Science [2 Mark Questions]

Following are four activities in daily life which are eco-friendly:

1. Walking for short distance commute: This activity helps in preventing air pollution.
2. Using bicycle for going to school: This activity prevents air pollution which can happen when we use car for this purpose.
3. Reusing water for mopping floor: This helps in conservation of water. Water which is collected after washing clothes and vegetables should be used for mopping the floor.
4. Using public transport for long distance commute: In a mode of public transport, many people can travel together. This helps in reducing the number of cars and bikes on roads. Thus, it helps in preventing air pollution.

An improper disposal of wastes means addition of pollutants into environment - air, water, soil. They will harm living beings, human assets and human beings. For example, passage of sewage into water body will cause eutrophication, stink, development of sludge, killing of animals and source of water borne pathogens.

Substances that are broken down into simpler substances by biological processes are said to be biodegradable. Examples, wood, paper.
Substances that cannot be broken down into simpler ones by biological processes are said to be non-biodegradable. Examples, plastic, DDT.

Biodegradable	Non-biodegradable
They are decomposed by microbes.	They cannot be decomposed.
They are environment friendly.	They are not environment friendly.
Examples: fruit peels, jute bags, stale food.	Examples: plastic bags, glass, aluminium cans.

The microorganisms, comprising bacteria and fungi, break-down the dead remains and waste products of organisms. These microorganisms are the decomposers as they break-down the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants.
This decomposer acts as cleaning agents of environment by decomposing the dead bodies of plants and animals and help in recycling of materials, replenishment of soil’s nutrients etc.
Following are the consequence of their absence in an ecosystem:
Dead bodies and plants would keep lying and their number will keep on increasing. Their accumulation will cause land and water pollution. Also, substances from which these bodies are made such as soil and water will never be recycled.