Growth and Development of Plants
You must have seen beautiful plants growing in pots in a garden. The plant grows while the pot does not. As a rule living things grow, but non-living things do not. Some non- living things however appear to grow. For example, if you suspend a crystal of alum or common salt in its saturated solution you find an increase in the size of the crystal due to the deposition of more alum or common salt around it. But if you suspend the crystal in its solvent, water, you will find that the crystal becomes smaller and may ultimately disappear. If you repeat the experiments with the plant, you will observe that the plant does not decrease or disappear. Evidently the growth of the plant takes place by the addition of more living matter.
A plant or animal usually starts its existence as a minute cell, not more than a fraction of a millimetre in diameter and grows to enormous size. The process by which a single cell becomes a full-fledged individual is known as development. It involves not only an increase in size but an increase in complexity as well. Growth and development are important characteristics of living beings. Growth involves an increase in the size of cells or an increase in the number of cells, or both. It occurs when the organism takes in food from the environment, for example, food and organises it into its own structures. A cat can live on the same food that we eat. The cat however, converts the food into its own tissues becoming a bigger cat whereas we transform the food we eat into our tissues and grow as humans. In each instance the characteristic pattern into which the nutrients are assembled is governed by the information encoded in the genes.