The reason why nature is vibrant is because of its diverse and diverse organisms. However, no matter how many organisms change, they are generally divided into two categories, namely animals and plants. Since ancient times, people have simply believed that all living organisms are animals, and those that live and cannot move are plants; the vast majority of plants are green, while animals have various colors and patterns; From small to large, plants grow roots and leaves, and blossom and bear fruit. Most vertebrates, regardless of age, do not increase or decrease their senses and limbs, just differ in size. However, due to the many exceptions, it was difficult for our ancestors to define what were plants and animals in simple terms.
In the 17th century, the microscope was invented. Because it could observe many things that could not be seen with the naked eye, people curiously put various objects under the microscope to explore, and observed the most magical discovery in the field of biology-cells. Modern science shows that cells are the basic units of organisms and usually have structures such as cell nuclei, cytoplasm and cell membranes. However, plant cells and animal cells are significantly different. For example, whether there is a cell wall on the outside becomes animal cells and plant cells. One of the main differences. Because almost all plant cells, whether they come from plant roots, leaves, or flowers and fruits, have the structure of cell walls, while the cells that make up the animal body have no cell walls. Therefore, the presence or absence of cell walls has become the main criterion for judging animals and plants. In addition, mature plant cells generally have vacuoles, and photosynthetic cells (usually found in leaves and young stems) contain chloroplasts or chromophores, which animal cells do not.
There is also a clear difference between animals and plants in the way they ingest substances and energy. Animals, without exception, feed on existing organic matter (plants or other animals), which we call heterotrophic, while most plants synthesize their own organic matter by photosynthesis, using water and carbon dioxide, which we call autotrophic. However, there are a small number of plants also live a "heterotrophic" life, such as mushrooms, fungus and other fungi and parasitic plants in higher plants, such as dodder, gastrodia elata, and oedipus. Although they are not green, their cells all have cell walls, indicating that they still belong to plants.