阅读背景知识之植物细胞构成

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　　The cells of a plant'are organized into three tissue systems:dermal,vascular, and ground tissue. Each tissue system is continuous throughouttheplant's body. The specific characteristics of each tissue, however, aredifferent in the different organs ofthe plant.

　　The dermal tissue system is the "skin" of the plant. The dermal system, orepidermis,is a single layer of cells covering the entire body of the plant. Themailn function of the epidermis is to protect the plant. The epidermis also hasspecialized characteristics for the particular organs it covers. For example,the epidermis ofleaves and stems has a waxy coating that helps the plantconserve water, and the epidermal cells near the tips of the　plant's roots helpthe plant absorb water and nutrients from the soil.

　　The second tissue system-the vascular system-is the transportation systemfor water and nutrients. Vascular tissue also helps to support the plant'sstructure. The third system- the ground tissue-makes up the bulk of a plant,filling all of the spaces between the dermal and vascular tissue systems. Groundtissue functions in photosynthesis, storage, and support.

　　1、How are the three tissue systems of a piant similar to each other?

　　They all continue throughout the plant's body

　　They all have a protective waxy coating.

　　They all consist of a single layer of cells.

　　They all perform the same bodily functions.

　　2、which ofthe following statements best scribes the plant's epidermis?

　　It helps the plant to stand upright

　　It transports water and nutrients.

　　It covers the plant's entire body.

　　It is found only in young plants.

　　3. Which type of tissue does a plant's body mainly consist of?

　　Dermal

　　Vascular

　　Epidermis

　　Ground