NCERT Exemplar Solutions Class 7 Science Forests Our Lifeline

Multiple Choice Questions....................

Question 1:  Which of the following serve as green lungs?

(a) The green pigment of the plants

(b) Forests

(c) Kitchen gardens

(d) Greenhouse gases 

Solution 1:  (b) Forests

Plants emit oxygen that is used by all species during photosynthesis. Plants help to control CO₂ and oxygen concentrations. They are, thus, called green lungs.

Question 2:  Boojho visited a forest near his town with his classmates and his teacher. As they were entering the forest, their class teacher told them not to make noise in the forest as noise could disturb the

(a) birds

(b) animals

(c) both birds and animals

(d) plants 

Solution 2:  (c) both birds and animals

Both birds and animals used to live in the forest so the noise could disturb both of them.

Question 3:  Which among the following forest animals is the smallest?

(a) Fox

(b) Boar

(c) Bison

(d) Porcupine 

Solution 3:  (d) Porcupine 

Porcupine is the smallest forest animal.

Question 4:  Which of the following has the strongest stem?

(a) A tree

(b) A creeper

(c) A climber

(d) A bush 

Solution 4:  (a) A tree

Tree has the strongest stem.

Question 5:  Which of the following is not prepared from the wood obtained from forest?

(a) Paper

(b) Thermocol

(c) Matchsticks

(d) Plywood 

Solution 5:  (b) Thermocol

Paper, match sticks and plywood are made from forest-based wood, while thermocol is made from synthetic fibers.

Question 6:  Which of the following is not the name of a tree?

(a) Teak

(b) Sal

(c) Porcupine

(d) Kachnar 

Solution 6: (c) Porcupine

Teak, Sal and Kachnar are trees while Porcupine is an animal.

Question 7:  Pick the option which gives the names of a tree and an animal, respectively from the following.

(a) semal, hornbill

(b) sal, khair

(c) chinkara, blue bull

(d) neem, palash 

Solution 7: (a) semal, hornbill 

Semal is the name of tree and hornbill is the name of an animal.

Question 8:  Which of the products is not obtained from a forest?

(a) Honey

(b) Catechu

(c) Gum

(d) Ginger 

Solution 8:  (d) Ginger 

Ginger is not a forests item in fact it is cultivated in the farms.

Question 9: The branchy part of a tree above the stem is known as

(a) crown

(b) canopy

(c) sapling

(d) humus 

Solution 9:  (a) crown

The highest section of the tree, composed of all the roots and leaves of the tree, is the crown.

Question 10:  Forests are not responsible for

(a) providing medicinal plants.

(b) maintaining the flow of water into the streams.

(c) creating flood conditions.

(d) absorbing rainwater and maintaining the water table 

Solution 10:  (c) creating flood conditions. 

Forests do not create rivers, but by percolating the rainwater, they avert the floods.

Very Short Answer Questions...............

Question 11:  Paheli while moving in a forest observed that there was no noise pollution, though lots of heavy vehicles were passing from the nearby highway. Explain why? 

Solution 11:   No noise emissions will arise in trees, as woods contain noise.

Question 12:  State whether the following statements are true or false. If false, give the correct statement.

(a) Forests influence climate, water cycle and air quality.

(b) In a forest, trees form the uppermost layer, followed by herbs. The shrubs form the lowest layer of vegetation.

(c) The forest keeps on growing and changing and can regenerate.

(d) Forests protect the soil from erosion. 

Solution 12:

a) True

b) False- In a woodland, the uppermost layer forms trees, accompanied by shrubs. The herbs form the vegetation's lowest layer.

c) True

d) True

Question 13:  Paheli wrote a food chain in the following way:

frog → eagle → insects → grass → snake

The chain is not in the correct order. Help her to write the food chain correctly. 

Solution 13:  grass→insects →frog →snake→eagle

Short Answer Questions.....................

Question 14:  Give names of any four birds which you expect to see in a forest. 

Solution 14:   Kingfisher, myna, Jungle crow, dove. 

Question 15:  Two friends shared their experiences of their vacation trip to two different forests. Do you think they would have seen the same type of plants and animals during their respective trips? Give reason. 

Solution 15:   No, in two separate questions, they would not see the same type of plants and animals because climatic conditions in the two forests will be different, leading to differences in the types of plants and animals.

Question 16:  “A bunch of seedlings were seen sprouting on a heap of animal dropping in a forest.” How do you think is the seedling benefited from the animal dung? 

Solution 16:    Nutrients from rotting animal heaps are harvested by growing seedlings.

Question 17:   Match Column I with Column II:

Solution 17:

Question 18:  Deforestation may lead to floods. Why? 

Solution 18:   The soil loses its water holding capacity in the absence of vegetation, which induces flooding. Deforestation thereby contributes to flooding.

Question 19:  Name any four useful products other than wood, which we get from forests. 

Solution 19:   Gum, Spices, medicinal plants, catechu

Long Answer Questions............

Question 20:  Figure 17.1 shows a part of a forest.

Write any three activities going on in the forest on the basis of this figure. 

Solution 20:

i) The plants' leaves give away oxygen.

ii) In order to prepare their food by the photosynthesis process, plants absorb carbon dioxide.

iii) Decomposers play an essential part in supplying plants with nutrients.

Question 21:  People say that nothing goes waste in a forest. Can you explain, how? 

Solution 21:  Nothing goes waste in a forest for the following reasons

• To a dark colored material called humus, dried leaves and remains of dead animals are transformed. This provides the plants with nutrients.
• Dead remains of the animals become food for vultures, crows, jackals and insects.
• Broken branches of trees are used by people who live near the forest as fuel.

Question 22: Give any four factors which are responsible for the destruction of forests. 

Solution 22:  Factors responsible for the destruction of forests are

(i) construction of the roads.

(ii) construction of the buildings.

(iii) industrial development.

(iv) increasing demand for the wood.

Question 23:  Draw a figure showing two animals, two birds and a few trees as a part of a forest. 

Solution 23:

Question 24:  All the needs of animals living in a forest are fulfilled. Justify this statement in a few sentences. 

Solution 24:   For many things, animals are dependent upon plants in the forest. Plants provide the animals to breathe with CO₂. Animals are either directly or indirectly dependent on plants for food. Herbivores derive food directly from plants, while carnivores rely on herbivores for food. Trees in the forest provide forest animals with shelter. It is also said that the needs of animals living in a forest are fulfilled.

Question 25:   “Forests are our lifeline.” Write five sentences on this topic. 

Solution 25:  Forests are our lifeline because of the following reasons:

(i) To keep us alive, forests offer oxygen.

(ii) Forests absorb carbon dioxide, a gas which, if its concentration increases in the atmosphere, contributes to climate change.

(iii) Forests give us with wood, gum, medicinal plants and spices.

(iv) Forests protect the soil from getting eroded.

(v) Forests prevent floods by increasing the soil's water holding capacity.