Question

Q.8. Give reasons to justify the following:
1) The existence of decomposers is essential in a biosphere.
i) Flow of energy in a food chain is unidirectional.
m) Damage to the ozone layer is a cause for concern.







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Answer 1

Answer :-

i.) The existence of decomposers in a biosphere is essential - Decomposers usually are regarded as 'cleaners of environment'. The clean up the environment by decomposing organic and decomposable waste. They are essential because of the following reasons :-

• The help to clean the environment by consuming up organic and biodegradable waste.
• After decomposing, they produce fertile manure for the plants in that surrounding.
• Even, certain types of decomposers, like cynobacteria or blue - green algae helps to make soil fertile by fixing up nitrogen.
• Decomposers, act as link between living and dead environment. That is, according to the nature cycle, when any organism dies, on feeding on them, decomposers help other species to grow at those places.

ii) Flow of energy in a food chain is Unidirectional - In food chain, energy travels in a single direction that is, if a organism consumes other, its energy goes to higher level and further on. It again does not come back to the lower level. If so happens, the energy cycle won't exist in environment and anyone can consume any organism. According to Landermann, a 10% cycle exists in nature that determines the flow of energy. Let us see this, by an example :-

Plant => Rabbit => Snake => Eagle

Here we see, the energy stored in plant's body is took over by rabbit and from it to further on snake and eagle . This shows that energy travels in one direction from lower to higher trophic level. If energy goes back, then of course plant can eat rabbit but which is not possible.

iii) Damage to Ozone layer is a cause for concern - Absolutely true. Nowadays the ozone layer has been degraded by the use of excessive harmful CFCs (Chlorofluorocarbons) which in presence of Ozone molecule forms a hole and patch in it by constant thinning of layer. This is also known as Ozone Hole. Its a matter of great concern because :-

• Ozone layer protects us from harmful ultraviolet radiations of sunlight by making it reflect back.
• This radiation causes skin cancer, lowering in immunity, rashes, lower eyesight, cancer, etc.
• Even, this radiation has harmful effects on nature as well. It causes dryness and wilting of plants. Also it makes soil infertile.
• Ultraviolet Rays, cause harm to the monuments by degrading its bases through its deep penetrating nature.

★ More to know :-

• Decomposers - These are organisms that consume and get nutrition from dead and decay matter.

• UV Rays - Ultraviolet Rays, regarded as UV are the harmful radiations emitted along with sunlight that is harmful for health and environment.

• Landermann's 10% Law - This law states that, 10% of the existing energy in a trophic level is the basis of the energy that goes to the higher trophic level.

• Ozone Layer - It is a layer, better to say a shield, over the atmosphere formed by Ozone molecule (O3), that prevents the entry of harmful UV rays from sun.

• Trophic Level - It is a level of existence of one organism, where organisms of similar type live together and perform their daily routine. For e.g.,grass level is considered the first trophic level.

Answer 2

Answer:

Step-by-step explanation:

ANSWER:-

1) The existence of decomposers is essential in a biosphere.

This is because:-

• Decomposers are the organisms and microorganisms that help to decompose waste and biodegradable matter.
• Decomposers are essential as without them we would see heaps of waste everywhere.
• For Example:-
• If you see  , we need to clean an aquarium on daily basis but not ponds and lakes. This is because aquarium lacks decomposers.

i) Flow of energy in a food chain is unidirectional.

This is because:-

• The flow of energy starts from Autotrophs, and the plants derive their energy from the Sun.
• We see that the food chain is upto 3 to 4 stages.
• This is because maximum amount of energy is lost from 1st to 2nd level, and other in metabolic process , so for next progression energy levels slow down. Hence it does not revert back also.

m) Damage to the ozone layer is a cause for concern.

This is because:-

• Ozone layer is protective layer. Its formula is $\sf{O_3}$
• Oxygen is a survival gas for many organisms but Ozone is a deadly poison.
• It protects us from UV  ie UltraViolet Rays. These rays are known to cause skin cancer.
• So, the Ozone layer is being degraded by use of CFC's , hence it is a need to look after this issue.