So far in this chapter, we have looked at the structure of a typical
plant cell in the prime of its life.
Like organisms, cells have a life cycle that includes youth, maturity, and
old age. At the end of their life cycle, cells can either divide or die. For
plant cells, death is not necessarily the end of their usefulness because
the cell walls of dead cells become permanent parts of the plant body.
In large trees, for example, more than 99% of the cells in the trunk
are dead. These cells serve a variety of useful functions, including
conducting water and providing the structural support necessary to lift the
leaf canopy into the sunlight.
到本章為止 我們已經看過了植物成熟時期的構造 就像一個生物的生命週期 細胞也有幼
年 成熟 老年期 當一個週期完成時 細胞可以選擇分裂或者死亡 就植物而言 死亡並
不代表失去功能 像死細胞的細胞壁就成了植物體永久的一部分 例如一棵大樹
99%的樹幹細胞是死的 這些細胞仍然有著重要的功能 包括輸送水分 支撐樹冠層使其
可以吸收陽光
無聊翻譯一下
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