Plants get their food from the sun light that is given off by the sun and the green leaves on the plants can absorb the sun light, the Carbon Dioxide and water. .
What's in a breath?.
Air consists of a mixture of gases that widen from the earth's surface to outer space. The earth's gravity holds the air in place around the earth. The gases of the air move about freely among one another. As sunlight passes through the earth's atmosphere, it strikes molecules of the gases. The molecules scatter the sunlight, which is a mixture of all colours, in every direction. The principal gases of the air are nitrogen and oxygen. Other gases include argon, water vapour, carbon dioxide, neon, helium, krypton, hydrogen, xenon, and ozone. The water vapour in the air is water in the form of an invisible gas. Nitrogen makes up about 78 per cent of dry air--that is, air from which all water vapour has been removed. Oxygen accounts for about 21 per cent of dry air. The remaining 1 per cent consists chiefly of argon, with only extremely small amounts of the other gases important. When we breathe, we take in oxygen from the air and give out carbon dioxide. Air also contains trace amounts of ammonia and hydrogen sulphide. These are important for maintaining life.
What is respiration?.
Respiration is the process by which human beings and other living things obtain and use oxygen. Except for certain micro-organisms, all living things require oxygen to live. Respiration also involves the elimination of carbon dioxide, a gas produced when cells use oxygen. Respiration may be divided into three phases: (1) external respiration, (2) internal respiration, and (3) cellular respiration. In external respiration, or breathing, a plant or animal takes in oxygen from its environment and releases carbon dioxide. In internal respiration, oxygen is carried to the cells of the organism and carbon dioxide is carried away from them.
