The DAV Class 7 Science Book Solutions and DAV Class 7 Science Chapter 15 Question Answer – Forests are essential study tools for DAV public school students in Class 7.
DAV Class 7 Science Ch 15 Question Answer – Forests
DAV Class 7 Science Ch 15 Solutions – Forests
Something To Know
A. Fill in the blanks.
Quiestion 1.
Decomposers play an important role in ________ of nutrients.
Answer:
Recycling
Quiestion 2.
Herbs are found in ________ layer of the forest.
Answer:
Understory
Quiestion 3.
Forests maintain a balance between ________ and ________ gases of the atmosphere.
Answer:
Oxygen and Carbon dioxide
Quiestion 4.
Overgrazing in forests may cause a decrease in soil ________ and an increase in soil ________
Answer:
Fertility, Erosion.
Quiestion 5.
________ is the national tree of India.
Answer:
Banyan
B. Write True or False for the following statements.
1. Forests protect soil from erosion.
2. Raw material for paper is obtained from forests.
3. Forests depend on man for water and fertilisers.
4. Plants and animals in a forest are not dependent on one another.
5. Forests play an important role in water cycle.
Answer:
1. Forests protect soil from erosion. (True)
2. Raw material for paper is obtained from forests. (True)
3. Forests depend on man for water and fertilisers. (False)
4. Plants and animals in a forest are not dependent on one another. (False)
5. Forests play an important role in water cycle. (True)
C. Tick (✓) the correct option.
1. The layer of forest, where intertwined branches of trees are found, is known as the—
(a) Canopy (b) Understory
(c) Crown
(d) Forest floor layer
Answer:
(a) Canopy
2. Decomposers help in
(a) Cooling of atmosphere
(b) Recycling of nutrients
(c) Absorption of excess water
(d) Feeding the animals
Answer:
(b) Recycling of nutrients
3. An increase in cutting down of the trees in forests will lead to
(a) An increase in the amount of carbon dioxide in air
(b) A decrease in the amount of carbon dioxide in air
(c) An increase in the amount of oxygen in air
(d) A decrease in the amount of both oxygen and carbon dioxide in air FORESTS
Answer:
(a) An increase in the amount of carbon dioxide in air
4. The tree, that is thought of as an ‘important tree’ is the
(a) Ashoka tree
(b) Banyan tree
(c) Neem tree
(d) Teak tree
Answer:
(c) Neem tree
5. The tree that is often referred to as The golden shower tree’ is the
(a) Ashoka tree
(b) Deodar tree
(c) Amaltas tree
(d) Sal tree
Answer:
(c) Amalatas tree
D. Answer the following questions in brief.
Question 1.
Define the terms ‘food chain’ and ‘food web’.
Answer:
Food chain: A linear chain showing relationship among prey and predator is called food chain. A food chain is composed of a producer, and one or more levels of consumers.
Food web: A food web is a network of many food chains. In the real world, we see food webs only.
Question 2.
Name the different layers of the forest.
Answer:
Different layers of the forest are as follows:
- Forest floor layer
- Understory layer
- Canopy
- Emergent layer
Question 3.
Give the meaning of the term ‘soil erosion’.
Answer:
Re; oval of topsoil by agents of weathering is called soil erosion.
Question 4.
Na; e four useful products that are provided to use by the forests.
Answer:
Timber, firewood, lac, kendu leaves
Question 5.
Name any four trees that are common to the Indian subcontinent.
Answer:
Neem, Banyan, Peepal, Deodar
E. Answer the following questions.
Question 1.
Comment on the statement: “Early man began his life as a forest dweller.”
Answer:
Early man used to live in forests. He got his every need fulfilled by forests. He used
to get fruits and meat for food from forests. He used leaves, wood and firewood for different purposes. Hence, it is correct to say that early man began his life as forest dweller.
Question 2.
How are the shapes of crown of trees, and their location on earth related to each other?
Answer:
Crowns of trees near equator are almost fiat at top. This ensures that the leaves get maximum amount of sunlight. The crowns of trees in Arctic Circle are cone¬shaped. The sunlight reaches obliquely in these regions and hence this shape is ideal for getting maximum sunlight.
Question 3.
State any five points highlighting the importance of forests to mankind.
Answer:
Importance of Forests:
- Forests are the habitat for a variety of living beings.
- Agriculture and animal husbandry are dependent on forests.
- Forests help in improving the moisture in the atmosphere and thus help in bringing precipitation.
- Forests clean the air by maintaining the balance of oxygen and carbon dioxide in the atmosphere.
- Forests produce lot of humus and thus help in maintaining soil fertility.
- Forests help in recharge of groundwater.
- Forests prevent soil erosion.
- Forests are source of a variety of resources; like medicinal herbs, forest produce and raw materials for industrial products.
Question 4.
Discuss, in brief, the likely consequences of deforestation.
Answer:
Deforestation: Indiscriminate cutting or over harvesting of trees for timber or pulp, or to clear the land for various human activities is called deforestation. Consequences of Deforestation:
- Clearing of forests disturbs the carbon cycle. This leads to excess of carbon dioxide in the atmosphere.
- Clearing of forests hampers the natural recharge of groundwater. This leads to shortage of drinking water.
- Clearing of forests leads to soil erosion and ultimately to desertification.
- Clearing of forests results in increased occurrences of floods and draughts.
- Many species lose their habitat and become extinct because of deforestation.
Question 5.
How are the Eucalyptus tree, Teak tree and the Neem tree important for us?
Answer:
Eucalyptus tree gives useful items which are used in making medicines. Wood from
Eucalyptus is also used in paper industry. Wood from teak is used for making furniture. Neem tree provides many products which are used in making medicines.
Value Based Question
Sonu was a rather ‘self-centered’ boy and never cared to help others. His sister, Shweta, on the other hand, always showed empathy towards the needs of the others and would go out of the way, to help and guide others. Their mother advised Sonu to follow the example of his sister. She told him that all of us are interdependent on one another in much the same way as the many biotic and abiotic components, of a forest, are interdependent on one another.
Question 1.
State the values that you think Sonu needs to imbibe.
Answer:
Friendly behaviour, helpful attitude
Question 2.
Name any two components of a forest and discuss their interdependence on each other.
Answer:
Biotic components take raw materials from aboitic components. Biotic components help in proper recycling of abiotic components.
Something To Do
Question 1.
Adopt a tree: Cutting down of trees is a major concern for mankind. Choose a tree near your school or house and prepare a scrap book about it. You can find out its name in different languages as well as its scientific name. Draw pictures or click photographs of that tree. Also write how this tree is useful for the community (medicinal value, providing shade, etc.)
Answer:
Do it yourself.
Question 2.
Visit a forest and make a list of animals and plants that you see. Try to prepare diagrammatic representations of food chains and food webs that exist in that forest.
Answer:
Do it yourself.
Question 3.
Make a list of wildlife sanctuaries and national parks in India. Try’to locate them on the map.
Answer:
Do it yourself.
DAV Class 7 Science Chapter 15 Solutions – Forests
I. Fill in the blanks.
Quiestion 1.
Soil, air and water make the ________ component of forest.
Answer:
Abiotic
Quiestion 2.
Living beings make the ________ component of forest.
Answer:
Biotic
Quiestion 3.
________ play the role of producer in a forest.
Answer:
Green plants
Quiestion 4.
Herbivores play the role of ________ in a forest.
Answer:
Primary consumer
Quiestion 5.
Carnivores plat the role of ________ in a forest.
Answer:
Secondary consumer
Quiestion 6.
Pulp of eucalyptus is used in making ________
Answer:
Paper
II. Match the following:
| Column A | Column B |
| 1. Cone shaped trees | (a) Forests |
| 2. Lungs | (b) Coniferous trees |
| 3. Neem tree | (c) Arctic circle |
| 4. Emergent layer | (d) Miracle tree |
| 5. Deodar | (e) Tropical rainforests |
Answer:
| Column A | Column A | |
| 1. Cone shaped trees | c | 1. Cone shaped trees |
| 2. Lungs | a | 2. Lungs |
| 3. Neem tree | d | 3. Neem tree |
| 4. Emergent layer | e | 4. Emergent layer |
| 5. Deodar | b | 5. Deodar |
III. Tick (✓) the correct option.
1. Which of these would always be at the bottom of a food pyramid?
(a) Grass
(b) Deer
(c) Lion
(d) Eagle
Ans.
(a) Grass
2. Which of these would always be at the top of a food pyramid?
(a) Green plant
(b) Deer
(c) Rabbit
(d) Eagle
Ans.
(d) Eagle
3. Which of the following trees has conical canopy?
(a) Banyan
(b) Babool
(c) Deodar
(d) Peepal
Ans.
(c) Deodar
4. Which of these is an example of decomposer?
(a) Mushroom
(b) Money plant
(c) Bougainvillea
(d) Eucalyptus
Ans.
(a) Mushroom
5. Which gas is released by a green plant during photosynthesis?
(a) Carbon dioxide
(b) Oxygen
(c) Hydrogen
(d) Nitrogen
Ans.
(b) Oxygen
6. Which of the following is a forest product?
(a) Gums
(b) Resins
(c) Dyes
(d) All of these
Ans.
(d) All of these
7. Decomposers help in
(a) Cooling of atmosphere
(b) Cycling of nutrients
(c) Water absorption
(d) Feeding the animals
Ans.
(b) Cycling of nutrients
8. Cutting down of forests will
(a) Increase CO2 in air
(c) Increase O2 in air
(b) Decrease CO2 in air
(d) No effect on CO2 or O2
Answer:
(a) Increase CO2 in air
IV. Answer the following questions in brief.
Question 1.
Define a forest.
Answer:
An area with a high density of trees is called forest.
Question 2.
What do you understand by biotic components?
Answer:
The living beings in the forest make biotic components. Plants, animals, fungi, bacteria, etc. are the biotic components.
Question 3.
What do you understand by abiotic components?
Answer:
The non-living things make the abiotic components of a forest. Soil, air and water are abiotic components.
Question 4.
Give an example of a simple food chain.
Answer:
Grass → Deer → Lion
Question 5.
Write a short note on decomposers.
Answer:
Bacteria, fungi and some worms feed on dead and decaying materials. While doing so, they decompose the dead and decaying materials and return the raw materials back to the environment. Due to this, these organisms are called decomposers.
Question 6.
Write a brief note on canopy.
Answer:
The mass of intertwined branches of a tree makes the canopy. This is also called the crown of a tree. This part of the tree receives the maximum sunlight and that is why this is the part where maximum food is produced.
V. Answer the following questions.
Question 1.
Early man began his life as a forest dweller. Explain.
Answer:
Early man began his life as forest dweller. Initially, man was food gatherer and depended for all his needs on forests. Forests provided food in the form of fruits, roots, game animals, etc. Subsequently, man turned into food grower but continued to depend on forests for his various needs. Even today, we depend on forests for many needs.
Question 2.
List the components of a forest.
Answer:
The components of forest are as follows:
(a) Biotic components
(b) Abiotic components
Question 3.
What is the relationship between crowns of trees and their location on earth?
Answer:
The shape of the crown is affected by the climate in which a tree grows. The crown of the trees near equator is almost flat at top. This is due to the maximum amount of sunlight falling near the equator. The flat crown gets maximum sunlight and hence is able to produce the maximum food. The crown of trees in Arctic Circle is cone-shaped. The sunlight reaches obliquely in these areas. Conical shape is more suited to exploit sunlight in these conditions.
Question 4.
Why are forests known as lungs of the earth?
Answer:
Trees take in carbon dioxide and give out oxygen during photosynthesis. Thus, trees help in maintaining a balance between carbon dioxide and oxygen in the atmosphere. Due to this, forests are known as lungs of the earth.
Question 5.
Name any four tree common to the Indian subcontinent.
Answer:
Four trees common to the Indian subcontinent are:
(1) Banyan
(2) Teak
(3) Neem
(4) Deodar
VI. Differentiate between:
Question 1.
Food chain and food web
Answer:
A food chain is a simple chain which is composed of each of producer, primary7 consumer and secondary consumer. A food web is a complex interplay of many food chains. A food web has many producers, primary consumers, secondary consumers and tertiary consumers. A food chain is a simple representation, while a food web is the reality.
Question 2.
Canopy and under story layer in a forest
Answer:
The canopy is made of thick foliage of the top of trees. The canopy gets the maximum amount of sunlight. The understory is composed of bushes, shrubs and herbs which are adapted to grow in shade. Sunlight seldom reaches the understory in a forest.
VII. Projects
Question 1.
Collect pictures of various animals and plants and make a food web by arranging these pictures.
Answer:
Do it yourself.
Question 2.
Search the internet and make a project on WWF (World Wide Fund For Nature). You can visit this website: www.wwf.org
Answer:
Do it yourself.