Facts about How Plants Work, The body of a plant is divided into roots, stem, and leaves. Each of these parts have particular functions, which are nearly the same in all plants.
However, their shape and size varies considerably, depending on such factors as the age of the plant, and where it lives.
The roots have two functions. First, they anchor the plant and help to prevent the soil from being blown away. Second, they take in water and nutrients from the soil. A typical root system begins with a primary root, which is attached to the base of the stem. This divides into a number of secondary roots, which branch repeatedly. The finest root branches, the root hairs, which are only one cell thick, take up water.
Some plants, such as grass, have no primary roots; instead, they have a mass of fibrous roots just below the soil surface. The roots of other plants penetrate deeper. The large primary roots, or tap roots, of thistles and dandelions reach deep into the soil.
The stem also has two functions. First, it supports the leaves and flowers. Small plants have green stems and the support is provided by stiffing cells inside the stem.
large plants develop wood to give extra support and they become covered in bark for protection.
The stems second function is to transport the water up to the leaves and food materials to all the parts of the plant. Water is conducted through a plumbing system of tubular cells called the xylem. Food materials are carried in the tissue called the phloem.
The leave have the most important function of all. Without their work, no life would exist on the planet. This is because leaves make food for the plant, which in turn may be eaten by animals.
Plants make food by using energy from sunlight in a process called photosynthesis. Inside the cells of the leaves are organelles, called chloroplasts. These contain a green pigment called chlorophyll, which is the chemical that enables photosynthesis to take place. It converts light energy into chemical energy. This allows carbon dioxide, which plants take from the air, to react with water ro form sugar (food). At the same time oxygen is formed and released into the air.
The sugar is then either stored as starch or used immediately in a process called respiration (breathing) to create energy for the other processes that take place in the cells of the plant. During respiration, oxygen from the air is used to breakdown the sugar, releasing carbon dioxide and energy.
The gases (oxygen and carbon dioxide) that are taken in and released during respiration enter and leave the leaf through tiny holes in the under-surface, called stomata (or stoma) Stomata also play an important part of the process called transpiration.
Transpiration is the evaporation of water from the stomata. It has two main purposes. First, it helps to keep the plant cool on hot days. The stomata can be opened or closed to control the rate at which water is lost by transpiration. Second, it draws water up from the roots, and water contains minerals that are essential for the plant.