Class 9 Science_clone

Floating plants
Those plants which float freely on water surfaces are called floating
plants.

Lemna Pistia

Examples:- Lemna, pistia, wolffia, water hyacinth, etc.

Rooted and emergent plants
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DQG URRWHG WR WKH VRLO EXW XSSHU SRUWLRQ UHPDLQ DERYH WKH ZDWHU DUH
FDOOHG URRWHG DQG HPHUJHQW SODQWV

Marsilea Lotus

Examples:- Lotus, water lily, marsilea, etc.

Adaptational characteristics of hydrophytes
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URRW FDS and root hairs.
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which are less affected by the current of water.
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WKH OHDYHV RI VXEPHUJHG SODQWV DUH ORQJ WKLQ DQG ULEERQ
VKDSHG

297 Times' Crucial Science Book - 9

%RG\ RI K\GURSK\WHV LV FRYHUHG ZLWK ZD[\ FRDWLQJ which
SUHYHQWV WKHP IURP GHFD\LQJ LQ ZDWHU
+\GURSK\WHV FRQWDLQ DLU VWRUDJH WLVVXHV FDOOHG aerenchyma
ZKLFK SURYLGH WKHP buoyancy.
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roots to breathe inside the water.
Mesophytes and their adaptational characteristics
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FDOOHG PHVRSK\WHV. Mango, rose, crops, marigold, mustard, etc are
mesophytes. They have following adaptational characteristics.
7KH\ KDYH ZHOO GHYHORSHG URRW DQG VKRRW V\VWHP
7KH URRWV DUH ORQJ DQG VXSSOLHG ZLWK URRW KDLUV
7KH OHDYHV DUH JHQHUDOO\ ODUJH EURDG DQG YDULRXVO\ VKDSHG

with numerous stomata.
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5. &OLPEHU SODQWV OLNH FXFXPEHU SXPSNLQ HWF FRQWDLQ KRRNV
WHQGULOV DHULDO URRWV HWF IRU VXSSRUW

Mango Apple Banyan

Xerophytes and their adaptational characteristics
7KH SODQWV WKDW JURZ RQ WKH GU\ DQG KRW FOLPDWH DUH FDOOHG
[HURSK\WHV They are also called desert plants. Cactus, aloe,
calotropis, opuntia, etc are xerophytes. Their adaptational
characteristics are as follows:
7KH\ KDYH ZHOO GHYHORSHG URRW V\VWHP 7KH\ JURZ GHHS LQWR

the soil to absorb water.
7KH OHDYHV DUH PRGLILHG WR thorns RU QHHGOH VKDSH WR UHGXFH

WKH ORVV RI ZDWHU E\ WUDQVSLUDWLRQ
3. The stems are flattened and fleshy to store water. The stems

Times' Crucial Science Book - 9 298

DUH DOVR JUHHQ WR FDUU\ RXW SKRWRV\QWKHVLV
7KH OHDYHV DQG VWHP KDYH WKLFN FXWLFOH RQ WKHLU VXUIDFH WR

DYRLG WKH ORVV RI ZDWHU
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They remain closed at day time to reduce the loss of water by
WUDQVSLUDWLRQ
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barks.

Cactus Opuntia

Fact Reason

Why do desert plants don’t have leaves?
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transpiration as there is scarcity of water in the desert. Hence,
desert plants don’t have leaves.

Adaptation in animals

Animals are categorized into mainly two categories on the basis of
their habitat. They are :

(i) aquatic animals (ii) terrestrial animals

Aquatic animals

7KH DQLPDO ZKLFK OLYH LQ ZDWHU DUH FDOOHG DTXDWLF DQLPDOV They
grow and multiply in water. They have following adaptational
features.
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SDVVDJH ZKLOH VZLPPLQJ
2. Air sacs DUH SUHVHQW LQ WKHLU ERG\ ZKLFK KHOS WKHP IORDW LQ

water.
3. The limbs are modified to fins (e.g. fish) or IOLSSHUV or SDGGOHV

H J ZKDOH ZKLFK KHOS WKHP IRU VZLPPLQJ
7KH\ KDYH JLOOV IRU EUHDWKLQJ H J ILVK

299 Times' Crucial Science Book - 9

7KH\ KDYH ODWHUDO OLQH DV VHQVH RUJDQ LQ WKHLU ERG\ ZKLFK
KHOSV WR detect SUHVVXUH DQG WHPSHUDWXUH H J ILVK .

Dolphin Fish Duck
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SUHYHQW IURP GHFD\LQJ
7KH\ KDYH D ORQJ WDLO WR FKDQJH WKH direction while swimming.

Terrestrial animals

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They are further categorized into five groups. They are:

i. Cursorial animals ii. Fossorial animals
iii. Arboreal animals iv. Aerial animals
v. Desert animals.

Adaptational characteristics of cursorial animals

7KH DQLPDOV ZKLFK OLYH RQ RSHQ SODFH DQG DUH DGDSWHG WR UXQ RQ
hard grounds are called cursorial animals. Lion, deer, dog, horse,
buffalo, etc are examples of cursorial animals. Cursorial animals
have following adaptational characteristics:
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PRYHPHQW E\ UHGXFLQJ friction.
7KH\ KDYH ORQJ DQG VWURQJ OLPEV ZLWK VKRUW digits for fast

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WZR KRRYHV LQ WKHLU IHHW
7KH\ KDYH VWURQJ PXVFOHV ZKLFK KHOS WKHP IRU IDVW UXQQLQJ

Tiger Lion Deer

Times' Crucial Science Book - 9 300

Adaptational characteristics of fossorial animals
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called fossorial animals. Rat, rabbit, mole, etc are examples of
fossorial animals. Fossorial animals have following adaptation
characteristics:
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suited for digging holes on the land.
2. Their forelimbs are short with SRZHUIXO FODZV.
3. Their eyes and ears are small.

Rabbit Rat

Adaptational characteristics of arboreal animals
7KH DQLPDOV ZKLFK DUH DGDSWHG IRU FOLPELQJ DQG VSHQG PRVW RI
time on trees are called arboreal animals.
Lizards, monkey, squirrel, tree snakes, etc are arboreal animals.
Arboreal
animals have following adaptational characteristics:
7KH\ KDYH ORQJHU DQG stronger forelimbs.
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GHYHORSHG
7KH GLJLWV RI OL]DUGV DUH SURYLGHG ZLWK DGKHVLYH SDGV which

KHOS WKHP WR FOLPE RU PRYH RQ WKH ZDOOV
6RPH RI WKHP KDYH ORQJ WDLOV WR EDODQFH WKHLU ERG\

Chimpanzee Monkey Squirrel
301
Times' Crucial Science Book - 9

Adaptational characteristics of aerial animals
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aerial animals. Birds, butterfly, housefly, etc are aerial animals.
They have following adaptational characteristics:
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air while flying.
2. Bones are hollow and air-filled called SQHXPDWLF ERQHV.
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SDWDJLXP.
$LU VDFV DUH SUHVHQW LQ WKHLU ERG\ ZKLFK UHGXFH WKHLU ERG\
weight.

Butterfly Pigeon

Adaptational characteristics of desert animals
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GHVHUW RU [HULF DQLPDOV Camel, lizard, rodents, etc are desert
animals. They have following adaptational characteristics:
1. The desert snakes UDWV HWF PDNH GHHS EXUURZV DQG UHPDLQ

inside them during day time and come on the surface only
at the night time.
6RPH RI WKHP KDYH ZDWHU SRXFKHV to store water.
3. Camel has KXPS at the back which stores fat.
'HVHUW OL]DUGV KDYH K\JURVFRSLF VNLQ which absorb moisture
IURP DWPRVSKHUH
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urine to minimize loss of water.
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ZDWHU E\ SHUVSLUDWLRQ SURFHVV

Times' Crucial Science Book - 9 302

Camel Desert lizard

Fact Reason

Camel can survive for a long time without food and water?
Camel has hump in its back to store food in the form of fat and
water pouches to store water. Hence, camel can survive for a long
time without food and water.

Activity17 .1 1. Visit a pond nearby your school or house. Observe some

aquatic plants and animals. Mention any three adaptational characteristics
of each.
2.Visit your locality and observe various types of animals and plants Mention
their names and adaptational characteristics.

Micro-organisms
There is a vast population of invisible organisms. These invisible
organisms are found almost everywhere and are known as microbes.
We cannot see these organisms with our naked eyes because they
are unicellular and microscopic organisms. The organisms whose
body is made of single cell are called unicellular organisms. The
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WKH\ DUH H[WUHPHO\ VPDOO DQG ZH QHHG D PLFURVFRSH WR VHH WKHP
Bacteria, virus, yeast, amoeba, paramecium, etc are unicellular
organisms.

The organisms which contain many cells in their bodies are called
multicellular organisms. We can see these organisms with our
naked eyes. Ant, housefly, fish, birds, cow, dog, buffalo, human
beings, etc are multi cellular organisms.

303 Times' Crucial Science Book - 9

Prokaryotic and eukaryotic cell

The cells of organisms can be categorized into two types on the
basis of nuclear organization. They are prokaryotic cell and
eukaryotic cell.

The cell whose nucleus is not bounded by a nuclear membrane is
FDOOHG SURNDU\RWLF FHOO The organisms having prokaryotic cell are
called prokaryotic organisms or prokaryotes. Bacteria, blue green
algae, etc are prokaryotes. The cell whose nucleus is bounded by a
nuclear membrane is called eukaryotic cell. Such cells are present
in all multicellular organisms. The organisms having eukaryotic
cell are called eukaryotic organisms or eukaryotes.
Differences between prokaryotic and eukaryotic cells

SN Prokaryotic cell Eukaryotic cell

1 The genetic material is not bounded The genetic material is bounded by a
by any nuclear membrane. nuclear membrane

2 Mitochondria are absent. Mitochondria are present.

3 Golgi bodies are absent. Golgi bodies are present.

4 Endoplasmic recticulum is absent. Endoplasmic reticulum is present.

5 Examples: Bacteria, cyanobacteria, Examples: Algae, fungi, protozoa,
red blood cells, azobactor, etc. plants and animals

Bacteria
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organisms. They are found almost everywhere on the earth. They
are present in air, water, soil, plants and animals. Some species of
bacteria can live in ice whereas some can remain alive in boiling
water. The bacteria were discovered by Anton Von Leeuwenhoek
for the first time in 1676 AD. There is a separate science dealing
with bacteria. The branch of science which deals with bacteria is
called bacteriology.
The bacteria may have spherical, rod shaped, spiral, coiled, comma
or thread like body. Their average size ranges between 0.5 to10
microns (1 micron, μm = 10-6m). The structure of the commonest
bacteria is as follows:

Times' Crucial Science Book - 9 304

The body of bacteria is composed of a single cell, which is covered
by a distinct cell wall. The cell wall is made of proteins and
carbohydrates. There is cell membrane just inside the cell wall.
The cytoplasm is spread uniformly inside the cell membrane.
It contains ribosome, nuclear material (DNA) and a number of
vacuoles. The cell organelles such as mitochondria, endoplasmic
reticulum, etc are absent in bacterial cells.

Plasma membrane
Cytoplasm

Cell Wall

DNA

Ribosomes
Pili

Flagella

Bacteria are of several kinds. Bacillus, Coccus, helical, Vibrio, etc
are some kinds of bacteria.
Most species of bacteria lack chlorophyll and they have
heterotrophic mode of nutrition, i.e. they absorb their food from
dead and decaying things. Some bacteria contain chlorophyll and
can prepare their food themselves. Some bacteria are parasitic,
i.e. they take food from the body of living things and infect them.
Some bacteria are present in the root nodules of some plants.
These bacteria are called symbiotic bacteria. These bacteria absorb
nitrogen from the atmosphere and provide nitrogenous compound
to the soil. It means that they help in nitrogen cycle. Rhizobium is
an example of symbiotic bacteria.
Importance of bacteria
1. Bacteria such as Lactobacillus and $FLGRSKLOOXV FRQYHUW

milk into yogurt.
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to make FRPSRVW PDQXUH
3. The symbiotic bacteria such as Rhizobium FRQYHUW WKH

DWPRVSKHULF QLWURJHQ LQWR VROXEOH QLWUDWH 7KH QLWUDWH LV DQ
HVVHQWLDO QXWULHQW IRU WKH SODQWV.

305 Times' Crucial Science Book - 9

Harmful effects of bacteria
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H[DPSOH 6DOPRQHOOD W\SKL FDXVHV W\SKRLG 'LSORFRFFXV
SQHXPRQLDH causes SQHXPRQLD Vibrio cholerae causes
FKROHUD Mycobacterium tuberculosis FDXVHV WXEHUFXORVLV HWF
in human beings.
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fruits in summer.
3. Some bacteria such as Pseudomonas decrease the fertility of
soil.
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Control measures of bacterial diseases
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DLU HWF
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3. Using antibiotics to treat bacterial diseases
4. Using bacteria resistant YDULHWLHV RI VHHGV RI FURSV YHJHWDEOHV
IUXLWV HWF
5. Consulting doctor in case of infection of the bacterial diseases
Virus
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organism. It is much smaller than bacteria (about 50 times smaller
than bacteria) and cannot be seen even by a compound microscope.
Their size ranges between 25 – 250 nanometers (1nm = 10-9m). The
viruses are the total parasite. They remain quite inactive outside
the body of living organisms. They need a living host to grow and
reproduce. Hence, they are also known as obligatory parasites.
In 1892, Dmitry Ivanovsky showed that a disease in a tobacco plant
was due to an infectious substance. Later on Martinus Beijerinck
called the infectious substance a "virus" meaning poison. Hence,
the credit for the discovery of virus goes to Dmitry Ivanovsky. And
this discovery is considered to be the beginning of virology.
The viruses show the characters of both living and non-living
things. As living beings, they can attack a proper host cell to begin
infection and self reproduction. As non-lying things, they can be
crystallized and are unable to carry out their own metabolism.
Hence, viruses are taken as the border line between living and
non-living things.

Times' Crucial Science Book - 9 306

Some viruses do not have nucleus whereas some have no cytoplasm.
The viruses are made of DNA (Deoxyribonucleic acid) or RNA
(Ribonucleic acid). The structure of a common virus named
bacteriophase is given below:

Bacteriophase is a common virus. Nuclear Capsid
It is called so because it attacks material
bacteria. The bacteriophase virus Tail Head
contains a head and a tail, which fibre Tail
are covered by a protein cover. The
protein coat that surrounds the Basal plate
head of a virus is called capsid. Bacteriophase virus
The head contains nucleic acid as
a nuclear material. The end of the
tail has a basal plate which bears
long tail fibres.

Types of virus
The virus can be categorized into three types on the basis of host.
They are:
1. Plant virus: The viruses which attack plants are called

plant virus. These viruses are also called cynophase virus.
TMV (Tobacco mosaic virus), potato virus, CMV (Cucumber
Mosaic Virus), etc are plant virus.
2. Animal virus: These viruses attack and infect animals.
Rabies virus, Rhino virus, Measles virus, Paramyxo virus,
Polio virus, HIV, etc are animal virus.
3. Bacteriophase virus: The virus which attacks bacteria is
called bacteriophase virus. It is a tadpole shaped virus.
Viruses have either DNA (Deoxyribonucleic acid) or RNA
(Ribonucleic acid) as the nuclear material but not both. The viruses
can be divided into two types on the basis of nucleic acid. They are:
1. DNA Virus: These viruses contain only DNA as their genetic
material. For example, bacteriophase virus, influenza virus,
small pox virus, etc.
2. RNA Virus: The virus that contains ribonucleic acid as
genetic material is called RNA virus. For example, polio
virus, retrovirus, HIV, rhino virus, mosaic virus, etc.

307 Times' Crucial Science Book - 9

Mode of transmission of viral diseases
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3. Some insects such as $SKLGV eat and damage the roots and

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:KHDW PRVDLF YLUXV LV WUDQVPLWWHG WKURXJK FRQWDPLQDWHG

soil.
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6. They are also transmitted WKURXJK FRQWDPLQDWHG IRRG ZDWHU

and air.
7. Wound or cut in the body is the direct route for the transmission

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Control measures of viral infection
7KH YLUXV infected SDUW RI SODQW VKRXOG EH UHPRYHG DQG EXUQW
2. Use of insecticides kills insects so that they cannot transmit

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HIV.

Fungi

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ZKLFK GR QRW KDYH FKORURSK\OO
and grow on decaying organic
matter. They bear eukaryotic cells.
Fungi are unicellular as well as Gills Annulus

multicellular. For example, yeast Stype

is a unicellular fungus. Mushroom Velum
is a multicellular fungus. The
branch of biology that deals with Mushroom

fungi is called mycology.

Structure

A multicellular fungus consists of a number of thread-like
structures called hyphae. The hyphae develop in all directions and

Times' Crucial Science Book - 9 308

form a network like mass which is called mycelium. The mycelium
absorbs food from the organic matter. The part of mushroom which
is seen above the ground is called fruiting body. It is also known as
basidiocarp. It contains three main parts – stype, gills and pileus.

Mode of Nutrition

Fungi cannot prepare their food themselves due to the lack of
chlorophyll. So, they have either saprophytic or parasitic mode
of nutrition. The saprophytic fungi absorb their food from dead
and decayed organic bodies. Mucor, moulds, mushroom, etc are
saprophytic fungi. On the other hand, the parasitic fungi grow on
the plant or animal body and get their food from them. For example,
puccinia, albugo, etc are parasitic fungi.

Reproduction

Fungi mainly reproduce by asexual methods. Fragmentation,
fission, budding and sporulation are the main asexual methods of
reproduction. However, sexual reproduction also occurs in fungi.

Importance of fungi
1. The fungi like yeast are used in brewery and bakery industries.

<HDVW FDQ SURGXFH WKH HQ]\PHV LQYHUWDVH and zymase.
2. Some mushrooms are edible. They are the good sources of

SURWHLQV YLWDPLQV DQG PLQHUDOV
3. Many antibiotics such as Penicillin DUH H[WUDFWHG IURP IXQJL
)XQJL DOVR VHUYH DV WKH GHFRPSRVHUV LQ WKH ecosystems.

Harmful effects of fungi
1 6HYHUDO YDULHWLHV RI IXQJL FDXVH GLVHDVHV LQ KXPDQ EHLQJV

7KH\ FDXVH VNLQ GLVHDVH KLJK IHYHU allergy HWF
2. ,W FDXVHV JUD\LQJ GLVHDVH RI PDL]H EXUQLQJ GLVHDVH RI SRWDWRHV

etc.
5KL]RSXV 0XFRU HWF FDXVH IRRG SRLVRQLQJ and serious health

SUREOHP LQ KXPDQ EHLQJV

Control measures of fungi infection
1. )RRGVWXIIV VXFK DV PLON PHDW ÀVK IUXLWV HWF FDQ EH NHSW VDIH

IURP IXQJL E\ NHHSLQJ WKHP LQ D fridge.
)XQJL FDQ EH NLOOHG E\ XVLQJ fungicides.
)XQJL LQIHFWLRQ LQ OHDI\ YHJHWDEOHV DQG IUXLWV FDQ EH PLQLPL]HG

by using salt.
4. )XQJL LQIHFWLRQ RI VNLQ FDQ EH DYRLGHG WKURXJK FOHDQOLQHVV

309 Times' Crucial Science Book - 9

Protozoa
Some protozoans like Plasmodium, Leishmania, Giardia, Trypanosoma
cause disease in humans. Protozoans that cause diseases in human
beings are:

Disease Causative organisms
1. Amoebiasis/ dysentery Entamoeba histolytica
2. Sleeping sickness 7U\SDQRVRPD JDPELHQVH
3. Kalazar /HLVKPDQLD GRQRYDQL
4. Malaria 3ODVPRGLXP VSHFLHV
5. Toxoplasmosis 7R[RSODVPD JRQGLL
6. Giardiasis Giardia lamblia

It is essential to remain away from sick people to remain safe from
the attack of microorganisms. In addition to this, personal cleanliness
is equally important. As some of the insect bites transmit dangerous
diseases, we should protect ourselves from insect bites.

Learn and Write
1. Aquatic plants have spongy stem. Why?

Spongy stem of aquatic plants can store air which makes
them light and buoyant. Thus, they easily float on water.
2. Leaves of cactus plant are modified to thorns. Why?
Leaves of cactus plant are modified to thorns so that the sites
for the transpiration process are minimized. Thus, the loss of
water by the trans-piration process is reduced.
3. Camel is called the ship of the desert. Why?
The feet of camel is flat with pads. So, it can easily walk on
the desert. Moreover, it can walk for many days without
eating and drinking. Due to this reason, it is used to carry
loads and people from one place to another. Therefore, it is
called the ship of the desert.
4. Frogs have triangular head and webbed legs. Why?
Triangular head of frog reduces the friction while swimming
inside water. The webbed legs can push the water in backward
direction for the forward movement of frogs. Thus, triangular
head and webbed legs help the frogs swim in water.
5. Body of a yak is covered with thick fur whereas body of terai
buffalo is covered with thin fur. Why?
Yaks live in cold the himalayan region. To protect them from
cold, their body is covered with thick fur. But terai buffalos live
in hot terai region. If they have thick fur, they feel uncomfortable
due to heat conserved by thick fur. Therefore, they have thin furs.

Times' Crucial Science Book - 9 310

Glossary

Primitive : very poorly developed
Micro-organism : so tiny that it cannot be seen without using a microscope
Obligatory : complete, total, compulsorily
Flexible : elastic
Buoyancy : tendency to float in water
Marshy : wet and muddy
Swift : active and fast
Adhesive : a substance that unites or attaches surfaces together

Symbiotic : a relation in which both are benefitted and no one is harmed

Main points to remember
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0HVRSK\WHV KDYH ODUJH EURDG DQG YDULRXV VKDSHG OHDYHV ZLWK

numerous stomata.
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7KH OHDYHV RI [HURSK\WHV DUH PRGLÀHG WR WKRUQV WR UHGXFH WKH ORVV RI

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Exercise
1. Answer these questions in very short.

a. What is adaptation ? What happens to an organism if it is
unable to adjust to the environment?

b. How does an organism show adaptation in an environment?
c. Mention any three adaptational characteristics of aquatic plants.
d. What are mesophytes? Mention any three adaptational

characteristics of mesophytes.
e. What are xerophytes? Mention any three adaptational

characteristics of xerophytes.
f. Mention any two characteristics of a cactus plant which

helps it to survive in the desert.

311 Times' Crucial Science Book - 9

g. Write any three adaptational features of the organisms
shown in the figure.

h. Mention any three adaptational characteristics of
aquatic animals.

i. What are cursorial animals? Mention any three
adaptational characteristics of cursorial animals.

j. What are fossorial animals? Mention any three
adaptational characteristics of fossorial animals.

k. Mention any three adaptational characteristics of birds
2. Identify the organisms on the basis of following features:

a. Leaves are modified to thorns and stem is fleshy to store water.
b. Body is covered by water proof scales and gills are present

for breathing.
c. Stem is slender, long and flexible which are less affected

by current of flowing water.
3. Differentiate between:

a. Submerged and floating plants
b. Aquatic animals and terrestrial animals
c. Mango and lotus
d. Arboreal and aerial animals
4. Give reasons:
a. A camel has water pouch.
b. Birds have air sacs.
c. Body of aquatic animals are covered by water proof scales
d. Cucumber and pumpkin plants contain hooks and tendrils.
e. Birds have pneumatic bones in their body.
f. Aloe has thick and fleshy leaves.

Project Work

Study the adaptational characteristics of animals and plants that are
present in your surrounding and prepare a project work report based on
your study.

Times' Crucial Science Book - 9 312

Chapter 6\VWHPV

18

Robert Hooke

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Objectives ƐƟŵĂƚĞĚ WĞƌŝŽĚƐ ͗ ϳ

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Mind Openers

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Relationship between cells, tissues and organs

All living things are composed of cells. Some living things are
composed of only one cell. They are called unicellular organisms.
In such organisms, all life activities take place within a single cell.
But, some organisms are made up of many cells. They are called
multicellular organisms. In such organisms, various organs and
systems are formed for carrying out various functions.

For example, for breathing and respiration function, organs like
nose, lungs, pharynx, bonchi, trachea, etc come into use. These
organs collectively form the respiratory system. Organs are
formed by the combination of tissues. Thus, organ can be defined
a part of system which is formed by the combination of tissues of
various types.
Tissues are formed by the combination of cells of similar or
different types. In human beings too, cells of similar type or
origin combine together to form tissue. Tissues carry out certain
functions. Tissues of various types remain in group to form organs.
An organ is a part of system which performs a particular function.

313 Times' Crucial Science Book - 9

Group of various organs work together to form a system. Body of an
organism functions due to interrelationship among cells, tissues,
organs and systems.
The following table shows the systems in human body, their organs,
tissues and functions.

SN System Organs of System Kinds of Tissues Major Functions

1. Digestive Mouth, stomach, liver, Columnar epithelium, Grinding,digestion,
System pancreas, intestine involuntary muscle absorption of foods

2. Respiratory Nasal chamber, trachea, pavement epithelim, Inhale and exhale of
System bronchus, lungs, etc. cubical epithelium oxygen

3. Excretory Kidney, liver, ureter, Pavement and cubical Excretion of waste
System urinary bladder, gall epithelim products
bladder

Circulatory Heart, blood vessels, Cardiac muscle, To supply food and
4. System blood connective tissue, oxygen, fight with
pavement epithelium disease germs.

5. Skeletal Bones and Cartilage Connective tissue To give framework,
System to help in locomotion

6. Reproductive Testes, ovaries, vagina, Cubical and columnar Reproduction
System penis epithelium

7. Nervous Brain, spinal cord and Nervous tissue To conduct all
System nerves activities of the body

8. Muscular Muscle cells and muscle Skeletal, smooth and Gives shape to the
System fibres cardiac muscles body and helps in
movement.

9. Glandular Group of specialized cells Glandular tissues Produces enzymes
System and hormones.

Plant tissues
Plant body is composed of various types of tissues. Plant tissues are
mainly of three types on the basis of types of cells found in them.
They are:
i) Meristematic tissue ii) Permanent tissue iii) Special tissue
Meristematic tissue
7KH WLVVXH ZKLFK FRQWDLQV WKH FHOOV KDYLQJ FDSDFLW\ RI FHOO GLYLVLRQ
is called meristematic tissue. The cells are closely attached to each
other. The cells contain protoplasm with large nucleus. Vacuoles
are absent in them. The cell wall is thin. Meristematic tissue is
further classified into three types on the basis of location. They are:

Times' Crucial Science Book - 9 314

i) Apical meristematic tissue ii) Lateral meristematic tissue
iii) Intercalary meristematic tissue
Apical meristematic tissue
It is present at the apex of stem, root or branch. It is responsible
for increasing the length or height of a plant.
Lateral meristematic tissue
It is present along the side of the stem or root. Due to its location
at the side, it is called lateral meristem. It is responsible for the
increase of thickness or girth of stem or root of plants.
Intercalary meristemic tissue
The meristematic tissue located at the base of leaves or flowers
above the node is called intercalary meristematic tissue. It
increases length of internodes or axis in plants.

Apical Meristem

Intercalary Meristem

Lateral Meristem
Types of meristematic tissue

Fact Reason

A plant doesn’t grow vertically if we cut the tip, why?
The tip of the plant consists of apical meristematic tissues which
is responsible for vertical growth of the plants. Hence, a plant
doesn’t grow vertically if we cut the tip.

Permanent tissue

7KH WLVVXH ZKLFK FRQWDLQV WKH FHOO KDYLQJ QR FDSDFLW\ RI FHOO
GLYLVLRQ LV FDOOHG SHUPDQHQW WLVVXH The cells may be either living
or dead and thin walled or thick walled. The permanent tissues
are of three types. They are:

i) Simple permanent tissue ii) Complex permanent tissue

iii) Special permanent tissue

315 Times' Crucial Science Book - 9

Simple permanent tissue

A simple permanent tissue consists of similar types of cells. They
perform common functions. It is further classified into parenchyma,
collenchyma and sclerenchyma.

Parenchyma Nucleus
Cytoplasm
It is composed of oval, spherical or
polygonal cells. It is found in root,
stem and leaves of plants. The cells
are living and thin walled. The Vacuole

SDUHQFK\PD FRQWDLQLQJ FKORURSK\OO LV Parenchyma
called chlorenchyma. It is responsible
for photosynthesis. The parenchyma containg air spaces between
the cells is called aerenchyma. Parenchyma conducts water, food,
etc. It protects and keeps the plant in turgid condition.

Collenchyma Lumen
It consists of living cells with thick Thickening of cell
cell wall. In these cells, corners
are thick due to deposition of extra
cellulose and protein at the edges of
the cells.

It is located below the epidermis
of stem, petiole of leaves, etc. It
provides mechanical support to the Collenchyma

plant body. The collenchyma containing chlorophyll is responsible
for photosynthesis too.

Sclerenchyma Narrow Lumen

The cells of sclerenchyma are very Lignified thick wall
long, narrow and thick walled dead
cells. The cytoplasm is little or
absent. The cell wall is thick due to
deposition of cellulose and lignin.

It is located at the hard parts of Sclerenchyma
plants like seeds, cover of seeds,
shells of nuts, etc. It provides mechanical support and hardness to
the various parts of plants.

Times' Crucial Science Book - 9 316

Complex permanent tissue

The permanent tissue which consists of various types of cells that
work together is called complex permanent tissue. Xylem and
phloem are examples of complex permanent tissue. Xylem and
phloem are responsible for the conduction of materials in various
parts of a plant. Therefore, xylem and phloem are collectively
called vascular or conducting tissue.

Xylem

It is a complex permanent tissue which Xylem
consists of four types of cells. They are
tracheids, vessels, wood fibres and wood
parenchyma. All cells are dead except
wood parenchyma. It is located in the
internal part of root, stem, leaves of
plants, etc.

It is responsible for the conduction of water and minerals from
roots to the leaves. It also provides mechanical support to the
plants.

Phloem

It is also a permanent complex Sieve Tube Companion Cell

tissue which consists of four
types of cells. They are sieve
tube, companion cells, phloem
parenchyma and phloem fibres.
All cells are living except
phloem fibres. Phloem Phloem
Parenchyma

It is located in the roots, stem
and leaves. It is responsible for the transportation of prepared
food from leaves to the various parts of plants. It also stores the
prepared food.

Differences between xylem and phloem

Xylem Phloem

1. It conducts water and minerals 1. It conducts the prepared foods from
from roots to the leaves. leaves to different organs.

317 Times' Crucial Science Book - 9

2. It consists of tracheids, 2. It consists of sieve tubes, companion
vessels, wood fibres and wood cells, phloem fibres and phloem
parenchyma. parenchyma.

3. The major cells of this tissue 3. The major cells of this tissue are living.
are dead.

Activity18 .1 Do this activity under the supervision of teacher

Materials required:

Compound microscope, blade, young stem of dicot
plant, safranin, etc.

Procedure :

1. Take a young stem of dicot plant (gram plant).

2. Hold it with left hand and blade with right Vascular
hand. Cut the stem with the blade into Bundles
thin sections.

3. Place the cut sections in a watch glass and add little water then a few
drops of safranin on it. Select a thin and complete section and place it
on a glass slide.

4. Add a drop of glycerine on the slide and cover it with a cover slip.

5. Observe the slide under a compound microscope. What do you observe ?

2EVHUYDWLRQ

The section of the stem is seen as shown in above diagram. The dense
part is the vascular bundle which contains xylem and phloem.

Special Permanent Tissue

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secretary tissues. They are further divided into:

i. lactiferous tissue ii. glandular tissue.

Lactiferous tissues

Lactiferous tissues are thin walled, elongated and branched ducts
which are responsible for the production of yellow or milky juices
called latex. Such tissue is found in plants like papaya, banyan,
opium, calotropis, argemone, etc. It acts as storage of foods and
waste products.

Glandular tissue

Glandular tissue secretes various juices like oil, mucilage, resin,
nectar, gum, etc. It is found in plants like pine, tobacco, tulsi,
pudina, lemon, citrus fruits, etc

Times' Crucial Science Book - 9 318

Introduction to skeletal system

Bones and cartilages make framework of human body. The
supporting framework of a body is called skeletal system. Human
skeleton is made by bones and supporting tissues. Bone is the
hardest tissue which is made up of calcium, silicon, phosphorus,
and other organic materials. Calcium makes the bone hard. All
bones are covered with a thin and delicate membranes with blood
vessels called periosteum. The inner part is hollow which is called
medullary cavity. It contains yellow bone marrow. The anterior
part is spongy which contains red bone marrow. Yellow bone
marrow produces white blood cells and red bone marrow produces
RBCs.
Besides bones and cartilages, there are other two more connective
tissues in skeletal system. They are ligaments and tendons.
Ligaments are strong and elastic bands of connective tissue which
bind two or more bones in joints. Tendons are tough and inelastic
tissues that connect muscles with bones.
Skeletal system is a supporting framework of a body which consists
of bones and other supporting tissues. The major functions of
skeletal system are as follows:

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Types of skeleton
On the basis of location, human skeleton is divided into two parts.
They are:

a) axial skeleton
b) appendicular skeleton

319 Times' Crucial Science Book - 9

Clavicle Skull
Ribs
Maxilla
Ulna Mandible
Carpals
Scapula
Sternum

Humerus

Lumbar Vertebra
Pelvic Bone

Radius

Metacarpals

Phalanges
Femur

Fibula Patella
Tibia

Metatarsals Tarsals

Phalanges

Human Skeleton

Axial skeleton

The skeleton present in the axis of human body is called axial
skeleton. It includes skull, vertebral column and thoracic cage.
There are altogether 80 bones in axial skeleton of adults and 87
bones in infants.

Times' Crucial Science Book - 9 320

Skull
The bone of head region is called skull. It is further divided into (i)
cranial bones (ii) facial bones (iii) ear ossicles (iv) hyoid. Altogether
there are 29 bones in skull.
a. Cranial bones [8]
Cranium is a bony box inside which brain is located. It is also called
brainbox. It consists of eight flat bones which are interlocked by
saw-like edges called suture.

Sphenoid Bone

Coronal Suture

Parietal Bone Frontal Bone

Temporal Bone Ethmoid Bone
Occipital Bone Nasal Bone
Maxilla
Lacrimal Bone
Zygomatic Bone Mandible

Structure of Skull

The bones of cranium are called cranial bones. They are as follows:
i. Frontal bone [1]: It is one in number and is located at the

forehead part of cranium. It forms the roof of eyes and nose.
ii. Parietal bone [2]: Parietal bones are two in number. They

form the side and roof of cranium.
iii. Temporal bones [2]: Temporal bones are two in number. They

form the base of the cranium at either side.
iv. Occipital bone [1]: It is one in number and forms the back of

the head. It also forms the posterior base of skull.
v. Sphenoid [1]: It is one in number. It lies in the front of

temporal at the base of skull. When viewed from above it
seems like wings-spread bat. It is connected to temporal,
frontal and parietal bones.
vi. Ethmoid [1]: It is one in number. It forms anterior base of
cranium. It forms the side wall of orbital cavity and roof of
nose.

321 Times' Crucial Science Book - 9

b. Facial bones [14]
There are 14 bones in the face called facial bones. They are as
follows:
i. Mandible [1]: It forms the chin. It is only the movable part of

skull. It has sixteen sockets for the lower set of teeth. It is also
called lower jaw bone.
ii. Maxilla [2]: Two maxillae join together to form the upper jaw.
They form a portion of roof of oral cavity. Each maxilla has 8
sockets for upper sets of teeth. It is also called upper jaw bone.
iii. Palatine bone [2]: They form the upper part of palate and roof
of mouth cavity.
iv. Zygomatic bone [2]: Two zygomatic bones form the protruded
parts of cheeks. They form a part of floor and lateral wall of
orbital cavity.
v. Nasal bone [2]: They are two flat bones which form the bridge
of nose.
vi. Vomer [1]: It is a thin and flat bone which forms a part of
middle partition of nose.
vii. Lacrimal bone [2]: They are two small bones which are situated
in each inner wall of orbit of the eyes. They are shaped like
finger nails.
viii. Inferior nasal conchae [2]: They are two in number. They are
located one at the side of each nostril.
c. Ear ossicles [6]
There are three bones in each middle ear. They are called ear
ossicles. Each ear contains malleus [1], incus [1] and stapes [1].
Stapes is the smallest bone of a human boy.

Malleus Incus Stapes

d. Hyoid [1]
It is one in number and is situated just below the mandible and
above the larynx. It is horse shoe shaped. It supports the tongue
base.

Times' Crucial Science Book - 9 322

Bones of trunk

Trunk consists of bones of vertebral column and thorax.

Vertebral column [26]

Vertebral column is made up of 33 small and irregular bones in
infants but the bones of lower part fuse and make 26 bones in
adults. Each bone is called a vertebra. Vertebral column is attached
to the base of skull. It forms the central supporting rod or pillar
of human skeleton. Each vertebra has a hole called neurocoel
through which spinal cord passes. Between two vertebrae there is
a pad of cartilage which absorbs shock and gives flexibility.

The vertebral column is divided into five regions. They are:

i. Cervical vertebrae Cervical Vertebrae (7)
The cervical vertebrae are seven Thoracicvertebrae (12)
pieces of vertebrae in the neck
region. The first piece is called
atlas and the second is called
axis. The atlas supports the skull
whereas the axis combines with
the atlas and the third vertebra to
form pivot joint. This joint helps
the head move side wise.

ii. Thoracic vertebrae

There are 12 vertabrae in thoracic Lumbar vertebrae (5)
region. They are called thoracie
vertebrae. Each vertebra gives
attachment for a pair of ribs.

iii. Lumbar vertebrae Sacral vertebrae (5)
Five vertebrae of bigger size at the
lower side of back form lumbar
vertebrae. They withstand the coccyx (4)
heavy weight of body. Vertebral Column

iv. Sacral vertebrae

It consists of five small pieces of bones in infants but they
fuse together to form a single bone in adults.

323 Times' Crucial Science Book - 9

v. Coccygeal vertebrae or coccyx

It is also called a tail bone. In infants, it consists of four pieces
of small bones but in adults, they fuse together to form a
triangular bone.

Thoracic bone [25]

Thorax contains 12 pairs of semicircular bones called ribs and a
long and flat bone called sternum. Ribs are flat and semicircular
bones which are attached with the thoracic vertebrae at the back
but may or may not attach with sternum at the front. The spaces
between ribs are occupied by muscles named intercostal muscles
which help for the movement of ribs during breathing.

On the basis of attachment with the sternum, ribs are grouped into
three classes. They are:
True ribs: The first seven Ribs

pairs of the ribs which are True ribs Sternum
directly attached to the
sternum are called true ribs.
False ribs: The three pairs Costal
of ribs (8th, 9th and 10th pairs) False ribs Cartilage

which are attached to the 7th Floating
rib but not to the sternum ribs Thoracic Cage
directly are called false ribs.

Floating ribs: The last two pairs of ribs (11th and 12th) which are
attached only with the vertebral column but not with the sternum
are called floating ribs.

The thoracic bones make a cage called rib cage. It protects the
heart and lungs. It also protects a part of stomach and kidneys. It
helps for breathing process too.

Appendicular skeleton

The skeleton present in the lateral side of human body is called
appendicular skeleton. It consists of bones of upper appendages with
pectoral girdle and bones of lower appendages with pelvic girdle.

Pectoral girdle [4]

Pectoral girdle contains four bones: two on each side. The two
bones of each side are scapula and clavicle. Scapula is a flat and

Times' Crucial Science Book - 9 324

broad triangular bone located at the backside of rib cage. It is also
called shoulder blade. Clavicle is a long curved bone attached to
the scapula at the backside and the sternum at the front side. It
covers the ribs partially at the neck.

Bones of upper limbs [60]

The upper limb (hand) consists of following bones:

i. Humerus [1]: It is a long bone Clavicle
extending from shoulder to elbow. It Scapula
is the second longest bone of human
body. It is attached with shoulder
at the space made by scapula and
clavicle.

ii. Radius and ulna [2]: Radius and Humerus
ulna are two bones located at the
forearm. They are located between Radius
elbow and wrist. Radius lies in the Ulna
thumb side and ulna lies in the
little finger side. Radius is bigger Carpals
than ulna. Metacarpels
Phalanges
iii. Carpels [8]: Carpels are the bones
of wrist. They are eight in number.
They lie in two rows, four in each
row. These bones are tightly fitted
and held with ligaments which
allow movement at the wrist.

iv. Metacarpels [5]: Metacarpels are Bone of upper limb
five in number and are located at
the palm of upper limb. They are attached to the carpals at
the upper side and to the phalanges at the lower side.

v. Phalanges [14]: Phalanges are the bones of fingers and are
fourteen in number. The thumb contains two phalanges
whereas other each finger contains three phalanges. In this
way, there are 32 bones in each upper limb.

Bones of lower appandages [62]

It includes pelvic girdle and bones of lower limb.

325 Times' Crucial Science Book - 9

Pelvic girdle [1 on each side]

Pelvic girdle consists of two wide hip bones connected to the thigh
bone and vertebrae. Each hip bone is
formed by the fusion of three bones Ilium

named ilium, ischium and pubis. On
its lower surface there is a deep
socket called acetabulum into which
the head of thigh bone articulates. Acetabulum

The pelvic girdle forms a cavity Ischium
called pelvis in which various organs
like stomach, urinary bladder, Pubis

reproductive organs, intestine, etc
are protected. The pelvis of women is wider than that of male to
accommodate the baby in pregnancy period and to allow free
passage of baby during birth.

Bones of lower limbs [60]

Each lower limb consists of following bones:

i. Femur [1]: It is the longest and Femur
strongest bone of human body.
It is located at thigh. Its head is Patella
spherical which articulates with Tibia
acetabulum of pelvic girdle. Its
lower end articulates with tibia Fibula
and patella.

ii. Patella or knee cap [1]: It is one in
number in each leg. It is flat and
roughly circular and is present in
the front of knee.

iii. Tibia and fibula [2]: Tibia and fibula
are two bones which are present
below the knee. Tibia is larger and Tarsals
stronger. It supports the weight of Metatarsals
body. It is also known as shin bone.
Phalanges

The fibula is slender and thin. It is Bones of lower limbs
located at the outer side of tibia.

iv. Tarsals [7]: Tarsals are seven in number in each leg. They are
present at the posterior part of the foot called ankle.

Times' Crucial Science Book - 9 326

v. Metatarsals [5]: Metatarsals are straight and long bones
which are present at the base of foot. They are five in number
in each leg.

vi. Phalanges [14]: Phalanges are the bones located at the
toes. The first toe consists of two bones whereas other each
toe consists of three bones. Altogether there are fourteen
phalanges in each leg.

Thus, there are 31 bones in each leg.
Fact Reason
Why does the bone become soft when it is kept in acid?
The calcium in the bone dissolves in acid due to which bone
becomes soft. Hence, the bone become soft when it is kept in acid.

Movement in human beings
Movements in human being are carried out by the combined efforts
of bones and muscles. Muscles are the elastic bands which have
the ability to contract and relax. The process of contraction and
relaxation of the muscles whenever required is called muscular
tone.
Skeletal muscles are attached to the bones with tendons. The
skeletal muscles work in pair during movement. Lets take
an example of human arm. Biceps muscles remain above the
humerus whereas triceps muscles remain on the lower side
of humerus. These two muscles work in pair. When the biceps
muscles contract, the triceps muscles relax. In this condition, the
lower arm is raised near to upper arm. Similarly, when triceps
contract, the biceps relax causing the lower arm go away from the
upper arm thereby making the lower arm straight.
Movement of a body part is possible only by contraction not by
relaxation. The muscle which causes the body parts to move
towards the body due to contraction is called flexor. Similarly, the
muscle which causes the body parts to move away from the body
due to contraction are celled extensor. Here in the arm, biceps are
flexor and triceps are extensor.
The pair of muscles which cause the movement of body parts in
opposite direction are called antagonistic muscles. Flexor and
extensor are antagonistic muscles.

327 Times' Crucial Science Book - 9

Digestive system

We take food from mouth. It is chewed in mouth and is swallowed.
The swallowed food passes through oesophagus and reaches
stomach. In stomach, food is stored for some time and then it
travels towards small intestine. Breaking down of food into simple
soluble substances is completed in the small intestine. The food
then goes to large intestine, excess of water is absorbed and semi-
solid waste material is pushed toward anus. This whole process
occurs in digestive system. The group of organs responsible for
the ingestion of food, its digestion, absorption and egestion of
undigested wastes from the body is called digestive system. The
digestive system consists of two major parts: alimentary canal and
digestive glands.
Alimentary canal
The alimentary canal is the main part of digestive system. A long
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is called alimentary canal. It consists of seven main organs: mouth,
pharynx, oesophagus, stomach, small intestine, large intestine and
anus

Mouth

Small Liver Pharynx
intesine
{ Gall bladder Oesophagus
Duodeum
Stomach
Jejunum Pancrease
Ileum Large intesine

Rectum
Anus

Digestive system

Times' Crucial Science Book - 9 328

Mouth

Mouth is the uppermost and Lower jaw Upper jaw Hard palate

the beginning part of digestive
system. It forms a wide cavity
known as buccal FDYLW\. The Soft palate

buccal cavity consists of teeth, Uvula
tongue, muscles and three Tongue
SDLUV of VDOLYDU\ glands. These
glands produce saliva which
contains an enzyme called
salivary amylase. An enzyme
is a substance produced in Mouth

certain parts of alimentary canal, which helps to digest food. The
salivary amylase digests the carbohydrate of food and converts it
into glucose.

The teeth are essential for cutting and chewing the food. There
are no teeth in the mouth of new born baby. The first tooth
appears when the baby reaches the age of six to twelve months
and within the age of about 3 years, the baby possesses a set of 20
temporary teeth. These teeth are called milk teeth. The milk teeth
start falling one by one from the age of six and new ones grow in
their places. By the age of twelve or thirteen, there is a set of 28
SHUPDQHQW teeth in the mouth. Four more teeth known as wisdom
teeth grow between the age of 16 to 21 years. Finally, an adult has
a set of 32 teeth in the mouth; 16 in upper jaw and 16 in lower jaw.
The teeth are originated from the jaws. The upper jaw is fixed
whereas the lower jaw is movable. Each tooth consists of three
main parts: - crown, neck and root. There are four kinds of teeth.
They are: incisors, canines, premolars and molars.

Enamel

Dentine

Incisor Canine Pre-molar Molar Gum
7\SHV RI WHHWK
Pulp

Cement
Jaw bone

Parts of teeth

329 Times' Crucial Science Book - 9

Pharynx

It is a wide opening at the back of mouth. The swallowed food
travels towards oesophagus through pharynx. It is the common way
for both swallowed food and inhaled air. The pharynx leads into
two tubes-food pipe and windpipe. 7KH EHJLQQLQJ RI WKH ZLQGSLSH
FRQVLVWV RI D PXVFXODU IODS FDOOHG HSLJORWWLV The epiglottis closes
the opening of windpipe while swallowing the food.

Oesophagus

It is a long narrow muscular tube, which connects pharynx to
stomach. Food travels quickly through it and no digestion of food
occurs in it. It is because no digestive juices are produced in the
oesophagus.

Stomach

Stomach is a large muscular elastic bag Liver
that lies between oesophagus and small
intestine. It is J-shaped and is present Stomach

on the left side of abdomen. It stores the
ingested food for some hours. The interior
Pancreas

walls of stomach contain gastric glands,
which secrete gastric juice and mucus. The
gastric juice contains the enzymes pepsin, lipase and renin. It also
contains hydrochloric acid. The enzyme pepsin digests protein into
peptide. Lipase converts fat in to fatty acid and glycerol. Renin
helps in the digestion of milk. Hydrochloric acid activates pepsin
as well as kills the germs present in food. A complete mixture of
food and enzymes is formed in the stomach which is called chyme.

Fact Reason

Why is hydrochloric acid in the stomach important for the
digestion of food?
Hydrochloric acid activates pepsin and dissolves the mineral
substances in the food. Hydrochloric acid also kills the germs
that get into stomach along with the food. So, hydrochloric acid is
important for digestion.

Small intestine
It is a long, narrow and coiled muscular tube that lies between
stomach and large intestine. It is the longest part of alimentary
canal. It consists of three main parts-duodenum, jejunum and

Times' Crucial Science Book - 9 330

ileum. The beginning part of small intestine is called duodenum.
It is C-shaped and is about 30 cm long. The duodenum receives
pancreatic juice from pancreas and bile juice from liver through
common bile duct. Jejunum is the middle part of small intestine.
It is about 2.5 meters long. The last part of small intestine is ileum
which is a highly coiled region. It ia about 3 meters long. The inner
wall of ileum consists of millions of finger like muscular folds
known as villi. The villi are the main sites from where digested
food is absorbed into the blood stream.
The inner walls of small intestine contain glands. These glands
are called intestinal glands which produce digestive juices known
as intestinal juice. This juice contains the enzymes like amylase,
maltase, sucrase, lactase, aminopeptidase, lipase, etc.

Large intestine
It is the short and broad part of alimentary canal. It begins from
small intestine and ends at anus. The large intestine can be
divided into six main parts - caecum, ascending colon, transverse
colon, descending colon, sigmoid and rectum.

Transverse colon Descending colon
Ascending colon

Sigmoid
Rectum

Caecum

The beginning part of large intestine is called caecum. It leads
to ascending colon, which moves upwards from the caecum. The
transverse colon remains horizontal near the duodenum. The
transverse colon moves down to form descending colon. The bend
of descending colon is called sigmoid. The last wider and elastic
part of large intestine is called rectum.
Anus
It is the last part of alimentary canal. It helps in the egestion of
undigested semi-solid materials from the body.

331 Times' Crucial Science Book - 9

Digestive glands

Salivary glands, gastric glands, intestinal glands, liver and
pancreas are the main digestive glands present in the alimentary
canal of human beings.

1. Salivary glands

There are three pairs of salivary glands in the buccal cavity.
They are parotid glands, sub maxillary glands, and sublingual
glands. 7KH VHFUHWLRQ RI VDOLYDU\ JODQGV LV FDOOHG VDOLYD The
saliva is watery and contains the enzyme salivary amylase
along with mucin and other substances. Saliva moistens and
lubricates the food to make it easier to swallow. It digests
carbohydrate of food in to glucose. It also helps in speaking.

2. Liver

The liver is the largest Liver

gland of the body. It
secrets a brownish- Gall bladder
green liquid, which is
known as bile. The bile
is stored in the gall bladder. When the food reaches to the
duodenum, the gall bladder squeezes to release bile. The bile
passes down the liver through hepatic ducts and is poured
into common bile duct that opens into the duodenum. Bile
emulsifies fat and helps in its digestion.

3. Pancreas

The pancreas is located in the bend of duodenal loop. The
SDQFUHDV VHFUHWHV D MXLFH FDOOHG SDQFUHDWLF MXLFH ZKLFK SDVVHV
GRZQ WKURXJK SDQFUHDWLF GXFW The pancreatic duct joins
common bile duct to enter the duodenum. The pancreatic juice
contains the three enzymes -trypsin, amylase, and lipase.

4. Intestinal glands

A large number of glands are present in the inner parts of small
intestine which secrete intestinal juice. The intestinal juice
contains several enzymes, which convert all the components
of semi-digested food into their end products.

Process of digestion

7KH SURFHVV RI EUHDNLQJ GRZQ RI FRPSOH[ IRRG LQWR VLPSOHU VROXEOH
forms that can be absorbed by the body cells is called digestion.

Times' Crucial Science Book - 9 332

The digestion of food begins from the mouth. The food gets mixed
with saliva which moistens and lubricates the food. Tongue moves
the food and teeth chew it. The chewed food is turned into a ball
like shape called bolus by tongue and is pushed towards the
oesophagus.
The swallowed food passes down the oesophagus to reach
stomach. The food is stored in the stomach and is mixed with the
fluid called gastric juice. The gastric juice contains the enzymes
pepsin and renin along with hydrochloric acid. Hydrochloric acid
activates pepsin. It also dissolves the mineral substances in the
food. Hydrochloric acid also kills the germs that get into stomach
along with the food. Pepsin changes the protein part of food
into peptones and polypeptides while renin converts milk into
paracasein. The food remains in the stomach for some hours and
then passes into the small intestine.
The food gets mixed with bile and pancreatic juice in the duodenum
of small intestine. Bile emulsifies the fat and turns it into small
droplets. The pancreatic juice contains three enzymes-amylase,
lipase and trypsin. Amylase digests starch (carbohydrate) and
converts it into simple sugars like maltose, isomaltose, etc. Lipase
acts upon emulsified fat and converts it into fatty acids and
glycerol. Trypsin acts upon polypeptides (protein) and changes
them into dipeptides and amino acids. The semi -digested food
then passes toward the jejunum and ileum of small intestine. The
glands of small intestine secrete intestinal juice. The intestinal
juice contains a large number of enzymes, which convert all the
components of semi-digested food into their end products. Glucose,
fructose, glactose, glycerol, fatty acids and amino acids are the
final products of digestion. These are the soluble forms which get
dissolved in water and are absorbed into the blood stream.
The digestion of food is completed in small intestine. It is then
absorbed by the villi of small intestine. The remaining part of food
is pushed toward the large intestine. The large intestine absorbs
the excess of water from the food and turns it into semi-solid form.
About 90% water is absorbed by large intestine. The undigested
and waste form of food travels down and gets collected in the
rectum, which is passed out from the anus.

333 Times' Crucial Science Book - 9

Digestion is not required for minerals and vitamins because they
are soluble in water and can directly be absorbed by the villi.
Importance of digestive system
,W FRQYHUWV FRPSOH[ organic food LQ WR VLPSOH VROXEOH IRUPV

so that they are absorbed to body. This food is the source of
energy for the body.
2. It throws out the undigested SDUW RI IRRG DV ZDVWH PDWHULDO
through anus.
Respiratory system
We get oxygen necessary for the body through breathing and obtain
energy through respiration. The process of supplying pure oxygen
to the cells and eliminating carbon dioxide out of the body is called
breathing. The process of burning of food in the cells to produce
energy in the body is called respiration. 7KH JURXS RI RUJDQV WKDW ZRUN
WRJHWKHU WR VXSSO\ R[\JHQ WR WKH ERG\ EXUQ IRRG WR UHOHDVH HQHUJ\ DQG
WKURZ FDUERQ GLR[LGH IURP WKH ERG\ LV FDOOHG UHVSLUDWRU\ V\VWHP
The process of respiration continues non-stop throughout the life. Our
body needs more energy while playing or doing hard works. So, our
rate of respiration becomes faster in order to produce more energy.
We do not need much energy while we are having rest or sleeping, so
the rate of respiration becomes normal. The normal rate of respiration
for a healthy adult is about 16 breathes per minute.

Organs of respiratory system

The respiratory system consists of following organs:

1. Nose

2. Pharynx Nose Pharynx
3. Larynx (voice box) Trachea
Bronchus
4. Trachea (wind pipe) Larynx

5. Bronchus

6. Bronchioles Bronchioles
7. Alveoli (air sacs)

8. Lungs

9. Diaphragm Lungs
10. Intercostal muscles
Respiratory system

Times' Crucial Science Book - 9 334

1. Nose
Nose is the outermost part of respiratory system. Our nose
consists of two nostrils. It is formed by two nasal bones and
cartilage. The nostrils lead to the nasal cavities, which are
covered by epithelial tissues. The nasal epithelium produces
a slippery liquid called mucus. The mucus and the hairs
inside the nose filter the air going from outside and stop
the dust particles as well as germs. The mucus also helps in
making the nose moist. The nose helps to detect the smell of
the substances as well.

2. Pharynx
The pharynx is the common way to both food and air. It directs
food to pass toward food pipe (oesophagus) and air toward
windpipe (trachea). The opening part of the windpipe (larynx)
has epiglottis which closes the windpipe while swallowing
food. Its functioning will be disturbed if the ingested food and
inhaled air pass through the pharynx together. This results
in coughing and may lead to serious respiratory problem.

3. Larynx
Pharynx leads into larynx. It is also known as voice box. The
larynx lies at top of the windpipe. It is made of cartilage and
looks like a pointed bone in our throat. This bone is known
as Adam's Apple (Rudraghanti). The larynx consists of a leaf
like covering of cartilage known as epiglottis.
The larynx consists of vocal cords. When air is forced through
the larynx, the vocal cords vibrate and produce the sounds.

4. Trachea
Trachea is a tube-like flexible pipe made of rings of cartilage
that joins larynx to bronchi. It is also known as windpipe. At
the lower end, trachea divides into two tubes called right and
left bronchi leading to the lungs. The function of trachea is to
pass the air from larynx to lungs and vice -versa.

5. Bronchus and bronchioles
The trachea divides into two branches - left and right
branch, which are called bronchi (sing. bronchus). The right
and left bronchi join right and left lungs respectively. The
bronchi divide and re-divide to form finest branches called
bronchioles.

335 Times' Crucial Science Book - 9

6. Alveoli
The bronchioles end up into the very tiny muscular sacs
called alveoli. They are also called air sacs. The alveoli are
surrounded by a network of blood capillaries. The exchange
of gases occurs in the alveoli of lungs, i.e. the blood gives out
carbon dioxide and takes up oxygen in the alveoli.

7. Lungs
There are two lungs – left and right in our body. The lungs
are made of soft, spongy and elastic tissues. The left lung is
narrower and smaller than the right one. The right lung has
three lobes whereas the left lung has only two. The lungs are
FRYHUHG ZLWK WZR OD\HUV RI WKLQ PHPEUDQHV FDOOHG SOHXUD The
pleura contains a slippery liquid which prevents the friction
between the lungs at the time of respiration.

8. Diaphragm
$ WKLQ EDQG RI GRPH VKDSHG PXVFOHV ZKLFK VXSSRUWV WKH OXQJV
LV FDOOHG GLDSKUDJP. It separates the chest from stomach and
helps the lungs to expand and contract. The diaphragm plays
a significant role during inspiration and expiration.

9. Intercostal muscles
7KH PXVFOHV SUHVHQW LQ WKH VSDFHV EHWZHHQ ULEV DUH FDOOHG
intercostals muscles. There are eleven pairs of intercostal
muscles in between the spaces of twelve pairs of ribs. The
contraction and expansion of these muscles plays a significant
role during inspiration and expiration.

Process of respiration
While inhaling, the intercostal muscles contract and diaphragm
falls down due to relaxation. As a result the chest becomes bigger
and the lungs expand. This decreases the air pressure in the
lungs so that outer atmospheric pressure becomes higher. So, the
atmospheric air enters into the lungs. This process of inhalation of
atmospheric air into the lungs due to the contraction of intercostal
muscles and relaxation of diaphragm is called inspiration.
While exhaling the intercostal muscles relax and the diaphragm
moves up due to contraction. As a result, the chest becomes smaller
and the lungs contract. Thus, the air pressure in the lungs becomes
greater than the outer atmospheric pressure. Hence, the air is
pushed out of the lungs. This process of throwing out of carbon
dioxide rich air from the lungs is called expiration.

Times' Crucial Science Book - 9 336

The inhaled air is rich in oxygen. When it reaches to the alveoli
of lungs, the oxygen mixes with the blood by replacing carbon
dioxide. The blood combined with oxygen is called oxygenated
blood. The oxygenated blood goes to the heart through pulmonary
veins. The heart pumps the oxygenated blood to all the parts
(upto tissues and cells) of the body. The cells also get digested food
(glucose) through the blood. A chemical reaction occurs between
glucose and oxygen in the cells. This chemical reaction is called
respiration. This process produces energy. This energy keeps
us warm and alive. It also enables us to do all works. Excess of
energy is stored in the body.
The chemical reaction that occurs during respiration is given below:
*OXFRVH 2[\JHQ ń&DUERQ GLR[LGH :DWHU (QHUJ\
CarbonCd6iHox1i2dOe6a+nd6wOa2 tńer a&r2e 2the+side pr6oHdu2Octs + Energy
of respiration.
The carbon dioxide gets mixed with the blood and makes the blood
impure. The impure blood from the body is collected by veins
and then sent to heart through superior and inferior venacavas.
The heart then pumps the impure blood to the lungs through
pulmonary artery so that the lungs purify it and return pure blood
to the heart through pulmonary veins.
Importance of respiratory system
,W VXSSOLHV R[\JHQ QHFHVVDU\ IRU WKH ERG\
,W KHOSV WR eliminate FDUERQ GLR[LGH IURP WKH ERG\ ZKLFK LV
harmful for the body.
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ZRUNV JURZWK DQG YHU\ RWKHU SXUSRVHV
,W KHOSV LQ WKH SURSHU IXQFWLRQLQJ RI QHUYRXV V\VWHP

Excretory system

Different unnecessary substances are formed in our body during
different processes such as digestion, respiration, etc. These
unnecessary substances are called wastes and are removed
from different parts of our body. The organs such as skin, nose,
mouth, lungs, liver, kidney, anus, etc are involved in removing
wastes from the body. The organs which are involved in removing
unnecessary waste materials from the body are called excretory
organs and the system formed by such organs is called excretory
system.

337 Times' Crucial Science Book - 9

Skin is one of the excretory organs. It removes salts, water and
urea from the body in the form of sweat. The process of removing
salts, water and urea from the body in the form of sweat from the
body is called perspiration. Similarly, nose and mouth help to
remove mucus, spit, cough, etc from the body. Large intestine and
anus remove the undigested and unnecessary food wastes from the
body. Lungs expel the unwanted carbon dioxide and excess of water
vapour from the body. Liver collects several harmful substances in
bile and pours them to the intestine. The harmful substances are
then excreted along with food wastes.
Urinary system is the chief excretory system in the human body. It
removes the very harmful nitrogenous wastes from the body. The
urinary system consists of a pair of kidneys, a pair of ureters, a
urinary bladder and urethra.

Adrenal gland Renal artery
Right kidney Renal vein
Left kidney

Ureter Abdominal aorta
Inferior venacava

Urinary bladder Common iliac
artery and vein

Urethra
([FUHWRU\ V\VWHP

Each kidney is bean shaped with dark purple colour. Kidneys are
located on either side of vertebral column in front of the last pair of
ribs. There are millions of nephrons in each kidney. The nephrons
are the filtering units of each kidney. They filter the blood to
separate the harmful nitrogenous wastes and produce urine.
The urine is collected in the urinary bladder which is thrown out
through urethra periodically.

Importance of excretory system
1. 8UHD DQG RWKHU QLWURJHQRXV ZDVWHV DUH YHU\ KDUPIXO IRU WKH ERG\

7KHVH ZDVWHV DUH UHPRYHG IURP WKH ERG\ E\ H[FUHWRU\ V\VWHP

Times' Crucial Science Book - 9 338

7KH ZDVWHV SURGXFHV GXULQJ PHWDEROLF DFWLYLWLHV in the body
are thrown out of the body.

7KH ZDVWHV VXFK DV FDUERQ GLR[LGH ZDWHU YDSRXU HWF DUH
UHPRYHG IURP WKH ERG\

7KH SURFHVV RI SHUVSLUDWLRQ DOVR KHOSV WR PDLQWDLQ WKH
WHPSHUDWXUH of the body.

Learn and Write
1. Cell is called structural and functional unit of life. Why?

All organisms, from unicellular to gigantic, are made up of cells.
Their body structure is determined by the arrangement of cells.
Various life activities like respiration, growth, reproduction,
excretion, etc take place inside the cells. Therefore, a cell is
called structural and functional unit of life.
2. Mitochondria are called powerhouse of a cell. Why?
Oxidation of food takes place in mitochondria which results
in the production of energy. The energy thus produced is
used for various activities. Therefore, mitochondria are
called powerhouse of a cell.
3. Height of a plant does not increase when its tip is cut. Why?
At the tip of a plant, there is meristematic tissue. This tissue
contains the cells having capacity of cell division which cause
the growth in the plants. When the tip is cut, the plants stop
growing and their height does not increase.
4. Movement of our hands is under our will but the movement
of our alimentary canal is not under our will. Why?
Our hands contain voluntary muscle which can be moved as
per our wish. But the alimentary canal is made of involuntary
muscles whose movement is not under our control. Therefore, we
can move our hands as per our wish but not the alimentary canal.
5. Cardiac muscles are the combined form of skeletal and
smooth muscles. Why?
Cardiac muscles have dark and light bands as in skeletal
muscle but they are involuntary in nature. Therefore, cardiac
muscles are the combined form of skeletal and smooth muscles.
6. Bones of infants are soft but those of adults are hard. Why?
Bones become hard due to deposition of calcium salts. Infants
have less deposition of calcium in their bones. Thus, they are
soft. But, there is more deposition of calcium in the bones of
adult causing the bone to be hard.

339 Times' Crucial Science Book - 9

7. Females have wider pelvis than males. Why?
Females have to accommodate baby during pregnancy stage.
In addition to this, wider pelvis allows the easy passage of the
baby during child birth.
Thus, females have wider pelvis than males.

8. Generally, old people suffer from jointache. Why?
In old people, the production of synovial fluid is reduced.
The synovial fluid works as a lubricant for the movement of
bones. When production of synovial fluid is reduced, there
occurs friction between the bones in the joints. This causes
the jointache.

9. Our hands can be moved in all directions. Why?
There is a ball and socket joint between the humerus and pectoral
girdle. Such type of joint allows the free movement of one bone
over another. Thus, hands can be moved in all directions.

Glossary

Meristematic tissue : a living tissue of plants which is found in the tip of the
growing area
Atlas : first bone of cervical vertebra to which the head is
connected
Deposition : collection
Periosteum : thin and delicate covering of bone
Zygomatic bones : cheek bones
Articulate : connect
Egestion : excretion of unwanted semi-solid materials from anus

Nephrons : filtering units of kidney

Main points to remember

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&RQQHFWLYH WLVVXHV DUH WKH WLVVXHV ZKLFK FRQQHFW ELQG DQG SURYLGH

VXSSRUW WR YDULRXV WLVVXHV RU RUJDQV

Times' Crucial Science Book - 9 340

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Exercise

1. Answer these questions
1. What is cell?
2. What are cell organelles? Name some cell organelles
found in plant cell.
3. What are mitochondria? Why are they important for cells?
4. Draw an animal cell and label its important parts.
5. Draw a plant cell and label its important parts.

341 Times' Crucial Science Book - 9

6. What is meristematic tissue ? Explain various types of
meristematic tissues.
7. Draw a neuron and label its important parts.
8. What is permanent tissue? Mention various types of
simple permanent tissue.
9. What is complex permanent tissue? Explain its various
types.What is skeletal system ? What are various types
of skeleton?
10. What is axial skeleton? What are its parts?
11. What is cranium? What are the bones of cranium?
Mention their numbers too.
12. Write the name of facial bones and their numbers.
13. What are the bones of ear?
14. What is vertebral column? Mention the names and
number of various bones of vertebral column.
15. Draw a diagram of vertebral column and label its
important parts.
16. What are ribs? Mention the name of various types of ribs.
17. What is intercostal muscle ? What is its function?
18. What is appendicular skeleton? What are its parts?
19. Mention names and number of bones of upper appendages.
20. Mention names and number of bones of lower appendages.
21. Draw (i) upper appendages (ii) lower appendages.
22. What is a joint ?
23. What are antagonistic muscles?
A
2. Label the parts shown in the diagram.

B C
3. Give reasons: D

a) Complex permanent tissues are called E
vascular tissues.
b) Milk-like substance comes out when we pluck a leaf of
a rubber plant.
c) A cell is called structural and functional unit of life.
d) Hydrochloric acid has an inportant role in stomach.
e) No digestion occurs in oesophagus.
f) Bone when kept in acid becomes soft.
g) Pelvis of female is wider than that of male.
h) Old people suffer from joint ache.

Times' Crucial Science Book - 9 342

4. Differentiate between:
a. Plant cell and animal cell
b. Xylem and phloem
c. Meristematic tissue and permanent tissue
d. Parenchyma and sclerenchyma
e. Simple permanent tissue and complex permanent tissue
f. Small intestine and large intestine

5. Identify the following tissues

a. b.

c.

d. e.

6. Name the part of skeleton where the following bones are
present:
(i) Vomer (ii) Tibia (iii) Femur (iv) Atlas
(v) Frontal (vi) Metatarsals (vi)Radius

7. Define: (ii) Tendon (iii) Flexor muscle
(i) Cartilage (v) Sternum
(iv) Ligament

8. Answer these questions in very short.
a. Mention functions of skeletal system.
b. What are biceps and triceps?
c. How do biceps and triceps move the arms?
d. Draw human skull and label its important parts.

Project Work

1. Study the different types of plant tissues under the microscope and
prepare a brief report of your study.

2. Visit a butcher’s shop and study different types of bones of goat. The
bones of goat are very similar to those of human beings because both goat
and human belong to the same class mammalia.

343 Times' Crucial Science Book - 9

Chapter

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Adolf Gaston Eugen Fick

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Objectives

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• describe the structure of sense organs.

Mind Openers

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Introduction
Living things are made aware about external environment by some
organs like eye, nose, skin, tongue, ear, etc. These organs contain
receptors which receive the stimulus from the environment and
send to the central nervous system. Stimulus is the change in
environment which activates the receptors of the sense organs.
Receptors are of different types. On the basis of the stimulus
(plural-stimuli) received, they are of following types:
i) Photoreceptors: The receptors which respond to light are

called photoreceptors. Example: receptors in eyes.
ii) Thermoreceptors: The receptors which respond to the heat

are called thermoreceptors. Example: nerves in skin.
iii) Chemoreceptors: The receptors that respond to chemicals are

called chemoreceptors. Example: nerves in tongue.
iv) Olfactoreceptors: The receptors that respond to smell are

called olfactoreceptors. Example: nerves in nose.
v) Mechanoreceptors: The receptors that respond to the touch

are called mechanoreceptors. Example: nerves in skin.
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are called sense organs.

Times' Crucial Science Book - 9 344

Eyes: organs of sight Cilliary body Sclera
In human body, there are a Choroid
pair of eyes which are located Iris Retina

in orbital cavity. Human eyes Fovea Centralis
are protected by eyebrows and Optic disc
eyelids. Eyebrows are small Pupil (Blind Spot)

hairs which protect eyes from Cornea Blood vessels

dust, sweat, etc. Eyelids are Lens Optic nerve
the cover of skin which contain Suspensory
eyelashes and protect the eyes Ligament
from dust, insects, injury and Eyeball

other foreign bodies. Tear gland produces tears which keeps the
eyes moist and washes away the dirts. Each eye contains a ball
called eyeball. Each eyeball contains three layers. They are:
i. Sclerotic layer ii. Choroid iii. Retina
a) Sclerotic layer
It is the outermost layer and is made up of tough connective tissue.
It contains two parts: posterior sclera and anterior cornea. Sclera
is opaque and white part which gives shape to the eyeball and
protects the inner parts.
Cornea is a transparent and thin layer which is bulging outside.
It is not supplied with blood vessels. It is covered externally by a
very thin transparent membrane called conjunctiva. Cornea is also
called the window of the eye because light enters the eyes through
cornea.
b) Choroid
It is the middle layer of eyeball which is made up of thin layer
of connective tissue. It is dark pigmented and supplied with
blood vessels. The dark pigment absorbs light and prevents the
reflection of light within the eye. At the anterior part, this layer
gets separated from cornea forming iris. Iris is a dark coloured disc
shaped structure which lies infront of the lens. It is the pigmented
part of eye seen from outside. In the middle of the iris, there is a
small round hole. It is pupil. Light enters the eyes through pupil .
The amount of entering light is regulated by changing the size of
pupil by iris. In bright light and near vision, size of pupil decreases
and its size increases in dim light and far vision.
Just behind the iris, there is a transparent, crystalline and biconvex
lens made up of proteins. It is suspended by suspensory ligaments
and ciliary muscles produced from choroid layer. Ciliary muscles

345 Times' Crucial Science Book - 9

change the shape and focal length of eye lens by contraction and
relaxation. This process is called accommodation.
The lens divides the cavity of the eye ball in to two chambers: anterior
and posterior. The anterior cavity is filled by clear watery fluid called
aqueous humour and the posterior cavity is filled by thick, gelatinous
substance called vitreous humour. The aqueous humour inflates
the frontal part of eye ball and keeps the lens moist whereas the
vitreous humour maintains the shape of eyeball, supports retina and
maintains liquid pressure within the eyeball.
c) Retina
It is the innermost layer of eyeball. It is provided with many layers
of nerve fibres called photoreceptor cells. There are two types of
photoreceptor cells. They are rods and cones. Rods are the rod
shaped photoreceptor cells which are more sensitive to dim light.
Similarly, cones are the cone shaped photoreceptor cells which
are sensitive to bright light and are responsible to distinguish
colours. Rods contain purple pigment known as rhodopsin which
is formed from vitamin A. Similarly, cones contain violet pigments
called iodopsin which is also formed from vitamin A. Deficiency of
vitamin A in rods cause night blindness and deficiency of vitamin
A in cones causes colour blindness.
Retina has two spots. They are yellow spot and blind spot. Blind
spot does not contain any photoreceptor cells. So, image is not
formed when light falls on blind spot. But yellow spot contains
only cones. The sharpest image is formed, when light falls on it.
Optic nerves originate from the posterior part of the retina. These
nerves carry the impulses from the retina to the brain.

Fact Reason

Why cannot we distinguish colours in moon light?
Cones are responsible for day and colour vision and rods are
responsible for dim light vision as well as moonlight vision which
cannot distinguish colours. So, we cannot distinguish colours in
moon light.

Working of eye
The light rays coming from an object enter the eyes through
cornea then through pupil. The lens refracts the rays and forms
real, inverted and very much diminished image on the retina.
The photoreceptors, i.e. rods and cones get activated by the light
rays and generate impulses. The impulses are sent to the brain

Times' Crucial Science Book - 9 346