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#### Question A:

Solve the following crossword puzzle:
Figure

Across
3. Growing trees on a large scale
4. Branched part of a tree above the stem

Down
1. It refers to the diverse forms of life on the earth
2. Roof formed by the branches of tall trees over other small plants
5. An international organization

#### Question B.1:

The first link in all food chains is
(a) herbivores
(b) carnivores
(c) green plants
(d) all of these

(c) green plants
The first link in all food chains are green plants.

#### Question B.2:

Which of the following is a producer?
(a) herbivore
(b) green plant
(c) carnivore
(d) decomposer

(b) green plant

Green plants produce food using water and carbon dioxide, in the presence of sunlight. As a result, green plants are known as producers.

#### Question B.3:

Which of the following is not a forest product?
(a) wood
(b) honey
(c) nylon
(d) gum

(c) nylon
Nylon is a synthetic fibre and is not a forest product.

#### Question B.4:

Which of the following is a decomposer?
(a) tulsi
(b) snake
(c) fungi
(d) lion

(c) fungi
Fungi are decomposers. They decompose dead plants and animals and return nutrients to the soil.

#### Question B.5:

The lowest layer in the forest is occupied by
(a) trees
(b) shrubs
(c) herbs
(d) all of these

(c) herbs
Herbs occupy the lowest layer in a forest.

#### Question C:

Fill in the blanks:
1. Humus is rich in ........................... .
2. The branched part of the trees above the stem is called ........................... .
3. Plants are called ........................... in a food chain.
4. Destruction of forests leads to ........................... erosion.
5. Forests occupy ........................... per cent of the geographical area in India.

1. Humus is rich in nutrients.
2. The branched part of the trees above the stem is called crown.
3. Plants are called producers in a food chain.
4. Destruction of forests leads to soil erosion.
5. Forests occupy 21 per cent of the geographical area in India.

#### Question 1:

Sun is the ultimate energy source for all food chains. But from where will animals who live deep down on the ocean bed and have never seen sunlight get energy?

Deep ocean life is usually found in the vicinity of hot vents. In these vents, hot gases boil up from volcanic vents, with a temperature of around 350oC. The gases contain many sulphides and various minerals. When these hot gases hit the cold water, many of these minerals precipitate out of the water.
Specially adapted bacteria inhabit the regions around the hot vents and they directly convert the chemicals precipitating from the hot vents into energy by a process called chemosynthesis. In a way, these bacteria replace plants in the deep marine ecosystems.
Animals living in the vicinity of the hot vents either host the bacteria in their bodies or consume them directly. Other animals then eat these animals that directly feed on bacteria or host them in their bodies, leading to the formation of a complete food chain.

#### Question 2:

What will happen to the agricultural productivity if the number of snakes suddenly become less in a particular area?

A reduction in the number of snakes in an area will cause an explosion in the number of rodents, which in turn will destroy crops, resulting in a reduction in agricultural productivity.

#### Question D:

Match the items in Column A with the items in Column B:

 Column A Column B 1. Green plants (a) Afforestation 2. Deer (b) Decomposer 3. Tiger (c) Carnivore 4. Bacterial and fungi (d) Herbivore 5. Planting trees on large scale (e) Producer (f) Deforestation

 Column A Column B 1 Green plants (e) Producer 2. Deer (d) Herbivore 3. Tiger (c) Carnivore 4. Bacteria and fungi (b) Decomposer 5. Planting trees on a large scale (a) Afforestation

#### Question E:

Write True (T) of False (F) against the following statements in the given brackets:
1. Forests are rich in biodiversity ( )
2. A forest is a purifier of air and water. ( )
3. Animals help in seed dispersion. ( )
4. Excreta of animal pollute the soil. ( )
5. Mass-scale planting of trees is called deforestation. ( )

1. True (T)

2. True (T)

3. True (T)

​4. False (F)
The excreta of animals is decomposed by decomposers such as bacteria and fungi; this contributes to soil fertility.

5. False (F)
Mass-scale planting of trees is known as afforestation.

#### Question F:

Word map

 Write these words in the correct place on the word map: Omnivore, Lion, Producer, Carnivore, Decomposer, Herbivore.
Figure

1. Producer
2. Herbivore
3. Lion
4. Carnivore
5. Omnivore
6. Decomposer

#### Question A.1:

What do you mean by understoreys?

The different horizontal layers in a forest that are formed by herbs, shrubs and trees are called understoreys.

#### Question A.2:

Name two plants that give us medicines.

Cinchona and aloe vera are two medicinal plants.

#### Question A.3:

What is a canopy?

In a forest, the branches of trees meet and form an umbrella overhead so that very little sunlight reaches the ground. This is known as a canopy.

#### Question A.4:

What name is given to branchy part of a tree above the stem?

The branchy part of a tree above the stem is known as the crown.

#### Question A.5:

What are decomposers?

Decomposers are microorganisms that break down complex substances, such as those that make up the bodies of plants and animals, into simpler substances. Decomposers act on dead organic matter and return nutrients to the soil.

#### Question A.6:

What are the ultimate sources of food for all animals?

All animals depend on plants for nutrition. Herbivores consume plants directly. Carnivores eat herbivorous animals, so they also depend indirectly on plants for nutrition.

#### Question B.1:

What is a food chain? Explain with an example.

A food chain is a graphical representation of the transfer of energy from one organism to another.
An example of a food chain is given below:
$\mathrm{Plants}\to \mathrm{Rabbit}\to \mathrm{Snake}$

#### Question B.2:

Why are forests considered a dynamic entity?

A forest is home to many organisms such as plants, animals and microorganisms:

1. Plants are eaten by herbivorous animals.
2. Herbivores are in turn a source of food for carnivores.
3. Microorganisms are decomposers that break down the bodies of dead plants and animals, returning them to the soil, thus promoting the growth of new plants.
Owing to the continuous cycle of nutrients, we can say that a forest is a dynamic entity.

#### Question B.3:

In what way do forests help in regulating the climate of a place?

The roots of the trees present in the forest prevents water from running off during heavy rainfall by holding the soil particles firmly. This helps in preventing floods.

#### Question B.4:

In what way do forests help in regulating the climate of a place?

Forests increase the amount of water vapour in the air due to transpiration. This keeps the atmosphere cool and helps in rainfall, thereby regulating the climate of a place.

#### Question B.5:

How will snakes be affected if all rats disappear from the forest?

If all the rats in a forest disappear, the snakes will run out of food and they will perish. In turn, animals that depend upon snakes for food, such as hawks and eagles, will also die.

#### Question B.6:

How are animals classified according to their role in the food chain?

Animals are classified as follows according to their role in the food chain:

1. Herbivores: animals that directly consume plants. Eg: deer, rabbits etc.
2. Carnivores: animals that consume other animals. Eg: foxes, lions, tigers etc.
3. Omnivores: animals that consume both plants and other animals. Eg: humans, bears.

#### Question B.7:

What is forest conservation?

Forest conservation refers to the conservation of forests by preventing activities that cause destruction to them. Forests are maintained properly by taking various steps.

#### Question B.8:

How do forests help to control soil erosion?

The roots of trees firmly hold soil particles and prevent them from being washed away or blown away by water and wind. This helps in preventing soil erosion.

#### Question C.1:

How do decomposers help in maintaining balance in nature?

Decomposers break down the bodies of dead plants and animals, allowing nutrients to return to the soil. Thus, decomposers help in maintaining the balance in nature by making nutrients available for new plants, restarting the food chain.

#### Question C.2:

Why do we say that there is no waste in a forest? Explain.

In a forest, all organic material is either eaten by other animals or is broken down into simpler substances and returned to the soil by decomposers. As a result, there is no wastage in a forest.

#### Question C.3:

What is meant by interdependence of plants and animals?

The interdependence of plants and animals can be understood by the following points:

1. All animals depend on plants for food, either directly or indirectly.
2. Plants depend on animals for dispersing their seeds. Plants also benefit from animal dung, which is a good fertiliser.
3. Plants provide oxygen to animals for respiration and animals release carbon dioxide, which is consumed by the plants for preparing their food by photosynthesis.

#### Question C.4:

List five methods for the conservation of forests.

Five methods for conservation of forests are as follows:

1. Large scale afforestation must be encouraged in open areas that are unfit for cultivation, such as the side of highways, playground fringes etc.
2. Deforestation must be stopped. If trees are felled, many more must be planted to replace them.
3. Cooking on open fires in forest areas must not be practised to avoid forest fires.
4. Overgrazing by cattle, goats etc. must be avoided.
5. Air, water and soil pollution must be avoided to prevent destruction of plants and trees.

#### Question C.5:

How do forests reduce atmospheric pollution?

Trees absorb atmospheric carbon dioxide for photosynthesis. Also they allow suspended dust to settle on their leaves. Thus, forests help reduce atmospheric pollution.

#### Question C.6:

What is humus? How is it useful for soil?

Humus is a dark, porous and soft substance that is obtained by the decomposition of dead plants and animals. Humus is very useful for soil as it is rich in nutrients and also retains moisture well. This helps in increasing soil fertility.

#### Question C.7:

Write a short note on the Chipko movement.

The Chipko movement was initiated in March 1973 in the Terai forest around the Himalayan village of Gopeswar in the Chamoli district of present day Uttarakhand. The movement was led by the noted environmentalist, Sunderlal Bahuguna.
Women of the village played an active role in the movement, by hugging trees to prevent them from being cut down.

#### Question C.8:

How are forests beneficial to man? Explain it in points.

Forests are beneficial to man in the following ways:

1. Forests provide timber and wood, which are used for manufacturing furniture, railway sleepers, carts, boats, sporting goods, etc.
2. Plants and trees and their fruits and the meat of forest animals are sources of food.
3. Plants in forests are a source of medicines, for example, neem leaves and the bark of the cinchona plant.
4. Forests provide many other resources such as gum, oil, honey and lac. Forest animals are a source of hide, fur, ivory, musk, etc.
5. Forests transpire water vapour, thus ensuring a cool climate and adequate rainfall.
6. Forests absorb carbon dioxide and allow particulate matter to settle on tree leaves. Thus, forests reduce atmospheric pollution and global warming.

#### Question C.9:

What is the difference between food chain and food web? Explain it with suitable examples.