NCERT Textbook: The Living Organisms - Characteristics & Habitats | Science & Technology for UPSC CSE PDF Download

 Page 1


58 SCIENCE
6
The Living Organisms —
Characteristics and Habitats
P
aheli and Boojho went on
vacation to many places of
interest. One such trip took
them to the river Ganga in Rishikesh.
They climbed the mountains of the
Himalayas, where it was very cold. They
saw many kinds of trees on these
mountains — oaks, pines and deodars,
very different from the ones near their
home on the plains! In yet another trip,
they travelled to Rajasthan and moved
on camels through the hot desert. They
collected different kinds of cactus plants
from this trip. Finally, they went on a
trip to Puri and visited the sea beach,
dotted with casuarina trees. While
recollecting all the fun that they had on
these trips, a thought struck them. All
these places were so different from one
another, some were cold, some very hot
and dry, and some places so humid. And
yet all of them had many organisms
(living creatures) of various kinds.
They tried to think of a place on Earth
where there may not be any living
creatures. Boojho thought of  places near
his home. Inside the house, he tried the
cupboards. He had thought that there
may not be any living organisms here,
but he found one tiny spider in the
cupboard. Outside the home too, there
did not seem to be any place, he could
think of, that did not have living creatures
6.1 ORGANISMS AND THE
SURROUNDINGS WHERE THEY LIVE
Another thought that occurred to Paheli
and Boojho was about the kinds of living
organisms that were present in different
locations that they had visited. The
deserts had camels, the mountains had
goats and yak. Puri had some other
creatures — crabs on the beach and
such a variety of fish being caught by
the fishermen at the sea! And then,
there did seem to be some creatures like
ants that were present in all these
different locations. The kinds of plants
found in each of these regions were so
different from the plants of the other
regions. What about the surroundings
of some kind or the other (Fig. 6.1). Paheli
started thinking and reading about far
away places. She read that people have
even found tiny living organisms in the
openings of volcanoes!
Fig. 6.1 Search for living organisms
Rationalised 2023-24
Page 2


58 SCIENCE
6
The Living Organisms —
Characteristics and Habitats
P
aheli and Boojho went on
vacation to many places of
interest. One such trip took
them to the river Ganga in Rishikesh.
They climbed the mountains of the
Himalayas, where it was very cold. They
saw many kinds of trees on these
mountains — oaks, pines and deodars,
very different from the ones near their
home on the plains! In yet another trip,
they travelled to Rajasthan and moved
on camels through the hot desert. They
collected different kinds of cactus plants
from this trip. Finally, they went on a
trip to Puri and visited the sea beach,
dotted with casuarina trees. While
recollecting all the fun that they had on
these trips, a thought struck them. All
these places were so different from one
another, some were cold, some very hot
and dry, and some places so humid. And
yet all of them had many organisms
(living creatures) of various kinds.
They tried to think of a place on Earth
where there may not be any living
creatures. Boojho thought of  places near
his home. Inside the house, he tried the
cupboards. He had thought that there
may not be any living organisms here,
but he found one tiny spider in the
cupboard. Outside the home too, there
did not seem to be any place, he could
think of, that did not have living creatures
6.1 ORGANISMS AND THE
SURROUNDINGS WHERE THEY LIVE
Another thought that occurred to Paheli
and Boojho was about the kinds of living
organisms that were present in different
locations that they had visited. The
deserts had camels, the mountains had
goats and yak. Puri had some other
creatures — crabs on the beach and
such a variety of fish being caught by
the fishermen at the sea! And then,
there did seem to be some creatures like
ants that were present in all these
different locations. The kinds of plants
found in each of these regions were so
different from the plants of the other
regions. What about the surroundings
of some kind or the other (Fig. 6.1). Paheli
started thinking and reading about far
away places. She read that people have
even found tiny living organisms in the
openings of volcanoes!
Fig. 6.1 Search for living organisms
Rationalised 2023-24
59 THE LIVING ORGANISMS — CHARACTERISTICS AND HABITATS
in these different regions? Were they
the same?
Activity 1
Let us start with a forest. Think of all
the plants, animals and objects that can
be found there. List them in Column 1
of Table 6.1. List things, animals and
plants, found in the other regions that
are also shown in the table. You can
collect the examples scattered through
this chapter to fill Table 6.1. Discuss
also with your friends, parents and
teachers, to find more examples to fill
the tables. You can also consult many
interesting books in libraries that talk
of animals, plants and minerals of
different regions.
Try and include many plants,
animals and objects, big and small, in
each of the columns in this table. What
kind of objects will we find that may not
be animals or plants? Perhaps parts of
plants like dried leaves, or parts of
animals, like bones. We may also find
different kinds of soils and pebbles.
Water in the oceans may have salts
dissolved in it as discussed in Chapter
3. There could be many more objects.
As we go through the chapter, keep
adding more examples to Table 6.1. We
will discuss the table as we travel
through many more interesting places.
6.2 HABITAT AND ADAPTATION
What do you find from the plants and
animals listed in Activity 1? Did you find
a large variety in them? Look at what you
have entered in the column for the desert
and the column for the sea in Table 6.1.
Did you list very different kind of
organisms in these two columns?
What are the surroundings like, in
these two regions?
In the sea, plants and animals are
surrounded by saline (salty) water. Most
of them use  the air dissolved in water.
There is very little water available in
the desert. It is very hot in the day time
and very cold at night in the desert. The
animals and plants of the desert live on
the desert soil and breathe air from the
surroundings.
The sea and the desert are very
different surroundings and we find very
different kind of plants and animals in
these two regions, isn’t it? Let us look
at two very different kind of organisms
from the desert and the sea – a camel
and a fish. The body structure of a camel
helps it to survive in desert conditions.
Camels have long legs which help to
Table 6.1 Animals, plants and other objects found in different surroundings
t s e r o f e h t n I s n i a t n u o m n O t r e s e d e h t n I a e s e h t n I ? r e h t o y n A
Rationalised 2023-24
Page 3


58 SCIENCE
6
The Living Organisms —
Characteristics and Habitats
P
aheli and Boojho went on
vacation to many places of
interest. One such trip took
them to the river Ganga in Rishikesh.
They climbed the mountains of the
Himalayas, where it was very cold. They
saw many kinds of trees on these
mountains — oaks, pines and deodars,
very different from the ones near their
home on the plains! In yet another trip,
they travelled to Rajasthan and moved
on camels through the hot desert. They
collected different kinds of cactus plants
from this trip. Finally, they went on a
trip to Puri and visited the sea beach,
dotted with casuarina trees. While
recollecting all the fun that they had on
these trips, a thought struck them. All
these places were so different from one
another, some were cold, some very hot
and dry, and some places so humid. And
yet all of them had many organisms
(living creatures) of various kinds.
They tried to think of a place on Earth
where there may not be any living
creatures. Boojho thought of  places near
his home. Inside the house, he tried the
cupboards. He had thought that there
may not be any living organisms here,
but he found one tiny spider in the
cupboard. Outside the home too, there
did not seem to be any place, he could
think of, that did not have living creatures
6.1 ORGANISMS AND THE
SURROUNDINGS WHERE THEY LIVE
Another thought that occurred to Paheli
and Boojho was about the kinds of living
organisms that were present in different
locations that they had visited. The
deserts had camels, the mountains had
goats and yak. Puri had some other
creatures — crabs on the beach and
such a variety of fish being caught by
the fishermen at the sea! And then,
there did seem to be some creatures like
ants that were present in all these
different locations. The kinds of plants
found in each of these regions were so
different from the plants of the other
regions. What about the surroundings
of some kind or the other (Fig. 6.1). Paheli
started thinking and reading about far
away places. She read that people have
even found tiny living organisms in the
openings of volcanoes!
Fig. 6.1 Search for living organisms
Rationalised 2023-24
59 THE LIVING ORGANISMS — CHARACTERISTICS AND HABITATS
in these different regions? Were they
the same?
Activity 1
Let us start with a forest. Think of all
the plants, animals and objects that can
be found there. List them in Column 1
of Table 6.1. List things, animals and
plants, found in the other regions that
are also shown in the table. You can
collect the examples scattered through
this chapter to fill Table 6.1. Discuss
also with your friends, parents and
teachers, to find more examples to fill
the tables. You can also consult many
interesting books in libraries that talk
of animals, plants and minerals of
different regions.
Try and include many plants,
animals and objects, big and small, in
each of the columns in this table. What
kind of objects will we find that may not
be animals or plants? Perhaps parts of
plants like dried leaves, or parts of
animals, like bones. We may also find
different kinds of soils and pebbles.
Water in the oceans may have salts
dissolved in it as discussed in Chapter
3. There could be many more objects.
As we go through the chapter, keep
adding more examples to Table 6.1. We
will discuss the table as we travel
through many more interesting places.
6.2 HABITAT AND ADAPTATION
What do you find from the plants and
animals listed in Activity 1? Did you find
a large variety in them? Look at what you
have entered in the column for the desert
and the column for the sea in Table 6.1.
Did you list very different kind of
organisms in these two columns?
What are the surroundings like, in
these two regions?
In the sea, plants and animals are
surrounded by saline (salty) water. Most
of them use  the air dissolved in water.
There is very little water available in
the desert. It is very hot in the day time
and very cold at night in the desert. The
animals and plants of the desert live on
the desert soil and breathe air from the
surroundings.
The sea and the desert are very
different surroundings and we find very
different kind of plants and animals in
these two regions, isn’t it? Let us look
at two very different kind of organisms
from the desert and the sea – a camel
and a fish. The body structure of a camel
helps it to survive in desert conditions.
Camels have long legs which help to
Table 6.1 Animals, plants and other objects found in different surroundings
t s e r o f e h t n I s n i a t n u o m n O t r e s e d e h t n I a e s e h t n I ? r e h t o y n A
Rationalised 2023-24
60 SCIENCE
keep their bodies away from the heat of
the sand (Fig. 6.2). They excrete small
amount of urine, their dung is dry and
they do not sweat. Since camels lose
very little water from their bodies, they
can live for many days without water.
Let us look at different kinds of fish.
Some of these are shown in Fig. 6.3.
There are so many kinds of fish, but, do
you see that they all have something
common about their shape? All the ones
shown here have the streamlined shape
that was discussed in Chapter 5. This
shape helps them move inside water.
Fish have slippery scales on their bodies.
These scales protect the fish and also
help in easy movement through water.
We discussed in Chapter 5, that fish
have flat fins and tails that help them
to change directions and keep their body
balance in water. Gills present in the
fish help them to use oxygen dissolved
in water.
We see that the features of a fish help
it to live inside water and the features of
a camel help it to survive in a desert.
We have taken only two examples
from a very wide variety of animals and
plants that live on the Earth. In all this
variety of organisms, we will find that
they have certain features that help
them live in the surroundings in which
they are normally found. The presence
of specific features or certain habits,
which enable an organism to live
naturally in a place is called adaptation.
Adaptation of organisms differ
depending on their place of dwelling.
That is why a fish cannot live out of
water and a camel cannot live in sea.
The place where organisms live is
called habitat. Habitat means a dwelling
place (a home). The habitat provides
food, water, air, shelter and other needs
to organisms. Several kinds of plants
and animals live in the same habitat.
The plants and animals that live on
land are said to live in terrestrial
habitats. Some examples of terrestrial
habitats are forests, grasslands, deserts,
coastal and mountain regions. On the
other hand, the habitats of plants and
Fig. 6.2 Camels in their surroundings Fig. 6.3 Different kinds of fish
Rationalised 2023-24
Page 4


58 SCIENCE
6
The Living Organisms —
Characteristics and Habitats
P
aheli and Boojho went on
vacation to many places of
interest. One such trip took
them to the river Ganga in Rishikesh.
They climbed the mountains of the
Himalayas, where it was very cold. They
saw many kinds of trees on these
mountains — oaks, pines and deodars,
very different from the ones near their
home on the plains! In yet another trip,
they travelled to Rajasthan and moved
on camels through the hot desert. They
collected different kinds of cactus plants
from this trip. Finally, they went on a
trip to Puri and visited the sea beach,
dotted with casuarina trees. While
recollecting all the fun that they had on
these trips, a thought struck them. All
these places were so different from one
another, some were cold, some very hot
and dry, and some places so humid. And
yet all of them had many organisms
(living creatures) of various kinds.
They tried to think of a place on Earth
where there may not be any living
creatures. Boojho thought of  places near
his home. Inside the house, he tried the
cupboards. He had thought that there
may not be any living organisms here,
but he found one tiny spider in the
cupboard. Outside the home too, there
did not seem to be any place, he could
think of, that did not have living creatures
6.1 ORGANISMS AND THE
SURROUNDINGS WHERE THEY LIVE
Another thought that occurred to Paheli
and Boojho was about the kinds of living
organisms that were present in different
locations that they had visited. The
deserts had camels, the mountains had
goats and yak. Puri had some other
creatures — crabs on the beach and
such a variety of fish being caught by
the fishermen at the sea! And then,
there did seem to be some creatures like
ants that were present in all these
different locations. The kinds of plants
found in each of these regions were so
different from the plants of the other
regions. What about the surroundings
of some kind or the other (Fig. 6.1). Paheli
started thinking and reading about far
away places. She read that people have
even found tiny living organisms in the
openings of volcanoes!
Fig. 6.1 Search for living organisms
Rationalised 2023-24
59 THE LIVING ORGANISMS — CHARACTERISTICS AND HABITATS
in these different regions? Were they
the same?
Activity 1
Let us start with a forest. Think of all
the plants, animals and objects that can
be found there. List them in Column 1
of Table 6.1. List things, animals and
plants, found in the other regions that
are also shown in the table. You can
collect the examples scattered through
this chapter to fill Table 6.1. Discuss
also with your friends, parents and
teachers, to find more examples to fill
the tables. You can also consult many
interesting books in libraries that talk
of animals, plants and minerals of
different regions.
Try and include many plants,
animals and objects, big and small, in
each of the columns in this table. What
kind of objects will we find that may not
be animals or plants? Perhaps parts of
plants like dried leaves, or parts of
animals, like bones. We may also find
different kinds of soils and pebbles.
Water in the oceans may have salts
dissolved in it as discussed in Chapter
3. There could be many more objects.
As we go through the chapter, keep
adding more examples to Table 6.1. We
will discuss the table as we travel
through many more interesting places.
6.2 HABITAT AND ADAPTATION
What do you find from the plants and
animals listed in Activity 1? Did you find
a large variety in them? Look at what you
have entered in the column for the desert
and the column for the sea in Table 6.1.
Did you list very different kind of
organisms in these two columns?
What are the surroundings like, in
these two regions?
In the sea, plants and animals are
surrounded by saline (salty) water. Most
of them use  the air dissolved in water.
There is very little water available in
the desert. It is very hot in the day time
and very cold at night in the desert. The
animals and plants of the desert live on
the desert soil and breathe air from the
surroundings.
The sea and the desert are very
different surroundings and we find very
different kind of plants and animals in
these two regions, isn’t it? Let us look
at two very different kind of organisms
from the desert and the sea – a camel
and a fish. The body structure of a camel
helps it to survive in desert conditions.
Camels have long legs which help to
Table 6.1 Animals, plants and other objects found in different surroundings
t s e r o f e h t n I s n i a t n u o m n O t r e s e d e h t n I a e s e h t n I ? r e h t o y n A
Rationalised 2023-24
60 SCIENCE
keep their bodies away from the heat of
the sand (Fig. 6.2). They excrete small
amount of urine, their dung is dry and
they do not sweat. Since camels lose
very little water from their bodies, they
can live for many days without water.
Let us look at different kinds of fish.
Some of these are shown in Fig. 6.3.
There are so many kinds of fish, but, do
you see that they all have something
common about their shape? All the ones
shown here have the streamlined shape
that was discussed in Chapter 5. This
shape helps them move inside water.
Fish have slippery scales on their bodies.
These scales protect the fish and also
help in easy movement through water.
We discussed in Chapter 5, that fish
have flat fins and tails that help them
to change directions and keep their body
balance in water. Gills present in the
fish help them to use oxygen dissolved
in water.
We see that the features of a fish help
it to live inside water and the features of
a camel help it to survive in a desert.
We have taken only two examples
from a very wide variety of animals and
plants that live on the Earth. In all this
variety of organisms, we will find that
they have certain features that help
them live in the surroundings in which
they are normally found. The presence
of specific features or certain habits,
which enable an organism to live
naturally in a place is called adaptation.
Adaptation of organisms differ
depending on their place of dwelling.
That is why a fish cannot live out of
water and a camel cannot live in sea.
The place where organisms live is
called habitat. Habitat means a dwelling
place (a home). The habitat provides
food, water, air, shelter and other needs
to organisms. Several kinds of plants
and animals live in the same habitat.
The plants and animals that live on
land are said to live in terrestrial
habitats. Some examples of terrestrial
habitats are forests, grasslands, deserts,
coastal and mountain regions. On the
other hand, the habitats of plants and
Fig. 6.2 Camels in their surroundings Fig. 6.3 Different kinds of fish
Rationalised 2023-24
61 THE LIVING ORGANISMS — CHARACTERISTICS AND HABITATS
animals that live in water are called
aquatic habitats. Lakes, rivers and
oceans are some examples of aquatic
habitats. There are large variations
among terrestrial habitats like forests,
grasslands, deserts, coastal and
mountain regions located in different
parts of the world.
The organisms, both plants and
animals, living in a habitat are its biotic
components. The non-living things such
as rocks, soil, air and water in
the habitat constitute its abiotic
components. Are sunlight and heat
biotic or abiotic components?
We know that some plants grow from
seeds. Let us look at some abiotic factors
and their effect on seeds as they grow
into young plants.
Activity 2
Recall Activity 7 in Chapter 4 — we made
sprouts from gram and maize seeds.
When the seed turned into a sprout, it
is said to have germinated. This is the
beginning of life of a new plant.
Collect some dry moong seeds. Keep
20-30 seeds aside and soak the rest in
water for a day. Divide the soaked seeds
into four parts. Keep one part
completely submerged in water for 3-4
days. Do not disturb the dry seeds and
those submerged in water. Keep one part
of soaked seeds in a sunny room and
another in a completely dark
region like a cupboard that does not
allow any light to come in. Keep the last
part in very cold surroundings, say, in
a refrigerator or with ice around them.
Rinse them and replace the water every
day. What do you notice, after a few
days? Do the seeds in all the five
conditions germinate uniformly? Do you
find slower or no germination in any of
these?
Do you realise that abiotic factors like
air, water, light and heat are important
for the growth of plants. In fact, abiotic
factors are important for all living
organisms.
We find that organisms exist in very
cold as well as very hot climates, isn’t
it? How do they manage to survive?
Adaptation is the method by which
organisms get well adjusted to the
climate.
There are some changes that can happen in an organism over a short period of
time to help them adjust to some changes in their surroundings. For instance,
if we live in the plains and suddenly go to high mountain regions, we may
experience difficulty in breathing and doing physical exercise for some days.
We need to breathe faster when we are on high mountains. After some days,
our body adjusts to the changed conditions on the high mountain. Such small
changes that take place in the body of a single organism over short periods, to
overcome small problems due to changes in the surroundings, are called
acclimatisation. These changes are different from the adaptations that take
place over thousands of years.
Rationalised 2023-24
Page 5


58 SCIENCE
6
The Living Organisms —
Characteristics and Habitats
P
aheli and Boojho went on
vacation to many places of
interest. One such trip took
them to the river Ganga in Rishikesh.
They climbed the mountains of the
Himalayas, where it was very cold. They
saw many kinds of trees on these
mountains — oaks, pines and deodars,
very different from the ones near their
home on the plains! In yet another trip,
they travelled to Rajasthan and moved
on camels through the hot desert. They
collected different kinds of cactus plants
from this trip. Finally, they went on a
trip to Puri and visited the sea beach,
dotted with casuarina trees. While
recollecting all the fun that they had on
these trips, a thought struck them. All
these places were so different from one
another, some were cold, some very hot
and dry, and some places so humid. And
yet all of them had many organisms
(living creatures) of various kinds.
They tried to think of a place on Earth
where there may not be any living
creatures. Boojho thought of  places near
his home. Inside the house, he tried the
cupboards. He had thought that there
may not be any living organisms here,
but he found one tiny spider in the
cupboard. Outside the home too, there
did not seem to be any place, he could
think of, that did not have living creatures
6.1 ORGANISMS AND THE
SURROUNDINGS WHERE THEY LIVE
Another thought that occurred to Paheli
and Boojho was about the kinds of living
organisms that were present in different
locations that they had visited. The
deserts had camels, the mountains had
goats and yak. Puri had some other
creatures — crabs on the beach and
such a variety of fish being caught by
the fishermen at the sea! And then,
there did seem to be some creatures like
ants that were present in all these
different locations. The kinds of plants
found in each of these regions were so
different from the plants of the other
regions. What about the surroundings
of some kind or the other (Fig. 6.1). Paheli
started thinking and reading about far
away places. She read that people have
even found tiny living organisms in the
openings of volcanoes!
Fig. 6.1 Search for living organisms
Rationalised 2023-24
59 THE LIVING ORGANISMS — CHARACTERISTICS AND HABITATS
in these different regions? Were they
the same?
Activity 1
Let us start with a forest. Think of all
the plants, animals and objects that can
be found there. List them in Column 1
of Table 6.1. List things, animals and
plants, found in the other regions that
are also shown in the table. You can
collect the examples scattered through
this chapter to fill Table 6.1. Discuss
also with your friends, parents and
teachers, to find more examples to fill
the tables. You can also consult many
interesting books in libraries that talk
of animals, plants and minerals of
different regions.
Try and include many plants,
animals and objects, big and small, in
each of the columns in this table. What
kind of objects will we find that may not
be animals or plants? Perhaps parts of
plants like dried leaves, or parts of
animals, like bones. We may also find
different kinds of soils and pebbles.
Water in the oceans may have salts
dissolved in it as discussed in Chapter
3. There could be many more objects.
As we go through the chapter, keep
adding more examples to Table 6.1. We
will discuss the table as we travel
through many more interesting places.
6.2 HABITAT AND ADAPTATION
What do you find from the plants and
animals listed in Activity 1? Did you find
a large variety in them? Look at what you
have entered in the column for the desert
and the column for the sea in Table 6.1.
Did you list very different kind of
organisms in these two columns?
What are the surroundings like, in
these two regions?
In the sea, plants and animals are
surrounded by saline (salty) water. Most
of them use  the air dissolved in water.
There is very little water available in
the desert. It is very hot in the day time
and very cold at night in the desert. The
animals and plants of the desert live on
the desert soil and breathe air from the
surroundings.
The sea and the desert are very
different surroundings and we find very
different kind of plants and animals in
these two regions, isn’t it? Let us look
at two very different kind of organisms
from the desert and the sea – a camel
and a fish. The body structure of a camel
helps it to survive in desert conditions.
Camels have long legs which help to
Table 6.1 Animals, plants and other objects found in different surroundings
t s e r o f e h t n I s n i a t n u o m n O t r e s e d e h t n I a e s e h t n I ? r e h t o y n A
Rationalised 2023-24
60 SCIENCE
keep their bodies away from the heat of
the sand (Fig. 6.2). They excrete small
amount of urine, their dung is dry and
they do not sweat. Since camels lose
very little water from their bodies, they
can live for many days without water.
Let us look at different kinds of fish.
Some of these are shown in Fig. 6.3.
There are so many kinds of fish, but, do
you see that they all have something
common about their shape? All the ones
shown here have the streamlined shape
that was discussed in Chapter 5. This
shape helps them move inside water.
Fish have slippery scales on their bodies.
These scales protect the fish and also
help in easy movement through water.
We discussed in Chapter 5, that fish
have flat fins and tails that help them
to change directions and keep their body
balance in water. Gills present in the
fish help them to use oxygen dissolved
in water.
We see that the features of a fish help
it to live inside water and the features of
a camel help it to survive in a desert.
We have taken only two examples
from a very wide variety of animals and
plants that live on the Earth. In all this
variety of organisms, we will find that
they have certain features that help
them live in the surroundings in which
they are normally found. The presence
of specific features or certain habits,
which enable an organism to live
naturally in a place is called adaptation.
Adaptation of organisms differ
depending on their place of dwelling.
That is why a fish cannot live out of
water and a camel cannot live in sea.
The place where organisms live is
called habitat. Habitat means a dwelling
place (a home). The habitat provides
food, water, air, shelter and other needs
to organisms. Several kinds of plants
and animals live in the same habitat.
The plants and animals that live on
land are said to live in terrestrial
habitats. Some examples of terrestrial
habitats are forests, grasslands, deserts,
coastal and mountain regions. On the
other hand, the habitats of plants and
Fig. 6.2 Camels in their surroundings Fig. 6.3 Different kinds of fish
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61 THE LIVING ORGANISMS — CHARACTERISTICS AND HABITATS
animals that live in water are called
aquatic habitats. Lakes, rivers and
oceans are some examples of aquatic
habitats. There are large variations
among terrestrial habitats like forests,
grasslands, deserts, coastal and
mountain regions located in different
parts of the world.
The organisms, both plants and
animals, living in a habitat are its biotic
components. The non-living things such
as rocks, soil, air and water in
the habitat constitute its abiotic
components. Are sunlight and heat
biotic or abiotic components?
We know that some plants grow from
seeds. Let us look at some abiotic factors
and their effect on seeds as they grow
into young plants.
Activity 2
Recall Activity 7 in Chapter 4 — we made
sprouts from gram and maize seeds.
When the seed turned into a sprout, it
is said to have germinated. This is the
beginning of life of a new plant.
Collect some dry moong seeds. Keep
20-30 seeds aside and soak the rest in
water for a day. Divide the soaked seeds
into four parts. Keep one part
completely submerged in water for 3-4
days. Do not disturb the dry seeds and
those submerged in water. Keep one part
of soaked seeds in a sunny room and
another in a completely dark
region like a cupboard that does not
allow any light to come in. Keep the last
part in very cold surroundings, say, in
a refrigerator or with ice around them.
Rinse them and replace the water every
day. What do you notice, after a few
days? Do the seeds in all the five
conditions germinate uniformly? Do you
find slower or no germination in any of
these?
Do you realise that abiotic factors like
air, water, light and heat are important
for the growth of plants. In fact, abiotic
factors are important for all living
organisms.
We find that organisms exist in very
cold as well as very hot climates, isn’t
it? How do they manage to survive?
Adaptation is the method by which
organisms get well adjusted to the
climate.
There are some changes that can happen in an organism over a short period of
time to help them adjust to some changes in their surroundings. For instance,
if we live in the plains and suddenly go to high mountain regions, we may
experience difficulty in breathing and doing physical exercise for some days.
We need to breathe faster when we are on high mountains. After some days,
our body adjusts to the changed conditions on the high mountain. Such small
changes that take place in the body of a single organism over short periods, to
overcome small problems due to changes in the surroundings, are called
acclimatisation. These changes are different from the adaptations that take
place over thousands of years.
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62 SCIENCE
Adaptation does not take place in a
short time because the abiotic factors of
a region also change very slowly. Those
organisms which cannot adapt to these
changes die, and only the adapted ones
survive. Organisms adapt to different
abiotic factors in different ways. This
results in a wide variety of organisms in
different habitats.
Let us look at some habitats,
understood the abiotic factors and the
adaptations of animals in these habitats.
6.3 A JOURNEY THROUGH DIFFERENT
HABITATS
Some Terrestrial Habitats
Deserts
We discussed the abiotic factors of a
desert and the adaptations in camels.
What about other animals and plants
that are found in deserts? Do they
have the same kind of adaptations?
There are desert animals like rats
and snakes, which do not have long legs
that a camel has. To stay away from the
intense heat during the day, they stay
in burrows deep in the sand (Fig 6.4).
These animals come out only during the
night, when it is cooler.
Fig. 6.5 shows some typical plants
that grow in a desert. How are these
adapted to the desert?
Activity 3
Bring a potted cactus and a leafy plant
to the classroom.  Tie polythene bags to
some parts of the two plants, as was
done for Activity 4 in Chapter 4, where
we studied transpiration in plants.
Leave the potted plants in the sun and
observe after a few hours. What do you
see? Do you notice any difference in the
amount of water collected in the two
polythene bags?
Desert plants lose very little water
through transpiration. The leaves in
desert plants are either absent, very
small, or they are in the form of spines.
This helps in reducing loss of water from
the leaves through transpiration. The
leaf-like structure you see in a cactus
is, in fact, its stem (Fig. 6.5).
Photosynthesis in these plants is
usually carried out by the stems. The
Fig. 6.4 Desert animals in burrows
Fig. 6.5 Some typical plants that grow in desert
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