Air

Composition Of Air In Atmosphere

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Composition Of Air In Atmosphere

A thick blanket of air, called the atmosphere, surrounds our Earth. Air is also present in things which seem to be empty. It contains mainly nitrogen, and oxygen. It also contains carbon dioxide, noble gases, water vapour, dust particles, and traces of other gases. The composition of air is shown in Figure. Let us now verify the presence of some constituents of air.

Composition Of Air In Atmosphere 1
Composition of air

Nitrogen and Oxygen
Air contains about 78% nitrogen and 21% oxygen. Oxygen in air supports burning whereas nitrogen does not. Let us prove this by doing a simple activity.

Carbon Dioxide
Air contains about 0.03% of carbon dioxide. Plants and animals take in oxygen and give out carbon dioxide during respiration. When you burn something, carbon dioxide is also produced.

Water Vapour
Air contains varying amounts of water vapour depending on the weather of a place. You have learnt about the water cycle. The sun heats up the water in seas and oceans. This water evaporates and forms water vapour. You can verify the presence of water vapour in air by observing wet clothes drying on a clothesline. Where does the water from these wet clothes disappear? The water from the wet clothes forms water vapour and mixes with the air.

Composition Of Air In Atmosphere 2
Air contains water vapour

Dust and Smoke
Have you seen sun rays entering a dark room? Have you noticed tiny particles in the rays? These are dust particles. Air contains dust. Air also contains smoke released from factories and vehicles.

Composition Of Air In Atmosphere 3
Air contains dust and smoke

Activity

Aim: To show the presence of oxygen and nitrogen in air (adult supervision required)Activity
Materials needed: Big bowl, water, a candle, a matchbox, and a glass
Method:

    1. Take a candle and place it in a big bowl.
    2. Now fill the bowl with some water.
    3. Light the candle and cover it with an inverted glass.

Composition Of Air In Atmosphere 4

Observation: The candle keeps burning for some time. After some time, the candle blows out. The water level of the bowl also decreases after the candle goes out.
Conclusion: Oxygen helps in burning. When the oxygen inside the glass is used up, the candle is put out. Also the space occupied by oxygen inside the inverted glass becomes empty and water rises up to occupy this space. The major part of air left is nitrogen which does not support burning.

Activity

Aim: To show the presence of air in a bottle that looks empty.

Materials needed: An empty plastic/glass bottle and a tub of water.
Method:

  1. Take an empty bottle.
  2. Open its cap.
  3. Now immerse the bottle in water with the open end inside the water. Does water rush inside the bottle? Now tilt the bottle. What do you see? Does water rush inside the bottle?
    Composition Of Air In Atmosphere 5

Observation: You will see bubbles at the mouth of the bottle. This is because there was air inside the bottle which comes out on tilting the bottle (as it finds an opening). Before tilting, water does not enter the bottle as all the space inside the bottle is taken up by air. But as you tilt the bottle, air rushes out from the opening and water rushes in to fill the empty space.
Conclusion: Air occupies space.

How Air Supports Life In Plants And Animals

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Air Supports Life In Plants And Animals

We all need air to survive. Air contains oxygen and carbon dioxide useful to plants and animals. Plants use carbon dioxide of the air to make their own food by a process called photosynthesis. Let us see how air supports life in plants and animals.

In Plants
Plants have tiny pores called stomata, found on the underside of a leaf. Air containing carbon dioxide and oxygen enters the plant through these openings where it gets used in photosynthesis and respiration.
How Air Supports Life In Plants And Animals 1In Animals
All animals need to respire, be it a cockroach, a fish, or an elephant. It is just that they use different organs and mechanisms for respiration.
Sometimes, we wrongly use the terms breathing and respiration interchangeably. Breathing is a physical act of taking in oxygen and giving out carbon dioxide, whereas respiration is a chemical process by which glucose in the body breaks down to give energy.

How Air Supports Life In Plants And Animals 2In Aquatic Animals and Plants
Most aquatic animals like fish, tadpole, crab, and shrimp have special organs for respiration called gills. Gills help to take in oxygen and give out carbon dioxide. Some aquatic animals like dolphin and whale come to the surface of the water regularly to take in air, since they breathe with the help of lungs. Aquatic plants like Hydrilla also breathe in oxygen dissolved in water through their stomata.

How Air Supports Life In Plants And Animals 3In Amphibians
Amphibians like frog, newt, and salamander need breathing systems for both air and water. Crocodile and alligator swim through water with part of their snout above the water surface to breathe easily through nostrils.
How Air Supports Life In Plants And Animals 4In Birds
Birds have an efficient respiratory system as they need high levels of oxygen during flight. Birds have a pair of lungs with air sacs that remain open all the time, so that air can easily pass through them.

How Air Supports Life In Plants And Animals 5In Mammals
Most mammals breathe with the help of lungs. They take in oxygen and give out carbon dioxide.

BALANCE OF OXYGEN AND CARBON DIOXIDE IN THE AIR
The balance of oxygen and carbon dioxide in the atmosphere is maintained through respiration in plants and animals and by photosynthesis in plants. Plants produce oxygen during photosynthesis and utilize oxygen during respiration. They produce much more oxygen during photosynthesis than they consume, during respiration This is how the oxygen consumed by plants and to a large extent by animals is replenished in the air through photosynthesis.

Activity

Aim: To show the presence of air in soil
Materials needed: A jar, some soil, and a jug of water
Method:
1. Take some soil in a jar.
2. Pour water into it. Can you see bubbles coming out? What does it suggest?
Observation: The bubbles show the presence of air in soil.
Conclusion: Animals living inside the soil take in air present in soil.

What is an Abiotic Component

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What is an Abiotic Component

Abiotic Components
The word ‘abiotic’ means ‘non-living’. Light, air, water, soil, and temperature are some examples of abiotic components of the environment. Even though these components are themselves non-living, they have an effect on the living organisms, i.e., the biotic components of the environment.

Light
Plants use light to prepare their food.

Temperature
Temperature is a measure that tells us how hot or cold something is. Earth is the only known planet that has a temperature suitable for life to exist. Even on Earth, the temperature is not uniform all around. It is very hot near the equator, while places near the poles are very cold. Temperature affects the distribution of plants and animals around the planet.

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 like the desert and the Arctic region. Here, cold-blooded animals would have difficulty in surviving. Polar bear is adapted to survive in the harsh temperatures of the Arctic.

What is an Abiotic Component 1
Polar Bear

Air
Oxygen and carbon dioxide present in air are very important for the survival of organisms. Both plants and animals need oxygen for respiration. 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. Thus, green plants play a very important role in maintaining the balance of oxygen and carbon dioxide in the environment. Moving air or wind also helps in the reproduction of plants through pollination and dispersal of certain fruits and seeds.

What is an Abiotic Component 2
The balance of oxygen and carbon dioxide in atmosphere

Water
Water is very important for living organisms. Plants absorb water through their roots, which is then transported to different plant parts. Water is essential for carrying out photosynthesis in plants.
It also plays an important role in the human body. Blood, which transports substances within the human body, is largely composed of water. In fact, 70% of the human body consists of water.
Water dissolves vital gases like oxygen and carbon dioxide. This enables living beings to survive in water.

What is an Abiotic Component 3
Water is essential for living organisms

Soil
Soil is the uppermost layer of the Earth’s crust. It has four sub-layers – topsoil, subsoil, parent material, and the bedrock. It is in the topsoil that plants grow.
Soil is very rich in minerals like magnesium, potassium, and phosphorus. 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. This is why farmers plough their fields before sowing seeds.

What is an Abiotic Component 4
Sub layers of soil

Animals like earthworm and snail also make the soil loose by turning it.

Habitat
Thus in nature, biotic and abiotic components are closely interrelated. Biotic components (organisms) interact with one another too. A group of interdependent organisms that live in the same region and interact with one anotherform a biotic community. A biotic community includes plants, animals, and microorganisms.