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Uses of Solutions

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Times' Crucial Science and Environment 147 Book 7

Main Points to Remember

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Exercise

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iv. All of the above.

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Times' Crucial Science and Environment 148 Book 7

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common salts in three different beakers or glasses. Observe the effect
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Times' Crucial Science and Environment 149 Book 7

Chapter

14 0HWDOV DQG
1RQ PHWDOV

ƐƟŵĂƚĞĚ ƉĞƌŝŽĚƐ͗ϰ

OBJECTIVES
At the end of the lesson, the students will be able to :
 ĞdžƉůĂŝŶ ƚŚĞ ƉƌŽƉĞƌƟĞƐ ŽĨ ŵĞƚĂů͕ ŶŽŶͲŵĞƚĂů ĂŶĚ ŵĞƚĂůůŽŝĚƐ͘
 ĞdžƉůĂŝŶ ƚŚĞ ĐŚĞŵŝƐƚƌLJ ŽĨ ƐƵůƉŚƵƌ͕ ŝŽĚŝŶĞ͕ ďƌĂƐƐ ĂŶĚ ďƌŽŶnjĞ͘

MIND OPENERS
 tŚĂƚ ŬŝŶĚ ŽĨ ĞůĞŵĞŶƚƐ ĂƌĞ ƚŚĞ ŵĞƚĂůƐ͍
 ĂŶ LJŽƵ ŐŝǀĞ ƐŽŵĞ ĞdžĂŵƉůĞƐ ŽĨ ŵĞƚĂůƐ͍
 ĂŶ LJŽƵ ĚĞĮŶĞ ŶŽŶͲŵĞƚĂůƐ͍
 ,Žǁ ĂƌĞ ŵĞƚĂůůŽŝĚƐ ĚŝīĞƌĞŶƚ ĨƌŽŵ ŵĞƚĂůƐ ĂŶĚ ŶŽŶͲŵĞƚĂůƐ͍ ŝƐĐƵƐƐ͘

Introduction

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non-metals and metalloids on the basis of thermal and electrical
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electricity are called non-metals. There are some other elements which are
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Metals

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PDOOHDEOH GXFWLOH DQG OXVWURXV 7KH PHWDOV DUH JHQHUDOO\ KDUG ,URQ
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0HUFXU\ LV IRXQG LQ OLTXLG VWDWH

Properties of Metals

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3. A metal can be beaten into very thin sheets, i.e. metals are malleable.

Times' Crucial Science and Environment 150 Book 7

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Uses of Metals

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these metals are also known as coinage metals.

Non-metals

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metals. 7KH\ DUH EULWWOH DQG QRQ OXVWURXV 7KH\ DUH QRW PDOOHDEOH DQG GXFWLOH
1RQ PHWDOV DUH JHQHUDOO\ IRXQG LQ QDWXUH DV JDVHRV DQG VRIW VROLG VWDWH

Gases : +\GURJHQ KHOLXP QLWURJHQ R[\JHQ ÁXRULQH FKORULQH DUJRQ HWF
/LTXLG Bromine
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Properties of Non-metals

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electrodes.

Times' Crucial Science and Environment 151 Book 7

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Uses of Non-metals

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as animals.
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and makes waterdrinkable.
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jewellery.

Some Important Non-metals

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and in some minerals on the earth. It is a shiny, dark black and crystalline
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EXW SXUH LRGLQH LV SRLVRQRXV ,W LV XVHG LQ WKH IRUP RI LRGLGH FRPSRXQG

Times' Crucial Science and Environment 152 Book 7

Uses
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known as 7LQFWXUH RI LRGLQH, LV XVHG DV DQ DQWLVHSWLF ,W LV XVHG WR
NLOO JHUPV RQ FXWV DQG ZRXQGV
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of a child.
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gland.
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and animals.
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SUHYHQW JRLWUH.
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glands of mammals.

Times' Crucial Science and Environment 153 Book 7

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of iodine.

Sulphur

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FRPSRXQGV

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Uses

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DQG VXOSKXULF DFLG +2SO4

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and ointments for skin diseases.

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for some varieties of bacteria.

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Metalloids

7KH HOHPHQWV ZKLFK KDYH WKH SURSHUWLHV LQWHUPHGLDWH EHWZHHQ PHWDOV DQG
QRQ PHWDOV DUH FDOOHG PHWDOORLGV. They are also regarded as semi-metals.
The elements VLOLFRQ, JHUPDQLXP, DUVHQLF, VHOHQLXP and DQWLPRQ\ SRVVHVV
WKH FKDUDFWHULVWLFV RI ERWK PHWDOV DQG QRQ PHWDOV DQG WKXV DUH FDOOHG
metalloids. /LNH PHWDOV PHWDOORLGV SRVVHVV PHWDOOLF OXVWUH IRUP DOOR\V
DQG DUH KDUG VROLGV 2Q WKH RWKHU KDQG WKH\ DUH QRW PDOOHDEOH DQG GXFWLOH
similar to non-metals.

Times' Crucial Science and Environment 154 Book 7

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KHDW DQG HOHFWULFLW\ EHWWHU WKDQ QRQ PHWDOV EXW GR QRW FRQGXFW
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intermediate between the metals and non-metals.

2. Generally they are brittle.
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7KH\ SRVVHVV PHWDOOLF OXVWUH

5. They can form alloys.

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televisions, mobiles, etc.
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Metals Non-metals Metalloids

ϭ͘ DĞƚĂůƐ ĂƌĞ ŐŽŽĚ ϭ͘ EŽŶͲŵĞƚĂůƐ ĂƌĞ ƚŚĞ ďĂĚ ϭ͘ DĞƚĂůůŽŝĚƐ ĂƌĞ ƚŚĞ ƉŽŽƌ

ĐŽŶĚƵĐƚŽƌƐ ŽĨ ŚĞĂƚ ĐŽŶĚƵĐƚŽƌƐ ŽĨ ŚĞĂƚ ĂŶĚ ĐŽŶĚƵĐƚŽƌƐ ŽĨ ŚĞĂƚ ĂŶĚ

ĂŶĚ ĞůĞĐƚƌŝĐŝƚLJ͘ ĞůĞĐƚƌŝĐŝƚLJ͘ ĞůĞĐƚƌŝĐŝƚLJ͘

Ϯ͘ dŚĞLJ ĂƌĞ ŵĂůůĞĂďůĞ Ϯ͘ EŽŶͲŵĞƚĂůƐ ĂƌĞ ďƌŝƩůĞ͘ Ϯ͘ dŚĞLJ ƐŚŽǁ ƉŽŽƌ ŵĂůůĞĂďŝůŝƚLJ

ĂŶĚ ĚƵĐƟůĞ͘ ĂŶĚ ĚƵĐƟůŝƚLJ͘

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ƐŽůŝĚ͕ ŚĂƌĚ ĂŶĚ ƐƚƌŽŶŐ͘ ŐĂƐĞƐ͘ dŚĞ ƐŽůŝĚƐ ĂƌĞ ƐŽŌ ŚĂƌĚ ƐŽůŝĚƐ͘
ĂŶĚ ďƌŝƩůĞ͘

ϱ͘ DĞƚĂůƐ ŚĂǀĞ ŚŝŐŚ ϱ͘ EŽŶͲŵĞƚĂůƐ ŚĂǀĞ ůŽǁ ϱ͘ DĞůƟŶŐ ƉŽŝŶƚ ĂŶĚ ďŽŝůŝŶŐ
ŵĞůƟŶŐ ĂŶĚ ďŽŝůŝŶŐ ŵĞůƟŶŐ ĂŶĚ ďŽŝůŝŶŐ ƉŽŝŶƚƐ ŽĨ ŵĞƚĂůůŽŝĚƐ ĂƌĞ
ůŽǁĞƌ ƚŚĂŶ ƚŚŽƐĞ ŽĨ ŵĞƚĂůƐ
ƉŽŝŶƚƐ͘ ƉŽŝŶƚƐ͘ ĂŶĚ ŚŝŐŚĞƌ ƚŚĂŶ ƚŚŽƐĞ ŽĨ

ŶŽŶͲŵĞƚĂůƐ͘

ϲ͘ džĂŵƉůĞ͗ /ƌŽŶ͕ ϲ͘ džĂŵƉůĞ͗ ,LJĚƌŽŐĞŶ͕ ϲ͘ džĂŵƉůĞ͗ ^ŝůŝĐŽŶ͕
ĐŽƉƉĞƌ͕ ƟŶ͕ ŐŽůĚ͕ ŚĞůŝƵŵ͕ ŽdžLJŐĞŶ͕ ĐĂƌďŽŶ͕ ŐĞƌŵĂŶŝƵŵ͕ ĂƌƐĞŶŝĐ͕ ĞƚĐ͘
ŵĂŐŶĞƐŝƵŵ͕ ĞƚĐ͘ ĞƚĐ͘

Times' Crucial Science and Environment 155 Book 7

Alloys

$Q DOOR\ LV D VROLG VROXWLRQ RI D PHWDO ZLWK RQH RU PRUH RWKHU HOHPHQWV The
RWKHU HOHPHQWV PD\ EH D PHWDO RU QRQ PHWDO )RU H[DPSOH EUDVV LV DQ DOOR\
RI WZR PHWDOV FRSSHU DQG ]LQF VWHHO LV DQ DOOR\ RI D PHWDO ZLWK D QRQ PHWDO
i.e. iron and carbon, etc.

$Q DOOR\ SRVVHVV PHWDOOLF SURSHUWLHV 7KH DOOR\V DUH JHQHUDOO\ SUHSDUHG WR
JHW D SURGXFW ZLWK GHVLUDEOH SURSHUWLHV ZKLFK WKH FRQVWLWXHQW HOHPHQWV
GR QRW KDYH 7KH PRVW LPSRUWDQW DOOR\ LV VWHHO ZKLFK KDV D ZLGH UDQJH
RI GHVLUDEOH SURSHUWLHV VXFK DV WRXJKQHVV VWUHQJWK OXVWUH FRUURVLRQ
resistance, etc.

$OOR\V DUH SUHSDUHG E\ PHOWLQJ WKH PHWDOV DQG WKHQ PL[LQJ WKHP
KRPRJHQHRXVO\ ,I DQ DOOR\ FRQWDLQV PHUFXU\ DV RQH RI WKH FRQVWLWXHQWV LW
LV FDOOHG DPDOJXP ,Q RWKHU ZRUGV D KRPRJHQHRXV PL[WXUH RI D PHWDO ZLWK
PHUFXU\ LV FDOOHG DPDOJXP.

Some commercially important alloys:

%UDVV

%UDVV LV DQ DOOR\ RI FRSSHU DQG ]LQF ZKLFK FRQWDLQV
DERXW FRSSHU DQG ]LQF 7KH SURSRUWLRQ
RI FRSSHU DQG ]LQF FDQ EH YDULHG ZLWKLQ WKH DERYH
OLPLWV WR KDYH GHVLUDEOH SURSHUWLHV VXFK DV VWUHQJWK
FRORXU FRUURVLRQ UHVLVWDQFH GXFWLOLW\ HWF

%UDVVHV RI GLIIHUHQW FRORXUV FDQ EH SURGXFHG DV SHU WKH GHVLUH 7KH\ FDQ
KDYH UHG JROGHQ \HOORZ RU VLOYHU\ ZKLWH FRORXU %UDVV ZLWK PDQJDQHVH
LV FKRFRODWH EURZQ LQ FRORXU
Uses

%UDVV LV XVHG WR PDNH KRXVHKROG XWHQVLOV VKHHWV FRQGHQVHU WXEHV
etc.

,W FDQ EH XVHG LQ GHFRUDWLRQ GXH WR LWV JROGHQ \HOORZ DSSHDUDQFH

,W FDQ EH XVHG WR PDNH ORFNV JHDUV EHDULQJV GRRUNQREV HWF

,W FDQ EH XVHG WR PDNH HOHFWULFDO DSSOLDQFHV

,W LV XVHG H[WHQVLYHO\ LQ PXVLFDO LQVWUXPHQWV VXFK DV KRUQV DQG
EHOOV GXH WR LWV DFRXVWLF SURSHUWLHV

%URQ]H
%URQ]H LV DQ DOOR\ RI FRSSHU DQG WLQ ZKLFK FRQWDLQV DERXW FRSSHU
DQG WLQ ,W LV KDUG DQG EULWWOH EXW LV FRQVLGHUHG OHVV EULWWOH WKDQ
LURQ

Times' Crucial Science and Environment 156 Book 7

Uses
%URQ]H LV DOVR XVHG WR PDNH KRXVHKROG XWHQVLOV
,W LV XVHG WR PDNH FRLQV VWDWXHV DQG FKHDS RUQDPHQWV
,W LV XVHG LQ ERDW DQG VKLS ÀWWLQJ
,W LV XVHG LQ EHDULQJV FOLSV HOHFWULFDO FRQQHFWRUV HWF
,W LV FRPPRQO\ XVHG LQ VKLS SURSHOOHUV DQG VXEPHUJHG EHDULQJV

'ŽŽĚ ĐŽŶĚƵĐƚŽƌ ͗ Ă ƐƵďƐƚĂŶĐĞ ƚŚƌŽƵŐŚ ǁŚŝĐŚ ĐƵƌƌĞŶƚ ĐĂŶ ƉĂƐƐ

ĂĚ ĐŽŶĚƵĐƚŽƌ ͗ Ă ƐƵďƐƚĂŶĐĞ ƚŚƌŽƵŐŚ ǁŚŝĐŚ ĐƵƌƌĞŶƚ ĐĂŶŶŽƚ ƉĂƐƐ

ŽŝŶĂŐĞ ͗ ĐŽŝŶƐ ĐŽůůĞĐƟǀĞůLJ

<ŝƚĐŚĞŶ ǁĂƌĞƐ ͗ ƵƚĞŶƐŝůƐ ƵƐĞĚ ŝŶ ŬŝƚĐŚĞŶ

:ĞǁĞůůĞƌLJ ͗ ƉĞƌƐŽŶĂů ŽƌŶĂŵĞŶƚƐ

'ŽŝƚƌĞ ͗ ƐǁĞůůŝŶŐ ŽĨ ƚŚLJƌŽŝĚ ŐůĂŶĚ

^ĂŶŝƟnjĞƌ ͗ Ă ůŝƋƵŝĚ ǁŚŝĐŚ ŬŝůůƐ ŐĞƌŵƐ

/ŶƐĞĐƟĐŝĚĞ ͗ Ă ĐŚĞŵŝĐĂů ǁŚŝĐŚ ŬŝůůƐ ŝŶƐĞĐƚƐ

&ƵŶŐŝĐŝĚĞ ͗ Ă ĐŚĞŵŝĐĂů ǁŚŝĐŚ ŬŝůůƐ ĨƵŶŐŝ

Main Points to Remember

0HWDOV DUH WKH HOHPHQWV ZKLFK FRQGXFW KHDW DQG HOHFWULFLW\ DQG DUH
PDOOHDEOH GXFWLOH DQG OXVWURXV

1RQ PHWDOV DUH WKH HOHPHQWV ZKLFK GR QRW FRQGXFW KHDW DQG
HOHFWULFLW\ DQG DUH EULWWOH DQG QRQ OXVWURXV

7KH HOHPHQWV ZKLFK KDYH WKH SURSHUWLHV LQWHUPHGLDWH EHWZHHQ
metals and non-metals are called metalloids.

$Q DOOR\ LV D VROLG VROXWLRQ RI D PHWDO ZLWK RQH RU PRUH RWKHU
elements.

%UDVV LV DQ DOOR\ RI FRSSHU DQG ]LQF
%URQ]H LV DQ DOOR\ RI FRSSHU DQG WLQ
,RGLQH LV D QRQ PHWDOOLF HOHPHQW ZKLFK LV D VKLQ\ GDUN EODFN DQG

crystalline solid.
6XOSKXU LV D QRQ PHWDOOLF HOHPHQW ZKLFK LV D SDle yellow soft solid.

Times' Crucial Science and Environment 157 Book 7

Exercise

&KRRVH WKH EHVW DOWHUQDWLYH LQ HDFK FDVH

D :KLFK PHWDO H[LVWV LQ OLTXLG VWDWH DW WKH URRP WHPSHUDWXUH"

L 0HUFXU\ LL 6RGLXP

LLL 3RWDVVLXP LY 8UDQLXP

E 7KH QRQ PHWDO WKDW H[LVWV LQ OLTXLG VWDWH LV

L &KORULQH LL %URPLQH

LLL 3KRVSKRUXV LY 6XOSKXU

F 7KH QRQ PHWDO ZKLFK LV D JRRG FRQGXFWRU RI HOHFWULFLW\ LV

L &DUERQ LL 'LDPRQG

LLL *UDSKLWH LY ,RGLQH

G :KLFK RI WKH IROORZLQJ PHWDO LV VR VRIW WKDW LW FDQ EH FXW ZLWK D
NQLIH"

L 0DJQHVLXP LL ,URQ

LLL 6LOYHU LY 6RGLXP

H $ VROXWLRQ RI LRGLQH DQG SRWDVVLXP LRGLGH LQ DOFRKRO LV FDOOHG

L ,RGL]HG VDOW LL 7LQFWXUH RI LRGLQH

LLL 6DQLWL]HU LY $OFRKROLF LRGLQH

f. Brass is an alloy of

L &RSSHU DQG ]LQF LL &RSSHU DQG WLQ

LLL &RSSHU DQG VLOYHU LY =LQF DQG WLQ

J :KLFK RI WKH IROORZLQJ LV D PHWDOORLG"

L 0DJQHVLXP LL $OXPLQLXP

LLL 6LOLFRQ LY %URQ]H

$QVZHU WKHVH TXHVWLRQV LQ EULHI
D 0HWDOV DUH PDOOHDEOH :KDW GRHV LW PHDQ"
E 1DPH D PHWDO ZKLFK LV OLTXLG DW URRP WHPSHUDWXUH
F 1DPH D QRQ PHWDO WKDW FRQGXFWV HOHFWULFLW\
G 1DPH DQ\ WZR QRQ PHWDOV WKDW DUH OXVWURXV
H :ULWH GRZQ D XVH RI FKORULQH
I :KDW LV JRLWHU"
J :KDW LV WLQFWXUH RI LRGLQH"
K :KDW GRHV DQ LRGL]HG VDOW FRQWDLQ"

Times' Crucial Science and Environment 158 Book 7

L :KDW LV WKH FRORXU RI EUDVV ZLWK RQH SHUFHQW PDQJDQHVH"
M :KDW LV DQ DPDOJXP"

:ULWH GRZQ GLIIHUHQFHV EHWZHHQ
D 0HWDOV DQG QRQ PHWDOV
E 0HWDOV DQG DOOR\V
F %UDVV DQG EURQ]H
G 0HWDOV DQG PHWDOORLGV

:ULWH GRZQ WKH XVHV RI

D %UDVV E %URQ]H F 6XOSKXU

G ,RGLQH H 0HWDOORLGV

:ULWH GRZQ WKH H[DPSOHV RI
D 0HWDOV
E 1RQ PHWDOV WKDW DUH JDVHV
F 1RQ PHWDO WKDW LV OLTXLG DW URRP WHPSHUDWXUH
G 1RQ PHWDOV WKDW DUH VROLG
H 0HWDOORLGV
f. Alloys

$QVZHU WKH TXHVWLRQV LQ EULHI
D :KDW DUH PHWDOV" :ULWH GRZQ WKH SURSHUWLHV RI PHWDOV
E 'HÀQH QRQ PHWDOV $OVR ZULWH GRZQ WKHLU SURSHUWLHV
F :KDW DUH PHWDOORLGV" :KDW DUH WKHLU SURSHUWLHV"
G :ULWH GRZQ WKH XVHV RI PHWDOV
H ([SODLQ WKH XVHV RI QRQ PHWDOV
I :KDW LV LRGLQH" :KDW DUH LWV VRXUFHV"
J :KDW KDSSHQV LI WKHUH LV GHÀFLHQF\ RI LRGLQH LQ WKH ERG\"
K ([SODLQ WKH SURSHUWLHV RI VXOSKXU

Project Work

:KDW PHWDOV DQG QRQ PHWDOV DUH EHLQJ XVHG DW \RXU KRPH" 0DNH
WKHLU OLVW DQG H[SODLQ WKHLU SURSHUWLHV DQG XVHV

Times' Crucial Science and Environment 159 Book 7

Chapter &KHPLFDOV LQ
'DLO\ /LIH
15
ƐƟŵĂƚĞĚ ƉĞƌŝŽĚƐ͗ϲ

OBJECTIVES

At the end of the lesson, the students will be able to :
 ŐŝǀĞ ŝŶƚƌŽĚƵĐƟŽŶ ŽĨ ƐŽŵĞ ƵƐĞĨƵů ĐŚĞŵŝĐĂůƐ ƐƵĐŚ ĂƐ ƉŚĞŶŽů͕ ĚĞƩŽů͕

ĚĞƚĞƌŐĞŶƚ͕ ďĂŬŝŶŐ ƉŽǁĚĞƌ͕ ĐŚĞŵŝĐĂů ĨĞƌƟůŝnjĞƌƐ͕ ĞƚĐ͘
 ĞdžƉůĂŝŶ ƚŚĞ ƵƐĞƐ ŽĨ ƚŚĞƐĞ ĐŚĞŵŝĐĂůƐ͘

MIND OPENERS
 ĂŶ LJŽƵ ŶĂŵĞ ƐŽŵĞ ĐŚĞŵŝĐĂůƐ ƚŚĂƚ ĂƌĞ ďĞŝŶŐ ƵƐĞĚ Ăƚ LJŽƵƌ ŚŽŵĞ͍
 tŚLJ ĂƌĞ ƐƵĐŚ ĐŚĞŵŝĐĂůƐ ƵƐĞĚ͍ ŝƐĐƵƐƐ͘

Introduction

7KHUH DUH PLOOLRQV RI FKHPLFDO FRPSRXQGV GLVFRYHUHG VR IDU 6HYHUDO RI
WKHVH FKHPLFDOV DUH XVHIXO WR XV 7KH FKHPLFDOV DUH LPSRUWDQW IRU FXOLQDU\
PHGLFLQDO FOHDQVLQJ RU DJULFXOWXUDO XVH &RPPRQ VDOW YLQHJDU SKHQRO
GHWHUJHQWV EDNLQJ SRZGHU FKHPLFDO IHUWLOL]HUV HWF DUH VRPH XVHIXO
chemicals.

Phenol

3KHQRO LV D FRORXUOHVV FU\VWDOOLQH VROLG ZLWK D SOHDVDQW VPHOO
,W PHOWV DW DERXW ƒ& DQG ERLOV DW ƒ& 3KHQRO LV VROXEOH LQ
DOFRKRO DQG HWKHU EXW PRGHUDWHO\ VROXEOH LQ ZDWHU ,W LV NQRZQ
DV FDUEROLF DFLG LQ LWV DTXHRXV VROXWLRQ VWDWH $FWXDOO\ WKH
OLTXLG IRUP RI SKHQRO FRQWDLQLQJ DERXW ZDWHU LV NQRZQ DV
carbolic acid.

3KHQRO LV SURGXFHG LQ ODUJH VFDOH IURP FUXGH RLO XVLQJ WKH
LQGXVWULDO SURFHVVHV $ERXW ELOOLRQ NLORJUDPV RI SKHQRO LV
SURGXFHG HYHU\ \HDU IURP FUXGH RLO
Uses

7KH PDMRU XVHV RI SKHQRO FRQVXPLQJ WZR WKLUGV RI LWV SURGXFWLRQ
LQYROYH LWV FRQYHUVLRQ WR SODVWLFV RU UHODWHG PDWHULDOV

Times' Crucial Science and Environment 160 Book 7

3KHQRO VROXWLRQ LV XVHG DV DQWLVHSWLF DQG GLVLQIHFWDQW 3KHQRO LV XVHG
WR GLVLQIHFW EDWKURRPV WRLOHWV HWF ,W JLYHV SOHDVDQW VPHOO EHVLGHV
killing the germs.

,W LV DOVR XVHG LQ WKH SURGXFWLRQ RI DGKHVLYHV SDLQWV YDUQLVKHV
dyes, etc.

,W LV XVHG LQ WKH SURGXFWLRQ RI DQ H[SORVLYH FRPSRXQG FDOOHG SLFULF
acid.

3KHQRO LV XVHG WR PDQXIDFWXUH WKH PHGLFLQHV VXFK DV DVSLULQ DQG
PDQ\ RWKHU SKDUPDFHXWLFDO GUXJV

3KHQRO LV XVHG DV DQ RUDO DQDHVWKHWLFV RU DQDOJHVLFV LQ WKH SURGXFWV
VXFK DV FKORUDVHSWLF

%XW SKHQRO PD\ EH IDWDO LI VZDOORZHG LQKDOHG RU DEVRUEHG WKURXJK WKH
VNLQ 3KHQRO DQG LWV YDSRXUV DUH FRUURVLYH WR H\HV VNLQ DQG WKH UHVSLUDWRU\
WUDFW ,Q WKH FDVH RI H\H FRQWDFW SKHQRO FDQ FDXVH VHYHUH GDPDJH DQG
SRVVLEO\ EOLQGQHVV ,Q VXFK FDVH WKH H\HV VKRXOG EH ÁXVKHG LPPHGLDWHO\
ZLWK SOHQW\ RI ZDWHU IRU DW OHDVW PLQXWHV OLIWLQJ H\H OLGV RFFDVLRQDOO\
,PPHGLDWH PHGLFDO DWWHQWLRQ PD\ EH UHTXLUHG

Antiseptics

$QWLVHSWLFV DUH WKRVH FRPSRXQGV ZKLFK SUHYHQW WKH
DFWLRQ RI PLFUR RUJDQLVPV HLWKHU E\ VWRSSLQJ WKHLU
UHSURGXFWLRQ RU FDXVLQJ WKHLU GHDWK ([DPSOHV DUH
FKORUR[\OHQRO VDYORQ VDORO DFULÁDYLQ SRWDVVLXP
SHUPDQJDQDWH LRGLQH HWF
&KORUR[\OHQRO LV WKH PDMRU FRQVWLWXHQW RI 'HWWRO 7KH
'HWWRO LV WKH WUDGH QDPH IRU VHYHUDO DQWLVHSWLF SURGXFWV
PDQXIDFWXUHG E\ D PXOWLQDWLRQDO FRPSDQ\
7KH DQWLVHSWLF SURSHUW\ RI GHWWRO LV GXH WR LWV DFWLYH
LQJUHGLHQW FKORUR[\OHQRO. 7KH FKORUR[\OHQRO LV DQ DURPDWLF RUJDQLF
FRPSRXQG &KORUR[\OHQRO FRPSULVHV RI GHWWRO·V WRWDO PL[WXUH ZLWK WKH
UHVW FRPSRVHG RI SLQH RLO LVRSURSDQRO FDVWRU RLO VRDS FDUDPHO DQG ZDWHU
'HWWRO OLTXLG DQWLVHSWLF LV QRUPDOO\ OLJKW \HOORZ LQ FRORXU $V PDQ\
LQJUHGLHQWV RI 'HWWRO DQWLVHSWLFV DUH LQVROXEOH LQ ZDWHU LW SURGXFHV D ZKLWH
FRORXUHG PLON\ HPXOVLRQ RI RLO GURSOHWV ZKHQ GLOXWHG ZLWK ZDWHU GXULQJ LWV XVH
Uses

'LOXWHG GHWWRO LV XVHG WR FOHDQ FXWV ZRXQGV HWF
'HWWRO DQWLVHSWLF GLVLQIHFWDQW OLTXLG FDQ EH XVHG LQ FOHDQLQJ VNLQ ,W

Times' Crucial Science and Environment 161 Book 7

FDQ DOVR EH XVHG DV D GLVLQIHFWDQW LQ WKH KRPH LW NLOOV EDFWHULD DQG
SURYLGHV H[SHUW SURWHFWLRQ DJDLQVW JHUPV

'HWWRO DQWLVHSWLF FUHDP DQG GHWWRO DQWLVHSWLF VSUD\ DUH XVHG IRU ÀUVW
aid.

'HWWRO VRDS SURYLGHV D JRRG EDWK DV ZHOO DV DQWLVHSWLF DFWLRQV

'HWWRO QHXWUDO URRP VSUD\ NLOOV EDFWHULD UHPRYHV IRXO VPHOOV DQG
SURYLGHV IUDJUDQFH LQ D URRP

%XW GHWWRO KDV WKH SRWHQWLDO IRU FDXVLQJ OHWKDO WR[LFLW\ ,W LV SRLVRQRXV
ZKHQ LQJHVWHG RU LQKDOHG (\H FRQWDFW FDQ OHDG WR GDPDJH WR WKH H\HV
6R LW VKRXOG EH DYRLGHG +HQFH GHWWRO VKRXOG QRW EH RYHUXVHG RU VDIHW\
PHDVXUHV VKRXOG EH DGRSWHG ZKLOH XVLQJ LW

Detergents

$ GHWHUJHQW LV D PL[WXUH RI FKHPLFDO FRPSRXQGV DETERGENT
ZKLFK KDV FOHDQVLQJ SURSHUW\ LQ GLOXWH VROXWLRQ
7KH PDLQ FRQVWLWXHQWV RI GHWHUJHQWV DUH WKH DON\O
EHQ]HQHV VXOSKRQDWHV RI VRGLXP ZKLFK DUH PRUH
VROXEOH LQ KDUG ZDWHU 'HWHUJHQWV DUH FRPPRQO\
DYDLODEOH DV SRZGHUV RU FRQFHQWUDWHG VROXWLRQV
,Q JHQHUDO WKH GHWHUJHQWV XVHG IRU ZDVKLQJ
FORWKHV FRQWDLQ ZDWHU VRIWHQHUV VXUIDFWDQWV DON\O
EHQ]HQH VXOSKRQDWHV HQ]\PHV EULJKWHQHUV
IUDJUDQFHV SHUIXPH DQG PDQ\ RWKHU DJHQWV 7KH
GHWHUJHQWV XVHG LQ ZDVKLQJ GLVKHV GLIIHU VOLJKWO\
LQ FRPSRVLWLRQ

$Q XOWUD FRQFHQWUDWHG SRZGHUHG ODXQGU\ GHWHUJHQW FRQWDLQV VRGLXP
FDUERQDWH VRGLXP VLOLFDWH VRGLXP FLWUDWH VRGLXP ELFDUERQDWH VRGLXP
ERUDWH VRGLXP VXOSKDWH FHOOXORVH FROORLGV DQG FOHDQLQJ DJHQWV WKDW DUH
GHULYHG IURP SODQWV

6RPH GHWHUJHQWV DUH FDOOHG VRDSOHVV VRDS EHFDXVH WKH\ FRQWDLQ VRDSIUHH
OLTXLG FOHDQVHU 7KH\ DUH EHWWHU FOHDQVLQJ DJHQWV WKDQ WKH VRDS

7KH GHWHUJHQWV GR QRW GHFD\ LQ QDWXUH 7KH\ UHPDLQ XQDIIHFWHG IRU D ORQJ
WLPH DQG SROOXWH WKH HQYLURQPHQW

%DNLQJ 3RZGHU

%DNLQJ SRZGHU LV D GU\ FKHPLFDO OHDYHQLQJ DJHQW XVHG WR
LQFUHDVH WKH YROXPH DQG OLJKWHQ WKH WH[WXUH RI FDNHV PXIÀQV
VFRQHV HWF %DNLQJ SRZGHU ZRUNV E\ UHOHDVLQJ FDUERQ GLR[LGH
JDV LQWR D EDWWHU RU GRXJK WKURXJK D UHDFWLRQ 7KH JDV FDXVHV
EXEEOHV LQ WKH ZHW PL[WXUH WR H[SDQG DQG WKXV OHDYHQLQJ WKH

Times' Crucial Science and Environment 162 Book 7

PL[WXUH :KLOH EDNLQJ KHDW UHOHDVHV DGGLWLRQDO FDUERQ GLR[LGH JDV DQG
H[SDQGV WKH WUDSSHG DLU SRFNHWV LQ WKH EDWWHU )LQDOO\ LW H[SDQGV WKH EDNHG
food.
7KH EDNLQJ SRZGHU LV JHQHUDOO\ PDGH RI DQ DONDOLQH FRPSRQHQW 6RGLXP
ELFDUERQDWH NQRZQ DV EDNLQJ VRGD RQH RU PRUH DFLG VDOWV OLNH WDUWDULF
DFLG DQG DQ LQHUW VWDUFK 7KH LQHUW VWDUFK DEVRUEV WKH PRLVWXUH
Uses

%DNLQJ SRZGHU FDQ EH XVHG WR LQFUHDVH WKH YROXPH DQG OLJKWHQ WKH
WH[WXUH RI FDNHV ELVFXLWV HWF

%DNLQJ SRZGHU FDQ EH XVHG IRU QRQ EDNLQJ SXUSRVHV DOVR $ SDVWH RI
EDNLQJ SRZGHU ZLWK ZDWHU FDQ EH XVHG WR VKLQH VWDLQOHVV VWHHO

,W FDQ EH XVHG WR VRIWHQ WKH KDUG ZDWHU
,W FDQ EH XVHG DV D JHQWOH VFRXULQJ SRZGHU IRU NLWFKHQ FRXQWHUWRSV

Fertilizers

3ODQWV QHHG QXWULHQWV IRU WKHLU JURZWK 7KH\ DEVRUE WKH QXWULHQWV IURP WKH
VRLO ,I WKHUH LV GHÀFLHQF\ RI QDWXUDO QXWULHQWV LQ WKH VRLO ZH XVH FKHPLFDO
IHUWLOL]HUV
&KHPLFDO IHUWLOL]HUV DUH WKH ZDWHU VROXEOH FKHPLFDO VXEVWDQFHV ZKLFK DUH
DGGHG WR WKH VRLO WR VXSSO\ HVVHQWLDO HOHPHQWV UHTXLUHG E\ WKH SODQWV IRU WKHLU
SURSHU DQG KHDOWK\ JURZWK $ JRRG IHUWLOL]HU KDV WKH IROORZLQJ SURSHUWLHV

,W LV VROXEOH LQ ZDWHU
7KH QXWULHQW HOHPHQWV SUHVHQW LQ LW DUH UHDGLO\ DYDLODEOH
7KH QXWULHQW HOHPHQWV DUH DYDLODEOH IRU ORQJ SHULRG RI WLPH
7KH IHUWLOL]HUV FDQ EH GLYLGHG LQWR WKUHH W\SHV RQ WKH EDVLV RI QXWULHQWV WKH\
FRQWDLQ 7KH\ DUH
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Times' Crucial Science and Environment 163 Book 7

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3RWDVVLXP KHOSV LQ WKH GHYHORSPHQW RI URRWV TXLFNHQV WKH ULSHQLQJ RI
FHUHDOV DQG RIIHUV UHVLVWDQFH DJDLQVW GLVHDVHV ([DPSOHV SRWDVVLXP
FKORULGH SRWDVVLXP VXOSKDWH SRWDVVLXP QLWUDWH HWF

WŚĂƌŵĂĐĞƵƟĐĂů ͗ ƌĞůĂƚĞĚ ƚŽ ĚƌƵŐƐ

ŶĞƐƚŚĞƟĐ ͗ Ă ĐŚĞŵŝĐĂů ǁŚŝĐŚ ĐĂƵƐĞƐ ůŽƐƐ ŽĨ ƐĞŶƐĞ

ŶĂůŐĞƐŝĐ ͗ Ă ŵĞĚŝĐŝŶĞ ƚŽ ƌĞĚƵĐĞ ƉĂŝŶ

ĂƌĂŵĞů ͗ Ă ďƌŽǁŶ ĐŽůŽƵƌĞĚ ƐLJƌƵƉ ŽďƚĂŝŶĞĚ ĂŌĞƌ ŚĞĂƟŶŐ ƐƵŐĂƌ

ŵƵůƐŝŽŶ ͗ ŵŝdžƚƵƌĞ ŽĨ ŝŶƐŽůƵďůĞ ƐŽůŝĚ ĂŶĚ ůŝƋƵŝĚ

>ĂƵŶĚƌLJ ͗ ĐůŽƚŚĞƐ

dĞdžƚƵƌĞ ͗ ĂƉƉĞĂƌĂŶĐĞ

Main Points to Remember

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$Q DQWLVHSWLF LV D FKHPLFDO FRPSRXQG ZKLFK LQKLELWV WKH

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7KH GHWHUJHQWV DUH QRQ ELRGHJUDGDEOH DQG KHQFH SROOXWH WKH

environment.
%DNLQJ SRZGHU LV D GU\ OHDYHQLQJ DJHQW XVHG WR LQFUHDVH WKH YROXPH

DQG OLJKWHQ WKH WH[WXUH RI FDNHV ELVFXLWV HWF
&KHPLFDO IHUWLOL]HUV DUH WKH ZDWHU VROXEOH FKHPLFDO VXEVWDQFHV

ZKLFK DUH DGGHG WR WKH VRLO WR VXSSO\ HVVHQWLDO QXWULHQWV UHTXLUHG
IRU WKH SODQWV IRU WKHLU KHDOWK\ JURZWK

Exercise

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D :KLFK FKHPLFDO LV XVHG WR UHPRYH EDG VPHOO DQG NLOO ÁLHV LQ DQG
DURXQG RXU KRXVH"

i. Detergent ii. Phenol

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Times' Crucial Science and Environment 164 Book 7

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L +DYLQJ EDWK LL :DVKLQJ FORWKHV

LLL $V SHUIXPH LY &OHDQLQJ ZRXQG

G :KLFK RI WKH IROORZLQJ LV DQ DQWLVHSWLF"

i. Dettol ii. Savlon

iii. Salol iv. All of these

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L 7R NLOO JHUPV LQ VNLQ RU ZRXQG LL 7R KHDO WKH ZRXQG

iii. To wash clothes iv. To make skin soft

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Project Work

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GLIIHUHQW W\SHV RI IHUWLOL]HUV WKH\ XVH :ULWH GRZQ WKH PHWKRGV RI
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Times' Crucial Science and Environment 165 Book 7

Chapter

16 & ODVVLILFDWLRQ RI
$QLPDOV DQG 3ODQWV

ƐƟŵĂƚĞĚ ƉĞƌŝŽĚƐ͗ϲ

OBJECTIVES
At the end of the lesson, the students will be able to :
 ĐůĂƐƐŝĨLJ ǀĞƌƚĞďƌĂƚĞƐ͘
 ƚĞůů ĨĞĂƚƵƌĞƐ ĂŶĚ ĞdžĂŵƉůĞƐ ŽĨ ƉŝƐĐĞƐ ĂŶĚ ĂŵƉŚŝďŝĂ͘
 ƚĞůů ƚŚĞ ĨĞĂƚƵƌĞƐ ĂŶĚ ĞdžĂŵƉůĞƐ ŽĨ ƌĞƉƟůŝĂ ĂŶĚ ĂǀĞƐ͘
 ƚĞůů ƚŚĞ ĨĞĂƚƵƌĞƐ ĂŶĚ ĞdžĂŵƉůĞƐ ŽĨ ŵĂŵŵĂůŝĂ͘
 ĐůĂƐƐŝĨLJ ƉůĂŶƚƐ ŝŶƚŽ ŇŽǁĞƌŝŶŐ ĂŶĚ ŶŽŶͲŇŽǁĞƌŝŶŐ ƉůĂŶƚƐ͘
 ƚĞůů ƚŚĞ ĨĞĂƚƵƌĞƐ ŽĨ ŇŽǁĞƌŝŶŐ ƉůĂŶƚƐ͘
 ƚĞůů ƚŚĞ ĨĞĂƚƵƌĞƐ ŽĨ ŶŽŶͲŇŽǁĞƌŝŶŐ ƉůĂŶƚƐ͘

MIND OPENERS
 ĂŶ LJŽƵ ƚĞůů ƚŚĞ ĐůĂƐƐ ŽĨ ĚŝīĞƌĞŶƚ ĂŶŝŵĂůƐ͍
 /Ɛ ƚŚĞƌĞ ĂŶLJ ĚŝīĞƌĞŶĐĞ ďĞƚǁĞĞŶ ŵƵƐƚĂƌĚ ĂŶĚ ĨĞƌŶ ƉůĂŶƚ͍ /Ĩ LJĞƐ͕ ǁŚĂƚ

ĂƌĞ ƚŚĞLJ͍

Introduction

There are a number of living things around us. They differ from each other
in shape, size, habitat, physiology, etc. They are broadly categorized into
two groups. They are animals and plants. You have already studied about
differences between plants and animals in class VI. In this class, we shall
VWXG\ DERXW FODVVLÀFDWLRQ RI DQLPDOV DQG SODQWV

&ODVVL¿FDWLRQ RI DQLPDOV

There are a large number of animals around us. They differ from each
RWKHU LQ VKDSH VL]H VWUXFWXUH HWF &RZ PRVTXLWR EXWWHUÁ\ EXIIDOR
HOHSKDQW DQW VQDLO VWDUÀVK HWF DUH VRPH DQLPDOV $PRQJ WKHP VRPH DUH
vertebrates and some are invertebrates. Invertebrates are those animals
which do not have backbone whereas vertebrates are the animals which
have backbone in their body. Backbone is called vertebral column also.

Times' Crucial Science and Environment 166 Book 7

Activity 16.1 7R ¿QG WKH ORFDWLRQ RI \RXU EDFN ERQH

Put your hand at the back side of your body and press the
lower middle part of the back.

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Observation

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bigger at the lower part. This bone is vertebral column or

backbone. It consists of numerous small pieces of bones.

They are called vertebrae.

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The animals which have backbone in their body are called vertebrates.
)URJ ÀVK WLJHU OLRQ KXPDQ EHLQJ EDW VQDNH OL]DUG HWF DUH H[DPSOHV RI
vertebrates. Vertebrates have following features:

i. Vertebral column or backbone is present.

ii. Well developed nervous system is present. Nervous system contains
brain and spinal cord.

iii. They have gills or lungs for respiration.

iv. Their blood is red. It is due to the presence of haemoglobin.

v. Body is bilaterally symmetrical. Bilaterally symmetrical body is the
body which can be divided into two equal halves by a line passing
through the centre.

Vertebrates can be divided into two types, cold blooded animals and warm
blooded animals, on the basis of their body temperature. The animals whose
body temperature changes along with the change in the temperature of the
environment are called cold blooded animals. Fishes, frogs, snakes, lizards,
LQVHFWV HWF DUH WKH H[DPSOHV RI FROG EORRGHG DQLPDOV &ROG EORRGHG DQLPDOV
go far long sleep under the soil in winter season. It is called hibernation.

The animals whose body temperature does not change along with the
temperature of the surrounding are called warm blooded animals.

Birds, horse, man, elephant, tiger, lion, cat, etc are warm blooded animals.

2Q WKH EDVLV RI VWUXFWXUH YHUWHEUDWHV DUH GLYLGHG LQWR ÀYH FODVVHV 7KH\
are:

L 3LVFHV LL $PSKLELD LLL 5HSWLOLD

LY $YHV Y 0DPPDOLD

Times' Crucial Science and Environment 167 Book 7

Pisces
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features are as follows:

i. Their body is streamlined or boat shaped. This shape cuts the water
and helps for swimming in water.

ii. They contain gills for breathing.
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iv. The body is differentiated into head, trunk and tail.
v. Heart is two-chambered.
vi. They reproduce through eggs. Therefore, they are called oviparous.
Examples: 6KDUN 5RKX 6HD KRUVH HWF

Shark Rohu

Amphibia Sea-horse

The animals which live both on land and in water belong to the class
amphibia. They have following features:

i. They live both on land and in water

ii. Their heart contains three chambers.

iii. They breathe through skin in water and through lungs on the land.

iv. Two pairs of limbs are present.

v. They are cold blooded animals.

vi. Their body is covered by smooth and rough skin.

vii. They reproduce through eggs. Thus, they are oviparous.

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and female gamete takes place outside the body of female.

Examples: Frog, toad, salamander, newt, etc

Toad Frog Salamander
Book 7
Times' Crucial Science and Environment 168

Reptilia
7KH DQLPDOV ZKLFK FUDZO RQ WKH ODQG EHORQJ WR WKH FODVV UHSWLOLD 0RVW RI WKH
reptiles are found on the land. Salient features of class reptilia are as follows:

i. Their body is covered by hard, dry and horny scales.
ii. Their body is divided into head, neck, trunk and tail.
iii. Their heart contains three chambers. But some species of crocodiles

have four chambers in their heart.
iv. They are cold blooded animals.
v. Two pairs of limbs with clawed digits are present. But, snakes

have no limbs.
vi. They breathe through lungs.
vii. They are oviparous.
viii. Fertilization is internal.
Examples: Snake, lizard, crocodile, tortoise, etc.

Aves Snake Crocodile Tortoise

$OO ELUGV EHORQJ WR WKH FODVV DYHV 7KH\ DUH ZDUP EORRGHG DQLPDOV 7KHLU
salient features are as follows:

i. Their body is stream-lined and covered with feathers.

LL 7KHLU IRUHOLPEV DUH PRGLÀHG WR ZLQJV

iii. Their body is divided into head, neck, trunk and tail.

iv. Toothless beak is present.

v. Breathing takes place through lungs.

vi. The heart is four chambered.

vii. They are oviparous and fertilization is internal.

Example: Crow, sparrow, danphe, peacock, pigeon, etc

Crow Sparrow Danphe Peacock Pigeon
169 Book 7
Times' Crucial Science and Environment

Mammalia
Highly developed vertebrates like cow, buffalo, man, cat, goat, elephant,
etc belong to the class mammalia.

i. They have mammary glands (milk secreting glands).
ii. Their body is covered with hair.
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iv. Heart is four chambered.
v. They give direct birth to young ones. Therefore, they are called

viviparous animals.
vi. Their body is divided into head, neck, trunk and tail.
vii. Two pairs of limbs are present.
viii. Breathing takes place through lungs.
Examples: Bat, buffalo, whale, dolphin, dog, cat, cow, horse, etc.

Dolphin %X൵DOR
Bat Cow

Whale

Cat Dog Horse
Times' Crucial Science and Environment
170 Book 7

&ODVVL¿FDWLRQ RI YHUWHEUDWH DQLPDOV

1. Cow

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: Chordata
Phylum : Vertebrata
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Sub-phylum : Cow

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Type

Character

1. They give direct birth to young ones.
2. The body is covered with hair.

2. Pigeon

.LQJGRP $QLPDO
: Chordata
Phylum : Vertebrata
Sub-phylum $YHV
&ODVV : Pigeon
Type

Character

1. Their body is covered by feather.
2. They lay eggs to reproduce new ones.

3. Snake

.LQJGRP $QLPDO
: Chordata
Phylum : Vertebrata
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Sub-phylum : Snake

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Type

Character

1. Their body is covered by rough scales.
2. They have a long and round body without legs.

Activity 16.2 7R LGHQWLI\ RUJDQLVPV

2EVHUYH \RXU VXUURXQGLQJ DQG ÀQG DQ\ YHUWHEUDWHV 0HQWLRQ
their names and classify them.

Times' Crucial Science and Environment 171 Book 7

&ODVVL¿FDWLRQ RI SODQWV

There are various types of plants around us. They differ from each other in
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GR QRW EHDU ÁRZHUV 2Q WKH EDVLV RI SUHVHQFH RU DEVHQFH RI ÁRZHUV WKH
plants are categorized into two types. They are:

i) Phanerogams ii) Cryptogams
Phanerogams

7KH SODQWV ZKLFK EHDU ÁRZHUV DUH FDOOHG ÁRZHULQJ SODQWV 7KH\ EHORQJ WR
sub-kingdom ‘Phanerogam’. Generally they are bigger in size. Phanerogams
DUH DOVR GLYLGHG LQWR WZR GLYLVLRQV *\PQRVSHUPV DQG $QJLRVSHUPV
Gymnosperms

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.

Salient features

L 7KH\ EHDU FRQHV LQVWHDG RI WUXH ÁRZHUV 0DOH ÁRZHUV DQG IHPDOH
ÁRZHUV DUH VHSDUDWH

ii) Seeds are not enclosed inside the fruits.
iii) Leaves are needle shaped.
iv) The plant body is cone shaped. Cone shaped structure helps to cut

off the snow in cold season.
Example: &\FDV SLQH ÀU FHGDU HWF

Pine Fir Cycas Cedar

Angiosperm

7KLV GLYLVLRQ LQFOXGHV WKH ÁRZHULQJ SODQWV ZKLFK EHDU VHHGV HQFORVHG
inside the fruits. Generally they are cosmopolitan, i.e., they are found in
all places of the earth.

Times' Crucial Science and Environment 172 Book 7

Salient features
L 7KH\ KDYH ZHOO GHYHORSHG ÁRZHUV
ii) Seeds are enclosed inside the fruits.
iii) The plant body is made of well developed root, stem and leaves.
Example: $SSOH PDQJR EDQDQD PDL]H HWF

Apple Mango Banana Maize

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Dicotyledons.

Monocotyledons (Monocot)

The plants which contain only one cotyledon or seed leaf are kept in the
sub division monocotyledon. These plants have following features:

i) The seeds of these plants contain only one cotyledon or seed leaf.

ii) They have long leaves with parallel venation.

LLL 7KH URRW V\VWHP LV ÀEURXV URRW V\VWHP

LY 7KH QXPEHU RI SHWDOV RU VHSDOV LQ WKH ÁRZHUV LV WKUHH RU LWV PXOWLSOHV

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

Rice Sugarcane Banana Maize

Dicotyledons (Dicot)

The plants which contain two cotyledons or seed leaves are kept in the sub
division dicotyledon. These plants have following features:

i) The seeds of these plants contain two cotyledons.

ii) They have broad leaves having reticulate venation.

iii) Tap root system is present.

LY 7KH QXPEHU RI VHSDOV RU SHWDOV LQ WKH ÁRZHUV LV IRXU RU ÀYH RU WKHLU
multiple.

Times' Crucial Science and Environment 173 Book 7

Examples: 0DQJR EHDQ URVH PXVWDUG RUDQJH SHD DSSOH VXQÁRZHU HWF

6XQÀRZHU Bean Rose Mustard Orange

Differences between Dicot and Monocot Plants

Dicot Monocot

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ƚǁŽ ĐŽƚLJůĞĚŽŶƐ Žƌ ƐĞĞĚ ůĞĂǀĞƐ ĂƌĞ ŽŶĞ ĐŽƚLJůĞĚŽŶ Žƌ ƐĞĞĚ ůĞĂĨ ĂƌĞ ĐĂůůĞĚ

ĐĂůůĞĚ ĚŝĐŽƚLJůĞĚŽŶƐ͘ ŵŽŶŽĐŽƚLJůĞĚŽŶƐ͘

Ϯ͘ dŚĞŝƌ ƌŽŽƚƐ ĂƌĞ ƚĂƉ ƌŽŽƚƐ͘ Ϯ͘ dŚĞŝƌ ƌŽŽƚƐ ĂƌĞ ĮďƌŽƵƐ ƌŽŽƚƐ͘

ϯ͘ dŚĞLJ ŚĂǀĞ ƌĞƟĐƵůĂƚĞ ǀĞŶĂƟŽŶ ŝŶ ϯ͘ dŚĞLJ ŚĂǀĞ ƉĂƌĂůůĞů ǀĞŶĂƟŽŶ ŝŶ ƚŚĞŝƌ

ƚŚĞŝƌ ůĞĂǀĞƐ͘ ůĞĂǀĞƐ͘

ϰ͘ dŚĞ ŶƵŵďĞƌ ŽĨ ƉĞƚĂůƐ Žƌ ƐĞƉĂůƐ ŝŶ ϰ͘ dŚĞ ŶƵŵďĞƌ ŽĨ ƉĞƚĂůƐ Žƌ ƐĞƉĂůƐ ŝŶ ƚŚĞ
ƚŚĞ ŇŽǁĞƌ ŝƐ ĨŽƵƌ Žƌ ĮǀĞ Žƌ ƚŚĞŝƌ ŇŽǁĞƌ ŝƐ ƚŚƌĞĞ Žƌ ŝƚƐ ŵƵůƟƉůĞ͘
ŵƵůƟƉůĞƐ͘

Cryptogams
7KH SODQWV WKDW GR QRW EHDU ÁRZHUV EHORQJ WR WKH GLYLVLRQ ¶FU\SWRJDP· 7KH\
are ÁRZHUOHVV and seedless plants. They are simple type of plants.

Features of cryptogams

L 7KH\ GR QRW EHDU ÁRZHUV DQG VHHGV
ii) Generally, they reproduce through spores.
iii) They may be autotrophic or heterotrophic.
iv) Some plants like chlamydomonas, yeast, etc are unicellular whereas

WKH SODQWV OLNH QRVWRF XORWKUL[ VSLURJ\UD OLYHUZRUW PRVV IHUQV HWF
are multicellular plants.

Chlamydomonas Yeast Nostoc Spirogyra
174 Book 7
Times' Crucial Science and Environment

&U\SWRJDPV DUH IXUWKHU FODVVLÀHG LQWR WKUHH GLYLVLRQV 7KH\ DUH
i) Thallophyta
ii) Bryophyta
iii) Pteridophyta

7KDOORSK\WD

7KDOORSK\WD LQFOXGHV YHU\ VLPSOH W\SH RI QRQ ÁRZHULQJ SODQWV 7KHLU ERG\
is not differentiated into root, stem and leaves. The plant body without the
differentiated root, stem and leaf is called thallus. Some of the thallophytes
are green and some others are non-green. Some of them are unicellular
and some are multicellular. Thallophytes are further divided into two
sub-divisions.
D $OJDH E )XQJL
Algae
The sub-division algae includes green thallophyta.
Salient features

i) They are green due to the presence of chlorophyll.
ii) They grow in water or in damp soil.
iii) Their body may be unicellular or multicellular.
iv) They can prepare their foods themselves by photosynthesis.
Examples: &KODP\GRPRQDV VSLURJ\UD YROYR[ XORWKUL[ HWF

Chlamydomonas Spirogyra Volvox Ulothrix
Book 7
Activity 16.3 7R VWXG\ VSLURJ\UD

Materials required: 0LFURVFRSH SRQG ZDWHU
with spirogyra, etc.
Procedure
Visit a pond or stagnant water. You can see green
thread like structures. Bring some water with
spirogyra to your school. Take out the thread like
structures and observe under microscope.

Times' Crucial Science and Environment 175

:KDW GR \RX VHH"
Observation
You can see the structure as shown above in the diagram.
Fungi
This sub-phylum includes non-green thallophytes. Generally, they grow on
decaying materials.
Salient features
i) They are non-green plants due to the absence of chlorophyll.
ii) They cannot prepare their foods due to lack of chlorophyll. Therefore,

they are called heterotrophic plants.
LLL 0RVW RI WKH IXQJL OLNH PXVKURRP PXFRU \HDVW HWF JURZ RQ GHDG

and decaying material. They are called saprophytes.
iv) Their body is made of mycelium.
Examples: 0XVKURRP PXFRU \HDVW HWF

Mushroom Mucor Yeast

Activity 16.4 7R JURZ PXFRU DQG REVHUYH LWV VWUXFWXUH

Materials required
$ SLHFH RI EUHDG D SODWH VXJDU VROXWLRQ KDQG OHQV D JODVV VOLGH HWF
Procedure

i) Take a piece of bread and keep it on the plate.
ii) Spray sugar solution on the piece of bread to make it moist

then cover it.
iii) Put the plate with bread in warm and moist place for few days.

Times' Crucial Science and Environment 176 Book 7

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Observation
You can see white or green coloured cotton shaped structure growing
on the bread. When you observe it with hand lens, you can see the
branched structure of the mucor.
Conclusion:
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Differences between Algae and Fungi

Algae Fungi
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Ϯ͘ dŚĞLJ ĂƌĞ ĂƵƚŽƚƌŽƉŚŝĐ͘ Ϯ͘ dŚĞLJ ĂƌĞ ŚĞƚƌŽƚƌŽƉŚŝĐ͘

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ϰ͘ dŚĞLJ ŐƌŽǁ ŝŶ ǁĂƚĞƌ͘ ϰ͘ dŚĞLJ ŐƌŽǁ ŽŶ ĚĞĂĚ ĂŶĚ ĚĞĐĂLJĞĚ
ƐƵďƐƚĂŶĐĞƐ͘

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The plants of division ‘bryophyta’ are differentiated into leaves, stem and
rhizoids. They need water for reproduction. But, they grow on the land.
Hence, they are called amphibian plants.
Salient features

i) They grow in moist and shady places.
ii) The plant body is leaf like thallus. But, the body of moss is

differentiated into rhizoids, stem and leaves. Rhizoids are false
roots.
iii) They get attached to the soil or wood or stones by rhizoids.
iv) They need water for reproduction.
v) They are green and can prepare their foods.
Examples: 5LFFLD OLYHUZRUW PRVV HWF

Riccia Liverwort Moss
Times' Crucial Science and Environment 177 Book 7

Pteridophyta
The plants of division ‘Pteridophyta’ are highly developed cryptogams.
7KH\ FRQWDLQ YDVFXODU EXQGOHV L H [\OHP DQG SKORHP 7KHUHIRUH WKH\ DUH
called vascular cryptogams.
Salient features

i) Their body is differentiated into root (rhizoids), stem and leaves.
LL 7KH\ KDYH ZHOO GHYHORSHG YDVFXODU EXQGOHV L H [\OHP DQG SKORHP
iii) They are found in moist and shady places.
iv) They contain chlorophyll. Therefore, they can prepare their foods

themselves.
Examples: Fern plant, horsetail, lycopodium, etc.

Fern Lycopodium Horsetail

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1. Fern

Kingdom : Plantae

Sub-Kingdom : Cryptogam

Division : Pteridophyta

Type : Fern

Characters

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2. They bear feather like leaves.

2. Mango

Kingdom : Plantae
: Phanerogam
Sub-Kingdom $QJLRVSHUP
: Dicotyledon
'LYLVLRQ
0DQJR
Sub-division

7\SH

Times' Crucial Science and Environment 178 Book 7

Characters
1. They have seeds enclosed inside the fruits.

2. They have a big plant body with hard and woody trunk.

3. Maize

Kingdom : Plantae
: Phanerogam
Sub-Kingdom $QJLRVSHUP
0RQRFRW\OHGRQ
'LYLVLRQ 0DL]H

6XE GLYLVLRQ

7\SH

Characters
1. They contain seeds enclosed inside the fruits.

2. The seed contains single cotyledon or seed leaf.

4. Pine : Plantae
Kingdom : Phanerogam
Sub-Kingdom : Gymnosperm
Division : Pine
Type

Characters

1. Their seeds are not enclosed inside fruits.

2. They are very big cone shaped trees.

3. Mushroom

Kingdom : Plantae

Sub-Kingdom : Cryptogam

Division : Thallophyta

Sub-division : Fungi

7\SH 0XVKURRP

Character

1. Their body is not differentiated into root, stem and leaves.

2. They are non-green plants due to the lack of chlorophyll.

Activity 16.5 7R FODVVLI\ WKH DYDLODEOH SODQWV

Classify the plants rice, lotus, banana, cycas and liverwort with two
main features of each.

Times' Crucial Science and Environment 179 Book 7

dƌƵŶŬ ͗ ŵĂŝŶ ďŽĚLJ ŽĨ ĂŶŝŵĂůƐ ĞdžĐĞƉƚ ŚĂŶĚƐ ĂŶĚ ůĞŐƐ

WŝŶŶĂ ͗ ĞdžƚĞƌŶĂů ĞĂƌ ŽĨ ŵĂŵŵĂůƐ

ŵƉŚŝďŝĂŶ ƉůĂŶƚ ͗ ƉůĂŶƚ ƚŚĂƚ ŶĞĞĚƐ ďŽƚŚ ǁĂƚĞƌ ĂŶĚ ůĂŶĚ ƚŽ ĐŽŵƉůĞƚĞ ŝƚƐ ůŝĨĞ ĐLJĐůĞ

0DLQ 3RLQWV WR 5HPHPEHU

1. The animals which have backbone in their body are called vertebrates.
2. The animals whose body temperature changes along with the

change in the temperature of the environment are called cold
blooded animals.
3. The animals whose body temperature does not change along with
the change in temperature of the environment are called warm
blooded animals.
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$YHV DQG 0DPPDOLD
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7KH SODQWV ZKLFK GR QRW EHDU ÁRZHUV DUH FDOOHG FU\SWRJDPV
7. Gymnosperms are the plants whose seeds are not enclosed inside
the fruits.
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enclosed inside the fruits.
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seeds.
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leaves in the seeds.
11. Thallophyta includes the plants whose body is not differentiated
into root, stem and leaves.
12. Bryophyta includes the plants whose body is differentiated into
leaves, stems and rhizoids.
13. Pteridophyta includes the highly developed cryptogams which
contain vascular bundles.

Times' Crucial Science and Environment 180 Book 7

([HUFLVH

1. Choose the best alternative in each case.

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i. Fish ii. Frog

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E :KLFK RI WKH IROORZLQJ LV D YHUWHEUDWH"

L 6WDUÀVK LL 6QDLO

iii. Snake iv. Spider

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i. Bat ii. Blue whale

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iii. Lizard iv. None of these

e. The plant in which root, stem and leaves are not differentiated is

called

i. Thallophyta ii. Bryophyta

iii. Pteridophyta iv. Gymnosperms

2. Copy the correct statements and correct the false statements if any.
a. Backbone is present in all types of animals.
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F $PSKLELDQV KDYH WKUHH FKDPEHUHG KHDUW
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g. The plant which contains only one cotyledon in its seed is called
dicot plant.
h. Bryophytes are amphibian plants.
i. Pteriodophytes contain vascular bundles.

3. Mention the divisions of the plants having following features:

a. They grow on shady or moist places. They contain vascular
bundles.

Times' Crucial Science and Environment 181 Book 7

b. They grow on shady or moist place. They need water for
reproduction.

c. They have taproot and contain seeds with two cotyledons.

d. They bear seeds in cones. They grow on dry and cold regions.

e. They have non-green thallus and grow on dead and decaying
substances.

4. Differentiate between:

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F *\PQRVSHUP DQG $QJLRVSHUP

5. Answer these questions in short.
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E :KDW DUH FROG EORRGHG DQLPDOV" *LYH DQ\ ÀYH H[DPSOHV
F :KDW DUH ZDUP EORRGHG DQLPDOV" *LYH DQ\ ÀYH H[DPSOHV
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I 0HQWLRQ DQ\ IRXU IHDWXUHV RI UHSWLOLD ZLWK H[DPSOHV
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L :KDW DUH WKDOORSK\WHV" 0HQWLRQ LWV VXE GLYLVLRQV
M :KDW DUH EU\RSK\WHV" 0HQWLRQ WKHLU FKDUDFWHUV

6. Classify the following organisms and mention their two
characters.
Cow, shark, lizard, pigeon, moss, mushroom, mango, maize, pine,
fern

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VWXG\ WKHLU YDULRXV SDUWV LQ GHWDLO 0HQWLRQ WKHLU QDPHV DQG FODVVLI\
them.

Times' Crucial Science and Environment 182 Book 7

Chapter

17 3 DUWV RI 3 ODQWV

ƐƟŵĂƚĞĚ ƉĞƌŝŽĚƐ͗ϲ

OBJECTIVES
At the end of the lesson, the students will be able to :
 ƚĞůů ĚŝīĞƌĞŶƚ ƉĂƌƚƐ ŽĨ Ă ƉůĂŶƚ͘
 ĞdžƉůĂŝŶ ƚŚĞ ƐƚƌƵĐƚƵƌĞ ĂŶĚ ĨƵŶĐƟŽŶƐ ŽĨ ƌŽŽƚƐ͘
 ĞdžƉůĂŝŶ ƚŚĞ ƐƚƌƵĐƚƵƌĞ ĂŶĚ ĨƵŶĐƟŽŶƐ ŽĨ ůĞĂǀĞƐ͘
 ĞdžƉůĂŝŶ ƐƚƌƵĐƚƵƌĞ ĂŶĚ ĨƵŶĐƟŽŶƐ ŽĨ ƐƚĞŵ͘
 ĞdžƉůĂŝŶ ƐƚƌƵĐƚƵƌĞ ĂŶĚ ĨƵŶĐƟŽŶƐ ŽĨ ĚŝīĞƌĞŶƚ ƉĂƌƚƐ ŽĨ Ă ŇŽǁĞƌ͘

MIND OPENERS
 tŚŝĐŚ ƉĂƌƚ ŽĨ Ă ƉůĂŶƚ ĚŽ LJŽƵ ůŝŬĞ ƚŚĞ ŵŽƐƚ͍
 tŚŝĐŚ ƉĂƌƚ ŽĨ ƉůĂŶƚƐ ĚĞǀĞůŽƉƐ ŝŶƚŽ ĨƌƵŝƚ͍
 tŚLJ ŝƐ ƌŽŽƚ ŝŵƉŽƌƚĂŶƚ͍
 tŚĂƚ ĂƌĞ ƚŚĞ ĨƵŶĐƟŽŶƐ ŽĨ ůĞĂǀĞƐ͍

Introduction

There are various types of plants around us. Plants like mustard, rose,
PDQJR PDULJROG SDQV\ DSSOH HWF EHDU ÁRZHUV 7KH\ DUH FDOOHG ÁRZHULQJ
plants. Flowering plants are advanced types of plants. Their body can be
mainly divided into two parts. They are root and shoot.

Root Tap root Fibrous root

The part of the plant which
lies under the soil is called
root. ,W À[HV WKH SODQWV WR WKH
ground. The root system is of
two types: tap root system and
ÀEURXV URRW V\VWHP In dicot
plants, a main root develops
from the base of the stem
called tap root or primary
URRW $ QXPEHU RI VPDOO URRWV
originate side wise from tap

Times' Crucial Science and Environment 183 Book 7

root. They are called secondary roots. The secondary roots are further
GLYLGHG WR YHU\ VPDOO ÀEUH OLNH VWUXFWXUHV FDOOHG tertiary roots. Such root
system is called tap root system.
Functions of roots

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5RRWV À[ WKH SODQWV WR WKH JURXQG
7KH\ KROG VRLO SDUWLFOHV ÀUPO\ WR SUHYHQW IURP VRLO HURVLRQ

Activity 17.1 6WXG\ RI WDSURRW DQG ¿EURXV URRW

Materials required:
A monocot and a dicot plant with roots.

Procedure
a. Uproot a mustard and a grass plant.
b. Clean the roots of both the plants.
F 2EVHUYH WKH URRWV RI ERWK WKH SODQWV :KDW GR \RX VHH"

Observation
You can see the main root originated from the stem of the mustard
plant. It is tap root. From tap root, many small secondary roots are
developed. Tertiary roots are developed from secondary roots. But,
\RX FDQ VHH ÀEURXV URRWV GHYHORSHG IURP WKH EDVH RI WKH VWHP
Conclusion: Tap root system contains a main root and a number
of branches originated from main root.

6KRRW

The part of the plant which grows above the ground is called shoot. It
FRQVLVWV RI VWHP EUDQFKHV OHDYHV ÁRZHUV DQG IUXLWV 7KH VKRRW LV IXUWKHU
divided into vegetative parts and reproductive parts.

9HJHWDWLYH SDUWV

Stem, branches and leaves are vegetative parts.

Times' Crucial Science and Environment 184 Book 7

Stem Flower Apical bud
Stem grows upwards from the soil. It Axillary bud Fruit
IRUPV PDLQ D[LV RI WKH VKRRW V\VWHP Leaf
It is generally green in colour. It
bears branches. It is thick in the Inter node Node
lower part and gradually thinner Root Stem
at the upper part. It contains nodes
and internodes. Nodes are the Parts of a plant
swollen parts from where branches
and leaves originate. The part of the
stem between two nodes is called
internode. The stem of tree is thick
and strong. It is called trunk.
Stem contains two types of buds:
DSLFDO EXGV DQG D[LOODU\ EXGV
Apical buds are present at the tip
of the stem or branch. They help to
increase the height of the plant. The
EXGV SUHVHQW LQ WKH D[LO RI OHDYHV DUH
called axillary buds. $[LO LV WKH SDUW
of node from where leaves originate.

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1. The stem helps plants stand straight and support the branches,
OHDYHV ÁRZHUV IUXLWV HWF

2. It transports water and minerals from roots to the leaves.
3. It supplies foods prepared in the leaves to different parts of the

plants.
4. Some plants like carrot, radish, etc store food materials.
Leaves
/HDYHV DUH JUHHQ DQG ÁDW RXWJURZWK RI VWHPV RU EUDQFKHV Leaves vary from
SODQWV WR SODQWV LQ VKDSH VL]H DQG VWUXFWXUH $ OHDI FRQVLVWV RI OHDI EODGH
petiole and leaf base. The part of the leaf with which it is attached to the
branch or stem is called leaf base. Petiole is the stalk of the leaf which
is attached to the branch or stem. Leaf blade RU ODPLQD LV WKH ÁDW DQG
green portion of leaf. It contains a pipe like structure running from the
SHWLROH WR WKH DSH[ FDOOHG midrib. $ QXPEHU RI VPDOO veins originate from
the midrib and get scattered throughout the lamina. The arrangement of
veins in the lamina is called venation. In the leaves of dicot plants, the

Times' Crucial Science and Environment 185 Book 7

veins are arranged forming networks. Such arrangement of veins is called
reticulate venation. In the leaves of monocot plants, the veins are arranged
being parallel to each other. Such arrangement of veins is called parallel
venation. The veins transport water, minerals and foods to the various
parts of leaf. Veins also provide mechanical support to the leaf.

Leaf blade

Midrib Petiole

Leaf base

A monocot leaf Vein

A dicot leaf

)XQFWLRQV RI OHDYHV

i) Leaves prepare foods by using water and minerals absorbed from
WKH URRW DQG WKH FDUERQ GLR[LGH DEVRUEHG IURP WKH DLU

ii) Leaves contain tiny pores called stomata. 7KURXJK VWRPDWD H[FKDQJH
of the gases takes place during photosynthesis and respiration.

LLL 3ODQWV WKURZ RXW H[FHVV ZDWHU E\ transpiration process through
stomata.

iv) Some plants store foods in their leaves.

5HSURGXFWLYH 3DUW RI 3ODQWV

7KH ÁRZHU LV WKH UHSURGXFWLYH RUJDQ RI ÁRZHULQJ SODQW $ ÁRZHU KDV D
stalk called pedicel, with which it is attached to the stem or branch. The
ÁDWWHQHG WLS RI WKH SHGLFHO LV FDOOHG thalamus. 9DULRXV SDUWV RI WKH ÁRZHU
grow from the thalamus.

petals (corolla) Androecium

pistil(Gynoecium)

stamen

ovules (egg cells) sepals (calyx)

Reprocuctive parts of a Flower

Times' Crucial Science and Environment 186 Book 7

$ W\SLFDO ÁRZHU FRQVLVWV RI IRXU SDUWV 7KH\ DUH FDO\[ FRUROOD DQGURHFLXP
and gynoecium.
Calyx
,W LV WKH RXWHUPRVW ZKRUO RI D ÁRZHU ,W LV JUHHQ LQ FRORXU 2QH XQLW RI FDO\[
is called sepal 7KH VHSDOV PD\ EH IUHH RU MRLQHG 7KH ÁRZHUV ZLWK IUHH
sepals are called polysepalous ÁRZHUV 7KH ÁRZHUV ZLWK MRLQHG VHSDOV DUH
called JDPRVHSDORXV ÁRZHUV. 7KH VHSDOV SURWHFW ÁRZHUV LQ EXG VWDJH

Corolla *DPRVHSDORXV ÀRZHU 3RO\VHSDORXV ÀRZHU

7KH VHFRQG ZKRUO RI WKH ÁRZHU LV FDOOHG FRUROOD. One unit of it is called
petal. The petals are colourful and attractive. The petals may be free or
MRLQHG ZLWK HDFK RWKHU 7KH ÁRZHUV ZLWK IUHH SHWDOV DUH FDOOHG polypetalous
ÁRZHUV. )RU H[DPSOH PXVWDUG ZDWHU OLO\ ÁRZHU HWF :KLOH WKH ÁRZHUV
with petals joined with each other are called JDPRSHWDORXV ÁRZHUV. For
H[DPSOH SXPSNLQ ÁRZHU FXFXPEHU ÁRZHU HWF

*DPRSHWDORXV ÀRZHU 3RO\SHWDORXV ÀRZHU

Petals attract insects for pollination.
Androecium
$QGURHFLXP LV WKH WKLUG ZKRUO RI D ÁRZHU ,W LV
WKH PDOH UHSURGXFWLYH SDUW RI D ÁRZHU 2QH XQLW
of androecium is called stamen. $ VWDPHQ FRQVLVWV
of stalk like structure called ÀODPHQW and swollen
structure at the tip called anther. $QWKHU SURGXFHV
D QXPEHU RI JUDLQV FDOOHG SROOHQ JUDLQV 0DOH
gametes develop inside the pollen grains. 0DOH
JDPHWHV WDNH SDUW LQ VH[XDO UHSURGXFWLRQ

Times' Crucial Science and Environment 187 Book 7

Gynoecium
*\QRHFLXP LV WKH LQQHUPRVW ZKRUO RI D ÁRZHU ,W LV WKH IHPDOH UHSURGXFWLYH
SDUW $ J\QRHFLXP FRQVLVWV RI RQH RU PRUH FDUSHOV RU SLVWLOV 7KH FDUSHOV
PD\ EH IUHH RU IXVHG $ FDUSHO FRQVLVWV RI WKUHH SDUWV RYDU\ VW\OH DQG
stigma. The swollen base of a carpel is called ovary. The ovary contains
ovules. Female gametes develop inside the ovules. Female gametes take
SDUW LQ VH[XDO UHSURGXFWLRQ

6WLJPD

6W\OH

2YDU\

2YXOH

Style is a long, thread like structure developed from the ovary. The tip
of the style is little bit wider with lobes. It is called stigma. The stigma
catches the pollen grains during pollination.
7KH ÁRZHU KDYLQJ DOO IRXU ZKRUOV LV FDOOHG FRPSOHWH ÁRZHU. )RU H[DPSOH
PXVWDUG KLELVFXV URVH SHD HWF 7KH ÁRZHUV KDYLQJ WKH DEVHQFH RI RQH RU
more whorls are incomplete ÁRZHUV )RU H[DPSOH VXQÁRZHU PDL]H ÁRZHU
etc.

Activity 17.2 7R VWXG\ YDULRXV SDUWV RI ÀRZHU

Material needed: A mustard or hibiscus
ÁRZHU
Procedure

7DNH D PXVWDUG ÁRZHU RU KLELVFXV ÁRZHU
2. Observe its different parts. What do you

VHH"
Observation
You can see green leaf like parts surrounding the inner parts. These
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FRORXUIXO DWWUDFWLYH SDUWV 7KH\ DUH SHWDOV 5HPRYH WKHVH SHWDOV
carefully. You can see stalk like structure swollen at the top. They
are stamens. The sack like structure at the top of stalk is called
anther.

Times' Crucial Science and Environment 188 Book 7

The anther contains powdery yellow pollen grains.
5HPRYH WKHVH VWDPHQV FDUHIXOO\ 7KH UHPDLQLQJ SDUW LV FDUSHO ,W
contains swollen base called ovary and elongated style. The ovary
contains grain like ovules. The style ends with swollen top. It is
stigma.

Pollination

The process of transfer of pollen grains from anther of a stamen to the
stigma of a carpel is called pollination.

Pollination process may be carried out by insects, animals, air or water.
They are called pollinating agents.

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WR WKHLU KDLU\ OHJV DQG ERG\ :KHQ WKH VDPH LQVHFWV Á\ DQG JR WR RWKHU
ÁRZHUV WKH\ FDUU\ SROOHQ JUDLQV ZKLFK ZLOO EH GHSRVLWHG WR WKH VWLJPD RI
WKHVH ÁRZHUV 7KXV SROOLQDWLRQ RFFXUV

$IWHU SROOLQDWLRQ WKH PDOH JDPHWH FRQWDLQHG LQVLGH SROOHQ JUDLQV ZLOO PRYH
towards ovary and fuses with female gamete contained in the ovule. This
process is called fertilization.
Fertilization is the process of fusion of male and female gametes to form zygote.
$IWHU IHUWLOL]DWLRQ WKH RYXOHV JURZ LQWR VHHG DQG RYDU\ LQWR IUXLWV

Fruits

)UXLW LV D SDUW RI D SODQW ZKLFK LV GHYHORSHG IURP RYDU\ RI ÁRZHUV ,W FRQWDLQV
seeds. Fruits of various plants differ from each other in size, shape, colour,
etc. Fruit contains mainly three parts. They are epicarp, mesocarp and
endocarp.
Epicarp
It is the outermost cover of a fruit. It protects inner part of the fruit.

Times' Crucial Science and Environment 189 Book 7

Mesocarp
,W LV WKH PLGGOH SDUW RI D IUXLW ,W LV JHQHUDOO\ ÁHVK\ DQG IRUPV HGLEOH SDUW
Endocarp
It is the innermost hard and stony part of a fruit. It encloses seeds and
gives protection to the seeds.

Apple leaf Mango epicarp
mesocarp
stalk endocarp

mesocarp
seed
endocarp
epicarb

Parts of fruits

$OO IUXLWV FRQWDLQ VHHGV 6HHGV DUH GHYHORSHG IURP RYXOHV 6RPH VHHGV DUH
monocotyledonous whereas some are dicotyledonous. Seed contains mainly
three parts. They are

i) Seed coat
ii) Cotyledons
iii) Embryo
Seed coat: Seed coat is the cover of seed. Its colour varies from seeds to

seeds.
Cotyledons: It is the middle part of the seed. In dicot seeds, there are

two cotyledons. In monocot seeds, there is only one cotyledon.

Seed coat Seed coat Embryo
Radicle Immature

leaves
hypocotyl

radicle

Cotyledon
(stored food)

Parts of seed (Bean seed)
Embryo: $Q HPEU\R LV D EDE\ SODQW ,Q PRVW RI WKH SODQWV LW LV ORFDWHG

in the centre. The embryo develops into new plant after
germination.

Activity 17.3 7R REVHUYH WKH SDUWV RI D VHHG

Collect seeds of pea, or bean. Soak them in water for a day. Then
observe all parts of the seed.

Times' Crucial Science and Environment 190 Book 7

EŽĚĞ ͗ Ă ƉĂƌƚ ŝŶ ƐƚĞŵ ĨƌŽŵ ǁŚĞƌĞ ďƌĂŶĐŚ Žƌ ůĞĂǀĞƐ ŽƌŝŐŝŶĂƚĞ

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ƵĚ ͗ ĂŶ ŽƵƚŐƌŽǁƚŚ ŝŶ ƉůĂŶƚ ǁŚŝĐŚ ĚĞǀĞůŽƉƐ ŝŶƚŽ ŇŽǁĞƌ͕ ďƌĂŶĐŚ Žƌ ŶĞǁ ƉůĂŶƚ

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1. Body of plants is divided into root and shoot
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3. Tap root system is the root system in which there is a main root

developed from the base of stem and a small number of secondary
roots developed from the main root.
4. Fibrous root system is the root system in which a number of small
roots develop from the base of stem.
5. Shoot is the part of a plant which grows above the soil. It contains
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6. The stem is the part of a plant which grows upward and forms
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may be parallel or reticulate.
9. Flower is a colourful and attractive reproductive part of a plant.
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and gynoecium.
11.Pollination is the process of transfer of pollen grains from anther of
a stamen to the stigma of a carpel.
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1. Choose the best alternative in each case.

a. Fibrous root system is the characteristic feature of

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Times' Crucial Science and Environment 191 Book 7

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c. The stalk of the leaf which is attached to the stem is called

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i. Baby plant ii. Seed coat
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2. Fill in the blanks with appropriate words.

a. …………….is the root system which contains a main root from
which many secondary roots originate.

b. Stem, branches and leaves are ………….parts of a plant.

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e. Flowers are attached with the stem or branch with……………

f. …………is the unit of corrolla.

g. …………produces pollen grains.

h. ……………develop into fruits when they become matured.

i) …………..is the process of transfer of pollen grains from anther
of stamen to the stigma of carpel.

j. ……………is the process of fusion of male and female gametes.

3. Answer in short.
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leaves.
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parts.

Times' Crucial Science and Environment 192 Book 7

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important parts.

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4. Differentiate between
i. Gynoecium and androecium
ii. Fibrous root and tap root

5. Answer these questions in detail.
a. Describe the structure of leaves.
b. Describe the structure of fruits.
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6. Diagrammatic questions: D
a. Study the diagram and answer C
the questions.
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b. Draw a neat and clean diagram
of a fruit and label its parts.
c. Draw a clean diagram of a pistil
and show its parts.

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a) Visit a garden of your school or house and observe any ten plants.
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the type of venation, number of sepals, petals, types of roots, etc.

Fill in the given table

Sn. Name of the Plant Type of No. of Sepals No. of Petals Type of
sĞŶĂƟŽŶ Roots

Times' Crucial Science and Environment 193 Book 7

Chapter

18 & HOO DQG 7 LVVXH

ƐƟŵĂƚĞĚ ƉĞƌŝŽĚƐ͗ϲ

OBJECTIVES
At the end of the lesson, the students will be able to :
 ƚĞůů ǀĂƌŝŽƵƐ ƉĂƌƚƐ ŽĨ Ă ĐĞůů ĂŶĚ ƚŚĞŝƌ ƐƚƌƵĐƚƵƌĞƐ͘
 ƚĞůů ĨƵŶĐƟŽŶƐ ŽĨ ĞĂĐŚ ƉĂƌƚ ŽĨ ƚŚĞ ĐĞůů͘
 ĚŝīĞƌĞŶƟĂƚĞ ďĞƚǁĞĞŶ ƉůĂŶƚ ĐĞůů ĂŶĚ ĂŶŝŵĂů ĐĞůů͘
 ĞdžƉůĂŝŶ ƚŚĞ ƐƚƌƵĐƚƵƌĞ ŽĨ ĂŵŽĞďĂ ǁŝƚŚ ĚŝĂŐƌĂŵ͘
 ĞdžƉůĂŝŶ ƚŚĞ ƐƚƌƵĐƚƵƌĞ ŽĨ ŚLJĚƌĂ ǁŝƚŚ ĚŝĂŐƌĂŵ͘

MIND OPENERS
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 tŚĂƚ ĂƌĞ ƚŚĞ ǀĂƌŝŽƵƐ ƉĂƌƚƐ ŽĨ Ă ĐĞůů͍
 ĂŶ LJŽƵ ƚĞůů ĨƵŶĐƟŽŶƐ ŽĨ ŵŝƚŽĐŚŽŶĚƌŝĂ͍
 tŚĂƚ ŝƐ ƚŚĞ ƐŚĂƉĞ ŽĨ ĂŵŽĞďĂ͍
 ,ĂǀĞ LJŽƵ ĞǀĞƌ ƐĞĞŶ ŚLJĚƌĂ͍ ,Žǁ ĚŽĞƐ ŝƚ ŵŽǀĞ͍ ŝƐĐƵƐƐ͘

Introduction

There are various types of plants and animals around us. They differ from
each other in shape and size. But, they have one similarity, i.e., all of them
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are composed of cells. Cells can be compared as the bricks of buildings.
Bricks are joined by cement to make buildings. In the same way, cells
combine together to form body of living things. Shape and size of the body
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activities are taking place inside the cells. Therefore, FHOOV DUH GHÀQHG DV
structural and functional units of living things.
Cells are very small. So, they cannot be seen with naked eyes. We need a
microscope to observe them.

Activity 18.1 7R SUHSDUH VOLGH RI RQLRQ FHOOV

Materials required
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safranin, a brush, microscope, etc.

Times' Crucial Science and Environment 194 Book 7

Procedure
1. Take an onion bulb and cut into four pieces with a blade or
knife.
2. Take one leaf and peel off thin membrane from its outer side.
Put it in a watch glass.
3. Put little safranin in the membrane and leave it for one minute.
4. Wash the membrane with water.
5. Put a small piece of membrane with water on a slide and cover
it with a cover slip. Observe the slide under microscope. What
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Observation
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many compartments. Each compartment is onion cell. Cells
are separated from each other by cell wall. Each cell contains
nucleus, vacuoles, cytoplasm, etc.

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$ FHOO LV FRPSRVHG RI OLYLQJ VXEVWDQFH FDOOHG protoplasm. The protoplasm
mainly consists of cytoplasm and nucleus.
Cytoplasm contains many living parts such as mitochondria, ribosomes,
golgi bodies, plastids, centrosome, lysosomes, etc. They are called cell
organelles of a cell.
The non-living substances found in the cell are called cell inclusions.
Dissolved foods, droplets of waste materials, etc are cell inclusions.
The main parts of a cell are as follows:
Cell wall
It is the outermost covering of a plant cell. It lies outside the cell membrane.
It is rigid and non-living layer. It is made up of cellulose. It is freely
permeable. It means all substances can pass through it. Its main functions are:

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ii) It protects plasma membrane and internal parts of cell.

Times' Crucial Science and Environment 195 Book 7

Lysosome Centrosome Ribosome Cell wall
Cytoplasm Cell membrane
Nucleus Cell membrane Smooth endoplasmic Golgi body
reticulum Plastid
Mitochondrion Endoplasmic Large central
reticulum Nucleus
Ribosome Rough vacuole
endoplasmic
reticulum Mitochondrion
Cytoplasm
Vacuole

Golgi
body

Animal cell Plant cell

Cell Membrane

It is a thin membrane which lies as the outermost cover in an animal cell.
It lies inside cell wall in a plant cell. It is also called plasma membrane. It
is living and semi-permeable in nature. Semi-permeable means that it lets
only selective substances enter and leave the cell. It is made up of protein
and lipids.

Functions
a. It provides outer protective boundary to an animal cell.
b. It helps in the transport of materials in and out of the cell.

Cytoplasm

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consists of various cell organelles such as mitochondria, golgi bodies,
ribosomes, lysosomes, endoplasmic reticulum, etc. It also contains
non-living substances such as dissolved food materials, proteins, salts,
water, enzymes, etc.

Mitochondria

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organelles present in cytoplasm of both animal
and plant cells. It is enclosed by outer membrane
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in mitochondria and energy is produced. Thus,
mitochondria are the sites for energy production
of the cell and are called powerhouse of the cell.

Times' Crucial Science and Environment 196 Mitochondria
Book 7