What is a Living thing? What are the Living Things Around Us?

Microbiology, one of the Biology Topics, explores microorganisms and their effects.

Living and Non Living Things – Characteristics and Examples

There are different types of surroundings (or areas) in different parts of our country. The mountains of Himalayas are very cold places. The mountain areas have many kinds of trees like oaks, pines and deodars (which are very different from the trees found on the plains). The mountains have also unique animals like yak and mountain goats. The desert areas like that in Rajasthan are very hot and dry. The desert areas have many special type of plants such as cactus and animals like camels.

The coastal areas (sea-shore areas) are very humid and have an entirely different kind of trees such as palm trees. And the sea-water contains yet another kind of animals like fish and crabs, etc. From this discussion we conclude that the surroundings like the mountains, desert and sea-shore are so different from one another in climate but all of them have many living things (plants and animals) in them. Moreover, the kind of living things (plants and animals) found in each of these surroundings (or regions) are very different from the plants and animals of the other surroundings.

If we look inside our home, there may be a spider or a lizard on the wall. Rats and cockroaches can also be seen in a home. The garden in our neighbourhood has many types of plants. It may also have sparrows, crows, pigeons and squirrels. Dogs and cats are also found in most of the places. Thus, living things are found everywhere. In fact, there is no place on earth where living things do not exist. It has been found by scientists that tiny living organisms exist even in the openings of the volcanoes ! In this chapter, we will first discuss living things and their characteristics, and then we will describe their habitat (living places) and adaptations.

There is a large variety of things around us. Some of these are living things whereas others are non-living things. These are discussed below.

Those things which need food, water and air for their survival are called living things. All the animals need food, water and air to survive or live, so all the animals (including human beings) are living things.

Thus, a boy, a girl, cat, dog, monkey, cow, horse, goat, tiger, lion, birds (such as sparrow, crow, pigeon, peacock, etc.), frog, fish, hen, snake, snail, cockroach, lizard, squirrel, ant, insect, rat, earthworm, etc., are all living things (because they are all animals). All the plants also need food (which they make themselves by photosynthesis), water and air, so all the plants are also living things. Thus, rose plant, sunflower plant, neem tree, mango tree, creepers (plants having thin stems which spread on the ground. Example: money plant), climbers (plants having thin stems which climb on neighbouring objects. Example: bitter gourd or karela), grass, mushroom, water hyacinth, cactus, algae, etc., are all living things (because they are all plants). From this discussion we conclude that all the plants and animals are living things.

Those things which do not need food, water and air for their survival are called non-living things. For example, a table or chair do not need food, water or air to survive, so a table and a chair are non-living things. Some more examples of non-living things around us are pen, pencil, coin, toys, electric bulb, clothes, mug, bed, table lamp, soil, stone, rock, sand, salt, water, air, utensils, sewing machine, radio set, TV set, plough, bicycle, car, bus, train, ship, boat, aeroplane, dry leaves, clouds and moon.

The living things are called organisms. Thus, all the plants and animals are organisms. The study of living things (or organisms) is called biology. We will now describe the various characteristics of the living things in detail. This will help us in understanding the differences between living and non-living things more clearly.

Characteristics Of Living Things

All the living things have some common characteristics (or features) which make them different from non-living things. The characteristics of living things are given below:

1. Living things need food, air and water.
2. Living things can grow.
3. Living things can move by themselves.
4. Living things can respond to stimuli (or changes around them). They are sensitive.
5. Living things respire (release energy from food).
6. Living things excrete (get rid of waste materials from their body).
7. Living things can reproduce. They can have young ones.
8. Living things have a definite life-span (after which they die).

We will now discuss the characteristics of living things in some detail along with examples.

Food

All the living things (plants and animals) need food to stay alive. They also need air and water. Without food, air and water, living things will die. The plants make their own food by the process of photosynthesis. But animals obtain their food from plants or other animals. Figure shows an animal (cow) obtaining its food from plants. Food gives the material for growth, and energy to carry out various life processes taking place inside the living things. Non-living things do not need food, air and water. For example, a rock is a non-living thing which does not need food, air and water for its existence.

Growth

Growth means increase in size. All the living things can grow. The young ones of all the living things (plants and animals) grow and become bigger in size with the passing of time. For example, a seed grows and becomes a plant [see Figure (a)], Similarly, a baby grows and becomes an adult [see Figure (b)].

When living things grow, they become taller and bigger on their own. Here are some more examples of the growth in living things. A small puppy grows and becomes a dog ; a kitten grows and becomes a cat ; a chicken hatched from an egg grows and becomes a hen or cock ; and a small plant grows and becomes a big tree.

All the living things grow from a ‘single cell’. The growth in living things is from within the living thing (or living organism). The growth in living things occurs by the division of the single cell to form a large number of cells. As a living thing grows, the number of cells in its body go on increasing. Non-living things do not grow. For example, a rock is a non-living thing which does not grow and become bigger in size. Iri some cases, however, non-living things also appear to grow.

For example, a cloud in the sky appears to grow and become bigger. But the growth of a cloud is different from that of a living thing because it occurs from outside by the accumulation of more and more water vapours. So, even though a cloud appears to grow and become bigger in size, it cannot be said to be a living thing.

Movement

Movement is one of the most important signs of life in an organism. All the living things move by themselves (without any external help). The animals and plants move in different ways. Animals can move from one place to another or they can move their body parts. For example, a frog moves when it jumps into a pond [see Figure (a)]. A bird moves when it flies in the sky, we move when we go to school

and a fish moves when it swims in water. We move our hands when we clap and a dog can wag its tail. In general, animals move from one place to another for food, protection from enemies and protection from natural disasters like floods and forest fires.

The plants are fixed in the soil at a place, so they cannot move like animals from place to place. The plants can move only parts of their body such as leaves, flowers, shoots and roots. The plant parts move towards a stimulus such as sunlight, water or gravity. For example, the leaves and flower of a sunflower plant move by bending towards the sun to face the sunlight [see Figure (b)]. Here sunlight is the stimulus towards which the leaves and flowers move (or bend).

The movement of a part of the plant towards light is called phototropic movement. Some flowers show movement by opening or closing their petals. For example, the flowers of dandelion plant open up in the morning (in response to sunlight), and close in the evening when the light fades.

Non-living things cannot move by themselves. For example, a rock is a non-living thing which cannot move by itself from one place to another. In some cases, however, non-living things also appear to move but the movement of non-living things is different from those of living things. In living things, movement is caused by internal factors such as muscles pulling on bones, contraction and relaxation of only muscles or by the action of chemicals called hormones (as in plants). It is not so in the case of movement of non-living things. The movement in non-living things is caused by an external force such as the push of our hand, blowing air or wind, flowing water or hot and compressed gases.

For example, the cloud is a non-living thing which appears to move in the sky. The movement of clouds is caused by the force of blowing air or wind. The logs of wood move in a river by the force of flowing water. And a car or bus moves by the force of hot and compressed gases produced by the burning of petrol or diesel in its engine. An example of a non-living thing which appears to show two characteristics of living things is a cloud. This is because, just like living things, a cloud grows in size and it also shows movement.