A plant may not look lively and active. But inside its millions of microscopic cells, thousands of chemical changes take place as part of the plant’s life processes. Like an animal’s body, a plant’s body has many specialized parts for different jobs. The roots take in water, minerals, salts and other substances from the soil in which the plant grows. The stiff stem holds the main parts of the plant above the surface, away from animals on the ground that might eat it, and above other plants so that the leaves can catch more sunlight.
A plant’s leaves are “light-powered food factories”. They are broad and flat so that as much light as possible falls on them. A green substance called chlorophyll in the leaves catches or absorbs the energy in light. It uses this energy to make a chemical reaction. Water, taken up from the soil, and carbon dioxide, taken in from the air, join together to form sugar, which contains lots of energy in chemical form. The plant then uses the sugar to power its life activities. The process is called photosynthesis —a word meaning “making with light”.
The carbon dioxide for photosynthesis comes from the air. It seeps into the leaf through tiny holes in its lower surface, known as stomata. In addition to sugar, photosynthesis also produces oxygen, which seeps out into the air. Living things including ourselves need oxygen to survive. Plants help to top up its level in the air.
FLOWERS AND POLLEN
A plant’s flower is designed to reproduce—make seeds which grow into new plants. A typical flowering plant has both male and female parts. The male parts make tiny particles, pollen grains, which look like fine yellow powder. Each grain contains a male cell. Pollen is produced in bag-like anthers on stalks, called filaments. The female cells or ovules (eggs) are in the ovary, a fleshy part at the flower’s base. A taller part, called the style, sticks up from this, with the stigma at its top. Pollen must travel from the anthers of one flower to the stigma of another of the same kind, so the male and female cells can join and develop into seeds.
The transfer of pollen is called pollination. Some pollen grains are light and balloon-like and are blown by the wind. Others are sticky and carried by animals. To attract animals, the flower has colourful petals and a strong scent and makes sugary liquid called nectar. When animals come to drink the nectar, the pollen sticks on them. It brushes off at the next flower on to the stigma. A tube grows from the pollen grain down the style to the ovary. The male cell moves down this to join the ovule.
Picture Credit : Google