Forests: Our Lifeline

Punjab State Board PSEB 7th Class Science Book Solutions Chapter 17 Forests: Our Lifeline Textbook Exercise Questions and Answers.

PSEB Solutions for Class 7 Science Chapter 17 Forests: Our Lifeline

PSEB 7th Class Science Guide Forests: Our Lifeline Textbook Questions and Answers

Fill in the blanks:

(i) Animals helps plants in the ……………… of seeds.
Answer:
formation

(ii) ………………… gas is released by plants during photosynthesis.
Answer:
Oxygen

(iii) …………….. and ……………….. are major threats to forest.
Answer:
Fire, Pollution

(iv) Large scale planting of tree sapling is called …………….. .
Afforestation.

State True or False:

(i) Animals provide nutrients to plants.
Answer:
False

(ii) The forest cover in India is only 15% of its total land area.
Answer:
False

(iii) Crown is the shape of the trees.
Answer:
True

(iv) Deforestation is cutting of trees to clear area for building houses and farming.
Answer:
True

(v) Deforestation takes place due to overgrazing.
Answer:
True

3. Match the Column ‘I’ with Column ‘II’:

Column ‘I’	Column ‘II’
1. Plants	(a) Forest
2. A renewable natural sources	(b) Practice of planting trees on a largescale
3. Afforestation	(c) Deforestation
4. Removal of plants	(d) Producers

Answer:

Column ‘I’	Column ‘II’
1. Plants	(c) Producers
2. A renewable natural sources	(a) Forest
3. Afforestation	(b) Practice of planting trees on a largescale
4. Removal of plants	(d) Producers

4. Choose the correct answer:

Question (i)
Which of the following is not a forest product ?
(a) Plywood
(b) Kerosene
(c) Sealing wax
(d) Gum.
Answer:
(b) Kerosene.

Question (ii)
A food chain includes:
(a) Producers and herbivores
(b) Producers and carnivores
(c) Producer and decomposers
(d) Producers, herbivores and carnivores.
Answer:
(d) Producers, herbivores and carnivores.

Question (iii)
Bacteria and fungi act as:
(a) Decomposers
(b) Herbivores
(c) Omnivores
(d) Carnivores.
Answer:
(d) Carnivores.

Question (iv)
Microorganisms act upon the dead organisms to produce:
(a) Humus
(b) Wood
(c) Soil
(d) All of these
Answer:
(a) Humus.

5. Very Short Answer Type Questions:

Question (i)
How much land area on the earth is covered with forest ?
Answer:
About 13% of the earth’s surface is covered by forests.

Question (ii)
What is an ecosystem ?
Answer:
Ecosystem. Organisms and their environment combine to form ecosystems or ecological system. Plants, animals and microorganisms are biological components of ecosystems.

Question (iii)
What is afforestation ?
Answer:
Afforestation. For compensation of cut down forest trees, the process of large-scale tree plantation is called Afforestation (replenishment of forest).

Question (iv)
What causes global warming ?
Answer:
Causes of global warming. The main cause of global warming is the increase in greenhouse gases in the atmosphere due to human activities. In greenhouse gases the main gases are carbon dioxide, methane, nitrites, oxides, ozone and chlorofluorocarbons.

6. Short Answer Type Questions:

Question (i)
In terms of food chain, discuss the interdependence of plants and animals.
Answer:
The interdependence of plants and animals. Like plants, humans and animals cannot prepare their own food. Plants produce food for humans and animals. Many plants also provide shelter and protection for wildlife such as bats, squirrels and insects and many more. As for example during summer trees provide shade to many animals.

Question (ii)
How do forests help in conservation of soil ?
Answer:
There are many plants, shrubs and trees in forests that hold the top layer of forest soil with their roots. It does not allow natural forces like wind and flood (water) to carry away the soil with it and retains the ability of soil to hold water. So forests help in the Conservation of soil.

Question (iii)
Give two examples which show how that plants depends on animals.
Answer:
Examples of plants dependence on animals.
(1) Carbon dioxide released by animals during respiration is used by plants in photosynthesis process. In this process plants prepare their food in the presence of Carbon dioxide and Sunlight.

(2) If a number of plants grows on a place there will be competition among them for food. This causes threatening to the life of the plants. Thus animals helps in the dispersal of seeds and fruit to new places to avoid overcrowding of seeding at one place.

Question (iv)
Explain how forests prevent floods.
Answer:
Forests acts as a natural agents of absorbing rain water. They did not allow the rainwater to fell directly on the surface of earth. For this reason water do not accumulate in the earth and slowly enters the surface of the earth and flew of the water in rivers remains controlled. Thus plant maintain adequate water level areas near forests and prevent floods.

Question (v)
List five products we get from forests ?
Answer:
Products we get from forest are:

1. We get several nuts and spices from plants growing in forests.
2. We get sal, mahogany, teak and rosewood trees.
3. We get fossil fuel from forest and cardboard and paper industries depends on forest.
4. From forest we get resins to make varnish and paint and latex used to make rubber.
5. We get many species of grasses such as lemon grass, vanilla, kewra, Khus and Sandalwood from forest.

7. Long Answer Type Questions:

Question (i)
What is deforestation ? Explain various causes responsible for deforestation.
Answer:
Deforestation.
The needs of the human population such as food, clothing, houses, roads, railways etc. are fulfilled by cutting trees and forests on large scale. This permanent cutting of forests is destruction of forest or deforestation.

Major causes of deforestation:

1. Increase in demands like land for housing and industry and food for the increasing human population.
2. Excessive grazing of domestic animals.
3. Excessive digging of land for food.
4. With more water logging and more irrigation, the ground table level goes down and with result trees and plants are unable to get water and ultimately and die.
5. Cutting down trees to get fuel wood and wilf and paper.

Question (ii)
Enlist various uses of forests.
Answer:
Uses of Forests. Humans are directly or indirectly dependent on forest to meet their needs. Forests therefore, make a significant contribution to our lives.

• The roots of plants and trees bind soil particles and keep the soil from carried away by water and wind. As a result, forests prevent erosion and flooding.
• We get a variety of dry fruits and spices from the plants growing in forests.
• Increases the amount of water vapour in the air, due to transcription by wild trees and plants the surrounding air remains cool. By raising water vapour content they also help in bring rain.
• From forests we get Latex for making rubber, fodder for animals, bamboo for basket making industry and wood for paper industry.
• Forests provide us with neem, timber sal and cinchona for making Ayurvedic medicines.
• Forests and trees reduce the green house effect by reducing the amount of carbon dioxide present in the air with the photosynthesis process which results in lowering global warming.
• Forests provide us with wood for making furniture, windows and doors of the house.

Question (iii)
Describe how animals depend on plants.
Answer:
Animal dependence on plants. Animals depend on plants as follows:

1. Food, which is a source of energy, is obtained from plant leaves, fruits and other plant products.
2. Animals get the oxygen they need for respiration from plants, which is produced during photosynthesis.
3. Animals get shelter from big trees and which also provide protection from sun and rain.
4. Birds live and build their nests on trees.
5. Wild animals protect themselves from predators by hiding in dense bushes and grass.

Question (iv)
What measures can be taken for the conservation of forests ?
Answer:
Measure for the conservation of forests:

• The use of wood as fuel should be reduced and instead of wood LPG and Biogas should be used as fuel for cooking.
• Planting as many new trees as possible to compensate for the trees cut down for furniture or amfor construction of buildings.
• Excellent fire extinguishers and fire breakers should be used to prevent forest fires so that there is no shortage of forests in the future.
• The government should make efforts to plant trees on a large scale every year.

PSEB Solutions for Class 7 Science Forests: Our Lifeline Important Questions and Answers

1. Fill in the Blanks:

(i) The insects, butterflies, honeybees and birds help flowering plants in ……………… .
Answer:
Pollination

(ii) A forest is a purifier of ……………….. and …………………. .
Answer:
Air, water

(iii) Herbs form the ………………… layer in the forest.
Answer:
Lower

(iv) The decaying leaves and animal droppings in a forest enrich the ………………….. .
Answer:
Soil

(v) During the process of photosynthesis, trees reduce the green-house effect by reducing
the amount of ………………… in the air.
Answer:
Carbondioxide

2. Match the Column ‘I’ with Column ‘II’:

Column I	Column II
(i) Trees control	(a) Food chains
(ii) Insects	(b) Prevent erosion and flooding
(iii) Trees	(c) Photosynthesis
(iv) Carbon dioxide released by animals during respiration	(d) Climate
(v) Food web	(e) Pollination of flowers

Answer:

Column I	Column II
(i) Trees control	(d) Climate
(ii) Insects	(e) Pollination of flowers
(iii) Trees	(b) Prevent erosion and flooding
(iv) Carbon dioxide released by animals during respiration	(c) Photosynthesis
(v) Food web	(a) Food chains

3. Choose the Correct Answer:

Question (i)
The animals found in the forest are helpful:
(a) For the forest growth
(b) Oxygen and carbon dioxide
(c) To prevent floods
(d) None of the above.
Answer:
(a) For the forest growth.

Question (ii)
Form oxygen and use carbon dioxide of the atmosphere:
(a) Animals
(b) Plants and trees
(c) Separator
(d) Herbivorous
Answer:
(b) Plants and trees.

Question (iii)
Deforestation will increase:
(a) The amount of oxygen
(b) The amount of nitrogen
(c) The amount of carbon dioxide
(d) None of the above
Answer:
(c) The amount of carbon dioxide.

Question (iv)
Forests help in the purification of:
(a) Water.
(b) Both air and water
(c) Air
(d) Air, water and soil
Answer:
(b) Both air and water.

Question (v)
Which of following is not a forest product ?
(a) Gum
(b) Plywood
(c) Sealing wax
(d) Kerosene.
Answer:
(d) Kerosene.

Question (vi)
Which of the following statements is not correct ?
(a) Forests protect the soil from erosion.
(b) Plants and animals in a forest are not dependant on one another.
(c) Forest influence the climate and water cycle.
(d) Soil helps forests to grow and regenerate.
Answer:
(b) Plants and animals in a forest are not dependant on one another.

4. State True or False:

(i) Forests are areas where animals and dense plants and trees are present.
Answer:
True

(ii) 11% of India’s area is under forest.
Answer:
False

(iii) Plants, animals and micro-organisms are the biological components of ecosystem.
Answer:
True

(iv) Producer → Herbivorous → Carnivorous is a food chain.
Answer:
True

(v) Trees do not control climate of a place.
Answer:
False

(vi) Forest help prevent erosion and floods.
Answer:
True

Very Short Answer Type Questions

Question 1.
What is a broad view of a forest ?
Answer:
A place where land is not visible but only treetops form the green cover over the land.

Question 2.
What type of environment is found in a forest ?
Answer:
Peaceful environment with cool breeze blowing.

Question 3.
Which human activity can disturb the animals living in the forest ?
Answer:
Noise.

Question 4.
What is attitude of animals when human being enters a forest ?
Answer:
Monkeys usually jump to higher branches.

Question 5.
Which small animals are found in the forest ?
Answer:
Insects, spiders, squirrels, ants, micro-organisms.

Question 6.
Name any four animals found in a forest.
Answer:
Bear, bison, jackal, monkeys, birds.

Question 7.
Name the different types of trees found in a forest.
Answer:
Sal, teak, semal, shesham, neem, amla, bamboo.

Question 8.
What is classification of different plants found in a forest ?
Answer:
Trees, shrubs, herbs, grass, climbers, creepers etc.

Short Answer Type Qucstions

Question 1.
Why does water not stagnate in forests ?
Answer:
Forests are natural absorbers of rain water and allow it to seep deep down the soil. Also, the direct pouring of rain is stopped by canopy of forest and it falls drip by drip on the ground. So, water does not stagnate in the forests.

Question 2.
Why is soil of forest rich in nutrients ?
Answer:
The soil of forest is rich in nutrients because dead and decaying leaves are decomposed by decomposers to give a brown coloured nutrient (Humus) to enrich the soil.

Question 3.
Explain why there is no waste in a forest.
Answer:
Forests are habitat of various animals. They excrete and die still there is no waste in forests. Because the dead bodies are food of vultures, crow, jackal and insects. While other things like excreta and remains of dead matter get decomposed by mushrooms and other micro-organisms to nutrients required by soil.

Question 4.
List five products we get from forests.
Answer:
Products obtained from forests are:

1. Wood,
2. Oxygen,
3. Medicinal plants,
4. Rain,
5. Lac, Gum, Resin etc.

Question 5.
Explain how animals dwelling in the forest help it grow and regenerate ?
Answer:
Animals live in forest. They either feed on it directly (herbivores) or indirectly (carnivores). In both cases, they consume plants and excrete thrown by their bodies get decomposed by microorganisms to produce simple forms and nutrients. These get dissolved and mixed in soil to be used by growing plants.

Animals also help in scattering seeds to different parts of the forest. When seeds get favourable conditions they grow and thus forests regenerate.

Question 6.
What are decomposers ? Name any two of them. What do they do in the forest ?
Answer:
Decomposers. The micro-organisms which convert the dead plants and animals to humus are known as decomposers. Examples are bacteria, mushrooms.
Decomposers help in maintaining the supply of nutrients to the growing plants in the forests.

Question 7.
Explain the role of forests in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
Answer:

Forests are large area covered with different trees. Trees are green in colour. Their leaves photosynthesize in the sunlight and use atmospheric carbon dioxide to produce oxygen. In this way, balance of oxygen and carbon dioxide is maintained in the forests. In this way forests help in maintaining a balance between oxygen and carbon dioxide in the atmosphere.

Question 8.
Why should we worry about the conditions and issues related to forests far from us ?
Answer:
Forests indirectly or directly influence human life. They control floods and rainfall. They maintain balance of oxygen and carbondioxide in the atmosphere. They are also provider of many useful items needed by us in our daily life. They provide food, shelter and habitat to many animals also. They form a part of food web. So, we should worry about the conditions and issues related to forests far from us.

Question 9.
Explain why there is a need of variety of animals and plants in a forest.
Answer:
When there is variety of animals and plants then opportunity increases for food and habitat for the herbivores. When herbivores increase, then there is also increase in number of carnivores of different varieties. Different varieties of animals help the forest to regenerate and grow.

Long Answer Type Question

Question 1.
Describe the importance of forests and consequences of depletion of forests.
Answer:
A forest is a natural ecosystem. Forests are essential for sustainence of life on earth.
Importance of forests:

1. Habitat for animals and plants.
2. Provide food for animals and micro-organisms.
3. Maintain water cycle.
4. Control the earth’s temperature.
5. Maintain a balance of oxygen and carbon dioxide in nature.
6. Prevent soil erosion.

Consequences of depletion of forests are:

1. Improper rainfall.
2. Landslides.
3. Extinction of wild animals.
4. Retardation of soil quality.
5. Causes increase in carbon dioxide, leading to increase in the greenhouse effect and global warming.