6th Class Science The Living Organisms and their Surrounding Abiotic Components

       Introduction

Various types of living and non-living things exist in our environment. The living and non-living things are differentiated according to their characteristic features. However, some features of both living and non-living things are same. For example, every living and non-living things have mass; they both are made up of unit particles etc. But some characteristic features of living and non-living things are different. For example, living things grow. They possess self-intelligence and reproduce their offspring. They adopt themselves according to their surroundings to survive. These features are absent in non-living things. Living organism is also called biotic component and non-living is called abiotic component and both of them are the components of environment. In this chapter, we will study about the different components of our environment.

        Abiotic Component

The non-living components of environment are called abiotic component. These are water, soil, light, air etc. Biotic components are greatly affected by abiotic components.

          Water

This is an important component for all living organism on earth to survive. Life is not possible without water. All living organism require water for different purposes.

Availability of water on the earth's surface varies from place to place. Some part of the earth has huge amount of water, whereas some areas are desert. An important property of water is, it dissolves gases. This property of water helps aquatic animal to live under water. Water takes more time to heat as compare to air and its cooling time is also longer as compare to air. Water is natural resource and its primary source is rain. The most part of the earth (71 %) is covered with water. The forms of water changes on increased and decreased temperature. Water evaporates on heat and changes into water vapor which form cloud for precipitation. Water on the earth follows a cycle is known as the water cycle.

            Light

Light is another important natural resource for the living organisms. Without light, plant cannot make their food. We see the things around us in the presence of light. Living organisms require light for two main purpose. For example, for photosynthesis in plants and vision for animals. The organ, which is responsible for the detection of light is called photoreceptor. Photosensitive pigments sense the incoming beam of light. The photoreceptor in a green plant is called chloroplast. Algae has plastids to sense the light. Rods and cones in the vertebrates work as the photoreceptor. Invertebrates have eyes to sense the light. A beam of light has different colours. Some colours are visible and some are not.

            Air

Air is a mixture of different gases. These gases are Nitrogen, Oxygen, Carbon dioxide, Argon etc. Percent of these gases in air are as follows: Nitrogen = 78 %, Oxygen =21% and remaining 1 % of air contains other gases including carbon dioxide. Air also helps in the dispersal of seeds, pollination and dispersal of pollutants. Strong current of air is called wind. Strong wind causes unstable environment. Air goes upward when heated, whereas, cool air comes downwards. Therefore, the density of air decreases according to an increase in height. Atmosphere of the earth is just up to the few kilometers above the Earth surface.

            Temperature

All living organisms require a specific range of temperature to survive. It is called optimum temperature.

This is another requirement for the living organism. Plant absorbs water and mineral from soil for their nutritional needs. The growth of a plant is totally depend on the types of soil. Some type of soil support the germination and growth of plants but some are not. A mango tree does not grow in desert because the profile of desert soil does not support the growth of the mango tree. Growing same kinds of plants on the same piece of land cause loss of humus and minerals in the soil. Therefore soil quality and fertility is protected by growing different crops on the same piece of land in different session. This is called crops rotation. Excess use of chemical fertilizers causes soil pollution.

             Pollution

The element which causes pollution is called pollutant. Non degradable elements when dumped into soil cause pollution. Excess use of pesticides and DOT is also the causes of soil pollution.

Look at the following picture of types of pollution and pollutants: