Class 9 Science_clone

Activity 14.4 To remove the permanent hardness of water by washing soda

Materials required:
Magnesium chloride, beakers, test tubes, burner, tripod stand, spoon, etc
Procedure:
1. Take some water in a beaker.
2. Add a spoonful of magnesium chloride into it and stir it well.
3. Prepare a soap solution in another beaker.
4. Pour some solution of magnesium chloride in a test tube and drop some

drops of soap solution into it.
5. Shake the test tube well. Will you observe lather?
6. Now, add one spoonful of washing soda into the magnesium chloride

solution of beaker and stir well.
7. Take a little of solution obtained from step no. 6 in a test tube and add

some drops of soap solution.
8. Shake the mixture well. Will you observe lather?
Observation:
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the second case.
Conclusion:
Permanent hardness can be removed by washing soda.

Advantages of hard water
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strong.
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Disadvantages of hard water
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capacity of soap.
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247 Times' Crucial Science Book - 9

Glossary : Water that flows on the surface of the earth, i.e. in
streams, springs, rivers, lakes, oceans, etc
Surface water
Fresh water : Water that does not contain dissolved salts in significant
Cohesion amount
Adhesion
Surface tension : The sticking together of particles of the same substance
: The force of attraction that causes two different substances
Permutit
to join
: The attractive force exerted upon the surface molecules of

a liquid by the molecules beneath that tends to draw the
surface molecules into the bulk of the liquid and makes
the liquid assume the shape having the least surface area
: An ion exchange resin

Main points to remember

1. Water is the most useful and most abundant substance on the earth.
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(vapour).

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form of vapour in the atmosphere.

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4. Water dissolves larger number of solutes than any other solvent. So,

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of calcium and magnesium is called permanent hardness.
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soda and Permutit process.
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industrial scale.
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Times' Crucial Science Book - 9 248

Exercise

1. Choose the best alternative in each case.
1. What is the percentage of fresh water in nature?
a. 1% b. 3% c. 97% d. 69%
2. The water of ocean and sea is unfit for domestic use because
it is
a. frozen b. polluted c. tasteless d. salty
3. When does water have maximum density and minimum
volume?
a. 4°C b. 0°C c. 1°C d. 100°C
4. The water which contains dissolved magnesium and calcium
bicarbonate is called…
a. Hard water b. Soft water
c. Temporary hard water d.Permanent hard water
5. The permanent hardness of water is removed by
a.Caustic soda b. Boiling c. Lime d. Permutit

2. Answer these questions in very short.
1. What are the taste, colour and odour of pure water?
2. What is meant by anomalous expansion of water?
3. What is the chemical composition of water?
4. What is hydrolysis reaction? Give an example.
5. What is meant by cohesive property of water?
6. What is the importance of cohesive and adhesive property
of water in plants?
7. Define soft water and hard water.
8. Write down one method each to remove temporary and
permanent hardness of water.

3. Give reasons:
1. It is difficult to wash clothes in hard water.
2. Sea and ocean water cannot be used as drinking water.
3. Water is regarded as universal solvent.
4. Washing soda removes the permanent hardness of water.
5. Hard water is not good for laundries.

4. Write down differences between:
a. Cohesion and adhesion
b. Hard water and soft water
c. Temporary hardness and permanent hardness of water

249 Times' Crucial Science Book - 9

5. Answer these questions in short.
a. Write short note on:
i. Occurrence of Water in Different Sources and States
ii. Solvent Property of Water
b. Write down the physical properties of water.
c. What is capillary action? Describe the capillary action of
water with an experiment.
d. Describe an experiment to distinguish between hard and
soft water.
e. What is temporary hardness of water? Name the salts with
their molecular formula that cause the temporary hardness
of water.
f. Write down the name and molecular formula of salts that
cause the permanent hardness of water.
g. Describe the process of removal of temporary hardness.
h. How do you remove the permanent hardness of water by
Permutit process? Describe with principle and process.
i. Write down the chemical properties of water with chemical
reactions.
j. Write down the advantages and disadvantages of hard
water.

Project Work

Collect water from different sources and test to identify whether the water
is soft or hard.

Times' Crucial Science Book - 9 250

Chapter

15 &KHPLFDO
)HUWLOL]HUV 8VHG
,Q $JULFXOWXUH
Friedrich Wohler
He is the best known for his synthesis of urea,
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elements.
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Objectives

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• ZULWH WKH DGYDQWDJHV DQG GLVDGYDQWDJHV RI RUJDQLF DV ZHOO DV LQRUJDQLF IHUWLOL]HUV
• explain the importance and effects of chemical fertilizers.

Introduction

The essential nutrients for the growth and productivity of plants
are available in soil. The plants get two types of nutrients from
soil. They are macro-nutrients and micro-nutrients. The nutrients
which are required by plants in large quantities are called macro-
nutrients. The compounds containing nitrogen, phosphorus and
potash are macro-nutrients. On the other hand, the nutrients
which are required by the plants in small quantity are called micro-
nutrients. The compounds containing boron, iron, magnesium, zinc,
sulphur, etc are micro-nutrients. If the soil contains both of such
compounds, the productivity of soil increases.

The use of land for cultivation of crops for a long time leads to the
loss of essential nutrients. It means that the fertility of the soil
decreases due to longterm cultivation RI FURSV LQ WKH ÀHOG 7KLV
results in the decrease in yield of crops. We can restore the fertility
of the soil by adding fertilizers. The fertilizers are the substances
which are added to the soil to increase the crop production by
supplying essential nutrients.

There are two types of fertilizers:
1. Organic fertilizers (manures)
2. Inorganic fertilizers

1. Organic fertilizers
The fertilizers which are obtained from the decomposition of the

251 Times' Crucial Science Book - 9

dead plants and the animal wastes are called organic fertilizers.
The organic fertilizer can be prepared by the decomposition of dung
and urine of cattle, leaves and soft twigs of trees, herbs, hay, straw,
dry leaves of trees, etc.
However, the decay and decomposition of such organic matter can
produce much methane gas and foul
smell. The mixing of much amount of
methane in the atmosphere causes air
pollution. This also causes greenhouse
effect and increases the temperature
of the earth. To avoid such effects, the
organic matter should be cut into
pieces before turning them into
fertilizers. The decaying matter
should be turned regularly so that
each part gets oxygen and decomposes
completely. Thus, there is good Compost fertilizer

fertilizer and less effect in the environment. Such a method of making
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method. The organic fertilizer can also be manufactured in the
absence of oxygen. Such a method is called anaerobic method. The
organic fertilizer can also be prepared by mechanical method.
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a. Green organic fertilizers b. Animal based organic
fertilizers

a. Green organic fertilizers: The fertilizer, which is prepared by
cutting green plants and decomposing them under wet soil is called
green fertilizer. It is also called green manure. The plants such as
Dhaincha, Asuro, Titepati, etc are used to make green manure. The
green manure mainly provides nitrogen to the plants in the form of
nitrate.

Asuro Dhaincha Titepati (Mugwort)

Times' Crucial Science Book - 9 252

b. Animal based organic fertilizers: The commonest method to
prepare organic fertilizer in Nepal is the composting of dung and urine
of cattle along with plant parts. In this method, dung, urine and the
remains of fodder of cow and buffalo are collected in a pit or shallow
area and are allowed to decompose. The decomposition of these matters
produces organic fertilizers. The animal based organic fertilizer is also
prepared by burying the dead body of animal in a deep pit and allowing
it to decay and decompose. However, such fertilizers do not contain the
inorganic nutrients such as nitrogen, potash and phosphorus.

Advantages
1. They are biodegradable and hence they cause less pollution.
2. Such fertilizers increase the water holding capacity of soil as well

as increase its fertility.
3. They are cheap as they are produced from wastes.
4. They are useful for all varieties of plants.
They do not have side effects on human beings as those of

inorganic fertilizers.

Disadvantages
1. Organic fertilizer LV UHTXLUHG LQ ODUJH TXDQWLW\ 6R LW LV GLIÀFXOW

to collect and transport them.
2. The organic fertilizers are insoluble in water.
3. Organic fertilizers are poor in inorganic nutrients like nitrogen,

phosphorus and potassium.

2. Inorganic or chemical fertilizers
The water soluble chemical compounds,
which are added to the soil to increase crop
production by supplying essential nutrients
are called inorganic or chemical fertilizers.
These fertilizers supply nitrogen, phosphorus,
potassium etc to the soil. Ammonium
sulphate, ammonium phosphate, urea,
potassium nitrate, etc are some examples of
chemical fertilizers.

Some chemical fertilizers

1. Nitrogen containing fertilizers

Ammonium sulphate : (NH4)2SO4
NH4NO3
Ammonium nitrate : NH2 CO NH2

Urea :

253 Times' Crucial Science Book - 9

Functions of nitrogen
1. It helps in rapid growth of plants.
2. It helps to increases the crop yield.
3. It helps chlorophyll of leaves to have faster rate of photosynthesis.
4. It increases the amount of protoplasm, protein and chlorophyll

in cells of plants.

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1. Reduction in crop yield
2. Reduced and yellow leaves in plants
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2. Phosphorus containing fertilizers

Ammonium phosphate : (NH4)3 PO4
Calcium super phosphate : Ca(H2PO4)2. 2CaSO4
Triple super phosphate : 3Ca(H2PO4)2
Bone meal (Bone dust)

Functions of phosphorus
1. It is needed for the growth of leaves, buds and roots.
2. It helps in developing seeds in crops.
3. It helps in fast maturity of the fruits and seeds.
4. It is essential for protein synthesis and cell division.

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The GHÀFLHQF\ of phosphorus in plants results in the following effects:
1. Poor growth of the roots of plants
2. Slowed rate of cell division in the plant

3. Potassium containing fertilizers

Potassium chloride : KCl

Potassium nitrate : KNO3

Potassium sulphate : K2SO4

Functions of potassium
1. It helps in preparing food for plants.
2. It helps in protein synthesis and cell division.
3. It increases disease resistant capacity of plants.
4. ,W SURPRWHV WKH ÁRZHULQJ RI SODQWV

Times' Crucial Science Book - 9 254

'HÀFLHQF\ RI SRWDVVLXP
1. Reduction in the amount of protein in the cell
2. Slow rate of cell division
3. Drying or the death of leaves of plants
4. 6PDOO SODQWV PD\ GLH GXH WR WKH GHÀFLHQF\ RI potassium.

Groups of fertilizers
The fertilizers can be divided into three groups on the basis of
number of inorganic nutrient present. They are:

a. Single fertilizer: The fertilizer which supplies only one basic
nutrient is called single fertilizer. Such fertilizer supplies only one
among nitrogen, phosphorus and potassium. For example, calcium
nitrate, potassium chloride, potassium sulphate, etc.

b. Mixed fertilizers: The fertilizers which supply more than one
basic nutrient are called mixed fertilizers. Ammonium phosphate,
potassium nitrate, etc are some examples of mixed fertilizers.

c. Complete fertilizers: The fertilizer, which contains all three
primary nutrients, viz, nitrogen, phosphorus and potassium, is
known as complete fertilizer or NPK fertilizer. They are made by
mixing two or more single or mixed fertilizers.

Fact Reason

Why is NPK fertilizer very important to plants?
NPK fertilizers provide all three essential nutrients nitrogen,
phosphorus and potassium to plants. Hence, NPK fertilizer is
essential to plants.

Advantages of chemical fertilizers
1. Chemical fertilizers are required in relatively small quantity. Hence,
it is easy to collect and transport them from one place to another.
2. They contain most of the nutrients essential for the growth and
development of the plants.
3. They are soluble in water and are easily absorbed by plants.
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Disadvantages of chemical fertilizers
Chemical fertilizers cause the pollution of soil and water. The
continuous use of chemical fertilizers reduces the natural fertility of
soil. They increase the acidity or alkalinity of soil. If the nitrogenous
fertilizer reaches the water body, it causes rapid growth of aquatic
plants. These plants use up the available oxygen and create

255 Times' Crucial Science Book - 9

GHÀFLHQF\ of oxygen in water. Hence, the aquatic animals die due
to the lack of oxygen. If children drink such nitrogenous fertilizer
containing water, their growth is retarded and they become dwarf.

Precautions while using chemical fertilizers
1. The excess use of chemical fertilizers may damage the plants.
So, we should use them in proper amount.
2. Urea can be easily damaged by water and moisture. So, it
should be stored in cold and dry place.
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FDXVH ÀUH hazards. Such fertilizers should be kept away from
dry wooden dust, coal, dry leaves, etc.
4. Chemical fertilizers should be stored away from the reach of
children.
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Fact Reason
Why should we limit the use of chemical fertilizers?
Chemical fertilizers cause environmental pollution and increase
acidity or alkalinity of soil and degrade the quality of the soil.
Hence, we should limit the use of chemical fertilizers.

Difference between organic fertilizers and chemical fertilizers

Organic fertilizers Chemical fertilizers

1. They are obtained by the 1. They are man-made chemicals
decomposition of dead plants and ZKLFK FRQWDLQ VSHFLÀF HOHPHQW
animal wastes. (s).

2. They are not soluble in water. So, 2. They are readily soluble in
they are absorbed slowly by plants. water and are quickly absorbed
by plants.

3. They are rich in organic nutrients 3. They are rich in nitrogen,
but poor in nitrogen, phosphorous phosphorus and potassium
and potassium (NPK). (NPK). They do not provide
organic nutrients.

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example, potassium containing
fertilizers provide only potassium.

5. They cause less environmental 5. They pollute the environment
pollution. to greater extent.

Times' Crucial Science Book - 9 256

Glossary fertilizers prepared from the wastes of animals as well
as dead animals and plant parts
Organic fertilizer : fertilizer prepared from different minerals
the chemicals that are used to kill harmful insects and
Inorganic fertilizer : worms
Pesticides :

Main points to remember

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available in soil.

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macro-nutrients.

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called micronutrients.

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SODQWV DQG WKH DQLPDO ZDVWHV DUH FDOOHG RUJDQLF IHUWLOL]HUV

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increase crop production by supplying essential nutrients are called
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IHUWLOL]HU

Exercise

1. Choose the best alternative in each case.
i. Which of the following is the micronutrient?
a. Nitrogen b. Phosphorus c. Iron d. Potash
ii. What is meant by organic fertilizer?
a. Fertilizers from decomposed matter of plants and animals
b. NPK fertilizer
c. Pesticides and insecticides
d. Green manure
iii. Which of the following is the source of nitrogen?
a. Triple super phosphate c. Ammonium nitrate
b. Potassium carbonate d. Amorphous
iv. Which of the following is not the function of potassium?
a. It helps in fast maturity of the fruits and seeds.

257 Times' Crucial Science Book - 9

b. It helps in protein synthesis and cell division.
c. It increases disease resistant capacity of plants.
d. It promotes the flowering of plants.
v. Which of the following is used to produce green manure?
a. Asuro b. Dhaincha c. Titepati d. All of these
2. Answer these questions in brief.
1. What is meant by chemical fertilizers? Give examples.
2. What is organic fertilizer? Explain in brief.
3. What is the importance of nitrogen for the plants? What
happens if there is deficiency of nitrogen in the plants?
4. What is NKP fertilizer? How is it prepared?
5. How is organic fertilizer prepared? Write down the steps
involved.
6. Write down three sources each of nitrogen, phosphorus and
potassium containing fertilizers.
7. What happens if there is deficiency of potassium in the
plants? Write the effects.
8. Explain the relationship between organic fertilizers and
chemical fertilizers.
9. Write down the advantages and disadvantages of organic
fertilizers.
10. What are the disadvantages of chemical fertilizers?
3. Write down differences between:
1. Compost manure and green manure
2. Organic fertilizers and chemical fertilizers

Project Work

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farmers or the concerned persons about types of fertilizers they use in
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and the method of their use. Also discuss the advantages of such
fertilizers to the plants. Prepare a report and present in the class.

Times' Crucial Science Book - 9 258

Chapter

16 &ODVVLILFDWLRQ
RI
/LYLQJ 7KLQJV Carolus Linnaeus
He is known for formalizing the modern
system of naming organisms called binomial
nomenclature.
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Objectives

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H[DPSOHV

Mind Openers

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Introduction
There are millions of organisms on the earth. They are different
from each other in shape, size, physiology, habitat, etc. It is
impossible to study each and every organism of the earth. It has
been estimated that only one-third of the total organisms are
identified and studied by this date. Study of the organisms of
enormous number can be made possible by classifying them on
the basis of similarities or dissimilarities. Many scientists worked
in the field of classification of organisms. But, Carolus Linnaeus,
(1707-1778AD), a Swedish scientist developed scientific system of
classification. Therefore, he is known as the father of taxonomy.
In the field of classification, some terms frequently come in use.
They are:
Taxonomy
It is the branch of biology which deals with identification,
classification and nomenclature of organisms.

259 Times' Crucial Science Book - 9

Identification
It is the process of finding a particular organism and determining
it as individual.
Nomenclature
It is the process of giving scientific names to plants and animals.
Carolus Linnaeus was the first person to give scientific names
to organisms. He named the organisms by using two words. The
first word is genus and the second word is species. This system of
nomenclature in which two names are given to each organism is
called binomial system of nomenclature. According to this system,
the first name is generic name (genus) and last one is specific
name (species). Binomial name is also called scientific name. He
framed certain rules while writing binomial name.

a) The generic name is written first with its first letter in &DSLWDO
DQG VSHFLILF QDPH LV ZULWWHQ DIWHU JHQHULF QDPH ZLWK LWV ILUVW
letter in small form.

E %RWK JHQHULF DQG VSHFLILF QDPHV DUH XQGHUOLQHG ZKHQ ZULWWHQ
by hand or written in italic font ZKHQ W\SHG )RU H[DPSOH
scientific name of tiger is Panthera tigris or Panthera tigris.

Species
It is a group of closely related organisms which are almost identical
in their structure and can interbreed to produce fertile offspring.
For example, all human beings belong to a species sapiens.
Genus
It is a group of closely related species which resemble with each
other. For example: lion, tiger, cat, etc belong to a common genus
Panthera or Felis.

SN Common Name Scientific Name
1. Mustard %UDVVLFD FDPSHVWULV
2. Frog Rana tigrina
3. Man +RPR VDSLHQV
4. Tiger Panthera tigris
5. Maize Zea mays
6. Pea 3LVXP VDWLYXP
7. Mango Magnifera indica

Times' Crucial Science Book - 9 260

Classification
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FDWHJRULHV WD[D RQ WKH EDVLV RI VLPLODULWLHV DQG GLVVLPLODULWLHV
Organisms are classified into kingdoms which are further classified
into divisions or phyla. Divisions or phyla are further classified
into classes and so on.
Importance of classification

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scientific.

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LLL ,W SURYLGHV VXSSRUW IRU RUJDQLF HYROXWLRQ.
LY ,W VKRZV QDWXUDO UHODWLRQVKLS RI RUJDQLVPV
Y ,W EULQJV uniformity in the study of organisms throughout

the world.
Classification of organisms
The organisms can be classified into different groups on the basis
of two prominent systems. They are two kingdom classification
and five kingdom classification. The organisms are categorized
into plant and animal kingdoms in two kingdom classification.
However, in five kingdom classification, organisms are categorized
into monera, protista, fungi, plantae and animalia kingdoms.
The five kingdom classification was introduced by an American
taxonomist Robert H. Whittaker in 1969AD. The five kingdom
classification is taken as more scientific and systematic
classification. It is supported by the following facts:

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JURXSV
7KHUH DUH VHSDUDWH NLQJGRPV IRU XQLFHOOXODU RUJDQLVPV L H

monera and SURWLVWD.
3. The green and QRQ JUHHQ SODQWV DUH SODFHG LQ VHSDUDWH
JURXSV
4. This system of classification is more concerned with the

HYROXWLRQDU\ history of organisms.
A brief discussion of the five kingdoms of organisms is given below:
1. Kingdom Monera
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261 Times' Crucial Science Book - 9

The nucleus of these organisms contains deoxyribonucleic acid
(DNA). The DNA is not surrounded by nuclear membrane. The
organisms of this group may be autotrophic or heterotrophic in
nature,. Bacteria, blue green algae, azotobacter, etc are some
organisms of kingdom monera.
2. Kingdom Protista
7KH JURXS RI HXNDU\RWLF XQLFHOOXODU RUJDQLVPV LV FDOOHG SURWLVWD
It includes all the animals of phylum protozoa of two kingdom
classification. Amoeba, Paramecium, Euglena, etc are some
examples of protista.
They have following characteristics:
1. They are unicellular and PLFURVFRSLF.
7KH\ DUH LUUHJXODU VSKHULFDO RU RYDO LQ VKDSH
&\WRSODVP LV GLIIHUHQWLDWHG LQWR RXWHU HFWRSODVP and the

inner-HQGRSODVP.
7KH\ FRPPRQO\ PRYH ZLWK WKH KHOS RI SVHXGRSRGLD IODJHOOD

or cilia.
0RVW RI WKHP OLYH LQ FOHDQ ZDWHU
7KH\ UHSURGXFH E\ ERWK VH[XDO and DVH[XDO method.

Pseudopodia Flagella

Amoeba Cilia Euglena
Paramecium

Examples: Amoeba, paramecium, euglena, plasmodium,
trypanosoma, giardia, etc.
3. Kingdom Fungi
,W LV WKH JURXS RI XQLFHOOXODU RU PXOWLFHOOXODU RUJDQLVPV KDYLQJ FHOO
ZDOO EXW QR FKORURSK\OO Their body is in the form of thalloid i.e.
the body is not differentiated into roots, stems and leaves. These
organisms have heterotrophic mode of nutrition. They absorb their
food from dead and decayed organic matter. Mushroom, Mucor,
Yeast, etc are some examples of fungi.

Times' Crucial Science Book - 9 262

They have following features:
1. They are non-green WKDOORSK\WHV due to the absence of

FKORURSK\OO
2. They are KHWHURWURSKLF L H WKH\ FDQQRW SUHSDUH WKHLU IRRGV

6RPH IXQJL OLNH PXFRU PXVKURRP \HDVW HWF DUH VDSURSK\WLF.
7KH\ JHW WKHLU QXWULHQWV IURP GHDG DQG GHFD\HG SODQWV RU
DQLPDOV· ERG\ 6RPH IXQJL OLNH SXFFLQLD DOEXJR HWF DUH
SDUDVLWLF. They get their nutrients from their host cells.
3. Their body consists of network of mycelium which contains
thread like structures called K\SKDH.
4. 7KH FHOO ZDOO LV PDGH XS RI IXQJXV cellulose or chitin.
5. They store their foods in the form of glycogen.
6. They may be unicellular (e.g. yeast) or multicellular (e.g.
PXVKURRP PXFRU HWF

Mushroom Mucor Yeast

Examples: Mushroom, mucor, yeast, rhizopus, penicillium, etc

4. Kingdom Plantae
The kingdom plantae includes all flowering as well as non-
flowering plants. All members of this group possess cell wall and
plastids in their cell. The plastids contain chlorophyll. The plants
may be either flowering or non-flowering.
7KH SODQWV ZKLFK EHDU IORZHUV DW DQ\ VWDJH RI WKHLU OLIH DUH FDOOHG
IORZHULQJ SODQWV 7KH SODQWV ZKLFK GR QRW EHDU IORZHU DW DQ\
VWDJH RI WKHLU OLIH DUH FDOOHG QRQ IORZHULQJ SODQWV It includes both
unicellular and multicellular plants having chlorophyll. The non-
flowering plants are also known as cryptogams.

The kingdom plantae is categorized into three divisions. They are
as follows:

1. Algae

263 Times' Crucial Science Book - 9

%U\RSK\WD
7UDFKHRSK\WD
1. Algae
This division includes green thallophytes. Mostly, they grow in
water. They have following features.
1. 7KH SODQW ERG\ LV WKDOOXV ZKLFK PD\ EH unicellular
H J YROYR[ FKODP\GRPRQDV HWF RU multicellular (e.g.
VSLURJ\UD FKDUD HWF
2. 7KH\ FRQWDLQ FKORURSK\OO DQG WKXV DUH JUHHQ LQ FRORXU
3. They are DXWRWURSKLF EHFDXVH WKH\ SUHSDUH WKHLU IRRGV
WKHPVHOYHV
4. 7KHLU FHOO ZDOOV DUH PDGH XS RI FHOOXORVH
5. 7KH\ UHSURGXFH E\ ERWK DVH[XDO DQG VH[XDO PHWKRGV
6. They store foods in the form of starch.

Chlamydomonas Spirogyra Volvox Ulothrix

Examples: Volvox, spirogyra, chlamydomonas, ulothrix, chara,
diatom, nostoc, etc.

Differences between algae and fungi

Algae Fungi

1. They contain chlorophyll. 1. They do not contain chlorophyll.

2. They are autotrophic. 2. They are heterotrophic.

3. Generally, they grow in 3. Generally, they grow on dead
water. and decayed materials.

4. Their cell wall is made up of 4. Their cell wall is made up of
cellulose. fungus cellulose and chitin.

5. They store food in the form 5. They store food in the form of
of starch. glycogen.

Times' Crucial Science Book - 9 264

2. Bryophyta (Bryo-moss, phyton-plant)
Bryophytes generally grow on old damp walls, moist grounds or
bark of trees. They need water for reproduction. Therefore, they
are also called amphibian plants. They are more advanced than
thallophytes but less developed than pteridophytes. They have
following features:
The plant body is thalloid, i.e. it is not differentiated into roots,
stem and leaves.
1. 7KH\ FRQWDLQ FKORURSK\OO 6R WKH\ DUH DXWRWURSKLF.
2. Vascular tissues are absent.
2. 7KH\ JURZ RQ PRLVW RU GDPS SODFHV
3. 7KH\ QHHG ZDWHU IRU UHSURGXFWLRQ
4. 7KH\ UHSURGXFH E\ YHJHWDWLYH DVH[XDO DQG VH[XDO PHWKRGV
5. They show alternation of generation in their life cycles.

Moss Liverwort Riccia

Examples: Moss, Marchantia, Riccia, etc.

Fact Reason

Why are bryophytes called amphibian plants?
Bryophytes are called amphibian plants because they need water
for fertilization.

3. Tracheophyta
It includes more developed plants which bear vascular tissues, i.e.
xylem and phloem. The division tracheophyta is further divided
into three sub-divisions. They are:

a. Pteridophyta
b. Gymnosperm
c. Angiosperm

265 Times' Crucial Science Book - 9

a. Pteridophyta (Pterido- feather, phyton-plant)
This division includes the most advanced cryptogams in which the
plant body is differentiated into root, stem and leaves. Their leaves
are shaped like feather. They contain vascular tissues named
xylem and phloem. Therefore, they are also called tracheophytes.
They have following features:
1. 7KH\ DUH PRVWO\ IRXQG LQ PRLVW DQG VKDG\ SODFHV
2. 7KHLU ERG\ LV GLIIHUHQWLDWHG LQWR URRW VWHP DQG OHDYHV
3. They bear feather-like OHDYHV
4. They contain YDVFXODU WLVVXHV [\OHP DQG SKORHP IRU WKH

conduction of materials inside the body.
5. 7KH\ UHSURGXFH E\ ERWK DVH[XDO DQG VH[XDO PHWKRGV
6. They show distinct alternation of generation in their life cycle.
7. 7KH\ FRQWDLQ FKORURSK\OO DQG WKXV DUH DXWRWURSKLF.

Leaf

Rhizome

Rhizoid Horsetail Lycopodium
Fern

Example: Fern, horsetail, lycopodium, equisetum, club moss,
marsilea, etc.

Fact Reason

Why is fern kept in pteridophyta?
Fern is kept in pteridophyta because it has feather shaped leaves.

b. Gymnosperms (Gym-naked, sperma-seeds)
This division includes cone bearing plants. Their seeds are not
covered by the fruits. Therefore, their seeds are naked. Generally,
they are found in cold and dry places.
1. They bear cones instead of true flowers. Male flowers and

IHPDOH IORZHUV DUH VHSDUDWH
2. Seeds are not enclosed inside the fruits.
3. /HDYHV DUH QHHGOH VKDSHG

Times' Crucial Science Book - 9 266

4. 7KH\ DUH FRQH VKDSHG &RQH VKDSHG VWUXFWXUH KHOSV WR FXW RII
the snow in cold season.

Foliage leaves Cone

Needle
shaped leaves

Stem

Cycas Pine

Example: Cycas, pine, fir, cedar, etc.

c. Angiosperm (Angio-case, sperma-seeds)

This division includes the flowering plants which bear seeds
enclosed inside the fruits. Generally, they are cosmopolitan, i.e.
they are found in all places of the earth.

1. 7KH\ KDYH ZHOO GHYHORSHG IORZHUV
2. Seeds are enclosed inside the fruits.
3. 7KH SODQW ERG\ LV PDGH RI ZHOO GHYHORSHG URRW VWHP DQG
OHDYHV.

Maize Mango Orange

Example: Apple, mango, banana, maize, etc.

Angiosperms are also divided into two classes-monocotyledons
and dicotyledons.

Monocotyledons
The plants which contain only one cotyledon or seed leaf belong
to the sub division monocotyledon. These plants have following
characteristics:
1. 7KH VHHGV RI WKHVH SODQWV FRQWDLQ only one cotyledon or seed leaf.
2. 7KH\ KDYH ORQJ OHDYHV ZLWK SDUDOOHO YHQDWLRQ.

267 Times' Crucial Science Book - 9

3. The root system is fibrous root system.
4. 7KH QXPEHU RI SHWDOV RU VHSDOV LQ WKH IORZHUV LV WKUHH RU LWV PXOWLSOHs.

Fruit Male flower

Leaf
Leaf Female flower

Stem

Rice Maize

Examples: Grass, maize, wheat, rice, sugarcane, banana, etc.

Dicotyledons (Dicot plants)
The plants which contain two cotyledons or seed leaves belong to the
sub division dicotyledons. These plants have following characteristics:

L 7KH VHHGV RI WKHVH SODQWV FRQWDLQ WZR FRW\OHGRQV
LL 7KH\ KDYH EURDG OHDYHV KDYLQJ UHWLFXODWH YHQDWLRQ.
iii) 7DS URRW V\VWHP LV SUHVHQW
LY 7KH QXPEHU RI VHSDOV RU SHWDOV LQ WKH IORZHUV LV IRXU RU ILYH
RU WKHLU PXOWLSOHV.

Fruit

Fruit

Stem

Stem

Mustard Plant Apple tree

Example: Mango, bean, rose, mustard, orange, pea, apple,
sunflower, etc.

Differences between dicot and monocot plants

Dicot Monocot

1. The plants which bear 1. The plants which bear
seeds with two cotyledons seeds with one cotyledon
or seed leaves are called or seed leaf are called
dicot plants. monocot plants.

Times' Crucial Science Book - 9 268

2. They have tap root system. 7KH\ KDYH ÀEURXV URRW

system.

3. They have reticulate 3. They have parallel
venation in their leaves. venation in their leaves.

4. The number of petals or 4. The number of petals or
VHSDOV LQ WKH ÁRZHU LV RU VHSDOV LQ WKH ÁRZHU LV
5 or their multiples. or its multiple.

Activity16 .1 Visit a forest and observe various types of cryptogams.

Classify them into algae , bryophytes and pteridophytes. Mention the
reasons for keeping them in the respective groups.

Some examples of classification of plants

a. Spirogyra b. Mucor

Kingdom - Plantae Kingdom - Fungi

Division - Algae Type - Mucor

Type - Spirogyra Main Feature

Main Feature They are non-green thallophytes.

They are green thallophytes.

c. Fern d. Pine

Kingdom - Plantae Kingdom - Plantae

Division - Tracheophyta Division - Tracheophyta

Sub-division - Pteridophyta Sub-division - Gymnosperm

Type - Fern Type - Pine

Main Feature Main Feature

They do not bear flowers but They bear cones instead of flowers.
contain vascular bundles.

5. Kingdom Animalia

There are millions of animals on the earth. They differ from each
other in shape, size, physiology, etc. All animals belong to the
kingdom ’Animal’. The animal kingdom is further divided into
two groups on the basis of presence or absence of backbone. They
are: invertebrates and vertebrates.

269 Times' Crucial Science Book - 9

Invertebrates
7KH DQLPDOV ZKLFK GR QRW KDYH EDFNERQH RU YHUWHEUDO FROXPQ DUH
FDOOHG LQYHUWHEUDWHV
Some of them are microscopic whereas some are large-sized. They
lack endoskeleton but some of them contain exoskeleton. Some of
them are unicellular. Most of them are multicellular which are
included in metazoa.

Differences between invertebrates and vertebrates

Invertebrates Vertebrates

1. Backbone or vertebral column 1. Back bone or vertebral column
is absent in them. is present in them.

2. Red blood cells are absent. 2. Red blood cells are present.

3. They are cold blooded animals. 3. They may be cold blooded or
warm blooded.

4. They have many pairs of 4. Appendages are more than two
appendages. pairs.

5. Asexual reproduction is more 5. Sexual reproduction is more
common. common.

6. The heart is dorsally or laterally 6. The heart is ventrally located.
located.

7. Skin contains only one layer. 7. Skin contains two layers.
Examples: amoeba, sycon, hydra, Examples: fish, frog, lizard, birds,
ant, snail, earthworm, etc. mammals, etc.

The sub kingdom invertebrates is also divided into 8 phyla.
They are:

Animal Kingdom
Sub-kingdoms

Invertebrates Vertebrates
Phylum
Porifera
Coelenterata Chordata
Platyhelminthes
Nemathelminthes Pisces
Annelida Amphibia
Arthropoda Reptilia
Mollusca Aves
Echinodermata Mammalia
Phylum
Class

Times' Crucial Science Book - 9 270

Porifera (Porus- Pore, ferre-to bear)
Animals of this phylum are primitive multicellular with numerous
pores on their bodies. They are also called pore bearers.
Characteristics
7KH\ KDYH WKH ERG\ VKDSHG OLNH YDVH VDF RU URXQGHG
7KHLU ERG\ FRQWDLQV QXPHURXV SRUHV FDOOHG ostia. There
LV D ODUJH SRUH RSHQLQJ DW WKH WRS FDOOHG osculum.
3. Water and food materials enter their body through ostia
DQG H[LW WKURXJK RVFXOXP
7KH\ DUH IL[HG WR FHUWDLQ substratum DQG GR QRW PRYH
7KXV WKH\ DUH VHVVLOH
5. Their body contains two layers- ectoderm and endoderm.
7KXV WKH\ DUH GLSOREODVWLF
7KH\ UHSURGXFH E\ ERWK VH[XDO DQG DVH[XDO PHWKRGV
7. They carry out breathing through body surface.
7KH\ GR QRW KDYH VSHFLILF RUJDQV IRU H[FUHWLRQ.

Osculum
Ostia

Bud

Sycon Euspongia Spongilla

Examples: Sycon, spongilla, euspongia, etc.
Coelenterata (coel = cavity, teron = intestine)
Animals of this phylum are aquatic having hollow body cavity
called coelenteron.
Characteristics
7KHLU ERG\ FRQWDLQV D KROORZ FDYLW\ FDOOHG coelenteron.
0RXWK LV SUHVHQW EXW DQXV LV DEVHQW

271 Times' Crucial Science Book - 9

3. Mouth is surrounded by tentacles ZKLFK KHOS IRU locomotion
and FDSWXULQJ WKHLU SUH\

7KH\ KDYH stinging cells called cnidoblast.
7KHLU ERG\ FRQWDLQV WZR OD\HUV 7KXV WKH\ DUH GLSOREODVWLF.
6. They are radially symmetrical.
7KH\ UHSURGXFH E\ ERWK DVH[XDO DQG VH[XDO PHWKRG

Mouth

Coelenteron Tentacle
Bud

Hydra Sea anemone Jellyfish

Examples: Hydra, jellyfish, sea anemone, coral, obelia, etc.
Radial symmetry
If the body of an animal can be divided into two similar parts by a
line passing through centre like radius of a circle, its body is called
radially symmetrical.
Platyhelminthes (Platy- flat, helmithes- worm)
This phylum includes the animals having flat and soft body. They
are also called flatworms. Most of them are parasites whereas
some are free living in moist soil.
Characteristics
1. Their body is GRUVR YHQWUDOO\ IODWWHQHG like leaf.
2. Their head contains hooks and suckers.
7KH\ KDYH PRXWK EXW QR DQXV LQ WKH DOLPHQWDU\ FDQDO
4. Their body contains three layers: ectoderm mesoderm

and endoderm 7KHUHIRUH WKH\ DUH WULSOREODVWLF animals.
5. They are KHUPRSKURGLWH. It means both male and female
VH[ RUJDQV DUH SUHVHQW LQ WKH VDPH LQGLYLGXDO
5HVSLUDWRU\ DQG circulatory system are absent.
([FUHWRU\ V\VWHP FRQWDLQV SURWRQHSKULGLD.
*HQHUDOO\ UHSURGXFWLRQ WDNHV SODFH WKURXJK VH[XDO PHWKRG.

Times' Crucial Science Book - 9 272

Tapeworm Liverfluke Planaria

Examples: Tapeworm, Liverfluke, Planaria, Blood fluke, etc.
Aschelminthes or Nemathelminthes (Nema-thread,
helminthes- worms)
This phylum includes unsegmented cylindrical worms. They are
commonly called round worms.
Characteristics
7KHLU ERG\ LV VOHQGHU unsegmented URXQG DQG F\OLQGULFDO
7KHLU ERG\ LV WULSOREODVWLF DQG bilaterally symmetrical.
7KHLU ERG\ LV FRYHUHG E\ WKLFN cuticle.
4. Alimentary canal LV FRPSOHWH ZLWK PRXWK DQG DQXV
5. They are XQLVH[XDO ,W PHDQV VH[HV DUH VHSDUDWH
7KH FLUFXODWRU\ DQG UHVSLUDWRU\ V\VWHPV DUH DEVHQW
7KH\ UHSURGXFH E\ VH[XDO PHWKRG RQO\
8. They are mostly SDUDVLWLF 6RPH DUH IUHH OLYLQJ.

Ascaris(Roundworm) Pinworm Hookworm

Examples: Ascaris, hookworm, pinworm, etc.
Bilateral symmetry
If body of an animal can be divided into two similar parts by only
one line passing along the length of the body, such body is called
bilaterally symmerical.

273 Times' Crucial Science Book - 9

Annelida (Annelus - ring)

This phylum includes the animals having numerous segmented
rings in their bodies. Generally, they are called ringworms.
Characteristics
1. Their body is VRIW HORQJDWHG DQG F\OLQGULFDO KDYLQJ QXPHURXV

circular rings.
7KH\ DUH WULSOREDVWLF DQG bilaterally symmetrical.
7KH\ KDYH moist skin through which they carry out breathing.
%UDLQ DQG QHUYH FHOOV DUH ZHOO GHYHORSHG
/RFRPRWLRQ WDNHV SODFH WKURXJK setae HDUWKZRUP sucker

(leech) or SDUDSRGLD (nereis).
'LJHVWLYH V\VWHP LV FRPSOHWH KDYLQJ ERWK PRXWK DQG DQXV
7. Some animals are KHUPDSKURGLWH HDUWKZRUP OHHFK ZKHUHDV

RWKHUV DUH XQLVH[XDO
([FUHWLRQ WDNHV SODFH WKURXJK QHSKULGLD.

Leech Earthworm Nereis

Examples: Earthworm, leech, nereis, etc.

Arthropoda (Arthro- jointed, podos -foot)
This phylum includes the animals having jointed appandages. It is
the largest phylum of invertebrates because about 9,00,000 species
of arthropods are known.

Characteristics
7KHLU ERG\ LV WULSOREODVWLF DQG ELODWHUDOO\ V\PPHWULFDO
2. Body is segmented DQG GLYLGHG LQWR WKUHH SDUWV 7KH\ DUH

KHDG WKRUD[ and abdomen.
3. The head contains brain and sensory organs.
7KHLU ERG\ LV FRYHUHG H[WHUQDOO\ ZLWK H[RVNHOHWRQ.
6H[HV DUH VHSDUDWH DQG OLIH F\FOH FRPSOHWHV LQ IRXU VWDJHV
$OLPHQWDU\ FDQDO LV FRPSOHWH
%UHDWKLQJ WDNHV SODFH WKURXJK WKH JHQHUDO ERG\ VXUIDFH gills

or trachea.
&LUFXODWRU\ DQG H[FUHWRU\ V\VWHPV DUH SUHVHQW

Times' Crucial Science Book - 9 274

Phylum arthropoda is further divided into four classes. They are:
i. Crustacea ii. Insecta iii. Arachnida iv. Myriapoda
Crustacea
1. The animals of class crustacea are aquatic.
2. 7KH KHDG DQG WKRUD[ DUH MRLQHG WR IRUP FHSKDORWKRUD[.
3. 5HVSLUDWLRQ WDNHV SODFH WKURXJK JLOOV RU ERG\ VXUIDFH
4. The head bears FRPSRXQG H\HV

Crab Prawn Lobster

Examples: Prawn, crab, lobster, etc.

Insecta
1. 7KHLU ERG\ LV GLYLGHG LQWR KHDG WKRUD[ DQG DEGRPHQ
2. +HDG FRQWDLQV PRXWKSDUWV FRPSRXQG H\HV and antennae.
3. The WKRUD[ EHDUV WKUHH SDLUV RI OHJV
4. %UHDWKLQJ WDNHV SODFH WKURXJK trachea.

Grasshopper Butterfly Silver fish

Examples: Grasshopper, butterfly, housefly, bees, silver fish, etc.

Arachnida
1. 7KHLU ERG\ LV GLYLGHG LQWR FHSKDORWKRUD[ and abdomen.
2. The animals of this class are terrestrial.
3. 7KH\ KDYH IRXU SDLUV RI OHJV
4. %UHDWKLQJ WDNHV SODFH WKURXJK trachea.
5. 7KH\ GR QRW KDYH antennae DQG FRPSRXQG H\HV

275 Times' Crucial Science Book - 9

Scorpion Spider

Examples: Spider, scorpion, etc.
Myriapoda
1. The animals of this class are mostly terrestrial.
2. %RG\ LV GLYLGHG LQWR KHDG DQG numerous segments: each
EHDULQJ RQH RU PRUH SDLU RI OHJV
3. 7KH\ KDYH FRPSRXQG H\HV DQG feelers.
4. 6H[HV DUH VHSDUDWH.

Centipede Millipede

Examples: Centipede, millipede, etc.
Mollusca (Mollus - Soft)
The animals of this phylum have unsegmented soft body. The soft
body may be covered by hard shells.
Characteristics
1. Their body is VRIW XQVHJPHQWHG DQG FRYHUHG E\ D KDUG VKHOO.

7KH KDUG VKHOO LV PDGH XS RI FDOFLXP FDUERQDWH
7KHLU ERG\ LV GLYLGHG LQWR KHDG YLVFHUDO PDVV and muscular

foot.
7KH KHDG EHDUV PRXWK tentacles and sense organs.
%UHDWKLQJ WDNHV SODFH ZLWK WKH KHOS RI JLOOV RU OXQJV
7KH\ KDYH PXVFXODU IHHW
'LJHVWLYH V\VWHP H[FUHWRU\ V\VWHP EORRG YDVFXODU V\VWHP

DQG QHUYRXV V\VWHP DUH ZHOO GHYHORSHG.

Times' Crucial Science Book - 9 276

Octopus Snail Slug

Examples: Slug, snail, unio, octopus, cuttlefish, squid, etc.
Echinodermata (Echino-Spiny, derma-skin)
This phylum includes aquatic animals having thorny or spiny
skin. They are marine and found at the bottom of sea.
Characteristics
7KHLU ERG\ LV FRYHUHG E\ WKRUQ\ RU VSLQ\ VNLQ
2. They are found in ocean water.
3. Their body may be VWDU VKDSHG HORQJDWHG RU JOREXODU RU

flower like.
%RG\ LV GLYLGHG LQWR RUDO ORZHU DQG aboral XSSHU VLGH
7KH\ KDYH WXEH IRRW IRU ORFRPRWLRQ
6H[HV DUH VHSDUDWH
7. Body is radially symmetrical.
5HSURGXFWLRQ WDNHV SODFH E\ regeneration method.

Starfish Sea-cucumber Sea-urchin

Examples: Starfish, sea-cucumber, sea-urchin, sea-lily, etc.

Classification of some invertebrates

a. Amoeba

Kingdom - Protista

Type - Amoeba

Character: They are unicellular and microscopic
animals.

277 Times' Crucial Science Book - 9

b. Housefly

Kingdom - Animalia

Sub kingdom - Invertebrata

Phylum - Arthropoda

Class - Insecta

Type - Housefly

Character: They have three pairs of jointed
legs.

c. Ascaris

Kingdom - Animalia

Sub kingdom - Invertebrata

Phylum - Nemathelminthes

Type - Ascaris

Character: They have long cylindrical unsegmented body.

d. Starfish

Kingdom - Animalia

Sub kingdom - Invertebrata

Phylum - Echinodermata

Type - Starfish

Character: They have soft star-shaped body covered by spiny skin.

Activity16 .2 Collect some invertebrates from your surrounding and

classify them into different phyla. Also mention the reasons for keeping them
in the respective phyla.

Vertebrates
The sub-kingdom vertebrates includes the single phylum chordata.
Phylum chordata
Phylum chordata contains all types of animals having backbone.
Fish, frog, lizard, bird, dog, tiger, elephant, human, etc come under
this phylum. The animals of this phylum have following general
characteristics:

Times' Crucial Science Book - 9 278

1. Just below the VSLQDO FRUG there is a tube like structure called
the notochord GHYHORSHG DW WKH HDUO\ VWDJH RI WKHLU OLIH

2. 'RUVDO WXEXODU QHUYH FRUG LV SUHVHQW MXVW DERYH WKH QRWRFKRUG
$ SDUW RI ERG\ FRQWDLQLQJ QRWRFKRUG RU YHUWHEUDO FROXPQ

SURMHFWV WR IRUP D WDLO
4. The SKDU\QJHDO UHJLRQV RI DOO HPEU\RQLF FKRUGDWHV KDYH gill

clefts.
6NXOO LV ZHOO GHYHORSHG DQG LQWHUQDO VNHOHWRQ LV FRYHUHG E\

muscles.
&ORVHG W\SH RI EORRG FLUFXODWRU\ V\VWHP LV SUHVHQW
Phylum chordata is further sub-divided into four sub-phylum:
hemichordata, urochordata, cephalochordata and vertebrata.
The main sub-phylum of chordata is vertebrata.
Sub-phylum: Vertebrata
It is the most important sub-phylum of chordata. Animals of this
phylum are commonly called vertebrates. In them, notochord is
present in the embryonic stage and is replaced later by vertebral
column in the adult stage.
They have following features:
7KH\ KDYH YHUWHEUDO FROXPQ ZKLFK VXSSRUWV WKH ZKROH ERG\
$ WXEXODU QHUYH FRUG LV SUHVHQW LQ WKH GRUVDO VLGH RI WKH

body which is differentiated into brain and VSLQDO FRUG.
3. Their bodies are bilaterally symmetrical.
&ORVHG W\SH RI EORRG FLUFXODWRU\ V\VWHP LV SUHVHQW %ORRG LV
UHG LQ FRORXU GXH WR WKH SUHVHQFH RI haemoglobin.
+HDUW LV SUHVHQW LQ WKH YHQWUDO VLGH
6. They may be cold blooded or warm blooded.
Bilaterally symmetrical animals: The animals whose body can
be divided into two equal parts by a line passing through their
axis are called bilaterally symmetrical animals. For example cow,
man, frog, fish, etc.
Cold blooded animals (poikilothermic animals): The animals
whose body temperature changes along with the temperature of
the surrounding are called cold blooded animals. These animals
are also known as poikilothermic animals. For example, fish, frog,
lizard, etc.

279 Times' Crucial Science Book - 9

Warm blooded animals (homeothermic animals): The animals whose
body temperature does not change along with the temperature of
the surrounding are called warm blooded animals. For example,
birds, monkey, human beings, etc. Sub- phylum vertebrata is
further classified into five classes. They are:
a) Pisces (b) Amphibia (c) Reptilia (d) Aves (e) Mammalia
a. Pisces
All fishes belong to the class pisces. They are found in water.
Their salient features are as follows:
1. Their body is streamlined RU ERDW VKDSHG 7KLV VKDSH FXWV WKH

ZDWHU DQG KHOSV IRU VZLPPLQJ LQ ZDWHU
2. They contain gills for breathing.
3. /RFRPRWLRQ WDNHV SODFH WKURXJK fins and tail.
4. 7KH ERG\ LV GLIIHUHQWLDWHG LQWR KHDG WUXQN DQG WDLO
5. Heart is two-chambered.
6. 7KH\ UHSURGXFH WKURXJK HJJV 7KHUHIRUH WKH\ DUH FDOOHG RYLSDURXV.

Shark Fish Sea-horse

Examples: Shark, Rohu, Sea-horse, etc.
b. Amphibia
The animals which live on both land and in water belong to
the class amphibia. They have following features.
1. 7KH\ OLYH ERWK RQ ODQG DQG LQ ZDWHU
2. Their heart contains three chambers.
3. They breathe through skin in water and through lungs on

the land.
4. 7ZR SDLUV RI OLPEV DUH SUHVHQW
5. They are cold blooded animals.
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DQG IHPDOH JDPHWHV WDNHV SODFH RXWVLGH WKH ERG\ RI IHPDOH.

Times' Crucial Science Book - 9 280

Frog Newt Salamander

Examples: Frog, toad, newt, salamander, etc

c. Reptilia

The animals which crawl on the land belong to the class reptilia.
Most of the reptiles are found on the land. They have following
salient features:
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2. 7KHLU ERG\ LV GLYLGHG LQWR KHDG QHFN WUXQN DQG WDLO
3. Their heart contains three chambers 7KH VLQJOH H[FHSWLRQ
WR WKLV LV FURFRGLOH ZKLFK FRQWDLQV D IRXU FKDPEHUHG KHDUW
4. They are cold blooded animals.
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6. They breathe through lungs.
7. They are RYLSDURXV.
8. )HUWLOL]DWLRQ LV LQWHUQDO.

Snake Lizard Crocodile

Examples: Snake, lizard, crocodile, tortoise, etc.
Fact Reason
Which reptile has four chambered heart?
Crocodile has four chambered heart.

d. Aves
All birds belong to the class aves. They are warm blooded
animals. Their salient features are as follows:

281 Times' Crucial Science Book - 9

1. Their body is streamlined DQG FRYHUHG ZLWK feathers.
2. Their forelimbs are modified into wings.
7KHLU ERG\ LV GLYLGHG LQWR KHDG QHFN WUXQN DQG WDLO
4. Toothless EHDN LV SUHVHQW
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6. The heart is four chambered.
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Crow Danphe Pigeon

Examples: Crow, sparrow, danphe, peacock, pigeon, etc.

e. Mammalia
Highly developed vertebrates like cow, buffalo, man, cat, goat,
elephant, etc belong to the class mammalia.
1. 7KH\ KDYH mammary glands.
2. Their body is FRYHUHG ZLWK KDLU
3. 7KH\ KDYH H[WHUQDO HDU FDOOHG SLQQD.
4. Heart is four chambered.
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DUH FDOOHG YLYLSDURXV
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7. 7ZR SDLUV RI OLPEV DUH SUHVHQW
8. %UHDWKLQJ WDNHV SODFH WKURXJK OXQJV

Buffalo Dolphin Horse

Examples: Human beings, buffalo, whale, dolphin, dog, cat, cow,
horse, etc.

Times' Crucial Science Book - 9 282

Examples of classification of some animals

a) Octopus b) Starfish

Kingdom: Animalia Kingdom: Animalia

Sub-kingdom: Invertebrata Sub-kingdom: Invertebrata

Phylum: Mollusca Phylum: Echinodermata

Type: Octopus Type: Starfish

c) Crayfish d) Man
Kingdom: Animalia Kingdom: Animalia
Sub-kingdom: Invertebrata Phylum: Chordata
Phylum: Arthropoda Sub-phylum: Vertebrata
Type: Crayfish Class: Mammalia
Type: Homo sapiens
e) Sea-horse
Kingdom : Animalia f) Lizard
Phylum: Chordata Kingdom: Animalia
Sub- phylum: Vertebrata Phylum: Chordata
Class: Pisces Sub-phylum: Vertebrata
Type: Sea horse Class: Reptilia
Type: Lizard

Mosquito

Mosquitoes are harmful insects. They carry the germs of various
diseases such as malaria, filaria, dengue, yellow fever, Japanese
encephalitis, etc. They annoy the humans at night and disturb their
sleep too. There are about 3000 species of mosquitoes. Anopheles,
Culex, Aedes and Mansonia are common species. Anopheles and
Culex are more common in Nepal.

Systematic Position

Kingdom - Animalia

Sub-Kingdom - Invertebrata

Phylum - Arthropoda

Class - Insecta

Type - Mosquito

283 Times' Crucial Science Book - 9

Habit and Habitat
Mosquitoes are found mostly in tropical and sub-tropical regions.
They are more active at night time. Thus, they are nocturnal
animals. Generally, they feed on plant juice. But female ones suck
the blood of animals. Thus, female mosquitoes are the vectors of
various diseases. The adult mosquitoes can fly well and cover long
distance in a single flight.
Structure of Mosquito
Mosquito is a small insect which measures 3-4mm in length. Its
body is covered with minute scales. Its body is divided into three
parts: head, thorax and abdomen.

Head Thorax

Wings

Compound eye

Antennae

Leg Abdomen

Structure of Mosquito

Head

Head of mosquito is small and almost spherical which is connected
to the thorax with a small neck. It contains a pair of kidney shaped
compound eyes, a pair of antennae and sucking and piercing type
of mouth parts. The antenna is made up of 13 segments with whorl
of hairs.

The antennae of males are more hairy. Mouth parts of females are
more specialized for both sucking and piercing whereas those of
males are for only sucking. Proboscis helps for sucking food.

Thorax

Thorax consists of three parts: prothorax, mesothorax and
metathorax. Each part bears a pair of long jointed legs. Mesothorax
bears a pair of membranous wings. The wings are larger in females
than in males. The wings produce buzzing sound through vibrations
during flight time.

Times' Crucial Science Book - 9 284

Abdomen
The abdomen is slender and made up of nine segments. The anus
is present on the 8th segment and a genital opening is present on
the 9th segment. The abdomen does not contain legs or wings.
Differences between male and female mosquitoes

Male mosquitoes Female mosquitoes

1. They feed on sap of flowers of 1. They feed on the blood of mammals.
plant.

2. The antennae are provided 2. The antennae are provided with
with long and dense hairs. short hairs.

3. They have smaller wings. 3. They have larger wings.

4. The mouth parts are adapted 4. Their mouth parts are adapted for
only for sucking. both sucking and piercing.

Life cycle of mosquito
The life cycle of mosquito completes in four stages. They are egg,
larva, pupa and adult. Adults spend most of their time in air and
on the land whereas other three stages remain in water.
Egg
Male and female mosquitoes copulate at the evening during their
flight. Then female mosquitoes lay eggs in stagnant water of
ponds, ditches or fields. A female Anopheles lays 40 to 100 eggs at
a time whereas a female culex lays about 300 eggs at a time.

Eggs of Anopheles Eggs of Culex

The eggs of anopheles are laid separately without being stuck
to each other. Each egg is spindle shaped having lateral air-
floats. Eggs of culex are cigar shaped and stuck together to form
a floating raft

285 Times' Crucial Science Book - 9

Eggs Larva Eggs Larva

Pupa Pupa
Adult Adult

Life cycle of Anopheles Life cycle of Culex

Larva
Under favourable conditions, eggs hatch out larva within 2 to 3
days. They are transparent. They swim by wriggling their body.
Thus, they are also called wrigglers. Its body is divided into
three parts. They are: head, thorax and abdomen.
Head has a pair of compound eyes and mouth parts. They contain
feeding brushes with the help of which they feed on bacteria,
algae, etc. The thorax is unsegmented, broad and limbless. But
it bears three pairs of tufts of hairs at the lateral side.
Abdomen is made up of 9 segments with tufts of hair from each
segment. The dorsal side of the 8th segment bears respiratory
siphon and 9th segment bears four tracheal gills.
Larvae of culex rest with hanging their heads downwards at
an angle in water with the tip of respiratory siphon outside the
surface of water. But the larvae of anopheles rest being parallel
to the water surface.

Abdomen

Head Thorax Thorax

Head Abdomen

Larva of Anopheles Larva of Culex

Times' Crucial Science Book - 9 286

Fact Reason

Why are the larva of mosquito called wrigglers?
The larva of the mosquito swim in the water with twist and turn
movement wriggling their body. Hence, larva of mosquito are
called wriggler.

Pupa
In favourable conditions, the larvae develop into comma-shaped
pupae. They are commonly called tumblers. Unlike the pupae
of other insects, it is active but does not eat. It contains mainly
two parts anterior cephalothorax and posterior abdomen. The
cephalothorax is broad and bears respiratory trumpets. The
abdomen is nine segmented. The ninth segment bears a pair of
large swimming paddles.

Cephalothorax

Pupa of Anopheles Abdomen
Pupa of Culex

Adult
After few days puparium ruptures and a fully developed mosquito
called imago emerges out. It dries its wings by vibrating and flies
in the air. This moment is very important. If it remains unbalanced
and cannot dry its wings, it gets drowned.

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DFWLYLWLHV LV FDOOHG PHWDPRUSKRVLV

Adult of Anopheles Adult of Culex

287 Times' Crucial Science Book - 9

Thus, complete life cycle of mosquito from egg to adult completes
in about 10 days depending upon the environment.

Differences between Culex and Anopheles

Culex Anopheles

Eggs

1. Eggs are stuck together to 1. Eggs are laid separately without
form a raft on water surface. being stuck.

2. They are cigar shaped. 2. They are spindle shaped.

3. About 300 eggs are laid at a 3. About 40 to 100 eggs are laid at a
time. time.

Larvae

1. The larvae of culex are 1. The larvae of anopheles are surface
bottom feeder. feeder.

2. The respiratory siphon is 2. The respiratory siphon is short.
long.

3. It makes an angle with water 3. It remains parallel with water
surface at rest stage. surface at rest stage.

Pupae

1. Pupae of culex are colourless. 1. Pupae of anopheles are green in
colour.

2. The respiratory trumpets are 2. The respiratory trumpets are short
long and narrow. and wide.

3. The abdomen is less bent. 3. The abdomen is more bent.

Adults

1. They have stouter legs. 1. They have delicate legs.

2. At rest, the body lies parallel 2. At rest, the body inclines at an angle
to the surface. of 450 to the surface.

3. It has wings of uniform color 3. It has spotted wings and cannot fly
and can fly for a long distance. for a long distance.

4. It transmits filaria. 4. It transmits malaria.

Diseases transmitted by mosquitoes

Mosquitoes transmit various types of disease like malaria, filaria,
dengue, yellow fever, meningitis, etc.

Malaria

Malaria is caused by a Protista named Plasmodium. Plasmodium
lives in the RBCs and liver of man and salivary gland and
alimentary canal of mosquito.

Times' Crucial Science Book - 9 288

When a female anopheles sucks the blood of a person suffering
from malaria, Plasmodiums are also sucked along with blood.
Plasmodiums multiply in the body of mosquito to form sporozoites.
They come to lie in the salivary gland of the mosquito.
When such mosquitoes bite a healthy person, the saliva having
thousands of sporozoites enter blood of the person. From the
blood they move towards the liver and enter liver cells where they
remain for about two weeks. They grow and multiply there. They
emerge out from the liver cells in large number and engulf RBCs.
This causes symptoms of malaria. High fever at an interval rate,
chilling and sweating, etc are major symptoms of malaria. Malaria
causes the death of humans if not treated in time.
Control measures of mosquitoes
Following are the control measures of mosquitoes:

1. Destruction of breeding places
Female mosquitoes lay eggs on the stagnant water. The larvae
and pupae also grow in the water. Stagnant water and swampy
areas should be drained to reduce the breeding areas. The ditches
should be filled with soil. The water container should be covered.
The puddles should be filled with soil.

2. Destruction of larvae and pupae
It is easier to kill larvae and pupae than adult mosquitoes. They
can be killed by spraying paraffin oil, kerosene, petroleum, etc on
the water. Those substances make a thin film of oil on the surface of
water. Thus, they die due to the lack of oxygen or suffocation. The
oil also enters the body through spiracles or siphons. Chemicals
like DDT, BHC, Paris green powder, etc also kill the larvae and
pupae.
The fishes like stickleback, trouts, gambusia, argentile, pearlfish,
etc, feed on larvae and pupae of mosquitoes. This method of
controlling mosquitoes is called biological method.

3. Destruction of adults
Adult mosquitoes can be killed by burning sulphur, tar, camphor,
etc. When such chemicals are burnt, poisonous fumes are produced
which kill adults. They can also be killed by using fly swatters,

289 Times' Crucial Science Book - 9

hands, etc. Spraying insecticides or pesticides also kills adult
mosquitoes.
Prevention from mosquito bite
Following activities should be done to prevent from mosquito bite:
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Learn and Write
1. Bryophytes are called amphibian plants. Why?

Bryophytes grow on moist land but they need water for
reproduction.Thus, water is essential for the completion
of life cycle of bryophytes. Therefore, bryophytes are called
amphibian plants.
2. Pteridophytes are called tracheophytes. Why?
Other cryptogams do not contain vascular tissues, i.e. xylem
and phloem. But, pteridophytes contain xylem and phloem.
Xylem and phloem together make pipe like structure for
the conduction of raw materials and prepared foods. Thus,
pteridophytes are called tracheophytes.
3. Spider is not an insect. Why?
Spider has four pairs of jointed legs. But the class insecta
includes the arthropods having three pairs of legs. Thus,
spider does not belong to class insecta.
4. Scientific names of organisms make their study easier. Why?
One organism is given various names in different places of the
world. These names are not understood in all places. Therefore,
internationally recognized and acceptable name should be
given to a particular organism. This name is scientific name.
Thus, scientific names of organisms make their study easier.

Times' Crucial Science Book - 9 290

5. Diseases can be transmitted by female mosquitoes only. Why?
Male mosquitoes feed on only juices of plants whereas the
female mosquitoes feed on the blood of animals. When female
mosquitoes feed on the blood of a sick person and then on
the healthy person, the diseases can be transmitted. But
males cannot do so. Thus, female mosquitoes can transmit
the diseases.

6. Spraying kerosene, paraffin oil or petroleum on the stagnant
water destroys larvae and pupae of mosquitoes. Why?
When kerosene, paraffin oil or petroleum are sprayed on the
stagnant water, they form a thin film on the water surface.
The thin film blocks the respiratory tube of the larvae and
pupae. Thus, they die of suffocation.

7. Mosquitoes are nocturnal animals. Why?
Mosquitoes become more active at night time. Therefore, they
are called nocturnal animals.

Glossary : related to genus
: huge, very large
Generic : consisting of two names
Enormous : gradual development of organisms from simpler to
Binomial
Evolution advanced forms
: clearly separated
Differentiated

Main points to remember

1. Carolus Linnaeus is known as father of taxonomy.
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291 Times' Crucial Science Book - 9

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Exercise
1. Answer these questions in very short.

a. What is classification ? Why is it important?
b. What is taxonomy ? Who is known as father of taxonomy?
c. What is binomial system of nomenclature?
d. What are cryptogams? Mention different divisions of

cryptogams?
e. Where are mosquitoes found ? Why are they harmful?
f. Draw a diagram of a mosquito and label its important

parts.
g. Explain the structure of a mosquito briefly.
h. What are the various stages of life cycle of mosquito?

Which stages grow in water?
i. What is the name of parasite that causes malaria?
j. How does malarial parasite attack human beings?
k. What are the control measures of mosquitoes?
l. How can a person prevent from mosquito bite?
m. Write any four features of bryophytes with two examples.
n. Mention the identifying features of pteridophytes with

two examples.

Times' Crucial Science Book - 9 292

o. What are invertebrates? Mention nine phyla of
invertebrates.

p. Mention any four features of protozoa with two examples.
q. Mention identifying features of porifera with two examples

2. Define following: Hermaphrodite
i) Genus ii) Species iii)
iv) Bilaterally symmetrical

3. Differentiate between:
i) Algae and fungi
ii) Invertebrates and vertebrates
iii) Bryophyta and pteridophyta
iv) Ascaris and earthworm
v) Spider and butterfly
vi) Jellyfish and starfish
vii) Male and female mosquito
viii) Larva of culex and larva of anopheles
ix) Pupa of culex and pupa of anopheles
x) Adult culex and adult anopheles

4. Define following terms:
i) Metazoa (ii) Bisexual animals (iii) Diploblastic
(iv) Autotrophic (v) Radially symmetrical

5. Identify the phylum of animals on the basis of following
features.
a. i) Body cavity is present ii) Mouth is surrounded by
tentacles.
b. i) Body is flat ii) Mouth is present but anus is absent
c. i) Body is soft but covered by hard shell.
ii) Movement is through muscular feet.
d. i) Body is covered by spiny skin ii) They are aquatic.

6. Give reasons.
i) Sponges are called pore bearers.
ii) Liver fluke is kept in phylum platyhelminthes.
iii) Earthworm is a hermaphrodite animal.
iv) Carolus Linnaeus is called father of taxonomy.
v) Mushroom is called saprophyte.
vi) Starfish is radially symmetrical.
vii) Female mosquitoes are more dangerous than male
mosquitoes.

293 Times' Crucial Science Book - 9

viii) Stagnant water should be drained to destroy mosquitoes.
ix) Mosquitoes can be destroyed by burning sulphur, camphor,

tar etc.

7. Mention the phyla of following organisms.
i) Sea urchin ii) Hook worm iii) Silver fish
iv) Jelly fish v) Coral vi) Octopus
vii) Hydra viii)Euglena ix) Sycon
x) Planaria xi) Amoeba xii) Earthworm

8. Classify the following organisms with a distinguishing
character.
i) Amoeba ii) Sea anemone iii) Marchantia
iv) Club moss v) Mucor vi) Spirogyra
vii) Ascaris viii) Leech ix) Butterfly
x) Sea-urchin xi) Slug.

9. Label the: X
a. Parts X, Y, Z. Y
b. Mention the function of those parts.

Z

Project Work

1. Collect any five invertebrates and cryptogams each and place
them in small plastic pouches. Fix them in a chart paper and
classify them with five distinguishing features. Show your work
to your teacher.

2. Visit a nearby ditch or pit filled with stagnant water. Collect
larvae and pupae of mosquitoes. Observe their structure with the
help of hand lens. Draw their diagrams and label important parts.

3. Catch an adult mosquito. Observe its various parts. Draw its
diagram and label important parts.

Times' Crucial Science Book - 9 294

Chapter $GDSWDWLRQ
RI
17
2UJDQLVPV
Jean-Baptiste Lamarck

He is known for describing the inheritance of
acquired characters in organisms

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Objectives

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Mind Openers

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Introduction
Our earth has great diversity in climatic and geographical
conditions in different places. For example, climatic and geographic
conditions of the desert are different from those of the marshy land.
Due to the diversity in the climatic and geographical conditions,
organisms living in one place are different from those living in other
places. For example, cows living in Himalayan region have long
and thick hairs whereas those living in terai region have short and
thin hairs. Similarly, the plants found in temperate and tropical
climate are tall with broad leaves whereas the plants found in cold
region are cone shaped with needle-like leaves.
Thus, the structure and physiological activities of organisms
differ from place to place depending upon the environment. Every
organism should be well adjusted to the environment to survive.
7KH SURFHVV RI DGMXVWPHQW RI DQ RUJDQLVP WR WKH HQYLURQPHQW LV
FDOOHG DGDSWDWLRQ If an organism is not well fitted, it may get
vanished after some generations.

An organism shows adaptation by the following ways :

i) By developing or losing some organs: Animals living in water
have gills to breathe whereas those living on the land have no gills.

295 Times' Crucial Science Book - 9

ii) By changing the colour: The colour of lizard changes
DFFRUGLQJ WR WKH HQYLURQPHQW
iii) By the modification of organs: The forelimbs of birds are

modified to wings.
LY %\ EHKDYLRUDO PRGLILFDWLRQV A turtle hides its head inside

shell when somebody touches its body.
Thus, adaptation includes structural, functional and behavioral
modifications which make them well fitted to the environment.

Fact Reason

How do chameleons protect themselves from the enemy?
Chameleons can change its body colour according to the
surroundings which helps them to disguise themselves in the
environment and protect themselves from the enemy.

Adaptation in plants
On the basis of habitat, plants are categorized into three classes.
They are hydrophytes, mesophytes and xerophytes.
Hydrophytes are the plants which are found in abundant amount
of water like pond, river, etc. Mesophytes are the plants which
grow on the land having moderate amount of water. Xerophytes
are the plants which grow on the land having less amount of water.
Adaptation of hydrophytes (aquatic plants)
7KH SODQWV ZKLFK JURZ LQ DEXQGDQW DPRXQW RI ZDWHU DUH
FDOOHG DTXDWLF SODQWV RU K\GURSK\WHV Their classifications and
adaptational characteristics are as follows.
Submerged plants
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VXEPHUJHG SODQWV

Vallisneria Hydrilla

Examples:- Hydrilla, vallisneria, etc.

Times' Crucial Science Book - 9 296