Samacheer Class 6 Science - Our Environment

True.
True.
False – Human and animal wastes are examples of bio-degradable waste.
False – Excess use of pesticides leads to land pollution.
False – In schools waste management rules say that we should separate waste in three categories.

The term ‘Biodegradable’ is used for those things that can be easily decomposed by natural agents like water, oxygen, ultraviolet rays of the sun, microorganisms, etc. (Eg.) Vegetable and fruit peel leftover food, grass, leaves, and twigs.

Do not pour leftover oil, old medicines or waste down the drain or into the toilet.
Reduce the use of chemical pesticides and fertilizers to grow crops.
Reduce the use of detergents and bleach to wash clothes.
Do not litter or dump waste always use a waste bin.

Learning about the food chain help us to understand the feeding relationship and interaction between organisms in any ecosystem.
It also help us to appreciate the energy flow and nutrient circulation in an ecosystem. This enable us to understand the movement of toxic substances and their impacts.

Examples of how we can Avoid waste:-
Avoid buying packaged foods. Refuse to buy ‘use-and-throw’ plastic products.
Examples of how we can reduce waste:-
Write on both sides of paper
Share newspaper and magazines with others.

Noise pollution affects the environment. We all like a quiet and peaceful place since unpleasant or loud sounds disturb us.
Loud music, the sounds of motor vehicles, fireworks and machines cause noise pollution. Continuous noise disturbs our sleep and does not let us study.
Noise pollution has been directly linked to stress and health impacts such as high blood pressure and hearing loss.
Loud noise or even loud music can damage our ears. Noise pollution also disturbs animals.
Birds have to communicate (talk) louder so that, they can hear each other in noisy areas.
Even underwater noise pollution from ships can make whales lose their way as they use sounds to navigate.
Reduce noise pollution :
Turn off your electronics when you do not use them.
Avoid fireworks.
Speak, do not shout.
Remind drivers not to use the horn too much.
Lower the volume when you watch TV (or) listen to music.

If an organism is removed from the food chain,
The food chain will fall apart.
The ecosystem will become imbalanced and collapse.
For example, Consider a food chain: Plants → grasshoppers → frogs → snakes → hawks.
If frogs were to die off in this chain, (due to disease/pollutants), then, there will be an increase in the number of grasshoppers. This will cause a major problem.

The substances consist of plastic materials, metal scraps, aluminium cans, and bottles which cannot be broken down or decomposed into the soil by natural agents are labelled as non-biodegradable.
When it rains, some of the water never reaches the ground as it collects in the plastic garbage at the dump.
Little pools of water let mosquitoes breed and they can spread unwanted diseases like dengue and malaria.
Aedes aegypti is the vector responsible for dengue transmission.
It breeds in solid waste mud pots and other junk materials.
We must know mosquitoes tend to breed in places which are dirty.

Turn off your electronics when we do not use them.
Lower the volume when we watch TV or listen to music.
Remind drivers not to use the horn too much.
Avoid fireworks.
Speak do not shout.

Natural Ecosystem:
Ecosystem Originated without human intervention
Ex: Sea, River, Lake, Forest
Artificial Ecosystem:
Ecosystem Originated by human
Ex: Paddy field, garden, aquarium

The microorganisms that break down tissues will also cause bones to decompose in a suitable aerated peaty soil.
In warm damp environments, bacteria and fungi attack the protein in the skeleton and it will break down in a matter of a decade or so.
But in a dry climate, it could take thousands of years
So bones do decay at a slower rate than other types of organic material and tissue.

Not all fabrics are safely biodegradable as they are made with artificial and chemical components.
It depends on what fibres or fabric is made from.
And also the more chemicals used the longer it takes to biodegrade.
Polyester has been introduced since 1951 created not by the textile industry but by American Chemical Company Dupont went on sale.
Polyester is a polymer or a long chain of repeating molecular units.
That basically means that our clothes are increasingly made of plastic.
In theory cotton, silk hemp is biodegradable and polyester is not.