Why are the leaves green? Why do they need it?

Plants - one of the five realms of living organisms of our planet. They belong to eukaryotes, that is, to creatures whose cells contain a nucleus.

Structure of the plant

They can be either unicellular or multicellular. The latter are divided into such departments as green, brown and red algae, spore, gymnosperms and angiosperms. The algae organism can consist of either one cell or many, but there are no organs in their structure, a solid body is called a thallus. In spore, gymnosperms and angiosperms (flowering), there are differentiated tissues and organs. The latter are divided into vegetative and generative. The first is the escape (stem and leaves), as well as the root. Many people are interested in the question: "Why are the leaves green?" Why this color? Also, many children ask the question: "Why are the leaves green?" And this article we will begin with this topic.

Why are the leaves green?

This color is due to the presence of chlorophyll. In autumn this pigment is lost, and the green leaf turns into red, orange or yellow. Why do we need this substance? It is simply vital for the plant. Without it, there can not be a process of photosynthesis, through which nutrients are produced. Organic plant chemicals are usually obtained only as a result of this process. However, some species living in the lower layers of the rainforest do not receive enough light for high-grade photosynthesis, therefore they resort to hunting for small insects, thereby compensating for the lack of organic compounds. These include sundew, a Venus shoe, and so on.

Briefly about the structure of the plant cell

It consists of a plasma membrane, cell wall from cellulose, cytoplasm, which contains organoids, and the nucleus in which DNA is located. The cytoplasm contains such organoids: mitochondria, ribosomes, endoplasmic reticulum, vacuole (in the old cell - one large, in the young - a few small ones), the Golgi complex and plastids (chloroplasts, leukoplasts, chromoplasts). Each of them performs its functions. Mitochondria produce energy, the ribosomes synthesize proteins, the endoplasmic reticulum (reticulum) produces lipids, vacuoles accumulate unnecessary substances, since they can not be led outside due to a solid cell wall, the photosynthesis process takes place in chloroplasts, chromoplasts contain pigments, leukoplasts store spare nutrients Basically, it's starch).

How does photosynthesis occur?

This process is carried out in chloroplasts, which are in the cytoplasm of the cell. These organelles are single-membrane, their structure includes thylakoids - thin plates assembled into granules - piles. It is in them that chlorophyll is contained - that is why the leaves are green. In addition, the chloroplasts contain ribosomes involved in the production of proteins, starch grains, as well as ring DNA molecules, which contain information on the substances that must be synthesized in the cell. In the process of photosynthesis, plants absorb solar energy, water and carbon dioxide, and produce oxygen as a by-product of reactions. Enzymes that help to carry out chemical interactions are directly in the matrix of the chloroplast (the substance filling it).

What do the leaves consist of?

In this organ can be found several types of plant tissue, there are four. This epidermis, mesophyll, conductive tissue (xylem and phloem), as well as mechanical tissues. Photosynthesis occurs precisely in the mesophyll, or parenchyma. You can see the cells of a green leaf under a microscope. This is the upper sphere - the epidermis. Its cells are located close to each other, but in this layer there are pores that allow to absorb carbon dioxide and release oxygen, and also to regulate the water and temperature balance. Parenchyma (mesophyll) is divided into two layers - one of the columnar cells, the other - from spongy cells. The first contains more chloroplasts than in the second. Xylem is represented by vessels through which liquid is supplied from the roots to the leaves, that is upwards, and the phloem consists of screen-like tubes through which water is transported downward. Mechanical fabrics also provide the sheet with rigidity and stability, a certain shape.