New Creative Science Book 9

MEMORY TIPS

The bones of flying birds are provided with air cavities to make them light and
rigid. Such bones are called pneumatic bones.

v. Class: Mammalia (Mammals)

They are the most advanced organisms in the animal kingdom:
i) They have mammary glands in their body.
ii) They are viviparous (give birth to their babies directly).
iii) They have a pair of external ears called pinnae.
iv) They have a four-chambered heart.
v) They respire through lungs.
vi) They show sexual dimorphism (i.e. male and female can be distinguished

from their physical appearance).
vii) They have two pairs of pentadactyl limbs (five fingers in each limb).
viii) Their body is covered with hair.

Examples: human beings, bat, monkey, dolphin, whale, duck billed platypus,
etc.

Whale Dolphin

Man

Bat Monkey Rat

MEMORY TIPS

 Animals having two pairs of (four) limbs are known as tetrapoda. Amphibians,
reptiles and mammals are tetrapods.

 Duck billed platypus and spiny ant-eaters lay eggs being mammalian.
 Sexual dimorphism is also exbited in Aves.

QUESTIONS >>
# What is the difference between the egg of a hen and the egg of a fish?

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ACTIVITY

Observe some common animals and plants and classify them with their salient features.

Differences between warm-blooded and cold-blooded animals

S.N. Cold Blooded Animals S.N. Warm Blooded Animals
(Poikilothermic) (Homoeothermic Animals)

1. Their body temperature changes 1. Their body temperature remains

according to the surrounding constant.

temperature.

2. They hibernate and aestivate. 2. They do not undergo hibernation
and aestivation.

3. Less food is necessary for them. 3. More food for the production of

Examples: Reptiles, Amphibians and energy is needed.

Pisces. Example: Aves and Mammals

Classification of some plants and animals

1. Pinus 2. Maize
Kingdom : Plantae
Division : Tracheophyta Kingdom : Plantae
Sub - division : Gymnosperm
Example : Pinus Division : Tracheophyta

Sub - division : Angiosperm

Class : Monocot

Example : Maize (Zea mays)

3. Pea 4. Rohu

Kingdom : Plantae Kingdom : Animal

Division : Tracheophyta Phylum: Chordata

Sub - division : Angiosperm Sub - phylum :Vertebrata

Class : Dicot Class : Pieces

Example : Pea(Pisum sativum) Example : Rohu

Mosquito

Mosquitoes are harmful insects. They are the vectors for many dangerous

diseases like malaria, filariasis, dengue, yellow fever, encephalitis, etc. Mosquitoes in

places with tropical climate all over the world. The systematic position of mosquito

is as follows:

Kingdom : Animal

Phylum: Arthropoda

Class : Insecta

Type: Mosquito

248 | Classification of Living Beings

Habit and habitat

Mosquitoes are found in tropical regions in damp and moist places. They are
nocturnal animals. Male mosquitoes only feed on plant juice but female mosquitoes
feed on the blood of mammals. An adult mosquito flies well and covers a long distance
in a single flight.

There are many genera of mosquitoes found in the world as anopheles, culex,
aedes, mansonia, etc. Among them anopheles and culex mosquitoes are common in
Nepal. The anopheles mosquitoes transmit malaria and culex mosquitoes transmit
filariasis and dengue.

Mosquitoes transmit not only disease but they also bite human beings which is
very painful and irritating. They annoy us at night.

MEMORY TIPS
Female mosquitoes become aggressive after copulation.

QUESTIONS >>
# Why are mosquitoes harmful to us?

External morphology

A mosquito is a greyish black insect which is about 3-4 mm in length. Its body is
covered with minute scales and the body is divided into head, thorax and abdomen.

1. Head
It has a small and almost spherical head. The head bears a pair of compound

eyes, a pair of antennae and the mouth parts. The antennae of the male are densely
covered with long hair while those of female are with short hair.

The mouth parts of females have piercing and sucking mode but the piercing
organs are reduced in the case of male mosquitoes. So, male cannot pierce the skin
and hence cannot suck the blood of mammals.

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2. Thorax

It consists of three parts i.e. prothorax, mesothorax and metathorax. Each part
has a pair of jointed legs. The thorax also bears a pair of wings. Females have wings
that are larger but in case of males they are shorter.

3. Abdomen

The abdomen of a mosquito is slender with nine segments. It bears the anus on
the eight segments and a genital pore on the ninth segment. In male mosquitoes, the
ninth segment bears an anal style which helps them in copulation.

Differences between male and female mosquitoes

S.N. Males S.N. Females

1. They feed only on the plant 1. They feed on the blood of human

juices. beings and other mammals.

2. Their antenna has long and 2. Their antenna has short hair.
dense hair.

3. Their abdomen is smaller 3. Their abdomen is longer compared

compared to that of the female. to that of the male.

4. Their mouth parts are used for 4. Their mouth parts are used for

only sucking. piercing and sucking.

Life Cycle of Mosquito

eggs

eggs

larva

larva pupa
pupa
adult

adult

Life cycle of culex mosquito Life cycle of anopheles mosquito

a. Eggs Eggs of culex and anopheles
A female anopheles mosquito lays 40 to 100

eggs and a female culex mosquito lays 200-400 eggs
at a time. They lay eggs in stagnant water of pond

250 | Classification of Living Beings

and ditches which is rich in organic matters.

The eggs of a culex mosquito are cigar-shaped and they are glued together to
form a small floating raft whereas, the eggs of anopheles mosquitoes are spindle-
shaped and they float separately on water.

b. Larva

After two to three days, the eggs hatch into larvae. The larvae are also known as
wriggler because they swim actively in water by wriggling movement. The body of a
larva is divided into head, thorax and abdomen.

The larva of a culex at rest hangs at an angle from the surface of water whereas
the larva of anopheles mosquitoes lies parallel to the surface of water as shown in the
figure.

Head Gills Head Siphon

Thorax Abdomen Siphon Thorax Abdomen Gills
Larva of anopheles
Larva of culex

The larva of a mosquito posses a siphon in its eighth segment of the abdomen
in which a pair of spiracles are present. The spiracles help in respiration. So, when
oil is spread on the water, it blocks the spiracles and hence the larvae die due to
suffocation. The larvae of the mosquito moult four times.

c. Pupa

After six to seven days, the larva moults into a pupa which is commonly known as
a tumbler. Unlike the pupa stage of other insects, the pupa stage of a mosquito is very
active and it always swims in water. The pupae have comma shaped body structures.
The body is divided into cephalothorax and abdomen. Pupae do not feed at all.

Trumpet

Abdomen Eye Abdomen
Cephalothorax
Anopheles
Culex
New Creative Science, Class 9 | 251

d. Adult mosquito

After 2-3 days the pupa develops into a
fully grown young mosquito or imago. The
adult female again lays eggs after copulation
and hence the life history of the mosquito
continues.

MEMORY TIPS

The period of rapid transformation from larval to the adult stage is called
metamorphosis.

Differences between life history of culex and anopheles mosquitoes

S.N. Culex S.N. Anopheles

Eggs

1. Eggs lie in clusters on the surface of 1. Eggs lie singly and horizontally on

water making rafts. the surface of water.

2. Eggs are cigar shaped. 2. Eggs are boat-shaped.

3. Lateral air floats are not provided. 3. Eggs have lateral air floats.

4. Culex lay eggs on dirty water. 4. Anopheles lay eggs on clean water.

Larvae

1. The larva of culex is a bottom 1. The larva of anopheles is a surface

feeder. feeder.

2. It has longer respiratory siphon. 2. It has shorter respiratory siphon.

3. It makes an angle inside water. 3. It lies parallel with water surface.

Pupa

1. The pupa has no colour. 1. The pupa has green colour.

2. They have longer respiratory 2. They have shorter respiratory

trumpets. trumpets.

3. Their abdomen is slightly bent. 3. Their abdomen is bend more than
that of a culex.

Adult

1. Their body is well-developed with 1. Their body has delicate legs.
stouter legs.

2. Wings are transparent. 2. Wings are spotted.

3. They can fly for a long distance. 3. They cannot fly for a long distance.

4. In females, small palpi are present 4. The proboscis and palpi are of some

near the proboscis. length in males and females.

252 | Classification of Living Beings

5. At rest, the state the body lies 5. The body is inclined at an angle of

parallel to the surface. 45° to the surface.

6. The female culex transmits filaria 6. The female anopheles transmits

parasite from person to person. malaria parasite from person to

person.

Mosquitoes and diseases

Mosquitoes are the vectors of many dreadful diseases. When an infected female
mosquito bites and sucks blood of a healthy person, the micro-organisms causing diseases
enter inside the person’s body and infect the various body parts. The mosquito-borne
diseases are as summarized below:

1. Malaria

Malaria is caused by an intracellular blood parasite, i.e. Plasmodium vivax.
Female anopheles mosquito is the carrier of this parasite. The parasite destroys the
RBC. As a result, there is a high fever at an interval of time. Chilling and sweating are
the symptoms of malaria fever.

2. Elephantiasis or Filariasis

It is caused by a parasitic round worm. Female culex mosquito is the carrier of
this parasite. In this disease, the patient suffers with the enlargement of limbs.

3. Dengue

It is caused by virus. Culex and aedes mosquitoes are the carrier of this disease.
It is characterized by a chin limbs, fever and rashes.

4. Yellow fever

It is also caused by virus. The aedes mosquito is the carrier of this disease. It is
characterized by high fever, internal bleeding, anaemia, destruction of the liver, etc.

5. Encephalitis

It is also caused by virus. Culex and Aedes mosquitoes are the carriers of this
disease. It is characterized by high fever.

Controlling measures of mosquitoes

Mosquitoes can be destroyed in the following ways:

a. Destruction of breeding places
The stagnant water of ponds and ditches is the breeding place of mosquitoes. The

egg, larva and pupa stage of mosquitoes grow into the water. So, by the destruction of
such places the mosquitoes could be controlled in an effective way.

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b. Destruction of larvae and pupae
Spreading oil or kerosene on the stagnant water of ditches, gutters and drains

blocks the spiracles of larvae and pupae. Hence, they die due to the suffocation.

Spraying DDT, BHC and other insecticides also destroy the mosquito larvae and
pupae. Cultivation of larvicidal fishes like sticklebacks, minnows, Gambusia, trouts,
etc. which feed on the larvae and pupae controls the mosquito.

c. Destruction of adult mosquitoes
Adult mosquitoes can be killed or driven by fumigation. It is the process of

producing poisonous fumes by burning sulphur, pyrethrum, tar, camphor, etc. to
repel or kill mosquitoes.

Similarly, spraying DDT, flit, pysethrum, etc. can control mosquitoes.

d. Personal protection against mosquito bites
Oil or anti mosquito cream (odomos) should be applied on the open areas of

the body. Mosquito nets should be used while sleeping. Wire nets should be used in
doors and windows.

ANSWER WRITING SKILLS

1) Classify the following living organisms.

a. Spirogyra b. Fern
Kingdom :
Division : Plantae Kingdom : Plantae
Type: Algae
Spirogyra Division : Tracheophyta

Sub-division : Pteridophyta

Type: Fern

c. Hydra Animalia d. Housefly Animalia
Kingdom : Coelenterata Kingdom : Arthropoda
Phylum : Hydra Phylum: Insecta
Type : Class : Housefly
Type :

2. Bryophytes are called amphibian plants. Why?
Ü Although bryophytes are essentially terrestrial. They need water for reproduction

as well as in the various steps of their life cycle. So, bryophytes are called
amphibian plants.

3. Why are algae called autotrophs?
Ü Algae are called autotrophs because they can prepare their own food as they

have chlorophyll to trap the sunlight.

4. The earthworm is called a hermaphrodite animal. Give reason.

254 | Classification of Living Beings

Ü In the body of an earthworm, both male and female reproductive organs are
present. So, it is called a hermaphrodite animal.

5. Why is a sycon called a sessile?

Ü A sycon is called a sessile because it does not have locomotory organs in its body
and remains attached to the substratum throughout its life.

6. The arthropoda is the largest phylum in the animal kingdom. Why?

Ü The arthropoda is called the largest phylum of the animal kingdom because it
contains the largest number of species. The animals of this phylum can live in air,
water as well as on land. Similarly, they can breed a number of times and in each
breed, they produce a large number of species.

7. Why are female mosquitoes harmful to us?

Ü Male mosquitoes feed on the plant juice only but female mosquitoes suck the
blood of human beings. In that course, they transmit various diseases like
malaria, filariasis, yellow fever, etc. So, they are harmful.

8. Spraying oil or kerosene on the stagnant water controls the mosquito. How?

Ü When oil or kerosene is spread on the stagnant water it forms a thin layer over
the surface of water. It blocks the respiratory organs or spiracles of the larvae and
pupae of the mosquitoes. Hence, they die due to the suffocation.

9. Male mosquitoes cannot bite and suck the blood from mammals. Why?

Ü The piercing organ in the male mosquito is reduced and the mouth is only
of sucking type. So, the male mosquito cannot bite and suck the blood from
mammals and only sucks the plant juices.

10. Differentiate between male ascaris and female ascaris.

S.N. Male ascaris S.N. Female ascaris

1. It is smaller than a female. 1. It is larger than a male.

2. Its tail is curved. 2. Its tail is straight and pointed.

3. Its tail contains a pair of penial 3. Penial setae is absent in its tail.
setae.

11. Differentiate between a tapeworm and a round worm.

S.N. Tapeworm S.N. Roundworm

1. It is a member of the phylum 1. It is the member of the phylum

platy- helminthes. aschelminthes.

2. Its body is segmented. 2. Its body is unsegmented.

3. Its body is flat. 3. Its body is long, cylindrical or

thread-like.

4. It is a hermaphrodite animal. 4. It is an unisexual animal.

New Creative Science, Class 9 | 255

SUMMARY
” The process of grouping organisms into different categories according to

their similarities and differences is called the classification of living beings.
” The system of assigning two names to a living organism is called the Binomial

System of Nomenclature.
” Carolus Von Linnaeus is known as the Father of taxonomy.
” A genus is the group of closely related species.
” A species is the group of closely related organisms which can interbreed freely

and produce fertile progeny.
” Cryptogams are non-flowering plants.
” Cryptogams are divided into three divisions i.e. algae, bryophyta and

tracheophyta.
” Pteridophytes are the most advanced non-flowering plants.
” The animals which lack a spinal chord, a backbone or a vertebral column are

called invertebrates.
” Invertebrates are divided into eight phyla.
” Vertebrates have only one phylum which is called chordate. It has five classes.
” Mosquitoes are the harmful insects found in tropical climate.
” There are mainly two genera of mosquitoes found in Nepal i.e. anopheles and

culex.
” Anopheles mosquitoes transmit malaria and culex mosquitoes transmit

filariasis.
” The adult anopheles rests at an angle of 45° to the surface and the adult culex

mosquito rests parallel to the surface.
” Mosquitoes can be controlled by spraying insecticides like DDT, BHC, etc.

They can be controlled by spreading oil and kerosene in the stagnant water as
well as by using using mosquito nets.

EXERCISE

17. What is the classification of living beings? Why is the classification of living beings
necessary?

18. Define.

(a) Taxonomy (b) Nomenclature (c) Classification (d) Genus

19. What do you mean by the Binomial System of Nomenclature? Give two examples.

20. Write two characteristics each of the following.

(a) Algae (b) Pteridophyta (c) Bryophyta

256 | Classification of Living Beings

21. Write differences between. (b) Monera and protista
(a) Algae and fungi (d) Male ascaris and female ascaris
(c) Bryophyta and pteridophyta
(e) Leech and tapeworm

22. Give reasons.
(a) Bryophytes are called amphibian plants.
(b) A fern plant is known as vascular cryptogams.
(c) Poriferons are called sessile.
(d) A housefly is an arthopoda.
(e) A starfish is an echinodermata.

23. Write three characteristics each of the following phylum.

(a) Porifera (b) Echinodermata (c) Arthropoda

24. Define the following terms.

(a) Triploblastic (b) Hermaphrodite (c) Autotrophic organisms
(d) Sessile (e) Cnidoblast

25. Classify the following organisms with their two salient features.

(a) ulothrix (b) mushroom (c) moss (d) fern (e) amoeba
(j) sea-urchin
(f) sponge (g) hydra (h) octopus (i) ant

26. Classify and write down any three characteristics of each pinus, maize, wheat
and cycas.

27. Write down any three characteristics and three examples of each class pisces,
amphibia, reptilian, aves and mammalia.

28. Classify rohu, frog, lizard, pigeon and cow.
29. Write the systematic position the mosquitoes. Why are mosquitoes harmful to

us?
30. Why are female mosquitoes more harmful to us?
31. Write two differences between male and female mosquitoes.
32. Write two differences between culex and anopheles mosquitoes.
33. Write the name of the diseases transmitted by mosquitoes.
34. Draw diagrams of the life cycle of anopheles and culex mosquitoes.
35. What are the differences between the eggs of anopheles and culex mosquitoes?
36. Why do mosquito larvae die when oil is sprayed on water?
37. Give two ways to control mosquitoes.
38. Modern science and technology have made different types of insecticides like

DDT, BHC, etc.The use of these insecticides is not a matter of interest but it is an
obligation. Justify the statement.

New Creative Science, Class 9 | 257

39. Name the different stages in the life cycle of anopheles mosquitoes.

40. Eggs of which mosquitoes are given in the figure?

AB

41. In the figure of given larvae which one 42. Identify the pupa of culex and

is culex and which one is anopheles? anopheles.

AA

B B

A

B GLOSSARY
C

Autotrophs: the living beings which can make their own food

Hermaphrodite: having male and female reproductive organs in the same body

Vertebral

column: The strong bone made by combining many vertebrae

Heterotrophs: the living beings which cannot make their own food

Marine: sea water

Ditches: small pits with water

Copulate: to have sex

Wriggling: twisting or turning body parts with quick short movements



258 | Classification of Living Beings

UNIT

17 ADAPTATION OF ORGANISMS

About the Scientist Introduction

M.S. Swaminathan The earth has great diversity in its geography and
climatic condition which directly influences the lifestyle of
Indian geneticist Monkombu the creatures living in that habitat. For example, the desert
Sambasivan Swaminathan plants have thorny leaves, deep-seated roots in soil and
used his skills in genetic fleshy barks whereas the plants in temperate and tropical
engineering to promote the climates are tall and have broad leaves. Similarly, the
green revolution in Asia. plants found in extremely cold climate have needle-shaped
He persuaded the farmers leaves arranged in cone shapes. This change in behaviour
to grow the new varieties of is also seen in case of animals. As we know, the Yaks
wheat developed by him. He (found in Himalayan region) have thick fur. Thus, living
even went on to set up about beings must change their body structure according to the
two thousand model farms to habitat they live in, otherwise, they cannot exist. However,
show the wonders of this new the change is very slow which we cannot notice in our life
variety of seeds. time. Every organism is well adopted to the environment
where it survives. Thus, the adjustment of organisms with
their environment is called adaptation. Adaptation is
necessary to increase the possibility of getting food, shelter
and protection for living organisms for their long life.

A. Aquatic adaptation

It is a known fact that two-third of the earth is covered
with water. There are a vast numbers of living creatures
which live in water and they have changed their body
structure accordingly. The adaptational characters of
aquatic plants and animals are discussed below.

(a) Adaptational characteristics of aquatic plants

The plants which grow in the aquatic habitat are called
hydrophytes. Hydrophytes are of the following types.

i) Free floating plants e.g. water hyacinth, pistia,
lemna, wolffia, etc.

New Creative Science, Class 9 | 259

Pistia Wolffia Jussiaea Water hyacinth

ii) Submerged floating plants e.g. utricularia, hydrilla, vallisneria, chara, etc.

Vallisneria Hydrilla Chara

iii) Rooted submerged or with freely floating leaves e.g. marsilea, lotus, water
lily, ranunculus, sagittaria, etc.

Lotus Water lily Marsilea Ranunculus Sagittaria

All hydrophytes are so adjusted that they do not decay in water and that they
can get food and survive in the aquatic habitat. The adaptational characteristics of
hydrophytes are as given below.

i) Their root system is poorly developed. They do not have root caps or root hairs.

ii) The submerged hydrophytes have long, slender, spongy and flexible stems
to move easily in the direction of water current.

iii) The leaves are thin and small in case of submerged plants whereas in the
free floating plants, the leaves are large and broad with air spaces which
make them lighter to float on water.

iv) Their conducting tissues (xylem and phloem) are poorly developed.

v) Floating plants have aerenchymatous tissues which provide buoyancy to
make them easy to float.

vi) Hydrophytes are covered with waxy layer which prevents water from
entering them and protects the plants from decaying.

v MEMORY TIPS

Ranunculus and limnophilia have two types of leaves. The forked leaves are inside
water and unforked leaves outside water.

260 | Adaptation of Organisms

QUESTIONS >>
# Why are aquatic plants covered with a waxy layer?

(b) Adaptational characteristics of aquatic animals

Not only plants but a large number of animals also inhabit inside water. From the
fresh water ponds and rivers to the deepest marine water, there are a vast numbers of
creatures which live in water. They grow, multiply and adjust in water. The following
are the major adaptational characters of the aquatic animals.

i) Their body is streamlined or boat-shaped so that they can swim easily in
water by reducing friction.

ii) The respiratory organs of aquatic animals are the pairs of gills. Dolphins
and whale- like sea mammals respire through lungs and they take in oxygen
from the air.

iii) They have fins (e.g. fish) or flippers and paddles (e.g. whale) or webbed-legs
(e.g. frog, tortoise) for locomotion or swimming in water.

iv) Their body is covered with waterproof scales or cuticle to protect the body
from decaying due to the entry of water inside it.

v) They have a long tail which helps to change the direction while swimming.

vi) The aquatic animals are cold-blooded animals or poikilothermic animals i.e.
they can adjust their body temperature to live in water in all seasons.

vii) They have air sacs or air bladder in their body which makes their body light
and easy for them to swim inside the water.

Fish Dolphin Frog Tortoise

B. Terrestrial adaptation

The adjustment of organisms on land is called terrestrial adaptation. On land,
plants and animals adapt themselves accordingly.

Terrestrial plants

Due to the climatic diversity and geographical conditions, there is a great
diversity in the features of plants. The terrestrial plants are divided into mesophytes
and xerophytes according to the physical condition.

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Adaptational characters of mesophytes

The plants which grow on a mesic habitat are called mesophytes e.g. apple,
mango, mustard, rose, etc.

Mango tree Rose plant Sunflower plant

The adaptational characters of mesophytes are as given below.
i) They have a well-developed root system and shoot system to grow on a

mesic climate.
ii) The vascular tissues (xylem and phloem) are well developed for the

conduction of food and water throughout the plant body.
iii) The leaves are large, broad, and thin with a number of stomata.
iv) The climber plants have tendrils for supporting their weak stem.

Adaptational characters of xerophytes

The plants which grow in the extreme climate, either dry and hot or dry and cold
climate are called xerophytes. Examples, cactus, agave, aloe, opuntia, pine, juniper, etc.

Cactus Agave Juniper

The adaptational characters of xerophytes are given below.
i) They have a well-developed root system which is fixed very deeply in the

soil to absorb water from soil. There are a number of root hairs present in
the roots.
ii) The leaves are reduced to thorns (in case of desert plants) and they are needle
shaped (in case of plants found in cold climate) to reduce transpiration and
prevent the leaves from decaying due to the snow respectively.

262 | Adaptation of Organisms

iii) The stems of desert plants are thick fleshy to store water.
iv) The leaves and stem have thick cuticle to reduce the loss of water.
v) The stomata are deep-seated which avoid the loss of water.
vi) The leaves of the plants found in cold climate are arranged in the shape of a

cone to drop the snow falling on them.

Terrestrial animals

The animals which live on land are called terrestrial animals. Their body structure
is modified according to their nature and habitat. The terrestrial animals are divided
into the following types according to their habitat.

i) Cursorial animals ii) Fossorial animals iii) Arboreal animals

iv) Aerial animals v) Desert animals

i. Adaptational characters of cursorial animals

The animals which live in open places are called cursorial animals, e.g. elephant,
deer, horse, leopard, etc. Their adaptational characters are as follows.

i) Their body is streamlined to run faster on the ground by reducing friction of air.
ii) They have long and strong limbs for fast running. Some animals like horses,

buffaloes have hooves in their feet.
iii) Their body muscles are also well developed.

Rhinoceros Tiger Leopard Deer Horse

ii. Adaptational characters of fossorial animals

The animals which are adapted to live in the burrow or the animals which live in
burrows or holes are known as fossorial animals, e.g. rats, rabbits, moles, anteaters,
etc. Their adaptational characters are as follows.

i) They have a small head with a strong snout, which helps them for digging holes
in the soil.

ii) They have short and strong forelimbs as well as small eyes.

Rabbit Rat

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iii. Adaptational characters of arboreal animals

The animals which spend most of their time in trees are called arboreal animals.
They are well adapted for the climbing mode of habitat as,

i) They have longer and stronger forelimbs.
ii) The muscles of their chest are well-developed.
iii) They have a stout body i.e. their ribs are very much curved.
iv) Some of them have a long tail for balancing the body.
v) They have patagium-like organs for gliding flight.

Squirrel Monkey

MEMORY TIPS

The legs of lizards with adhesive pads that help them to hold the wall or other
surfaces.

QUESTIONS >>
# Why is the chest muscles of arboreal animals strong?
# What is the use of a long tail of arboreal animals?

iv. Adaptational characters of aerial animals

The animals which spend most of their life time in air are called aerial animals,
e.g. birds, butterflies, some insects, etc. The adaptational characters of aerial animals
are as follows:

i) Their body is streamlined which reduces the friction of air during their
flight.

ii) Their forelimbs are modified into wings and their body is covered with
feathers.

iii) They have hollow and spongy bones filled with air which makes their body
light for flight.

iv) They have a tail for balancing their body during the flight.
v) They have sharp and well developed eyes but they do not have external

ears.
vi) They have a small head with a toothless beak.
vii) Their flight muscles or breast muscles are very strong.
viii) They have different shaped beaks according to their feeding habit.

264 | Adaptation of Organisms

ix) Their hind limbs are also modified for grasping, scratching, swimming,
perching, climbing and running.

Beaks of different birds

Claws of different birds

v. Adaptational characters of desert animals
The desert animals needs a special body structure to adjust themselves in the dry

and hot climate of the deserts, e.g. camel, lizard, rodents etc. They are also known as
xeric animals. The major adaptational characters of desert animals are as given below.

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i) They have thick skin to prevent the loss of water.

ii) They have dull colour which protects them from their enemies as the colour
gets matched with the sand of the desert.

iii) They have strong senses of sight, smell and hearing.

iv) Most of them are nocturnal.

v) They have water pouches in their body which store water (e.g. camel) and
thick layers of fat which store food (e.g. camel).

vi) Camels have strong limbs with a pad on the flat hoofs which helps them to
walk on the hot sand of desert.

vii) Some of them have poisonous glands in their body which help them for
protection, e.g. snakes, scorpions, spiders, etc.

viii) They have long eyelashes and muscular nostrils for the protection from
wind blown sand.

Camel Scorpion

MEMORY TIPS
The camel is known as the ship of the desert. A camel has a hump on the back, which
stores fat.

QUESTIONS >>
# Why is the camel known as the ship of the desert?

ACTIVITY

Collect some aquatic plants and animals and observe their adaptational characters.

Bacteria

Bacteria (singular: bacterium) are simple, single cellular, prokaryotic, microscopic
organisms. Some bacteria have photosynthetic pigments, so they can synthesize their
own food. Some bacteria derive their food from inorganic elements while some are
parasites and derive food from plants and animals. After virus, they are the smallest

266 | Adaptation of Organisms

organisms. They have a very old history of evolution.

The Dutch scientist Anton van
Leeuwenhoek (1632–1723) was
the first person to observe bacteria
and other microorganisms. Using a
single-lens microscope of his own
design, he described bacteria and
other microorganisms (calling them
“animalcules”). He sent a series of letters
to the Royal Society of London for their
verification. Louis Pasteur, Robert Koch
and Joseph Lister propounded bacteriology by analyzing the bacterial action on
food spoilage and diseases in plants, animals and human beings. Thus, the branch of
biology which deals with the bacteria is called bacteriology.

Occurrence of bacteria

Bacteria are found everywhere in the earth surface ranging from soil, rocks,
oceans and even hot water streams and arctic snow. Some bacteria live in and on
other organisms including plants, animals and human beings.

Shape, size and structure of bacteria

Bacteria have a very simple structure. They lack nucleus and other membrane
bounded cell organelle. So, they are also called prokaryotic organisms. Bacteria
contain flagella outward from their covering (capsule). It helps in their movement.
Different bacteria have different shapes and sizes. The size of a single bacterium
ranges from 0.2 micron to 20 micron in diameter. However, most of the bacteria are
found to be living in the form of chains, colonies and clusters. Based on the shapes,
bacteria are generally of four different groups. They are:

i) Coccus (pl. cocci)

The bacteria of this group have oval, elongated and one side
flattened cell. They may remain in single or combine to form a
long rod like structure or circular cluster.

ii) Bacillus (pl. bacilli)

They are rod shaped bacteria. Like coccus, they are also
found in single or in combined state. In a combined form, they
appear in pairs or chains.

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iii) Spiral

These are the group of bacteria which have one or more
twists in their cellular body. These bacteria look like a curved or
spiral rod. Highly spiral bacteria have flagella like structure for
their locomotion.

iv) Filamentous

They are elongated, thin and thread shaped bacteria. Some of them form
branching which looks like network of filament.

Importance of bacteria

We can find millions of bacteria everywhere from the food we eat necked to our
body. But, we are very lucky that only few bacteria cause diseases and harm humans.
Most of the bacteria are very important to humans. Some of the major importance of
bacteria are described below:

i) Bacteria degrade dead organic matter and recycle nutrients back into the
soil and maintain fertility.

ii) Bacteria like rhizobium, nitrobacter, cyanobacteria, etc. help in nitrogen
fixation in soil. It is necessary to synthesis protein.

iii) Bacteria like lactobacillus, acidophilus, etc. are very important to some
industries such as the production of cheese, yogurt, buttermilk, vinegar, etc.

iv) They are used in the preparation of antibiotics such as Streptomycin.
v) They are used in the tanning of leather and hides.
vi) Methane producing bacteria are used in sewage treatment plants to convert

the sludge into methane gas.
vii) Fermentation industries and chemical manufacturing industries use bacteria.

For example, acetone, alcohol, pharmaceutical products, perfumes, etc.
viii) They help cattle, sheep and goats to digest the tough cellulose present in

the grass.
ix) Bacteria in the human intestine help to produce vitamin K. Bacteria are also

used in commercial production of riboflavin and vitamin B.
x) Some of the bacteria are also used for biological control of pests.

Harmful effects of bacteria on human beings

i) Bacteria cause various diseases in human beings. For example, cholera,
typhoid, pneumonia, bacillary dysentery, tuberculosis, tetanus, etc. Some
common diseases and name of bacteria are given below:

268 | Adaptation of Organisms

Name of disease Name of bacteria
Cholera Vibrio cholera
Enteritis in the intestine Escherichia coli
Urinogenital infections Klebsiella spp.
Enteric fever Salmonella spp.
Bacillary dysentery Shigolla spp.
Tuberculosis Mycobacterium tuberculosis
Meningitis Neisseria meningitides
Diphtheria Corynebacterium diphtheria
Pneumonia Diplococcus pneumonia
Tetanus Clostridium tetani
Anthrax Bacillus anthraces

ii) Some bacteria cause diseases to plants. For example, ring disease of potato,
yellowing rot of wheat, citrus canker, wilt of cucumber, crown gall, etc.

iii) Some saprophytic bacteria grow on unprotected foodstuffs like fruits,
pickles, jams, jellies, bread, etc. and spoil them by causing decay.

iv) Anaerobic bacteria such as Bacillus denitrification reduce the nitrates of the
poorly aerated soil and liberate nitrogen causing loss of soil fertility.

v) Bacteria also pollute water and air.

Prevention and Controlling Measures of Bacterial Diseases

i) Always use properly cooked foods and pasteurized milk.
ii) Always use boiled water for drinking purposes.
iii) Use disease free seeds in agriculture.
iv) Antibiotics should be used during bacterial infections and diseases.
v) We should give vaccination to humans and pet animals against bacterial

diseases.

Fungi

Fungi are single cellular or multicellular organisms that do not contain chlorophyll
in them. They cannot synthesize their own food by themselves and are known as
heterotrophic organisms. They have a thalloid body that is not differentiated into
roots, stem and leaves. Fungi show both sexual and asexual reproduction. Asexual

New Creative Science, Class 9 | 269

reproduction occurs through vegetative spores or mycelial fragmentation. Sexual
reproduction occurs through meiosis.

Mushroom Yeast Penicillium Notatum

Occurrence of fungi

Fungi are found in wide range of habitats. They can be found freely in soil.
They are found in association with plants in the form of mycorrhiza. They are also
associated with algae and cyanobacteria in the form of lichens. Fungi are also found
in association with various insects. Some fungi are pathogenic and can invade the
organisms in the form of parasites and diseases. The branch of science that studies
fungi is called Mycology.

Characteristics of fungi

i) Fungi are eukaryotic; i.e. their cells contain a membrane-bounded nucleus
and other membrane-bound organelles.

ii) In fungi the cell wall is composed mainly of a carbohydrate called chitin.
iii) Fungi are achlorophyllous; which means they lack chlorophyll pigment.

Therefore, they are incapable of photosynthesis.
iv) In fungi, the stored food is called glycogen.
v) Fungi are heterotrophs; it means that they obtain nutrients by absorption.
vi) They are composed of individual microscopic filaments called hyphae.
vii) They reproduce both sexually and asexually.

Importance of Fungi

Fungi are eukaryotic, achlorophyllous, heterotrophic organisms. They are both
beneficial and harmful to us.

A. Beneficial activities of fungi

270 | Adaptation of Organisms

Some of the beneficial activities of fungi are mentioned below:
i) Fungi are widely used in various foods and beverages industries like baking

and brewing (Saccharomyces).
ii) Preparation of cheese also uses fungi (Penicillium).
iii) Fungi are also used for the commercial production of citric acid (Aspergillus

niger), lactic acid, oxalic acid, etc.
iv) The wonder drug, penicillin is an antibiotic extracted from a fungus

Penicillium notatum.
v) A fungus called Claviceps pupurea, contains a number of alkaloids which are

utilized in medicine and useful in controlling haemorrhage during child birth.
vi) Fungi like mushrooms and truffles are used as food as they are rich in

protein, vitamins and minerals.
vii) Majority of known fungi along with bacteria live on dead organic matters.

They decompose these dead organic matters performing a very useful
service in returning nutrients to the soil. It maintains soil fertility.
viii) Yeast, a fungus, provides vitamin B complex and vitamin E.

B. Some of the harmful effects of fungi
i) They cause diseases in crops, like late
blight of the potato (Phytophthora
infestans), black stem rust of wheat
(Puccinia graminis), brown spot of rice
(Helminthosporium oryzae), etc.
ii) They induce animal and human diseases, like mycosis caused by the
infestation of Aspergillus, Cercospora and Cryptococcus.
iii) Fungi and their spores are also found allergic to humans.
iv) They also spoil fruits, vegetables and foodstuff.
v) Various fungi like Rhizopus, Mucor, etc. can cause poisoning of foods.

C. Prevention and controlling measures to reduce harmful effects of fungi
i) Prescribed fungicides can be used in farmlands and houses to reduce their
harmful effects.
ii) Personal cleanliness and avoiding contact with fungi and suspected area.
iii) Timely polishing of wet leather protects fungal infection.
iv) We should avoid the use of fungal infected pickles and foods.
v) We should use sweet or salt in fruits, vegetables and leafy products to
remove fungi.

New Creative Science, Class 9 | 271

vi) We should store the foods and drinks in a refrigerator.
vii) It is necessary to do treatment, medication and vaccine against fungal

diseases.

Virus

The term ‘virus’ was taken from a
Latin word viron. It means poison. The
name virus was given by Louis Pasteur
and he had discovered the Rabies virus.
Besides Rabies, the other viral diseases
are hepatitis, polio, smallpox, AIDS, flu,
mumps, etc. The virus which causes
tobacco mosaic is called as Tobacco
Mosaic Virus (TMV). The science of study of virus is known as virology. They are the
smallest bodies which can only be seen through an electron microscope. Their size
ranges 20 nm–250 nm (1nm = 10-9m.). They are nearly 50 times smaller than bacteria.

Virus are the ultramicroscopic, the smallest bodies showing both the
characteristics of living and non–living things. They show the living characters inside
the living cell whereas outside the living cell, they are completely nonliving. Hence,
they are also regarded as an interesting biological puzzle and they are known as a
borderline between living and nonliving. Thus, they show the living characteristics
such as reproduction, spreading disease, etc. inside the specific living cells only. So,
they are also known as obligatory parasites.

Characteristics of Virus

1. Living characteristics of viruses
i) They contain the genetic material either DNA or RNA or both.
ii) They can grow and reproduce inside the host cell.
iii) They transfer the genetic characters to their offspring.
iv) They are capable of causing various diseases to the living organisms.
v) They respond to heat, light and chemicals.
vi) Some viruses like ‘smallpox virus’ contain the vitamins like Riboflavin and
biotin.
vii) They can undergo mutation.
viii) They can be transmitted from host to host.

272 | Adaptation of Organisms

2. Non–living characteristics of viruses
i) They do not have true cellular composition. They lack cytoplasm, nucleus
and cell organelles.
ii) They do not show any characters of living beings outside the living cell.
iii) They can be isolated, purified, crystallized and stored in the bottles like the
chemicals.
iv) They do not perform metabolic activities.

QUESTIONS >>
# Why is the virus known as an interesting biological puzzle?
# Why are viruses known as obligatory parasites?
# Why are viruses known as a borderline between living and non-living things?

Classification of virus

Viruses are classified in different groups on the basis of the type of the host and
their genetic materials.

1. Classification of virus (on the basis of the nature of host)

Viruses are host specific, (i.e. one kind of virus can infect and reproduce only
one type of host) and on the basis of their host, viruses are classified as:

a. Animal virus
The viruses which infect the animal cells are called animal virus, e.g. Poliomyelitis,

Rhino Virus, Retro Virus, Paramyxo Virus, SARS (Severe Acute Respiratory Syndrome)
virus, etc. They have DNA or RNA as the genetic material.

b. Plant virus
Plant virus infect the plant cells only, e.g. TMV, potato virus (PV), beet yellow

virus (BYV), turnip yellow virus (TYV), etc. They are only RNA viruses (every RNA
virus is also called retro virus), and they are less specific to the host than the animal
viruses.

c. Bacterial virus
Viruses which attack the bacterial cells are known as bacterial virus. They are

DNA viruses. They are also known as bacteriophage.

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2. Classification of virus (on the basis of genetic material)

On the basis of genetic material, viruses are classified into three types as;

a. RNA Virus b. DNA Virus c. RNA–DNA Virus

a. RNA virus
These viruses consist of RNA as their genetic material, e.g. all plant viruses like
TMV, PV, TYV, etc. They are also called ritro virus.

b. DNA virus
These viruses consist of DNA as their
genetic material, e.g. Bacteriophages and
some animal viruses like Herpes virus,
Adeno viruses, etc.

c. RNA–DNA virus
This virus consists of both DNA and RNA,
e.g. Rous Sacroma Virus (RSV) is the only
DNA–RNA virus.

Mode of transmission of virus

The route through which viruses are transmitted from the infected host to the healthy
host is known as the mode of transmission of the virus. The plant viruses are transmitted
through soil, seeds, vectors, vegetative propagation and other mechanical means.

Similarly, the animal viruses are transmitted by the direct contact to the infected
organisms by means of droplet infection, through air, water, food, etc. and by the vectors.

Control measures of virus

i) To control the plant virus the infected part of the plant must be burnt.
ii) The vector insects must be killed to control plant virus.
iii) Timely vaccination should be taken to control the animal virus.

Protozoa

Protozoa are the single celled, eukaryotic, aquatic, micro-organisms which occur
in different shapes and sizes ranging about 10 to 52 micrometers. Some protozoa like
an Amoeba can change its shape while others like Paramecium has its fixed shape

274 | Adaptation of Organisms

and complex structure. They live in a wide variety of moist habitats including fresh
water, marine environments and the soil. Protozoa reproduce asexually by binary
fission or multiple fission. Many protozoan species exchange genetic material, by a
sexual method through conjugation.

Protozoa are motile and their organs of movement are cilia, flagella and pseu-
dopodia. However, some protozoa do not move at all. On the basis of the move-
ment, protozoa are divided into four groups. They are flagellates (i.e. mastigophora),
ciliates (i.e. ciliophora), sporozoans (i.e. sporozoa) and rhizopods (i.e. sacrodina).
Flagellates move with the help of flagella. It is a long thread-like structure that ex-
tends from the cell surface. The organs of the movement for ciliates are cilia. They are
tiny hair like structures that cover the outer body surface. For example, Paramecium.
Rhizopods move with the help of pseudopodia. Pseudopodia are false feet. They are
formed temporarily from the cell membrane and cytoplasm. They make the cell ir-
regular shaped. For example, amoeba. Sporozoans are like plasmodium but they do
not move.

Paramecium Amoeba Euglena Entamoeba

Some protozoans are parasites. They live in plants and animals including humans.
They cause diseases over there. Plasmodium is an example of parasitic protozoa.
It causes malaria in human beings. It gets transferred from an infected person to a
healthy person from the bite of plasmodium-carrying mosquito. Except Malaria,
Giardiasis, Toxoplasmosis, Cryptosporidiosis, Trichomoniasis, Chagas disease,
Sleeping Sickness, Amoebic dysentery, Primary Amoebic Meningo-encephalitis, etc.
are some human diseases caused by protozoa.

Control measures of protozoa

Maintaining personal hygiene is one of the important measures to be safe from
protozoa. As protozoa can contaminate drinking water, we should always drink clean
and boiled drinking water. Avoid the bite of mosquitoes to be safe from protozoa.

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ANSWER WRITING SKILLS

1. Why is the lotus covered with a waxy substance?
Ü The lotus plant is covered with a waxy substance to prevent the water from

entering the plant body and hence it protects it from decaying.

2. Aquatic plants have a spongy and flexible stem. Why?
Ü Aquatic plants have spongy and flexible stems to move freely in the direction of

water currents.

3. The cactus has a fleshy stem. Why?
Ü The cactus is a desert plant which grows in extreme dry and hot climate. So, to

reduce water loss and to store water in the plants body, it has a fleshy stem.

4. A pine has a needle-shaped leaves. Why?
Ü A pine grows in the snow falling regions. So, to allow the fall of the snow on the

ground, to reduce the loss of water by transpiration and to protect the leaves
from decaying, their leaves are needle- shaped.

5. Fossorial animals have a strong stout and sharp claws. Why?
Ü Fossorial animals have a strong stout and sharp claws to dig holes in the ground.

6. The camel is called the ‘ship of the desert’. Why?
Ü The camel is an animal which can survive for many days without food and water

as it has water pouches and fat to store water and food. It can walk on the hot
sand as the feet are modified in the form of flat hooves with a pad. So, it is called
the ship of the desert.

7. Fish have a body covered with waterproof scales. Why?
Ü The scales prevent water from entering the body of fish and hence they prevent

them from decaying.

8. Ducks have webbed toes. Why?
Ü Ducks are aquatic birds. So, to make it easy for them to swim in water, they have

webbed toes.

276 | Adaptation of Organisms

SUMMARY
” The adjustment of organisms with their surrounding is called adaptation.
” Adaptation increases the survival of living organisms in that habitat.
” The submerged plants have small leaves, flexible stems and a poorly developed

root system.
” The floating plants have large leaves with the presence of air sacs which

provide them buoyancy for floatation.
” Aquatic animals have a streamlined body, paired and unpaired fins, waterproof

scales in their body.
” Mesophytes have a well-developed vascular system.
” Xerophytes have leaves reduced to thorns, fleshy barks and deep seated roots

inside the soil.
” Cursorial animals have long and strong limbs.
” The camel is the main means of transportation in a desert.

EXERCISE

1. Define adaptation. Why is adaptation necessary?
2. Write four adaptational characters of aquatic plants.
3. Write three adaptational characters of xerophytes.
4. Write two adaptational characteristics of fish.
5. Write difference between:

(a) Aquatic submerged plants and floating plants.
(b) Aquatic animals and terrestrial animals.
(c) Arboreal animals and aerial animals.
(d) Pine and cactus.
(e) Bacteria and virus
(f) Fungi and protozoa
6. Give reasons.
(a) Water hyacinth has air storage tissue.
(b) The camel has food and water storage system in its body.
(c) The leaves of cactus plants are reduced to thorns.
(d) We should drink the pure and boiled water.

New Creative Science, Class 9 | 277

7. How is can a camel adapt itself to an extreme climate?
8. Write the adaptational characters of arboreal animals.
9. How do birds adapt themselves? Mention any two characters of adaptation.
10. Introduce bacteria, virus, fungi and protozoa with examples.
11. List out the 4/4 diseases which are caused by protozoa, virus and fungi.
12. Describe the classification of virus with examples.
13. What should we do to protect ourselves from viral diseases?
14. What should be done to protect us from the bacterial diseases?
15. List out the living and non-living characteristics of viruses.
16. Describe useful and harmful activities of fungi.
17. Explain the importance of bacteria in points.
18. Write any three adaptational characters of the given figure.

A

B GLOSSARY
C

Submerged plants : the plants that remain inside water

Xerophytes : the plants that grow in extreme climate

Cursorial : the animals which live on open land

Fossorial : the animals which live in burrows or furrows



278 | Adaptation of Organisms

UNIT

18 SYSTEM

About the Scientist Introduction

Camillo Golgi As the bricks are the building blocks of the buildings,
(1843) the cells are the building blocks of every living organism.
The cell is the structural and functional unit of life. Every
The golgi bodies inside organism is composed of one or more same or different
the cell was first described types of cells. In an unicellular organism, all the metabolic
by Camillo Golgi. Golgi activities like respiration, digestion, excretion, etc. take
received the Nobel Prize place inside a single cell. In case of multicellular organisms,
in 1906 for his work on the metabolic activities take place inside the organ. The
the structure of nervous group of organs makes systems. The system is made up
system which he shared of tissues and each tissue is made up of group of cells.
with Santiago Ramony Thus, the group of similar cells performing a particular
Cajal. Indian geneticist function is called the tissue. The group of different tissues
Monkombu Sambasivan forms organs and the group of various organs performing
Swaminathan used his skills a particular function is called the system. The system forms
in genetic engineering to the whole body.
promote the green revolution
in Asia. He persuaded the Relation among cells, tissues, organs and
farmers to grow the new systems
varieties of wheat developed
by him. He even went on to Cells are the structural and functional units of life.
set up about two thousand All living beings are made up of cells. All the living
model farms to show the activities like respiration, excretion, reproduction, etc. are
wonders of this new variety performed inside the cells. So, the cells are also known
of seeds. as the building blocks of life. There are some organisms
which are made up of only one cell. They are called
unicellular organisms. For example amoeba, paramecium,
volvox, yeast, etc. Many organisms are made up of more
than one cells called multicellular organisms. The bodies of
the multicellular organisms are made up of group of cells
called the tissue. The cells of a tissue show similar pattern
of growth, structure and functions. The group of tissues

New Creative Science, Class 9 | 279

that perform a particular function is called an organ. In the body of an organism, a
set of organs act together to perform a certain function. For example, the digestive
system, the circulatory system, the reproductive system, the excretory system, etc.
Various systems act together and form a complete organism. Thus, there exists a close
relationship among cells, tissues, organs and system. The tissue and organ system is
the same in all animals and plants. For example, in plant the transport system is made
up of xylem and phloem. Similarly, in the higher animals, the circulatory system is
made up of blood, blood vessels and the heart. In human beings, the digestive system is
made up of the mouth, tongue, neck, food pipe, stomach, gall bladder, large intestine,
small intestine, pancreas, liver, etc. The main function of the digestive system is to
digest the food materials as well as to absorb the nutrition. In the digestive system,
the liver is the main organ. It performs the following functions.

i. It secretes bile juice. It helps to digest fat.

ii. It plays an important role to produce heat in the body.

iii. It regulates red blood cells.

iv. During metabolic activities, the body produces different toxic substances. The
liver removes these toxic substances and the drugs.

v. It synthesizes vitamins.

vi. It forms urea and uric acid that are excreted in urine.

vii. It converts glucose into glycogen and stores in it.

Cells + Cells → Tissue

Tissues + Tissues → Organ

Organs + Organs → System

Various systems, organs, and tissues of the human body and their functions
are given in the table.

System Organs Functions
Mouth, stomach, liver,
Digestive system pancreas, intestine, etc. Digestion and absorption
Heart, blood, blood vessel,
Circulatory etc. To supply food and oxygen,
system fight against infection, etc.
Respiratory Nose, windpipe, lungs, etc. To exchange oxygen and carbon
system dioxide
Kidney, liver, ureter,
Excretory system urinary bladder To excrete waste materials

Muscular system Various types of muscles To help in the movement of
body parts and to give shape

280 | System

System Organs Functions
To give internal framework, to
Skeletal system Bones and cartilage help in locomotion, etc.

Reproductive Testes, ovaries, vagina, Sexual reproduction
system penis, etc.
Sensory
Nervous system Brain, spinal cords and
nerves To secret hormones
Endocrine system
Endocrine glands

Plant tissue

Every organ of a plant such as the stem, root and leaf is made up of tissues.
Usually in an organ, various types of tissues are present. They perform inter-related
functions. On the basis of stages of development, there are three kinds of tissues.

i) Meristematic tissue or meristem ii) Permanent tissue iii) Special tissue

i) Meristematic tissue

Meristematic tissues contain the cells which are in the state of division or have
the capacity of diving. The meristem has small similar and immature cells which are
spherical, oval or polygonal in shape. The cell wall is thin and without intercellular
space. The cell contains active protoplasm with large nucleus. Vacuoles are absent in
them. The meristematic tissues are classified on the basis of origin, plane of division,
location and function.

On the basic of their origin
It is again divided into two types i.e. primary and secondary.

Primary tissues

These tissues originate from the embryonic stage of the plant or plant organs.
Primary meristems retain their power of division throughout the life of plants. Thus,
they are represent in apical meristem, intercalary and inter fascicular cambium.

Secondary meristems

They have already undergone differentiation. They are not present from the
beginning of the formation of plant organs but develop at later stage, e.g. cork-cambium,
cambium of roots, etc.

On the basis of location

The simple meristematic tissue is divided into three types according to the location.
They are,

New Creative Science, Class 9 | 281

 Apical meristems  Intercalary meristems  Lateral meristems

a) Apical meristems

They are present at the apices of the stem, Apical meristem
root and branches. These are responsible

for increasing the length. Many cells form

apical meristems.

b) Intercalary meristems

These are the parts of apical meristem Intercalary
which get separated from apex due to meristem
the development of permanent tissue in

between. These are found at the base of Laterial meristem
leaves above the nodes. It increases the

length of the internodes.

c) Lateral meristem

It is also derived from the apical meristem and occurs inside the vascular

tissue. It helps to increase the diameter of plants.

ii) Permanent tissues

These are composed of cells that have lost the power of division and have their
definite shapes and sizes. They may be living or dead and thin walled or thick walled.

Types of permanent tissues

Permanent tissues are classified into two types:

a) Simple permanent tissues b) Complex permanent tissues

a) Simple permanent tissues
A simple tissue is made of one type of cells that form uniform mass. It is of the

following kinds:

 Parenchyma  Collenchyma  Sclerenchyma
i) Parenchyma

Parenchyma are the living cells with oval, spherical or polygonal shapes.
When parenchymatous cells are exposed to
light, a thin layer of chlorophyll is developed
that is called chlorenchyma which is responsible
for photosynthesis. Large air cavities may be
present in the parenchymatous cells of aquatic
plants which provide buoyancy to the plant.
These tissues are called aerenchyma.
ii) Collenchyma
Collenchyma consists of living cells which have
the deposition of extra cellulose at its edges. It
provides mechanical support to young plants
and leaves.

282 | System

ii) Sclerenchyma
Sclerenchyma is composed of two types of cells i.e.
fibres and sclereids. They are mainly responsible
for providing strength and mechanical support.
Both fibres and sclereids have a greatly thickened
wall due to the deposition of lignin and a cellulose
which are secreted by protoplasm on these cells.
After gaining maximum thickness on their walls, protoplast dies. So, they
are dead at maturity.

b) Complex permanent tissue

It is made up of more than one kinds of cells. It is also known as vascular tissues.
Xylem and phloem constitute together to form vascular bundle. Xylem is responsible
for the conduction of water and dissolved mineral salts and phloem mainly carries
food.

Xylem : It is a complex tissue and constitutes the part of
vascular bundle. It is also known as wood. It contains
four kinds of cells i.e.

(i) tracheids (ii) vessels

(iii) wood fibres (iv) wood parenchyma

The xylem conducts water and minerals from roots to Complex permanent tissue

the different parts of the plant.

Phloem : It is also a complex tissue. Its main function is to conduct prepared food
from leaves to the storage organs and from storage organs to various parts
according to need of the organ. It consists of four elements.

(i) Sieve tube (ii) Companion cells (iii) Phloem parenchyma

(iv) Phloem fibres

S.N. Xylem S.N. Phloem

1. It is a complex tissue made up of 1. It is a complex tissue made up of

dead cells. living cells.

2. It has trachea, tracheids, xylem 2. It has sieve tubes, companion cells,

parenchyma and xylem fibres. phloem parenchyma and phloem

fibres.

3. It transports water and minerals 3. It transports food materials from

from roots to the different parts of leaves to the different parts of the

the plant. plant.

New Creative Science, Class 9 | 283

iii) Special tissue

This tissue includes cells concerned in the process of secretion or excretion of
various substances like gums, resins, mucilage, nectar, essential oils, latex, etc. These
tissues have neither common origin nor morphological continuity. The plants have
two kinds of secretory tissues.

 Lactiferous tissue  Glandular tissue
a) Lactiferous tissue

It consists of thin walled, branched, elongated ducts which contain a milky juice
called latex.
b) Glandular tissue
These tissues may have unicellular or multicellular glands which may
secrete or excrete chemicals. They may present externally or internally.

MEMORY TIPS
A nettle has poisonous glandular tissues in its body which causes irritation.

Human skeletal system

The bone is the hardest tissue of the body Skull
made up of calcium, silicon, phosphorous and Cranium
other organic and inorganic materials. Calcium
makes the bone hard. A human body consists Spinal Column Mandible
of 213 bones in infant stage which are fused to Cervical
form 206 bones of different types in the adult. Vertebrae Clavicle
Manubrium
All the bones are covered with a thin Thoracic Scapula
delicate membrane with blood vessels called Vertebrae Sternum
periosteum. The inner hollow part of a long
bone is called medullary cavity which contains L umbar Ribs
red bone marrow and yellow bone marrow. Vertebrae ( L I - L V)
RBCs are formed in red bone marrow and Humerus
WBCs are formed in yellow bone marrow. Sacrum
Coccyx U lna
The supporting framework of the body Radius
consisting of different shapes and types of Pelvic girdle
bones is called the skeletal system. The major
functions of the skeletal system are as follows: Carpals
Metacarpals
i) It forms the supporting framework of Phalanges
the body.
F emur
ii) It protects the internal organs like the Patella
heart, lungs, spinal cord, brain, etc. Tibia
F ibula

Tarsals
Metatarsals
Phalanges

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iii) It co-ordinates with muscles for locomotion.
iv) The blood cells are formed inside the bone marrow.
v) It provides proper shape and size to the body.

The skeleton present on the outer surface of the body is called exoskeleton, e.g.
hair, nail, claws, hooves, shells, feathers, scales, etc. Similarly, the bones present on
the inner surface of the body comprise the endoskeleton.

Types of skeleton

The endoskeleton is divided into two groups according to their position in the
body. They are:

(A) Axial skeleton (B) Appendicular skeleton

(A) Axial skeleton

The bones present in the longitudinal axis of the body is called axial skeleton.
There are altogether 80 bones in the axial skeleton of an adult and 87 bones in case of
the infants. The axial skeleton of the human body consists of the bones of: (1) Skull (2)
Vertebral column (3) Thoracic cage.

1. Skull

The bones of the head region of a person is called the skull. It consists of 29
bones. Out of them 8 comprise the cranium (brain box), 14 comprise the facial region,
6 are the ear ossicles and hyoid is one in number.

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a) Cranium
It is comprised of eight flat bones which are joined together with another by
the saw-like edges known as sutures to form the bony box. It protects the
brain. The bones of cranium are as follows:
i) Frontal bone (one in number): It forms forehead, orbits or sockets for
the eyes and the upper portion of the nose.
ii) Parietal bone (two in number): It forms the sides and roof of the
cranium.
iii) Temporal bone (two in number): They form the base of cranium on
the either side of the skull.
iv) Occipital bone (one in number): It forms the back of head forming
posterior base of the skull.
v) Sphenoid bone (one in number): It forms the central base and sides
of the skull.
vi) Ethmoid bone (one in number): It forms the side wall of orbital cavity,
roof of the nose and the anterior base of the brain.

(b) Facial Bone
It comprises 14 bones of various shapes. They are:
i) Mandible or lower jaw bone (one in number): It is the only movable
bone of the skull. It forms lower jaw.
ii) Maxillae or upper jaw bones (two in number): They form the roof of
the mouth
iii) Palatine bones (two in number): They form the roof of the mouth
cavity.
iv) Zygomatic bones (two in number): They form two cheeks and the
orbits of eyes.
v) Nasal bones (two in number): They form the bridge of nose.
vi) Vomer (one in number): It forms the middle partition in the nose.
vii) Lacrimal bones (two in number): They form the inner wall of eyes
near the lacrimal glands.
viii) Interior nasal conchae (two in number): They are located on the both
sides of the nasal pores.

(c) Ear ossicles

The bones present in the middle ear are called ear ossicles. Each ear contains
three ear ossicles i.e. malleus, incus and stapes. So, altogether there are six ear ossicles
in the both ears.

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MEMORY TIPS
Stapes are the smallest bones of the human body. They are present in the middle ear.

QUESTIONS >>
# Name the bones of the cranium and facial region.

(d) Hyoid

It is a u-shaped bone located in the neck region between mandible and
larynx.

Functions of the skull Epiglottis
(i) The cranial bones protect the master organ of Hyoid

the body i.e. the brain. Thyroid gland

(ii) The eye orbits give the housing and protection
to our important organs, i.e. the eyes.

(iii) The mandible and maxillae help to chew the
food as they give sockets for the teeth.

(iv) The ear ossicles help in the hearing.

(v) Temporal bones protect the ears.

2. Vertebral Column

Vertebral column or the backbone is the developed form of notochord present in

the chordates. The human vertebral column consists of thirty three bones in infants

which later fuse to form 26 bones when he grows up. The individual bones of vertebral

column are known as vertebrae. Each vertebra has a hole at the central region which

is known as neurocoel. The spinal cord is present in the neurocoel. Between two

vertebrae, there is a cartilaginous tissue which gives flexibility to the spinal cord and

absorbs shocks. The vertebral column is divided into the following five parts:

(a) Cervical vertebrae (b) Thoracic vertebrae

(c) Lumbar vertebrae (d) Sacral vertebrae or sacrum

(e) Coccygeal vertebrae or coccyx

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(a) Cervical vertebrae Cervical vertebrae
It consists of the first seven bones present in the Thoracic vertebrae
neck region. The first cervical vertebra is known
as atlas and the second one is known as axis.
The atlas and axis support the head and help
in the movement of the head from side to side
respectively.

(b) Thoracic vertebrae
It consists of twelve vertebrae present in the
thoracic region. It gives the articulation to the
twelve pairs of ribs.

(c) Lumber vertebrae Lumber vertebrae
Sacral vertebrae
These are the five vertebrae present in the lower
part of the back or the waist. They have the
maximum movement.

(d) Sacral vertebrae or sacrum Coccyx
Vertebral column
It consists of five vertebrae in infants which
are fused to form a single large bone known as
sacrum.

(e) Coccygeal vertebrae or coccyx

There are four coccygeal vertebrae in infants but later they fuse to form a very
small triangular bone known as coccyx or tail vertebrae.

Functions of vertebral column
1. It protects the spinal cord.
2. It helps in the slight movement of the body.
3. It gives articulation for ribs, shoulder, skull, etc.

QUESTIONS >>
# What are the functions of the vertebral column?
# How many bones are there in the vertebral column?

3. Thoracic cage

It is a bony cage which consists of twelve pairs of ribs and a sternum. Ribs are
long semicircular bones which may or may not attach with the sternum. But, they are
attached with the thoracic vertebrae in the backside.

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On the basis of the attachment of ribs with the sternum, ribs are of three types:

i) True ribs: The first seven pairs Sternum
of ribs which are directly
attached to the sternum are
called true ribs.

ii) False ribs: The three pairs of True rib (1 to 7)
ribs (eighth, ninth and tenth)

which are attached to the

seventh ribs but not to the False ribs (8th, 9th and 10th)

sternum directly are called

false ribs. Floating ribs (11th and 12th)

iii) Floating ribs: The last two

pairs of the ribs (eleventh and

twelfth) are only attached to the vertebral column but not to the sternum at

all are called floating ribs.

Functions of thoracic cage
i It protects the delicate organs like the heart and lungs.
ii. It helps in breathing process.
iii It connects upper limbs with axial skeleton.

MEMORY TIPS

The muscle between two ribs is called the intercostal muscle which helps in the
expansion and contraction of the thoracic cage during the breathing process.

QUESTIONS >>
# What do you mean by true, false and floating ribs?

ACTIVITY

Dip a piece of bone into dilute hydrochloric acid in a beaker and leave it for about few hours.
Observe the bone. Has it become softer? Why?

(B) Appendicular skeleton

The skeleton present on the bones of upper limbs (forelimbs) and lower limbs
(hind limbs)along with pectoral girdle and pelvic girdle is called the appendicular
skeleton.

a) Pectoral girdle and bones of forelimbs

The pectoral girdle or the shoulder girdle consists of four bones. Two on each
side of forelimbs. There are two clavicle and two scapula.

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The clavicle is a long bone which joins the sternum and the scapula, whereas, the
scapula is a triangular shaped flat bone on the back.

Similarly, the forelimbs consist of sixty bones, thirty on each limbs. The names of
the bones in each forelimb along with their numbers are given below.

i) Humerus: It is a single long bone in the upper Clavicle
arm whose proximal end joins with scapula Scapula
and the distal end articulates with the radius Humerus
and ulna.
Ulna
ii) Radius and ulna: There is one radius and one
ulna in the lower arm. Radius lies in the inner
side (in the side of thumb) and ulna lies in the
outer side.

iii) Carpals: They are eight small pieces of bones Radius
arranged in two rows at the wrist of the hand.
These are joined by ligaments which allow its Carpals
slight movement. Metacarpals
Phalanges
iv) Meta carpals: They are five in number and Bones of pectoral girdle
form the bones of the palm.

v) Phalanges: They are the fourteen small pieces of bone in fingers of the hand.

(b) Pelvic girdle and the bones of hind limbs

Pelvic girdle or the hipbone consists of three fused bones i.e. ilium, ischium and
pubis. There is a depression on the outer surface of pelvic girdle called acetabulum
which helps in the articulation of femur bone with the pelvic girdle.

The pelvic girdle of a female is more round and spacious than that of the male for
the protection of the baby inside the uterus and to allow the free passage of the baby
during the childbirth.

The hind limb also consists of sixty bones i.e. thirty bones in each. Their names
along with their numbers are given below.

male pelvic bone female pelvic bone

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i) Femur or thigh bone: It is the longest and the strongest bone. Its proximal

end is almost spherical and fits into the cavity

called acetabulum. Innominate bone

ii) Patella or knee-cap: In each leg, it is one in

number which is small, flat and triangular in

shape. It makes the knee cap.

iii) Tibia and fibula: Tibia and fibula are the two Femur
bones present in the leg below the knee. Tibia
lies in the inner side (in the side of thumb) and
fibula lies in the outer side.

iv) Tarsals: These are seven pieces of small bones Patella
present at the ankle region of the foot.

v) Metatarsals: These are the five bones which form
the base of foot.

vi) Phalanges: These are fourteen bones in each leg Tibia
forming the fingers. Fibula

Functions of appendicular skeleton

(i) These bones in coordination with muscles Tarsals
help in the movement of hands and legs. Metatarsals

(ii) Femur and the bones of lower limb help to Phalanges
support the body weight.
Pelvic girdle and bones
(iii) Pelvic girdle in female helps during the child
birth.

(iv) The long bones like humerus and femur help in the production of the blood
cells.

Nutrition in human body

Human beings like other animals are unable to prepare their own food. So,
the nutrition in human beings is heterotrophic. The human beings depend on plants
directly or indirectly for their food.

Digestive system in Humans

Digestion is a catabolic process or the process of breaking down of complex food
materials into simple forms which can be directly absorbed by the body. The organs
concerned with digestion are called the digestive system. The digestive system of the
human body consists of the mouth, the alimentary canal and the anus.

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Mouth

It is an opening through
which food is taken inside the
body. The food mixes with
saliva inside the mouth and
here the mechanical break
down of the food occurs with
the help of the teeth and the
tongue. Saliva contains the
enzyme ptyalin which helps
to breakdown carbohydrate
partially to the glucose.

QUESTIONS >>
# Why do we feel sweet when

we chew the beaten rice for
some time in our mouth?
# What is the role of ptyalin
in the digestion of food?

Alimentary canal

The alimentary canal is
basically a long tube extending
from the mouth to anus. It is necessary to move the food in a regulated manner along
the digestive tube so that it can be processed properly in each part. The linings of canal
have muscles that contract rhythmically in order to push the food forward. These
peristaltic movements occur all along the gut. Alimentary canal has the following
parts:

(1) Food pipe or oesophagus (2) Stomach (3) Small Intestine

(4) Large Intestine (5) Anus

(1) Food pipe or oesophagus
The food after chewing in the mouth, passes to the stomach through the food

pipe or oesophagus.

(2) Stomach
The stomach is a large organ which expands when food enters in it. The muscular
wall of the stomach helps in mixing the food thoroughly with more digestive
juices.
The digestive functions are carried out by the gastric glands present in the wall
of the stomach. The gastric glands release:

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(i) Hydrochloric acid
(ii) A protein digesting enzyme called pepsin
(iii) Mucus
The hydrochloric acid creates an acidic medium which facilitates the action of
enzyme pepsin. It also kills the bacteria present in the food. The food enters the
small intestine through the stomach.

(3) Small Intestine
This is the longest part of the alimentary canal which is excessively coiled. The
small intestine is the site of the complete digestion of carbohydrates, proteins
and fats. It receives the secretions of the liver and pancreas for this purpose.
The food coming from the stomach is acidic and has to be made alkaline for the
pancreatic enzymes to act. The food is made alkaline by the bile juice secreted by
the liver. The fat globule present in the large intestine is broken down.
The pancreatic juice secreted by the pancreas contains the enzymes like trypsin
to digest proteins and lipase to digest emulsified fats. The wall of the small
intestine contains glands which secrete intestinal juice. The enzymes present in it
finally convert the proteins to amino acids, complex carbohydrates into glucose
and fats into fatty acids and glycerol.

cross section of intestine and villi

The digested food is taken up by the walls of the intestine. The inner lining
of the small intestine has numerous finger-like projections called villi. They
increase the surface area for absorption. The villi are richly supplied with blood
vessels which take the absorbed food to each and every cell of the body where
it is utilized for obtaining energy, building up new tissues and the repair of old
tissues.

(4) Large Intestine
The unabsorbed food materials are sent into the large intestine where more villi
absorb water from these materials. The rest of the materials are removed from
the body through the anus. The exit of this waste material is regulated by the
anal sphincter. The process of throwing out of the waste materials from the body
is called egestion.

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MEMORY TIPS

The small intestines of herbivores are larger than that of carnivores because meat is
easier to digest than the cellulose.

The summary of the digestion of food is given in the table below.

S. N. Digestive Digestive Digestive Enzymes Products
organs glands juices

1. Mouth Salivary Saliva Ptyalin Starch is converted into
glands maltose.

2. Stomach Gastric HCl - Food changes into acidic
gland medium and germicides
Gastric Pepsin
juice Renin Proteins converted into
peptones

Milk protein (Casein) into
curd

Emulsifies fat and makes

3. Duodenum Liver Bile juice - medium neutral or slightly
Pancreas alkaline
Pancreatic Trypsin
juice Amylase Peptones → Peptides

Lipase Starch → Maltose

Fat → Fatty acid and glycerol

4. Small Intestinal Intestinal Erepsin Peptide → Amino acids
intestine Sucrase Sucrose → Glucose
gland juice Lactose → Glucose
Lactase Maltose → Glucose
Maltase

5. Large - - - Some important salts and
intestine water are absorbed

QUESTIONS >>
# What is the role of acid in our stomach?
# How is the small intestine designed to absorb digested food?

Assimilation

The absorbed food materials are taken to all cells of the body through blood.
These nutrients are used by the cells to perform various activities. This process is
called assimilation.

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Different kinds of teeth in Human beings

Most of the vertebrate animals have hard and bony
structures in their mouth which are called teeth. We use
teeth to tear, grind and chew the food in the first step of
digestion. Teeth also play a role in human speech and
also provide structural support to the muscles in the face
and form the human smile.

Humans have two sets of teeth, primary (or baby or
milk) teeth and then permanent teeth. Milk teeth erupt
out when a baby is above 6 months old. The development
of teeth continues and a child normally has 20 milk teeth.
Gradually, after 6-7 years, milk teeth are replaced by
permanent teeth. An adult has 32 permanent teeth (2 sets of 16 teeth) in their mouth.

Types of Teeth

There are four major types of
teeth. They are incisor, canine, pre
molar and molar.

(i) Incisors: Incisors are the eight teeth
in the front and centre of human
mouth (four on upper side and
four on the bottom). These teeth
are used to bite the food.

(ii) Canines: These are the sharpest
teeth. They are used for ripping
and tearing the food. They are
four in numbers (two at up and
two at down) just after the incisors. They are well developed in carnivorous
animals.

(iii) Premolars: Premolars or bicuspid are wide and flat teeth specialized for chewing
and grinding food. There are four premolars on each side of human mouth, two
on the upper and two on the lower jaw.

(iv) Molars: Teeth behind the premolars are the molars. Molars are the teeth
responsible for vigorous chewing. There are twelve molars (three sets in each
jaw). Each of the molar is referred to as the first, second and third molar. Third
molars are often called wisdom teeth.

The number and arrangement of teeth in the mouth of the animals is called
dentition. It is expressed in ratio which expresses the number of teeth in upper or
lower halves. In human it is I:C:PM:M = 2 × (2:1:2:3).

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Respiratory System

Energy requires for each and
every activity. It is required for
the functioning of each cell to the
functioning of the whole body.
The main source of energy is food.
Energy releases when the digested
food materials are oxidized. Thus,
respiration is the complex process
of oxidizing the digested food
materials in the cells to release
energy and carbon dioxide. This is
also known as cellular respiration
or internal respiration. External
respiration means normal breathing,
taking air in and throwing out the air through the nose.

Organs of the Respiratory System

(i) Nose and Nasal Cavity

The nose and the nasal cavity form the main external opening for the respiratory
system. They are the first section of the body’s airway. The function of the nasal cavity
is to warm, moisturize and filter air entering the body before it reaches the lungs.
Hairs and mucus lining the nasal cavity help to trap dust, molds, pollen grains and
other environmental contaminants before they can reach the inner portion of the body.

(ii) Pharynx

The pharynx is also known as the throat. It is a muscular funnel that extends
from the posterior end of the nasal cavity to the superior end of the esophagus and
larynx. It is diverted into the opening of the larynx by the epiglottis. The epiglottis
is a flap of elastic cartilage that acts as a switch between the trachea (air pipe) and
the esophagus (food pipe). The pharynx is also used to swallow food. The epiglottis
ensures that air passes into the trachea by covering the opening to the esophagus.

(iii) Larynx

The larynx is also known as the voice box. It is a short section of the airway that
connects the pharynx and the trachea. The larynx is located in the anterior portion of
the neck, just inferior to the hyoid bone and superior to the trachea. Several cartilage
structures make the larynx and give its structure. The epiglottis is one of the cartilage
pieces of the larynx and serves as the cover of the larynx during swallowing. It is also
called Adam’s apple as it is most commonly enlarged and visible in adult males.

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