章节大纲

  • 常规

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  • 叶叶和相光合成

    What you will learn
    ::你会学到什么

    • Structure and function of different kinds of specialized tissues in leaves - mesophyll , veins , and epidermis
      ::叶叶中不同种类专门组织的结构和功能 -- -- 中观、静脉和后皮
    • Role of stomata and guard cells to control transpiration and gas exchange
      ::调气和气体交换控制调气和气体交换的Stomata和看守牢房的作用

    Bright green leaves against a blue sky, symbolizing the process of photosynthesis.

    Oxygen — the oxygen that we breathe — is just a waste product of what reaction?
    ::氧——我们呼吸的氧气——只是什么反应的废物产物。

    Every split second that sunlight hits that leaf, is initiated, bringing energy into the . It could be said that this is one of the most important - if not the absolutely most important - . And it all starts with the leaf.
    ::阳光照到叶子的每一秒, 都会启动, 给叶子带来能量。可以说这是最重要的之一, 如果不是绝对最重要的的话。 这一切都是从叶子开始的。

    Factories for Photosynthesis
    ::光相合成工厂

    Photosynthesis is the process that uses energy from the sun, together with carbon dioxide and , to make glucose and oxygen. The primary role of photosynthesis is to make the , suggesting that oxygen, which is released back into the atmosphere , is just a waste product.
    ::光合作用是利用太阳能量以及二氧化碳和氧气制造葡萄糖和氧气的过程。 光合作用的主要作用是制造,这意味着氧气(释放回大气层)只是一种废物。

    You can think of a single leaf as a photosynthesis factory. A factory has specialized machines to produce a product. It’s also connected to a transportation system that supplies it with raw materials and carries away the finished product. In all these ways, a leaf resembles a factory. The cross section of a leaf in the Figure lets you look inside a leaf “factory.”
    ::你可以把单一叶子想象成一个光合作用工厂。 工厂拥有生产产品的专门机器。 工厂还连接到向它提供原材料并带走成品的运输系统。 在所有这些方面,叶子都类似于工厂。 图中的一片叶子的横截面让你可以看到叶子中的“事实 ” 。

    Cross section of a leaf showing structures like epidermis, mesophyll, veins, and stomata for photosynthesis.
    There’s more to a leaf than meets the eye. Can you identify the functions of each of the labeled structures in the diagram?

    A leaf consists of several different kinds of specialized tissues that work together to make food by photosynthesis. The major tissues are mesophyll, veins, and epidermis.
    ::叶子由几种不同的专门组织组成,它们通过光合作用来生产食物。 主要的组织是中观、静脉和皮皮。

    • Mesophyll makes up most of the leaf’s interior. This is where photosynthesis occurs. Mesophyll consists mainly of parenchyma with .
      ::叶叶的内部大部分是中观素,这里是光合作用的地方。 中观素素主要是近距离近距离的。
    • Veins are made primarily of xylem and phloem . They transport water and minerals to the of leaves and carry away dissolved sugar.
      ::水和矿物质主要由xylem和phloem制成,它们将水和矿物输送到叶子上,并带走溶解的糖。
    • The epidermis of the leaf consists of a single layer of tightly-packed dermal cells. They secrete waxy cuticle to prevent evaporation of water from the leaf. The epidermis has tiny pores called stomata (singular, stoma) that control transpiration and gas exchange with the air (see Figure ). For photosynthesis, stomata must control the transpiration of water vapor and the exchange of carbon dioxide and oxygen. Stomata are flanked by guard cells that swell or shrink by taking in or losing water through . When they do, they open or close the stomata (see Figure ).           
      ::叶子的上皮层由单层的严格包装的皮肤细胞组成,它们密藏着蜡性切片,以防止叶子中的水蒸发;其上皮层有小孔孔,叫做斯托马塔(单层、单层),可以控制气的蒸发和与空气的气体交换(见图)。光合作用,斯托马塔必须控制水蒸气的蒸发和二氧化碳与氧的交换。斯托马塔的侧侧侧是通过取进或输入水而膨胀或缩小的看守细胞。当它们这样做时,它们打开或关闭斯托马塔(见图 ) 。
     
    • Leaf cells with labeled structures: guard cells, stoma, chloroplasts, and others.
    • Microscopic view of leaf structure showing epidermis, stomata, and mesophyll cells.
    (first) Stomata are flanked by guard cells that swell or shrink by taking in or losing water through osmosis. (second) Stomata and guard cells of a xerophyte leaf.

     

     

     

     

     

    DID YOU KNOW?
    Not all plant have leaves that are green in color, some have red, yellow, or orange leaves. There are three kinds of primary pigments in the plant leaves: chlorophyll (green color), carotenoids (yellow or yellow-orange color), and anthocyanins (red or purple color).  The color of the leaf is determined by the pigment which is present in the highest concentration.
     

    Summary
    ::摘要

    • Specialized cells and tissues in leaves work together to perform photosynthesis.
      ::叶子中的专门细胞和组织一起工作,进行光合作用。
    • The major tissues in a leaf are mesophyll, veins, and epidermis.
      ::叶子中的主要组织是中观素、血管和后皮。

    Review
    ::回顾

    1. Explain how a leaf is like a factory.
      ::解释一下叶子像工厂一样
    2. Explain the role of stomata during photosynthesis.
      ::解释光合作用时斯托玛塔的作用。
    3. What controls the opening of stomata?
      ::是什么控制了 stomata 的打开 ?