些区别远比它们看上去的要深。 组成植物的细胞是不同的，换句话说，植物的细胞壁有特殊的东西。 首先不是所有的植物有细胞壁，另外，基于植物的种类细胞壁有很多不同。细胞壁在细胞膜的外面。通常坚硬不易破损，但柔韧性的程度不一样。细胞壁也多种方法工作来保护植物。更重要的是，控制水的出入。
小题1:细节理解题。根据 there are many differences of a cell wall based on the kinds of plant. 基于植物的种类细胞壁有很多不同，可知答案选C
小题2:推理判断题。根据It is usually hard通常坚硬 ，可知答案选D
小题3:细节理解题。根据Cells that make up the trunk of a tree are clearly less flexible than cells on a leaf.组成树干的细胞很明显没有树叶的细胞柔韧，可知答案选B
小题4:细节理解题。根据 More importantly, they control the water that goes in and out.更重要的是，控制水的出入 ，可知答案选D