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  • 生态系统中的能量流动

    View of yellow flowers silhouetted against the sun in a clear blue sky.

     

    What is the source of energy for almost all ecosystems?
    ::几乎所有生态系统的能源来源是什么?

    The   supports most of Earth's  ecosystems . Plants create  chemical energy  from  abiotic factors  that include solar  energy . The food energy created by  producers  is passed through the  food chain .
    ::植物从包括太阳能在内的非生物因素中产生化学能源,生产者创造的粮食能源通过食物链传递。

    How Energy Flows Through Ecosystems
    ::如何通过生态系统进行能源流动

    All living things need energy. They need it to power the processes of life. For example, it takes energy to grow. It also takes energy to produce offspring. In  fact , it takes energy just to stay alive. Remember that energy can’t be created or destroyed. It can only change form. Energy changes form as it moves through ecosystems.
    ::所有生物都需要能源,它们需要能源来给生命过程提供动力。例如,它需要能源来培育后代。事实上,它只需要能源来维持生命。记住能源不能创造或摧毁。它只能改变形态。随着生态系统的演变,能源会变化。

    The Flow of Energy
    ::能源流动

    Most ecosystems get their energy from the Sun. Only producers can use sunlight to make usable energy. Producers convert the sunlight into chemical energy or food. Consumers get some of that energy when they eat producers. They also pass some of the energy on to other consumers when they are eaten. In this way, energy flows from one living thing to another.
    ::大部分生态系统的能源来自太阳。 只有生产者可以使用阳光来生产可用的能源。 生产者可以将阳光转化为化学能源或食品。 消费者在吃生产者时获得部分能源。 当他们被食用时,他们也将部分能源传递给其他消费者。 这样,能源从一种生物流向另一种生物。

    Food Chains
    ::食物链链

    A  food chain  is a simple diagram that shows one way energy flows through an ecosystem. Pictured below is an example of a food chain ( Figure   ). Producers form the base of all food chains. The consumers that eat producers are called primary consumers. The consumers that eat primary consumers are secondary consumers. This chain can continue to multiple levels.
    ::食物链是一个简单的图表,它显示了能源通过生态系统的单向流动方式。以下是食物链的例子(图 )。生产者构成所有食物链的基础。食用生产者的消费者被称为初级消费者。食用初级消费者的消费者是次级消费者。这个链可以持续到多个层次。

    A food chain showing producers and primary, secondary, and tertiary consumers.

     

    What do the arrows stand for in a food chain?
    ::箭头在食物链中代表什么?

    At each level of a food chain, a lot of energy is lost. Only about ten percent of the energy passes to the next level. Where does that energy go? Some energy is given off as  heat . Some energy goes into animal wastes. Energy also goes into growing things that another consumer can't eat, like fur. It's because so much energy is lost that most food chains have just a few levels. There’s not enough energy left for higher levels.
    ::在食物链的每一个层次上,能源都会大量流失。只有大约10%的能源流向下一个层次。能源流向哪里?能源流向哪里?一些能源作为热能被释放出来。一些能源流入动物废物。能源还进入了另一个消费者无法吃的生长中,比如毛皮。这是因为能源流失如此之多,大多数食物链只有几层。没有足够能源可以达到更高的水平。

    Food Webs
    ::食品网

    Food chains are too simple to represent the real world. They don’t show all the ways that energy flows through an ecosystem. A more complex diagram is called a  food web  ( Figure   ). A food web consists of many overlapping food chains. Can you identify the food chains in the figure? How many food chains include the mouse?
    ::食物链太简单,无法代表真实世界。 它们没有展示能源通过生态系统的所有方式。 更复杂的图表被称为食物网(图 ) 。 食物网由许多互相重叠的食物链组成。 您能否辨别这个图中的食物链? 有多少食物链包括鼠标?

    A food web showing interactions among producers, primary consumers, secondary consumers, and tertiary consumers.

     

    The owl in this food web consumes at two different levels. What are they?
    ::这个食物网中的猫头鹰消耗了两个不同层次。它们是什么?

    Food webs also overlap. For example, an eagle is part of a land food web. But it might go to the sea to grab a fish. That fish is part of a marine food web.
    ::食物网也是重叠的。例如,鹰是陆地食物网的一部分。但是它可能去海中钓鱼。鱼是海洋食物网的一部分。

    Summary
    ::摘要

    • A food chain describes the passage of energy.
      ::食物链描述能源的通过。
    • A food web is a set of interconnected and overlapping food chains.
      ::食物网是一系列相互关联和重叠的食物链。
    • Food webs are interconnected.
      ::食物网是相互联系的。

    Review
     ::回顾

    1. What does a food chain depict?
      ::食物链描述什么?
    1. Why do scientists usually use a food web instead of a food chain?
      ::为什么科学家通常使用食物网而不是食物链?
    1. Start with the Sun. Describe what happens to energy as it moves through ecosystems.
      ::以太阳为起点。描述能源在生态系统中移动时会发生什么。

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    1. What do all organisms require?
      ::所有生物都需要什么?
    1. What provides the energy required by the ecosystem?
      ::什么是生态系统所需要的能量?
    1. How is energy transferred from one organism to another?
      ::能源是如何从一个生物体转移到另一个生物体的?
    1. How is some of the energy lost?
      ::一些能量是怎么损失的?
    1. How do nutrients move through an ecosystem?
      ::养分如何在生态系统中流动?
    1. How does the movement of energy and nutrients differ in ecosystems?
      ::在生态系统中,能源和养分的流动如何不同?