Tanubhrt.This.Side

We have heard—————————– these cycles.

The environment is a very common word which is used in television, newspapers and by people around us. Elders tell us it is not the way it used to be, some say environment should be healthy. There are so many globals submits discussing on the environment. In the biogeochemical cycles, the nutrients like nitrogen, carbon, oxygen, and water are changed.

What happens when we add our waste to the environment?

In our daily ——————– questions?

The food that we eat is digested by various enzymes in our body. Each enzyme is specific in nature and specific enzymes are needed to break down certain substances. It is because of the characteristics of the enzymes that human-made materials like plastics are not broken down by the action of bacteria or other saprophytes. Plastics and other materials are acted on by heat but because of the conditions found in our environment, they persist for a long time.

[Substances that are  ——————————————————– ecosystem.]

Substances which can be broken down by the biological processes are called biodegradable substances. Those which cannot be broken down by the biological process are called non-biodegradable process. These substances persist in the environment and harm the various members of the ecosystem.

Ecosystem – What are its components?

[All organisms such as ————————————————————– soil and minerals.]

All the living organisms interact with each other along with the physical surroundings. An ecosystem is actually a group of all the biotic organisms along with the non-biotic organisms like temperature, rainfall, wind etc.

[For example ——————————————————————- ecosystems].

Thee are two types of ecosystems –

1. natural – forest, ponds, lakes
2. man-made – garden, crop fields

[We have seen —————————————— producers.]

There are three types of organisms –

1. producers – those which produce food by themselves.
2. consumers – they either feed on producers or other consumers
3. decomposers

[Imagine ———————————– are not there?]

Decomposers are those that break down the dead remains and waste product of organisms. They break down the complex organic substances to simple organic substances that go into the soil and get used by the plants.

FOOD CHAINS AND WEBS

[In Activity 15.4 —————— food chain.]

The organisms take part in various biotic levels to form a food chain.

[Each step ————————— tropic levels.]

Each step in the food chain forms a tropic level. The autotrophs or the producers are at the first level. They are responsible for fixing up the solar energy and making it available for the heterotrophs or the consumers. The herbivores come at the 2nd level of the food chain, the small carnivores at 3rd and the large ones at the fourth.

[We know that the ——————————————————————- has been found.]

The food we eat provides us with energy to do work. The interactive among the various components of the environment involves the flow of energy from one component to another. Autotrophs capture the energy present in sunlight and convert it into chemical energy. This energy supports the activities of all the living organisms. When one form of energy is changed to another, some form of energy can be used again.

[The flow of energy —————————————————- food web.]

Following details have been found on studying the flow of energy –

1. Green plants in the terrestrial ecosystem capture 1% of the energy from the sun and convert it into food energy.
2. A lot of energy is lost to the environment when green plants are eaten by primary consumers. Some amoung goes into digestion some in doing work while rest towards growth and reproduction. Only 10% of it is present in the body which goes to the next level of consumers.
3. Only 10% of organic matter is present at each stage and reaches to the next level of consumers.
4. The reason for only 4 levels of food chains is that there is a huge loss of energy at each stage. After the 4th very little usable energy remains.
5. There are generally a greater number of individuals at lower trophic level.
6. Each organism is generally eaten by 2 or more kinds of the organism which in turn are eaten by other. SO, in our environment, it is actually a food web.

[From the energy, ——————————————————– the previous level.]

The energy flow is unidirectional. The energy that is captured by autotrophs does not revert back to solar input and energy which goes to herbivores does not come back to autotrophs.

[Another interesting aspect ———————————————— other means.]

When pesticide are thrown into the crops, they get washed down into the soil or into water bodies. These are taken up by plants from soil and from water by aquatic animals. These are accumulated at each trophic level. since human beings are at the highest, they are accumulated maximum by human bodies. This is called biological magnification. Our food grains as wheat and rice, vegetables and fruits contain pesticides which cannot be removed.

How do our activities affect the environment?

[Ozone ————————- human beings.]

ozone is formed by three atoms of oxygen and even though it seems poisonous to humans, out there in the atmosphere, it protects earth from UV radiations. UV radiations can cause skin cancer in human beings.

[Ozone ——————- showed.]

Ozone is formed by UV radiations acting on O2 molecule. Radiations split the oxygen to form separate oxygens. These when combined with O2 form ozone.

[The amount of ozone ———————————————– 1986 levels.]

Ozone started depleting in the 1980s because of use of CFCs in refrigerants and fire extinguishers. In 1987, an agreement was made to freeze CFCs produced at 1986 levels.

Managing the Garbage we produce

[Improvements ————————————————- environment.]

Improvements in life have resulted in greater amounts of waste material generation. Changes in attitude and packaging have resulted in much of our waste becoming non-biodegradable.

NCERTNotes