Chapter2 Nutrition 131007232016 Phpapp02

7/25/2019 Chapter2 Nutrition 131007232016 Phpapp02

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SCIENCE - FORM 2

Nutrition


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CLASSES OF FOOD

1. Food is a basic necessity for a i!in" t#in"s.

2. Food is i$%ortant in order to & 'a( Provide energyto carry out %#ysica acti!ities. 'b( Provide energyfor t#e %#ysioo"ica acti!ities in ife suc# as re%roduction) di"estion and

e*cretion. 'c( Build new cellsand ti repair tissuesin t#e body. 'd( Protectt#e body fro$ deseases. 'e( Maintaint#e body te$%erature. 'f( +ro$ote growth.

,. Food can be di!ided into se!en casses #ic# are & 'a( Carbo#ydrates 'b( +rotein 'c( Fats 'd( ita$ins 'e( Minera sats 'f( /ater


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'"( Fibres

'A( Carbo#ydrates

1. Carbo#ydrates are for$ed fro$ t#e ee$ents of carbon, hydrogenand oxygen.

2. Carbo#ydrates beon" to a cass of food t#atprovide energyto t#e body.

,. Carbo#ydrates are o*idised in t#e body durin" res%iration to reease ener"y.

0. Carbo#ydrates consist of four $ain for$s & 'a( Simple sugar is used directy by i!in" ces to %roduce ener"y. E*a$%es of si$%e su"ars are

"ucose) sucrose and actose. 'b( Starch) #ic# is a for$ of carbo#ydrate) is stored in %ants. E*a$%es of %ants t#at storestarc#

are ta%ioca) banana and #eat. E*tra "ucose t#at is %roduced by %#otosynt#esis is e%t in t#e

for$ of starc#. 'c( Glycogen) #ic# is a for$ of carbo#ydrate is stored in ani$as. yco"en is usuay stored in

t#e i!er and $usces. yco"en is ony used #en t#e body acs of si$%e su"ars. 'd( Celluloseis t#e $ain constituent of t#e ce a. 3#erefore) ceuose is found in abundance in

!a"etabes and fruits cannot be di"ested by t#e #u$an di"esti!e syste$.

4. Strac#) "yco"en and ceuose are $ade u% of "ucose $oecues 5oined to"et#er in a different$anner.

6. E*tra carbo#ydrates in our body are e%t in t#e for$ of fat.

7. 3#e %resence of starchin food can be tasted by usin" iodine solution. 3#e coour of iodine oudc#an"e to dark bluestarc# is %resent in a food sa$%e.


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8. 3#e %resence of simple sugarin food can be teated by usin" Benedicts solutionor t#e !ehlings

solution. " brick#red precipitatei be obtained #en si$%e su"ar is boied it# t#e rea"ents.

'9( +roteins

1. A ty%es of %roteins #a!e carbon, hidrogen, oxygenand nitrogen. So$e %roteins aso contain

sulphurandphosphorus.

2. +rotein $oecues are for$ed fro$ basic units caed a$ino acids. 3#ere are about 2: ty%es ofa$ino acids. So$e of t#ese amino acidscan be %roduced by t#e body and so$e $ust beconsu$ed fro$ t#e diet.

,. +rotein is a cass of food needed for t#e growthof t#e body) es%eciay in t#e buidin" of ce%roto%as$.

0. I$%ortant functions of %rotein incude & 'a( 9uidin" ne ces. 'b( Re%airin" da$a"ed tissue. 'c( 9uidin" en;y$e) antibodies) #or$ones and #ae$o"obin. 'd( Su%%ies ener"y) es%eciay if carbo#ydrate and fats are insufficient in t#e body.

4. +roteins are di!ided into to cate"ories & 'a( Plant proteinst#at are found in beans) corn and #eat.


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'b( "nimal proteinst#at are found in $eat) fis#) e"" #ite and c#eese.

6. C#idren need $ore %rotein co$%ared to aduts to su%%ort t#eir "rot#.

7. +rotein deficiency i cause as#ioror. 3#e sy$%to$s of a kwashiorkor%atient are enar"e$entof t#e sto$ac#) no a%%etite for food and diarr#oea.

8. E*tra %rotein is e*creted fro$ t#e body as urea in t#e urine.


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7. Fat $oecues are for$ed fro$ glyceroland &atty acids.

8. E*tra fat is e%t by t#e body under t#e sin.


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'E( Minera sats

1. Minera sats are inor"anic substances t#at are needed in s$a uantities to carry out body%rocesses and to maintain a healthy body.

2. I$%ortant $inera sats incude caciu$) %#os%#orus) iron) iodine) sodiu$ and fuorine.

,. Caciu$ and %#os%#orus are needed in ar"e @uantities co$%ared to ot#er ee$ents.

0. Minera sats do not %ro!ide ener"y) but ac of t#e$ can cause !aroious ty%es of disease.

3abe 2.2 Su$$arises t#e sources of $inera sats) functions and t#e effect of t#eir deficiencies.


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'F( /ater1. /ater is a food cass ta#t is needed t#e $ost co$%ared to ot#er food casses.

2. /ater constitutes about 7: of t#e body ei"#t of #u$ans.

,. /ater #as se!era functions ta#t are i$%ortant to t#e #u$an body. 'a( As a mediumfor c#e$ica reactions in our body. 'b( As a so!ent for t#e trans&erof substances suc# as di"ested food) o*y"en) carbon dio*ide)urea

and #or$ones. 'c( Contros our body temperatureby reeasin" #eat t#rou"# %ers%iration) res%iration) uniration

and defecation. 'd( Contros t#e concentrationof bood and body fuids. 'e( i!es a%%earances and shapeto t#e body. 'f( 3oreduce friction beteen 5oints.

0. Main source of ater is drinin" ater) fruits and !e"etabes.

4. 3#e body oses ater t#rou"# %ers%iration) res%iration) as e as strou"# dis%osa of urine and


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faeces.

6. E*cessi!e ater oss 'about 2: fro$ t#e a$ount of ater in t#e body( can cause deat#.

7. /ater is re@uired by our body about ' litres daiy or about ( glasses of ater e!ery day.


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Direct #eatin" for t#e "ucose and %rotein tests is not carried out but a ater bat# is used instead. 3#isis because t#e contents of t#e test tube i s%i out if it is directy #eated.

3#e food tests for carbo#ydrate ' starc# and "ucose () %rotein and fat are carried out usin" s%ecificrea"ents or $aterias.

3#e %resence of fat or oi) and !ita$in C can be fut#er tested as s#on beo.

'( Fibre


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1. !ibreor rou"#a"e is a food cass t#at consists of &ibrous $ateria )cellulose*t#at cannot bedigested by t#e #u$an di"esti!e syste$.

2. Fibre #e%s in t#e $o!e$entof food $aterias t#rou"# t#e s$a and ar"e intestines. Fibre #e%s tos$oot# t#e %eristasis %rocess in our intestine by absorbin" ater for t#e ease of %assin" $otion.

,. Sources of food t#at are ric# in fibre are !e"etabes) fruits) $us#roo$s and "rains.

0. Fibre deficiency can so don t#e $o!e$ent of di"ested food in t#e ar"e intestine. 3#is causes aot ofwaterto be reabsorbedfro$ t#e undi"ested food and t#e faeces beco$e #ard. 3#is resuts in

constipation.

3?E IM+OR3ANCE OF A 9ALANCED DIE3

1. A balanced dietis consu$in" food t#at contains a ty%es of food casses in t#e ri"#t @uantity.

2. A baanced diet consist of &

'a( Carbo#ydrates ' 44 - 64 (.

'b( Fats ' 2: - ,4 (. 'c( +roteins ' 1: - 14 (. 'd( Sufficient a$ount of !ita$ins and $ineras. 'e( /ater and fibres.

,. A baanced diet is i$%ortant to ensure t#at t#e body #as & 'a( Sufficient ener"y su%%y 'b( ood #eat#

0. Se!era ty%es of deseases suc# as aas#ioror) anae$ia) beri-beri) scur!y) ricets and ot#ers canoccur as a resut of an unbaanced diet.

4. 3#e content of a baanced diet differs accordin" to indi!idua needs and de%ends on t#e fooin"

factors & 'a( Sex- $en need $ore ener"y co$%ared to o$en. 'b( "ge - "roin" teena"ers need $ore ener"y because t#eir "rot# rate is #i"#er. 'c( Body si+e- t#e bi""er t#e si;e of t#e body) t#e $ore ener"y is needed. 'd( $ype o& occupationor acti!ity bein" carried out - t#e on"er t#e or or acti!ity is carry out) or

t#e #ea!ier t#e tas) t#e $ore ener"y is needed. 'e( Climate- %eo%e i!in" in cod countries need $ore ener"y co$%ared countries need $ore

ener"y co$%ared to %eo%e i!in" in #ot countries to $aintain t#eir body te$%erature.

'A( Food caorific !aue

1. 3#e caorie is t#e a$ount of ener"y in food.

2. Caories is defined as t#e a$ount of #eat ener"y needed to increase 1 " of ater by 1:

C at 1at$os%#eric %ressure.

,. 3#e units for food caorie are caorie or 5oue. ' 1 caorie B 0.2 5oues (.

0. Caorific !aue or ener"y !aue is t#e a$ount of ener"y reeased fro$ 1 "ra$ of food.

4. 3#e caorific !aue for se!en food casses are & 'a( Carbo#ydrates & 17.2 =1 "ra$ 'b( Fats & ,8.4 = 1 "ra$


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'c( +roteins & 22.2 =1 "ra$ 'd( ita$ins & : =1 "ra$ 'd( Minera sats & : =1 "ra$ 'e( /ater & : =1 "ra$ 'f( Fibre & : =1 "ra$

6. 3#e caorific !aue for se!era ty%es of food are s#on in tabe 2.,.

7. A food intae it# a #i"#er caorific !aue t#an t#e tota ener"y needed by t#e body can cause

obesity.

8. 3#e fooin" dia"ra$s s#o a baanced died for breafast) unc# and dinner. 'a( 9reafast

'b( Lunc#


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'c( Dinner


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2. 3#e #u$an di"esti!e syste$ sonsists of a on" cana ' < - 1: $ ( non as t#e ai$entary cana.

3#iscana be"ins in t#e $out# ca!ity and ends in t#e anus.

,. 3#e ai$entary cana consists of t#e $out#) oeso%#a"us) sto$ac#) s$a intestine ' duodenu$ andieu$ () bi" intestine and anus

0. Se!era ot#er or"ans in!o!ed in di"estion are sai!ary "ands) i!er) "a badder and %ancreas.

4. 3#e %assa"e of food in t#e ai$entary cana is as foos &


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'A( Di"estion in t#e duodenu$

1. 3#e duodenu$ is connected to t#e i!er and t#epancreas.

2. Food fro$ t#e sto$ac# is t#en) %us#ed into t#e duodenu$ and $i*ed it# bie andpancreaticuice.

,. 9ie is secreted by t#e i!er and stored in t#e "a badder.

0. 9ie is alkalineand neutrai;es t#e acidity of t#e food $i*ture fro$ t#e sto$ac# and %re%ares anaaine $ediu$ for t#e action of t#e %ancreatic 5uice.


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4. 9ie aso functions to emulsi&yfats into small droplets so t#at t#ey are easiy di"ested by t#ei%ase

en;y$e.

6. +ancreatic 5uice is %roduced by t#e %ancreas. 'a( 3#is 5uice is an alkalineand #as t#ree ty%es of en;y$e) #ic# are lipase) amylaseand trypsin. 'b( Li%ase di"ests fat into &atty acids and glycerol. 'c( "mylase di"ests starc# into $atose. 'd( $rypsin breas don %rotein intopolypeptides.

7. A%art fro$ %roducin" bie) t#e functions of t#e i!er in t#e di"estion %rocess incudes & 'a( 3o contro t#e su"ar e!e in t#e bood. E*tra "ucose is con!erted to glycogen and is stored in

t#e i!er. /#en it is re@uired by t#e body) "yco"en i be con!erted bac into "ucose to%roduce ener"y.

'b( 3o con!ert e*tra a$ino acids into urea. 3#en) t#e urea is e*creted in t#e urine. 'c( 3o storevitamins suc# as !ita$ins A and D) as e as mineral saltssuc# as iron.

Absor%tion of Di"ested Food

1. Di"ested food suc# as glucose, aminoacids, mineral salts andvitaminsare absorbed into t#e bodyt#rou"# t#e a of t#e s$a intestine bydi&&usion.

2. 3#e di"esti!e %roducts are absorbed into t#e boodstre$ t#rou"# t#e villi' sin"uar & !ius (.

,. ii are fine %ro5ections on t#e surface of t#e s$a intestine. ii increase t#e surface area of t#es$a intestine to about 0: $2.

0. ii #a!e thin walls to fasten t#e food absor%tion %rocess.

4. Eac# !ius is ric# it# blood capillaries to %ro$ote absor%tion of t#e di"ested food.

6. 3#e a of t#e !ius ony ao t#e di"esti!e %roducts t#at #a!e s$a $oecues to %ass t#rou"# it.

7. Si$%e su"ar) ie "ucose) to"et#er it# a$ino acids) $inera sats and ater-soube !ita$ins areabsorbed into t#e bood ca%iaries. /#ie "ycero) fatty acids and fat-soube !ita$ins ' !ita$ins A)

D) E and > ( are absorbed into t#e actea.

8. Once absorbed into t#e bood ca%iaries) t#e di"esti!e %roducts are trans%orted to t#e i!er.


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1. Di"ested food is sent to t#e i!er or t#elymphatic system. 3#en) it i be sent to t#e netire bodyt#rou"# t#e bood sircuatory syste$.

2. Di"ested food is used by t#e body ces in t#e fooin" %rocesses & 'a( -espiration& 3#e o*idation of "ucose to %roduce ener"y. 'b( "ssimilation& 3#e %rocess of con!ertin" di"ested food into subtances needed for t#e "rot#or

re%air of da$a"ed tissue. 'c( ecomposition& /aste $aterias or e*tra food t#at cannot be e%t i be deco$%osed into

$aterias t#at can be e*%eed t#rou"# t#e e*cretory syste$.

Di"estion

1. Di"estion is t#e %rocess of breain" don co$%e* food to si$%e $oecues for absor%tion intot#e bood circuatory syste$.

2. Di"estion taes %ace in to sta"es & 'a( +#ysica di"estion - bi" %ieces of food are broen don into s$aer %ieces by teet#. 'b( C#e$ica di"estion - en;y$es brea u% co$%e* food $oecues.

,. En;y$es are %roteins t#at s%eed u% t#e %rocess of di"estion. En;y$es brea u% co$%e* food$oecues to s$aer and si$%er $eecues.

Di"estion syste$


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1. 3#e di"esti!e syste$ consists of a t#e or"ans in t#e body t#at #e% in t#e di"estion of food.

2. 3#e ai$entary cana is $ade u% of t#e $out#) oeso%#a"us) sto$ac#) s$a intestine) ar"eintestine and anus ' starts fro$ t#e $out# and ends at t#e anus (

,. Food is %us#ed aon" t#e ai$entary cana by t#e $uscuar as t#at contract and e*%andaternatey t#rou"# t#e %rocess of %eristasis.

Mout#

1. Food is c#eid and broen u% into s$a %ieces by t#e teet#.

2. S$a %ieces of food #a!e a ide surface area for t#e sai!a to act u%on.

,. 3#e sai!ary "and secretes sai!a t#at is aaine and contains sai!ary a$yase en;y$es ' %taiin (.

0. Sai!ary a$yase di"ests starc# into $atose ' su"ar (.

Oeso%#a"us


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1. Food is %us#ed t#rou"# t#e oeso%#a"us into t#e sto$ac# by t#e aternatin" $uscuar contractionand rea*ation of t#e oeso%#a"us.

2. 3#is %rocess of aternatin" $uscuar contraction and rea*ation is non as %eristasis.

,. No di"estion taes %ace in t#e oeso%#a"us because t#ere are no di"esti!e en;y$es secreted.

Sto$ac#

1. Food is $i*ed it# "atsric 5uices in t#e sto$ac#.

2. astric 5uices are secreted fro$ t#e ces of t#e sto$ac# a. astric 5uices contain 'a( #ydrocoric acid. 'b( en;y$es ' rennin and %e%sin (.

,. 3#e functions of #ydrocoric acis incude & 'a( %ro!idin" an acidic $ediu$ for en;y$ic action. 'b( iin" bacteria found in food. 'c( neutraisin" t#e aaine %ro%erty of sai!a and sto%%in" t#e action of sai!ary a$yase

en;y$es.

0. +e%sin di"ests %roteins into %e%tones.

4. Rennin coa"uates $i in t#e sto$ac# to #e% in t#e e;y$ic action of %e%sin.

S$a intestine

1. 3#e duodenu$ is t#e first %art of t#e s$a intestine.

2. 3#e duodenu$ recei!es bie and %ancreatic 5uice.

,. 9ie is %roduced by t#e i!er and is stored in t#e "a badder. 3#e bie fos fro$ t#e "a badderinto t#e duodenu$ t#rou"# t#e bie duct. 3#e functions of bie are &

'a( e$usification of fat) i.e. breain" u% ar"e fatty "obues into s$a dro%ets for en;y$ic

action. 'b( %re%aration of an aaine $ediu$ for en;y$ic action.

0. +ancreatic 5uice) #ic# is %roduced by t#e %ancreas ces) contains t#ree ty%es of en;y$es) i.e.%anceatic a$yase ) %rotease and i%ase.

4. 3#e %ancreatic a$yase di"ests starc# into $atose.


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6. 3#e %rotease di"ests %e%tones into a$ino acids.

7. 3#e i%ase di"ets fat into fatty acid and "ycero.

8. 3#e s$a intestine ' ieu$ ( %roduces en;y$es #ic# di"est $atose into "ucose ' si$%e su"ar (.


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1. About 2 $ of abu$en soution is %oured into test tubes abeed A) 9) C and D.

2. 3est tubes A to D are fied it# t#e fooin" & A & 6 $ distied ater

9 & 6 $ %e%sin soution ' 1 ( C & 6 $ %e%sin soution ' 1 ( and 1 $ diute #ydroc#oric acid. D & 6 $ %e%sin soution ' 1 ( and 1 $ diute sodiu$ #ydro*ide soution

,. At t#e be"innin" of t#e e*%eri$ent t#e contents of a t#e test tubes are tested it# Mionsrea"ent.

0. 3#en a t#e four test tubes are #eated in a ater bat# at a te$%erature of 27:C for ,: $inutes.

4. 3#e contents of a t#e test tubes are tested it# Mions rea"ent a"ain at t#e end of t#ee*%eri$ent.

6. 3#e obser!ations are recorded.


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1. +e%sin acts best at a te$%erature of ,7:C) i.e. our body te$%erature.

2. 3#e di"estion of %roteins by %e%isn re@uires an acidic $ediu$.

,. 3#e acid s%eeds u% t#e %e%sin action on %rotein.

3#e en;y$e in t#e sto$ac# di"ests %roteins.


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1. Starc# $oecues are too bi" to diffuse t#rou"# t#e isin" tube. 3#e s$aer "ucose $oecuescan diffuse t#rou"# t#e isin" tube a t#at is se$i%er$eabe.

2. 3#e isin" tube is used as an anoo"y to re%resent t#e #u$an s$a intestine.


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,. 3#e ater in t#e boiin" tube is used an ano"y to re%resent t#e #u$an bood circuatory syste$.

1. 3#e #y%ot#esis $ade can be acce%ted.

2. 3#e si$%e di"ested food $oecues diffuse t#rou"# t#e s$a intestine as into t#e boodstrea$.

3#e s$aer "ucose $oecues diffuse t#rou"# t#e s$a intestine as into t#e boodstrea$.

REA9SOR+3ION OF /A3ER AND DEFECA3ION

Reabsor%tion of ater

1. 3#e $ain function of t#e ar"e intestine is to reabsorb ater.

2. 3#e substances t#at enter t#e ar"e intestine consist of ater and undi"ested food substances ieceuose fro$ t#e fibre of !e"etabes and fruit ' rou"#a"e (.

,. /ater is reabsorbed fro$ t#ese undi"ested food substances.

Defaecation

1. ndi"ested food in t#e ar"e intestine is e*%eed as faeces t#rou"# t#e %rocess of defecation.

2. 3#e faeces t#at reac# t#e rectu$ are $ade u% of undi"ested food substances. 3#e faecesaccu$uate in t#e rectu$.

,. /#en t#e rectu$ is fu of faeces) t#e rectu$ under"oes %eristasis and assested by abdo$inacontraction) i %us# t#e faeces t#rou"# t#e anus to be e*%eed.

0. If an indi!idua #as %robe$s %assin" $otion) #e or s#e is said to be consti%ated.

4. Consti%ation taes %ace because of t#e ac of ater and rou"#a"e in t#e diet.

?EAL3? EA3IN ?A9I3S

1. ?eat#y eatin" #abits i #e% $aintain a #eat#y body.

2. n#eat#y eatin" #abits cause !arious #eat# %robe$s.


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Food %yra$id

1. 3#e food %yra$id s#os t#e food "rou%s t#at ser!e as a "uide to a baanced diet.

2. 3#e foods t#at for$ t#e base of t#e food %yra$id are re@uired in bi" a$ounts daiy.

,. 3#e foods at t#e to% are re@uired in s$a a$ounts in our daiy diet.

0. A diet based on t#e food %yra$id i "i!e t#e re@uired nutrients and ener"y to $aintain a #eat#ybody.

?eat#y i!in" %ractices

1. /e i!in" in a carin" society. 3#erefore) e s#oud be "enerous.


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2. /e s#oud donate sur%us food to t#e %oor and needy.

,. /e s#oud res%ect eac# ot#ers cutures as Maaysia is a $utiracia and $utirei"ious country.

Copyright 2005 Kenshido International Sdn Bhd

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Chapter2 Nutrition 131007232016 Phpapp02

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