How do Plants Make and Take Their Food?

            It is a well-known fact that trees and plants are also living beings like humans. They need food, water and air for survival. It is interesting to know how they make their food.

Process of Photosynthesis taking place in the leaves of  plants

            Plants derive their food both from the earth and the air. If you minutely observe their roots, you will find that the ends of these roots are like fibers, also called root hairs. They absorb water and minerals and transport them upward to the leaves through the trunk and the branches. It is the leaves which make the food for the plant.

            Leaves have pores that are filled with air. They also have a green coloring matter called chlorophyll. This chlorophyll acts as a catalyst; it uses carbon dioxide from the air and the hydrogen from the water present in the leaves, to make carbohydrates sugars using sunlight as energy. This process is called photosynthesis. In this process, oxygen and water are by-products, which are releases by the leaves of plants.

            Sugar is further converted into starch. From these carbohydrates, the plants can build up complex substances as foods, which it needs for life and growth. These substances include proteins, juices, oils fats, etc. the water fro which the plants take hydrogen for photosynthesis contains dissolved minerals required for building various parts of the plant body. These are compounds of nitrogen, sulphur, phosphorus, sodium, calcium, magnesium, iron, etc.

            Food not immediately needed for growth is stored in the plant including its seeds, fruits, tubers or bulbs. On germinating, the new shoot uses the food that is accumulated in the seed.

How is Oxygen Useful to Us?

            Oxygen is the most important gas in the atmosphere. Without oxygen, there would be no life on the earth. No living being, plants or animals, can survive without it. Do you know what it is, and why is it absolutely essential for us?

            Oxygen is a gaseous element. Two scientists discovered oxygen independently. Carl Scheele, a Swedish Chemist, discovered oxygen in 1772 and Joseph Priestley from England in 1774. It is a colorless, tasteless and odorless gas. The atmosphere around us contains 21% oxygen, 78% nitrogen and other gases about 1%.

            On the earth’s crust, oxygen is found in the forms of oxides of metals. Oxygen can be liquefied at -182.9 degree centigrade under a certain pressure. In the liquid state, it becomes light blue in color. At -218.4 degree centigrade, it is converted into solid state.

            In the laboratory, oxygen is obtained by heating a mixture of potassium chlorate and manganese dioxide. Fro the atmosphere, it is obtained by the fractional distillation of air. The air is compressed to tow hundred times the normal atmospheric pressure and passed through a narrow hole into a chamber. When the pressure is suddenly dropped, the air gets liquefied and is collected in the chamber.

            Nitrogen gas is separated form this by special method ad oxygen is obtained in the liquid state.

            All living beings need oxygen for breathing. Plants also breathe oxygen. They absorb oxygen during the light. During the day, they give off oxygen by the process of photosynthesis.

            Burning oxygen gas along with acetylene gas produces a flame of high temperature called oxyacetylene flame. This flame is used for welding and cutting metals. Liquid oxygen is also used as a fuel in space vehicles.

            Oxygen cylinders are used by patients in hospitals having breathing problems and also by mountaineers and divers in the sea. Oxygen helps in the oxidation of food in our body, which ultimately give us energy. Fuels can burn due to oxygen in the atmosphere.

            We cannot breathe in pure oxygen, as it is harmful for our body cells. Fresh air in essential for us because it contains oxygen and other gases it he correct proportion. It is for this reason that we should keep the doors and windows of our rooms open to let in fresh air.

Sea-divers take oxygen cylinders with them to breathe while in the sea

            This is the reason why one should not cover one’s face while sleeping, as it would prevent him from breathing in fresh air. During winters, one should not close the doors and window and light a fire of coal inside the room to keep warm, because during this process, oxygen is used up and carbon dioxide is released, which is very harmful.