Environment

The flow of energy in the food chain is unidirectional. Why?

"The maximum concentration of harmful chemicals accumulates in human beings?" State the phenomenon involved and justify this statement.

Why are green plants called producers?

What is ozone? How does it protect the organisms on the earth?

For two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

a. Both A and R are true, and R is correct explanation of the assertion.

b. Both A and R are true, but R is not the correct explanation of the assertion.

c. A is true, but R is false.

d. A is false, but R is true.

Assertion: Hospital wastes like used syringes, urine bags, etc. can be incinerated.

Reason: Incineration burns the waste at very high temperature and converts it to ashes.

In a food chain comprising frogs, insects, birds and grass, which one of the organisms is likely to have maximum concentration of harmful non-biodegradable chemicals in the body.

Read the following and answer any four questions from: (i) to (v).

In any given ecosystem, all living organisms are linked in a systematic chain with respect to their mode of manufacturing food/ feeding habits. This sequential interlinking of organisms involving transfer of food energy from producers through a series of organisms with repeated eating and being eaten is called the food chain. A food chain may have 3-4 trophic levels.

(i). Which of the following statements regarding food chain is incorrect?

1. It is a single straight pathway through which food energy travels in the ecosystem.
2. It adds adaptability and competitiveness to the organisms.
3. Presence of isolated food chains adds to instability of the ecosystem.
4. Food chain binds up inorganic nutrients of the ecosystem.

(ii). Consider the following food chain.

Grass → A → Frog → Snake → Eagle.

Which of the following can be placed at A?

1. Grasshopper.
2. Rabbit.
3. Phytoplankton.
4. Rat.

(iii). Select the correct food chain.

1. Aquatic plants → Tadpole → Water beetle → Pike → Perch.
2. Grass → Grasshopper → Snake → Frog → Eagle.
3. Grass → Rabbit → Wild cat → Tiger.
4. Zooplankton → Phytoplankton → Small fish → Fish.

(iv). Food chains are sustained by producers and .

1. Herbivores.
2. Carnivores.
3. Omnivores.
4. Decomposers.

(v). Select the incorrect statement.

1. Food chain may terminate at level of herbivore.
2. Food chain is always straight.
3. Food chain may have 3-5 trophic levels.

d. in a food chain, 80 to 90% of potential energy is lost as heat, at each transfer.

Observe the food chain:

Plant (1000 kj) → Goat → Lion

(a) If autotrophs occupying the first trophic level are called producers, what are herbivores called as?

(b) How much energy does the lion get in the above food chain?

A high concentration of harmful chemical is highly injurious, even fatal to higher trophic level organisms. Mention the basis of classifying substances as biodegradable and non-biodegradable. Give two examples of each.

In the food chain Grass → Deer → Lion operating in a forest, what will happen if all the

(a) Lions are removed

(b) Deer are removed.

What are two main components of our environment?

Define

(a) Biomass

(b) Anaerobic degradation.

Which compounds are responsible for the depletion of ozone layer?

What is environment?

Name any two abiotic components of an environment.