Abiotic components

• The word 'abiotic' means 'non-living'.
• Sunlight, air, water, soil, and temperature are some examples of abiotic components of the environment.
• Even though these components are themselves non-living, they do have an effect on the living organisms, that is, the biotic components of the environment.

Light:

• The source of light on Earth is sunlight.
• Plants use sunlight to prepare their food.
• Plants, in turn, are a source of food for animals.
• Thus, the sun is the prime source of energy on Earth.

Forest floor

• Most plants need sunlight for proper growth.
• In dense forests, large trees block a lot of sunlight.
• Few plants grow on the forest floor as little sunlight is able to reach there.

Plants in water bodies

• Similarly, in water bodies lots of plants grow on the water surface, as they receive more sunlight.
• With the increase in depth, penetration of light decreases because of suspended materials such as mud, sand, and silt.
• Therefore, fewer plants grow on the floor of these water bodies.

Temperature:

• Temperature is a measure that tells us how hot something is.
• Earth is the only known planet that has a temperature suitable for existence of life.

• Even on Earth, the temperature is not uniform all around.
• It is much hotter near the equator, while places near the poles are very cold.
• Temperature affects the distribution of plants and animals around the planet.

Warm and cold blooded animals:

• Animals whose body temperature changes with the outside temperature are called cold-blooded animals.

• Most reptiles, insects, and amphibians are cold-blooded.
• Animals whose body temperature does not change with the outside temperature are called warm-blooded animals.

• Most mammals and birds are warm-blooded.
• Warm-blooded animals can survive in areas having extreme temperatures (areas that are too hot or too cold), such as the deserts and the Arctic regions.
• Here, cold-blooded animals would have difficulty in surviving.
• Plants and animals have developed various ways to survive in regions having extreme temperatures.

Air:

• Oxygen and carbon dioxide present in air are very important for the survival of organisms.
• Both plants and animals need oxygen for respiration.

Green plants release oxygen gas

• Animals and human beings release carbon dioxide during respiration, which is used by green plants for photosynthesis.
• Carbon dioxide is also released by burning of fuels in vehicles and factories. Plants, in turn, release oxygen into the environment.

The balance of carbon dioxide and oxygen in the atmosphere

• Thus, green plants play a very important role in maintaining the balance of oxygen and carbon dioxide in the environment.
• Moving air, called wind is useful in many ways:

1. Wind helps in pollination, which is an important step in the reproduction of plants.

Pollination in plants

2. Wind helps in the dispersal of several fruits and seeds, for example, hiptage and dandelion.
3. Wind blows away fine particles of dust suspended in the air. If these particles are not blown away by wind, they combine with smoke and water vapour and remain suspended in the air as smog (smoke + fog). Smog is very harmful as it may cause asthma and other respiratory diseases.

Water:

• Water is very important for living organisms to live.
• Plants absorb water through their roots, which is then transported to different plant parts.
• Water is essential for carrying out photosynthesis in plants.
• Water also plays an important role in the human body.
• Blood, which transports substances within the human body, is largely composed of water.

Blood in human body

• In fact, 70% of the human body consists of water.
• Water dissolves vital gases like oxygen and carbon dioxide and allows sunlight to penetrate water bodies.
• This enables living things to survive under water in water bodies.

Soil:

• Soil is the uppermost layer of the Earth's crust.
• It has four sub-layers - topsoil, subsoil, parent material, and bedrock.

Sub layers of soil

• It is in the topsoil that plants grow.
• Soil is rich in minerals such as magnesium, potassium, and phosphorus.

Diagrammatic representation of topsoil

• Without soil there would be no plants and thus, no food for us.
• Plants grow well in loosely packed soil as it allows their roots to grow deeper and also makes it easier for them to absorb water and nutrients, which is why the farmers plough the field before sowing seeds.
• Animals like earthworm and snail also make the soil loose by turning it.