Living Science Solutions for Class 7 Science Chapter 19 Our Forests are provided here with simple step-by-step explanations. These solutions for Our Forests are extremely popular among class 7 students for Science Our Forests Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Living Science Book of class 7 Science Chapter 19 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Living Science Solutions. All Living Science Solutions for class 7 Science are prepared by experts and are 100% accurate.

Page No 221:

Question 1:

The lowest layer in the understorey is formed by

(a) shrubs
(b) herbs
(c) trees
(d) tail grasses

Answer:

(a) shrubs
The lowest layer in the understorey is formed by shrubs.

Page No 221:

Question 2:

Which of these is not obtained from a forest product?

(a) paper
(b) furniture
(c) plastics
(d) medicines

Answer:

(c) plastics
Plastic is not a forest product, while paper, furniture and medicines are forest products. They are obtained from the forests.

Page No 221:

Question 3:

Which of the following are called producers?

(a) herbivores
(b) carnivores
(c) green plants
(d) bacteria and fungi

Answer:

(c) green plants

Green plants are called producers because they can produce their own food by photosynthesis.

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Question 4:

The first link in all food chains are

(a) herbivores
(b) carnivores
(c) green plants
(d) none of these

Answer:

(c) green plants
Green plants serve as the first link in all food chains. They are also called producers.

Page No 221:

Question 5:

Which of these enable nutrients present in the bodies of plants and animals to go back to the soil after they die?

(a) producers
(b) primary consumers
(c) secondary consumers
(d) decomposers

Answer:

(d) decomposers

Decomposers enable nutrients present in the dead bodies of plants and animals to go back to the soil. Examples of decomposers include bacteria and fungi.

Page No 221:

Question 6:

The primary source of energy in nature is

(a) oxygen
(b) carbon dioxide
(c) fuels
(d) sun

Answer:

(d) sun
Sun is the primary source of energy for all living organisms.

Page No 221:

Question 7:

Which of the following does a forest prevent?

(a) floods
(b) soil erosion
(c) water table from going down
(d) all of these

Answer:

(d) all of these
Forests prevent soil erosion and floods. They also prevent water table from going down. 

Page No 221:

Question 8:

Which of the following does a forest NOT do?

(a) supply oxygen
(b) supply carbon dioxide
(c) cool the air
(d) increase rainfall

Answer:

(b) supply carbon dioxide
A forest does not supply carbon dioxide. However, the trees in the forest release oxygen during the process of photosynthesis. Forests cause sufficient rainfall on earth and also keep the climate cool.

Page No 221:

Question 9:

Plants DO NOT depend on animals for
(a) pollination
(b) food
(c) seed dispersal
(d) nutrients

Answer:

(b) food
Plants do not depend on animals for food. They can produce their own food by photosynthesis. This is why they are also called producers.

Page No 221:

Question 10:

Flow of energy in nature takes the following path:

(a) carnivores → herbivores → green plants
(b) green plants → herbivores → carnivores
(c) sun → green plants → herbivores → carnivores
(d) sun → carnivores → herbivores → green plants

Answer:

(c) sun → green plants → herbivores → carnivores

Food chain is a simple representation of energy flow in nature. The correct order of energy flow in a food chain is:
sun → green plants → herbivores → carnivores

Page No 221:

Question 1:

What is the name given to the cover of branches of tall trees in a forest?

Answer:

Canopy is the name given to the cover of branches of tall trees in a forest.

Page No 221:

Question 2:

Name one medicinal plant.

Answer:

Neem is an example of medicinal plants. Its leaves are used as medicine.



Page No 222:

Question 1:

Why is it dark inside a forest?

Answer:

It is dark inside a forest because the canopy leaves intercept the sunlight available to the forest. As a result, less than 50% of total sunlight falling on the top of the forests manage to pass through the canopy and go down to the plants in the forest.

Page No 222:

Question 2:

In an area in which a forest was cut to make a city, it was found that the water table went down. What could be the reasons for this?

Answer:

Trees and plants of forests help in seepage of rainwater into the ground. In the absence of forest, little rainfall seeps into the ground. In such cases, more groundwater is drawn out for irrigation and other purposes than it gets replenished by rainfall. This depletes the water table.

Page No 222:

Question 3:

Name five products that we get from forests.

Answer:

Five products that we get from forests are timber, spices, oils, medicines and wood.

Page No 222:

Question 4:

Name two scavengers. How are they useful to the environment?

Answer:

Scavengers are animals, who eat dead bodies of plants and animals. Vultures and crows are two scavengers.  They eat dead bodies of plants and animals. This helps in keeping the environment clean.

Page No 222:

Question 5:

Give an example to show the interconnection between food chains.

Answer:

Several food chains that exist in nature are interconnected. Green plants are eaten by several plant-eaters. These plant-eaters in turn are eaten by several animal-eaters. In this way, many food chains are linked together to form a web called food web.

Page No 222:

Question 6:

How are forest fires controlled?

Answer:

Forest fires can be controlled by following methods:
i. Forest fires caused by human beings can be prevented by creating awareness and educating them 
ii. Prompt detection of fire through efficient ground patrolling and communication networks

Page No 222:

Question 7:

What is 'afforestation'?

Answer:

Afforestation is the process of renewing a forest by planting more trees. However, the process is slow because new saplings take several years to grow.

Page No 222:

Question 1:

Mention two ways in which plants are useful to animals and two ways in which animals are useful to plants.

Answer:

Plants are useful to animals in the following ways:
(i) Plants provide oxygen to animals. They also act as food for some animals.
(ii) They reduce the pollutants present in air; thus, protecting animals. They also provide shelter to some animals.

Animals are useful to plants in the following ways:
(i) Animals help plants in pollination and seed dispersal.
(ii) Animal excreta and dead animals add nutrients to the soil and provide minerals for plant growth.

Page No 222:

Question 2:

What is a food chain? Explain with an example.

Answer:

Food chain is a simple representation of energy flow in nature. It shows the relationship between producers, consumers and decomposers with the help of arrows showing who eats whom.

For example, a grasshopper feeds on leaves of a plant, a frog eats grasshopper and the frog in turn is eaten by a cat. The last link of a food chain is occupied by decomposers, who feeds on dead plants and animals.

Page No 222:

Question 3:

Explain the meaning of a 'food web'.

Answer:

An interconnected network of food chains that form a multitude of feeding connections among different organisms of a biotic community is called a food web.

A food web shows how different animals are interconnected by different paths.

 




 

 

Page No 222:

Question 4:

Explain how nature maintains a balance between living things.

Answer:

"To kill and to be killed, to grow and to die and get decomposed" is the law of nature. With the help of this law, nature maintains the population of each species of animals in sufficient numbers.
For example, consider a simple terrestrial food chain:
           
       plants → grasshopper → frogs → snake → eagle

Suppose, there are no eagles in a community. In the absence of eagles, the population of snake will increase. Increased population of snake will eat more frogs. Gradually, the population of frog will decrease.

Decrease in the population of frog will lead to increase in the population of grasshopper. Now, grasshopper will eat more plants. Decrease in the population of plants would disturb the entire ecological balance.

Page No 222:

Question 5:

When you conserve forests, you also conserve soil. Discuss.

Answer:

Forests prevent soil erosion and floods. Hence, they conserve soil. In the absence of forest, soil erosion occurs more rapidly, exposing the lower hard and rocky layer. As a result, the soil loses humus and becomes less fertile. Thus, fertile lands, which act as a source of living for farmers, get converted to a desert. This process is known as desertification of land.

Page No 222:

Question 6:

What do you mean by planned harvesting of forests? How does it help in conservation?

Answer:

Planned harvesting of forest is a method employed by the government to conserve forests. Under this, all the trees of a forest are prevented from getting cut while converting it into an agricultural land. Cutting of all the trees may lead to soil erosion and other natural problems.

Planned harvesting of forests maintains a balance between deforestation and afforestation, i.e., regeneration of new plants. Thus, it helps in conservation of forest.

Page No 222:

Question 7:

In what way are wildlife conservation, forest conservation and soil conservation related?

Answer:

Wildlife conservation, forest conservation and soil conservation -- all three are inter-related. It is because, by conserving the forest, wildlife and soil are automatically conserved.
When we conserve forests, we conserve soil by preventing soil erosion. They also maintain the fertility of soil.

Similarly, trees in the forest provide shelter and safety to animals. They also provide food to wildlife. Thus, conservation of forest means conservation of wildlife.

Page No 222:

Question 8:

List five ways in which forests are useful to us.

Answer:

Forests are useful to us in following ways:
(i) Forests prevent soil erosion and floods.
(ii) They maintain the balance between carbon dioxide and oxygen levels in the atmosphere.
(iii) They reduce global warming by using carbon dioxide during photosynthesis.
(iv) They maintain the climate of a place and cool the environment by releasing water vapours in the air.
(v) They provide all basic needs of the mankind including food, clothing, and shelter.

Page No 222:

Question 9:

Can large scale cutting down of forests have an effect on rainfall in the area? Give reasons.

Answer:

Yes, large scale cutting down of forests can affect the rainfall in the area. Trees absorb water through their roots and release water vapours in the air through transpiration. These water vapours then condense to form clouds. When water droplets (in form of clouds) become big, they fall as rain. When rain falls on the ground, the roots of the trees help water to seep down in the ground. Thus, by cutting down the forests, the entire process of water cycle would get affected, which in turn would result in the reduction of rainfall.

Page No 222:

Question 3:

If there are no plants in the soil, heavy rain will cause extensive soil ________

Answer:

If there are no plants in the soil, heavy rain will cause extensive soil erosion.

Page No 222:

Question 4:

Forests are called 'green lungs' because they supply ____________ to the atmosphere.

Answer:

Forests are called 'green lungs' because they supply oxygen to the atmosphere.

Page No 222:

Question 5:

Forests help in cloud formation as they release __________ in the air.

Answer:

Forests help in cloud formation as they release water vapour in the air.

Page No 222:

Question 6:

Are carnivores primary consumers or secondary consumers?

Answer:

Carnivores are secondary consumers as they feed on herbivores (animals who eat plants).

Page No 222:

Question 7:

A food chain shows the flow of energy from one organism to another. Which did this energy come from in the first place?

Answer:

Order of energy flow in a food chain is:

sun → green plants → herbivores → carnivores

Energy at the first place in this chain comes from sun.

Page No 222:

Question 8:

Name one decomposer that is not a microorganism.

Answer:

Cockroach is a decomposer that is not a micro-organism. It feeds on dead and decaying plants and animals.

Page No 222:

Question 9:

A food ___________ is made up of several connected food chains.

Answer:

A food web is made up of several connected food chains.

Page No 222:

Question 1:

What do you think will be the consequences if all forests on the earth disappear?

Answer:

If all the forests on earth disappear, it will lead to the following consequences:
(i) There will be an increase in earth's temperature.
(ii) Animals will not get food and shelter.
(iii) Soil will not hold water, which will cause floods.
(iv) There will be no purification of air.
(v) There will be no recycling of nutrients.



Page No 223:

Question 2:

To conserve forests, we should ban cutting down of trees completely. Do you agree?

Answer:

No; though forest trees are cut for various desirable uses, it is not necessary to ban the cutting down of trees completely. However, it should be done at a slow rate to allow the forest trees regenerate naturally. Also, more trees should be planted to maintain a balance of trees.

Page No 223:

Question 3:

'A forest has no waste.' Why?

Answer:

A forest has no waste because dead bodies are consumed and the remains are recycled. When animals die in a forest, they are eaten up by scavengers such as crows and vultures. Scavengers feed on the dead bodies of animals which in turn keep the forest clean. Moreover, decomposers like bacteria and fungi also decompose dead organisms and wastes into humus, which contains nutrients for plants.

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Question 4:

Suppose in a forest, the number of carnivores became more than the number of herbivores.
What will be the consequence?

Answer:

If the number of carnivores in a forest becomes more than the number of herbivores, the population of herbivores will decrease, as carnivores feed on herbivores. Decrease in the population of herbivores will further lead to an increase in the population of green plants (producers), as herbivores feeds on green plants. Hence, if the population of any of the members in a food chain increases or decreases, it will affect the population of other members. Their number will either increase or decrease substantially.



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