TEXTBOOK ANSWERS AND SOLUTIONS OF CBSE CLASS VIII SCIENCE Chapter 7 CONSERVATION OF PLANTS AND ANIMALS

Exercise
1)
Fill in the blanks

(a) A place where animals are
protected in their natural habitat is called a __sanctuary__.
(b) Species found only in a particular
area are known as __endemic__.
(c) Migratory birds fly to far away
places because of __climatic__ changes.
2)
Differentiate between the following.
(a)
Wildlife sanctuary and biosphere reserve
(b)
Zoo and wildlife sanctuary
(c)
Endangered and extinct species
(d)
Flora and fauna
ANSWER:-
a) Wildlife Sanctuary:-It is an area within which
animals are protected from possible dangers
such as hunting. Their habitat is also conserved in this area.
-It provides protection and suitable living
conditions to wild animals.
Biosphere Reserve:-It is a large protected area
constructed for the conservation of
biodiversity.
-It helps in the conservation of
various life forms such as plants, animals, and micro- organisms.
b) Zoo-Zoos are smaller places having some animals
protected for the public view.
-It is an artificial habitat.
-It provides protection only.
Wildlife Sanctuary:-Wildlife Sanctuary are larger places
having wild animals in their natural habitat
-It conserves the natural habitat of
animals.
-It provides protection and suitable
living condition to wild
animals.
c) Endangered-It is a population of species that is on the
verge of becoming extinct.
Extinct-It is a
population of species that no longer exists. Hence, it is extinct.
d) Flora-It refers to all living
plants in a particular area.
Fauna-It refers to all
animals living in a particular area.
3) Discuss the effects of deforestation
on the following.


ANSWER:-a) Wild animals: When forests are cut,
the natural habitat of the animals is destroyed. Without the natural habitat
the animals are left with no place to live and breed. As a result of this many
animals are at
the verge of extinction.

b) Effects of deforestation on the
environment: Plants absorb 
CO2 from the atmosphere to perform photosynthesis.
If plants are destroyed, then the level of 
CO2 in the atmosphere will rise.
As a result, COwill trap more heat
radiations, thereby adding to global warming. An increase in
the temperature of the
Earth will disturb the natural water cycle. As a result, there will be a change
in the rainfall pattern. This could lead to floods or droughts.

c) Roots of plants hold
soil particles together. In the absence of plants, the top layer of the soil
will be easily removed by the action of high speed
winds or water flow. Thus, deforestation increases
the chances of soil erosion. As a result, soil loses humus and become less
fertile.

d)Deforestation in
cities can increase the risk of many natural calamities such as floods and
droughts in that area. Also, it can lead to global warming due to an increase
in the level of 
CO2 in the atmosphere as a result of vehicular and industrial pollution.

e) As a result of deforestation,
chances of desertification, droughts, floods, etc. increase. Deforestation can
also increase the level of 
CO2 in the Earth. It will lead to an increase in
temperature i.e., global warming. As a result, the entire natural water cycle
will get disrupted

f) Deforestation is slowly changing
our environmental conditions. It is responsible for global warming, soil
erosion, greenhouse effect,
drought, floods, and many other global problems. As a
result, the next generation will have to face severe
consequences of deforestation.
4)
What will happen if?
(a)
We go on cutting trees.
(b)
The habitat of an animal is disturbed.
(c)
The top layer of soil is exposed
ANSWER:-a) If we go on cutting trees, the
natural habitat of many animals will get completely destroyed. As a result, the
biodiversity of many areas will be

severely affected. Also, there will be an increase in
the temperature of the Earth as a result of global
warming, which can disturb the natural water cycle. As a result, there will be
a change in the rainfall pattern. This could
lead to floods or droughts. This will also increase the risk of soil erosion,
desertification, and natural calamities.

(b) The habitat of an animal provides
it with necessities such as shelter, food, and protection.

If the habitat of an animal is disturbed,
then it will be forced to go to other places in search of
food and shelter. The
animal could get killed by other animals in this process.

(c) If the top layer of soil is l
exposed, then it will gradually expose the lower layer of soil, which is hard
and rocky in nature. This type of soil is less fertile as it contains less
humus. Continued soil erosion will make the land barren or infertile.
5)
Answer in brief:
(a)
Why should we conserve biodiversity?
(b)
Protected forests are also not completely safe for wild animals. Why?
(c)
Some tribals depend on the jungle. How?
(d)
What are the causes and consequences of deforestation?
(e)
What is Red Data Book?
(f)
What do you understand by the term migration?
ANSWER
:
– (a) Biodiversity
refers to the number and variety of various life forms such as plants, animals,
and micro-organisms in an area. Plants and animals
depend on each other
for survival. This means that the destruction of either of the two will affect
the life of the other. Hence, we need to conserve
biodiversity to maintain the balance of nature.

(b) Protected forests are not
completely safe for wild animals because people who live near or
adjacent to forests use
resources from forests to 
fulfill their own requirements. In this process, wild

animals are killed and sold for lucrative amounts of
money.

(c) Tribals gather food, fodder, and
fallen branches of trees from forests. Hence, they depend on forests for their
daily requirement

(d) Causes of deforestation:
(i) Forests are cleared for accommodating
expanding urban areas and for fulfilling their

ever-increasing requirements.
(ii) Forests are destroyed to clear
land for crops and cattle grazing.
(iii) Trees are cut down to be used
for firewood.
Consequences of deforestation:
(i) Soil erosion
(ii) Loss of biodiversity
(iii) Floods and droughts
(iv) Climate change due to global
warming
(v) Disruption of water cycle

(e) Red Data Book is a source book
that maintains an international list of all endangered
animal and plant
species. This book is maintained by IUCN (International Union for Conservation of Nature and Natural resources).

(f) Migration refers to the movement
of an organism or a group of organisms from its

natural habitat to another place at a particular time
every year
6)
In order to meet the ever-increasing demand in factories and for shelter, trees
are being continually cut. Is it justified to cut trees for such projects?
Discuss and prepare a brief report.


ANSWER:-No. It is not at all justified to cut
trees to meet the ever increasing demands of human population. Forests are the
habitat of several organisms including wild animals. They provide us with good
quality air as they give out O
2 and absorb the harmful CO2 gas from the
atmosphere. In the process, they prevent the excessive heating of the
atmosphere. They prevent soil erosion and natural calamities such as floods and
droughts. They increase the fertility of the soil and help conserve
biodiversity. The cutting of forests to meet the demands of growing human
population will lead to global
warming, soil erosion, greenhouse effect, droughts, floods,
and many more problems. The destruction of forests will disturb the balance of
nature.
7)
How can you contribute to the maintenance of green wealth of your locality?
Make a list of actions to be taken by you.
ANSWER:-I can help in maintaining the green
wealth of locality by taking care of the plants and trees growing in or around
my locality. I can plant more and more trees. I can also encourage the
people in my locality
to plant more trees by informing them about the importance of growing trees. I
can make young children aware of the effects
that deforestation has on our environment and on our planet. I can also ask them
to water the plants daily, which will take very little of their time.
8)
Explain how deforestation leads to reduced rainfall.
ANSWER:-Deforestation is the removal of trees
or other vegetation from an area for industrial, agricultural, or other purposes.
Plants or trees absorb 
CO2 from the atmosphere. If plants are destroyed, then
the level of 
CO2 in the atmosphere will rise. The high levels of CO2 in the atmosphere will
trap more heat radiations, leading to global warming. This increase in
temperature of the Earth will disturb the natural water cycle. As a result of
disruption in the water cycle, there will be a
change in the rainfall pattern.
10)
Why should paper be saved? Prepare a list of ways by which you can save paper.
ANSWER: – Paper should be saved because it
takes around
seventeen full grown trees to make one tonne of paper.
Trees, as we know, are important to maintain a
balance of nature. Therefore, in order to save trees and prevent the impact of
their loss on living organisms, we need to save
paper.
Ways by which paper can be saved:

(i) Collect used paper and recycle it.
(ii) Use both sides of a paper for
writing.