Section outline

  • General

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  • 生物学原则的原则

    What you will learn
    ::你会学到什么

    • The unifying principles of biology : , gene theory , and evolution
      ::生物学的统一原则:基因理论和进化

     

    Chromosomes representing genetic control of life characteristics.

    Reproduction, homeostasis, evolution, metabolism, heredity. What controls the characteristics of life?
    ::生殖、顺势、进化、新陈代谢、异端。什么控制着生命的特征?

    are controlled by genes , which are passed from parents to offspring, and are located on , like the ones shown here, that are found in every . This describes a fundamental idea of gene theory, one of the four unifying principles of biology.
    ::基因是由基因控制的,基因从父母传给后代,并且与这里所显示的基因一样,位于每个基因中。它描述了基因理论的基本概念,这是生物学四大统一原则之一。

    Unifying Principles of Biology
    ::统一生物学原则

    Four unifying principles form the basis of biology. Whether biologists are interested in ancient life, the life of , or how humans could live on the moon, they base their overall understanding of biology on these four principles:
    ::四条统一原则构成生物学的基础。 无论生物学家对古代生命、人类生命或人类如何在月球上生活感兴趣,他们对生物学的总体理解都基于这四条原则:

    1. cell theory
      ::单元格理论
    2. gene theory
      ::基因理论
    3. homeostasis
      ::常久久久久久久久
    4. evolution
      ::进进进进进进进进进进进进 进进进进进进进进进进进 进进进进进进进进进进进进进进 进进进进进进进进进进进进进进进进进进进进 进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进

    The Cell Theory
    ::细胞理论

    According to the cell theory , all organisms are made up of one or more cells, all the life functions of an organism occur within cells, and all cells come from preexisting cells . In fact, each living thing begins life as a single cell. Some living things, such as bacteria, remain single-celled. Other living things, including plants and , grow and develop into many cells. Your own body is made up of an amazing 100 trillion cells! But even you—like all other living things—began life as a single cell. 
    ::根据细胞理论,所有生物都由一个或多个细胞组成,一个生物体的所有生命功能都存在于细胞中,所有细胞都来自原已存在的细胞。事实上,每个生物体都以单一细胞开始生命。有些生物体,如细菌,仍然是单细胞。其他生物体,包括植物和生长和发育成许多细胞。你的身体是由一个惊人的100万亿细胞组成的。但即使你——像所有其他生物一样——像一个单一细胞一样,生命是比活物。

    Comparison of diatoms, single-celled organisms, and whale sharks, multi-celled organisms, highlighting cell theory.
    (A) Diatoms are about 20 µm in diameter and are made up of one cell, whereas (B) whale sharks can measure up to 12 meters in length and are made up of billions of cells.

     

     

     

    The Gene Theory
    ::Gene 理论

    The gene theory is the idea that the characteristics of living organisms are controlled by genes, which are passed from parents to their offspring. A gene is a segment of that has the instructions to encode a . Genes are located on larger structures, called chromosomes , that are found inside every cell. Chromosomes, in turn, contain large molecules known as DNA (deoxyribonucleic acid). Molecules of DNA are encoded with instructions that tell cells what to do.
    ::基因理论认为,活生物体的特性是由基因控制的,基因从父母传给后代。基因是具有编码指令的一部分。基因位于更大的结构上,称为染色体,每个细胞中都能找到。染色体反过来又含有称为DNA(脱氧核糖核酸)的大型分子。DNA的分子被编码为代号,指示细胞做什么。

     

    Homeostasis
    ::常态

    Homeostasis , which is maintaining a stable internal environment or keeping things constant, is not just a characteristic of living things. It also applies to nature as a whole. Consider the concentration of oxygen in Earth’s atmosphere . Oxygen makes up 21% of the atmosphere, and this concentration is fairly constant. What keeps the concentration of oxygen constant? The answer is living things. Most living things need oxygen to survive, and when they breathe, they remove oxygen from the atmosphere. On the other hand, many living things, including plants, give off oxygen when they make food , and this adds oxygen to the atmosphere. The concentration of oxygen in the atmosphere is maintained mainly by the balance between these two processes. 
    ::保持稳定的内部环境或使事物保持恒定的自闭症不仅仅是活物的特征。 它也适用于整个自然。 考虑氧在地球大气中的浓度。 氧占大气的21 % , 而这种浓度相当稳定 。 保持氧的浓度是常态的 ? 答案是活物 。 大多数活物需要氧来生存, 当它们呼吸时, 它们从大气中取出氧气。 另一方面,许多生物,包括植物,在生产食物时释放氧气,这增加了氧气到大气中。 氧气在大气中的浓度主要由这两个过程之间的平衡来维持。

     

    The oxygen-carbon dioxide cycle involving plants, animals, and the atmosphere.

    The oxygen cycle is the biogeochemical cycle that helps in maintaining almost constant levels (21%) of oxygen in the atmosphere.

    Evolution
    ::演变演变进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进进

    Evolution is a change in the characteristics of living things over time. Evolution occurs by a process called . In natural selection, some living things produce more offspring than others, so they pass more genes to the next generation than others do. Over many generations, this can lead to major changes in the characteristics of living things. Evolution explains how living things are changing today and how modern living things have descended from ancient life forms that no longer exist on Earth.
    ::进化是生命特性随时间变化。进化的过程被称为 。 在自然选择中,一些生物产生比其他生物更多的后代,因此它们会把更多的基因传给下一代。在很多代人中,这可以导致生命特性的重大变化。进化解释了生命事物今天是如何变化的,以及现代生物是如何从地球上不再存在的古代生命形式中诞生的。

    As living things evolve, they generally become better suited for their environment. This is because they evolve adaptations . An adaptation is a characteristic that helps a living thing survive and reproduce in a given environment. Look at the mole in Figure . It has tentacles around its nose that it uses to sense things by touch. The mole lives underground in the soil , where it is always dark. However, by using its touch organ , it can detect even tiny food items in the soil in total darkness. The touch organ is an adaptation because it helps the mole survive in its dark, underground environment.
    ::随着生命的演变,它们一般会变得更适合环境。这是因为它们会演变适应性。适应性是一种有助于生物在特定环境中生存和繁殖的特征。看看图中的内鬼。它的鼻子上有触摸感知事物的触角。内鬼生活在土壤的地下,那里总是黑暗的。然而,通过触摸器官,它可以在完全黑暗的土壤中探测到即使是很小的食物。触摸器官是一种适应性,因为它帮助内鬼在黑暗的地下环境中生存。

     

    Three moles nestled together in a bed of dry grass and soil.
    This mole uses its star-shaped nose organ to sense food by touch in the dark. The mole’s very large front claws are also an adaptation for its life in the soil. Can you explain why?
       

     

     


    DID YOU KNOW?
    Humans have evolved from chimpanzees is a myth!!! Humans and chimpanzees have in common almost 99% of their DNA but they did not evolve from each other. It is now known that humans, chimpanzees, and gorillas evolved from a common ancestor that existed more than 6 million years ago. 
     

     

    Summary
    ::摘要

    • The cell theory states that all living things are made up of cells, and living cells always come from other living cells.
      ::细胞理论指出,所有生物都是由细胞组成的, 活细胞总是来自其他生物细胞。
    • The gene theory states that the characteristics of living things are controlled by genes.
      ::基因理论指出,生物的特性受基因控制。
    • Homeostasis is maintaining a constant internal environment.
      ::保持了稳定的内部环境。
    • Evolution is a change in species over time.
      ::进化是物种随时间变化的一种变化。

    Review
    ::回顾

    1. Identify four unifying principles of modern biology.
      ::确定现代生物学的四项统一原则。
    2. How are genes related to chromosomes?
      ::基因与染色体的关系如何?
    3. Define homeostasis.
      ::定义常态。
    4. How are adaptations related to evolution?
      ::适应如何与进化相关?