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  • Imagine you are taking a walk on a trail through the park.

  • Trees and flowers surround the rocky pathway, birds chirp from nearby branches,

  • clouds float overhead, and a creek babbles nearby.

  • Some of these things are living and some are clearly not living.

  • But where do we draw the line between living and non-living things?

  • How do biologists specifically define life?

  • Living things all share seven distinct characteristics.

  • The grow and develop, they are able to reproduce,

  • they respond to their environment, they use energy

  • they maintain homeostasis, they have cellular organization,

  • and they are able to adapt, evolve, and pass

  • on their genetic information in the form of DNA.

  • So let’s look at these characteristics in terms of the things you encounter on your walk.

  • The trees that surround you are living things.

  • They started out as a single seed, then underwent growth and development to become trees

  • that reproduce again by producing more seeds.

  • They respond to their environment by growing towards light.

  • They make their own sugars, which they then metabolize for energy.

  • They keep their internal environments fairly constant.

  • If you were to zoom in closely on a leaf using a microscope,

  • you would see that it is composed of tiny individual units called cells.

  • DNA resides within the nucleus of each cell.

  • In contrast, let’s consider the creek running alongside the path.

  • While it may grow larger or change size due to increased rainfall

  • or other weather conditions, it is not made up of cells.

  • Water does not contain DNA.

  • It doesn’t reproduce or maintain homeostasis.

Imagine you are taking a walk on a trail through the park.


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B1 中級

生活の特徴 (Characteristics of Life)

  • 73 4
    Yrchinese に公開 2021 年 01 月 14 日