igcse biology notes updated april 2016 copy

8/16/2019 IGCSE Biology Notes Updated April 2016 Copy

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iGCSE Biology Notesaskmichellebiology.blogspot.com

Planning an experiment

NOTE: Pyrogailol dissolved in NaOH absorbs O2 from asystem whilst soda lime absorbs CO2

CORMS styled questions (usually 6 marks.

Have some repetition in it so that yo !an have !omparison" and to red!e ris#of errors and anomalies. $f yo were to only ta#e one measrement" and it%swrong" yo wold not have any valid data.

C!ange"Control

&hat fa!tor are yo investigating' &ill yo have a range of vales' ()always have a minimm of * vales in a range+ Or will yo have two grwith the fa!tor and one withot' &hat is yor !ontrol'

Organism &hat spe!ies,si-e,age,gender will yo se' Note if yo were plainvestigation into en-yme a!tivity" yo wold identify the en-ymesbstrate.

Repetition )o /0T ta#e more than one reading yo shold ta#e a minimm of and repeat the whole e3periment.

Measurement &hat will yo be measring" how often and what are the nits' )o sholdhow yo will ta#e the measrement" and with what e4ipment.

Same )o mst say what fa!tors yo will #eep the same to ma#e sre yo havot a fair test" e.g. temperatre,light intensity,volme of water et!.

E#e$t drinking tea !as on !eart rate

C!ange 2 grops: one grop with tea" the other with water

Organism hman" same gender 5 same age

Repetition how many people in ea!h grop

Measurement heart rate in beats per minte" des!ribe how yo wold do this"and when

Same temperatre of tea,water" volme of tea,water" level of e3er!ise beforedrin#ing tea" same room,temperatre of room

6fter !onsidering these fa!tors yo shold then write yor des!ription in fll.

%es$ri&e t!e le'els o organi)ation *it!in

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allows it to absorb light energy and !onvert it to !hemi!al energy dringphotosynthesis.

1. Plant !ells have a permanent 'a$uole that !ontains !ell sap9 it providesspport.

3la$$id = plant !ell la!#ing water reslts in little

trgor pressre" leading to the plant wilting.urgid = plant !ell fll of water" with a lot of trgorpressrePlasmolysis = severe la!# of water in plant leads tomembrane plling away from inelasti! !elllose !ellwall. The !ell dies.4ysis = too m!h water in animal !ell !ases it tobrst

Crenation =animal !ell la!# of

water leads to shrin#ing

Mo'ement o su&stan$es into and out o $ells

Spe$i5$ation+2.12 re!all simple de7nitions of di>sion" osmosis and a!tive transport2.1 nderstand that movement of sbstan!es into and ot of !ells !an be bydi>sion" osmosis and a!tive transport2.1* nderstand the fa!tors that a>e!t the rate of movement of sbstan!es into

and ot of !ells to in!lde the e>e!ts of srfa!e area to volme ratio"temperatre and !on!entration gradient2.1? des!ribe simple e3periments on di>sion and osmosis sing living and nonliving systems

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Spe$i5$ation+/-0/ re$all simple de5nitions o di#usion, osmosis and a$ti'e transport

%i#usion+ this is the net movement of @id mole!les from a region of high!on!entration to a region of low !on!entration. i.e down a !on!entrationgradient. The steeper the gradient" as in the bigger the di>eren!e in!on!entration" the faster di>sion will o!!r. $t is passive no energy is re4ired.

Osmosis+ this is li#e di>sion" e3!ept it involves water mole!les. 0o again"water mole!les move via osmosis from a region of high water potential to aregion of low water potential" throgh a partially permeable membrane. $n orbody !ells" the !ell srfa!e membrane is partially permeable" its fn!tion is to!ontrol what is allowed to enter the !ell.

$ti'e transport+ This is the a!tive pta#e of mole!les against a!on!entration gradient sing 6TP energy" throgh a sele!tively permeable

membrane.

e.g. root hair !ells ta#ing p nitrate ions

A1B 6!tive transport

0ometimes sbstan!es are re4ired to be moveagainst the Con$entration Gradient" or faster than they wold byPassive Transport. $n these !ases" $ti'e Pro$esses are sed" whi!hre4ire energy.

There are many o!!asions when !ells need to ta#e in su&stan$es whi!hare only present in small quantities arond them.

E.g.root !air

!ells in plants ta#e innitrate

ionsfrom

thesoil

. Their!on!entration are often higher inside the root hair !ell than in the soil" sothe di#usion gradient is from the root hair the soil. ;espite this" theroot hair !ells still !an ta#e nitrate ions in" by a$ti'e transport.

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The importan$e of a$ti'e transport+ energy!onsming pro!ess bywhi!h sbstan!es are transported against a !on!entration gradient" e.g.ion pta#e by root hairs and gl!ose pta#e by epithelial !ells of villi.

6!tive Transport,;i>sion

The a!tive transport is !arried ot by D$arrier proteins7 in themembrane" whi!h bind to the solte mole!le" !hange shape and !arrythe mole!le a!ross the membrane.

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/-01 understand t!at mo'ement o su&stan$es into and out o $ells $an

&e &y di#usion, osmosis and a$ti'e transport

;i>sion: e.g. o3ygen di>sing into red blood !ells" or !arbon dio3ide di>singinto leaves for photosynthesis" or gl!ose,maltose di>sing throgh one !ellthi!# epidermis of villi to the !apillaries.

Osmosis: e.g. when water di>ses into plant !ells it ma#es the !ells trgid" whi!hprovides the plant with spport so it !an stand pright. $f water di>ses ot of the !ell" it be!omes @a!!id and wilts. The !ell is trgid be!ase the waterentering the !ell ma#es the !ytoplasm and the va!ole psh against the !ellwall" e3erting turgor pressure.

6!tive transport: e.g. root hair !ells a!tively ta#ing p mineral ions s!h asmagnesim for !hlorophyll. $n hmans" in or #idneys" salts are a!tively ta#en pinto the blood.

/-08 understand t!e a$tors t!at a#e$t t!e rate o mo'ement o su&stan$es into and out o $ells to in$lude t!e e#e$ts o sura$e area to'olume ratio, temperature and $on$entration gradient

0rfa!e area to volme ratio: with a high srfa!e area" the mole!les have morespa!e to get into the !ell" !ompared to a !ell with the same volme bt lowersrfa!e area.

Temperatre: temperatre in!reases the #ineti! energy of the parti!les" sodi>sion o!!rs 4i!#er.

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Con!entration gradient: The steeper it is" i.e. the greater the di>eren!e in!on!entration between 2 regions" the faster the rate of di>sion,osmosis.

/-06 des$ri&e simple experiments on di#usion and osmosis using li'ingand non9li'ing systems

Potato e3periment. Ta#e a !ylinder of potato (whi!h has a high star!h !ontent+and pla!e it in a bea#er of distilled water. The potato with in!rease in volme asthe water moves from high water potential in bea#er to lower water potential inpotato" in!reasing its volme = the soltion is hypotoni! as it has lower!on!entration of soltes than the potato. Now do the same" bt with very sgarywater (su$rose and observe potato shrin# as water in potato moves fromhigher water potential in potato to the lower water potential in the s!rose" inhypertoni! soltion.($sotoni! soltion has same !on!entration of soltes = no !hange in si-eHypotoni! soltion has lower !on!entration of soltes = in!rease in si-eHypertoni! soltion has higher !on!entration of soltes = de!rease in si-e+

6lso" potassim permanganate e3periment" in whi!h yo simply 7ll a shallow!ir!lar tb with water then add potassim permanganate to one end and wat!hit di>se throghot the li4id gradally.

Farying volme agar Gelly !bes in hydro!hlori! a!id and a pH indi!ator"measring the time ta#en for entire !be to !hange !olor.

Nutrition in :umans ; Biologi$al Mole$ules

/-/8 understand t!at energy requirements 'ary *it! a$ti'ity le'els,age and pregnan$y

6s a yong person a lot of energy is sed be!ase: a!tivity levels tend to behigh9 energy is being sed for growth. 6s a person ages they no longer seenergy for growth and tend to have a less a!tive lifestyle: ths having lowerenergy re4irements.

Having a less or more a!tive lifestyle has an e>e!t be!ase the more yo do themore energy yo se the more yo need the higher energy re4irements. ore3ample" an athlete has a more a!tive lifestyle so has to eat more.

&hen pregnant a woman is not only spporting her own body bt also that of her baby" this mean she re4ires the energy for both of them" in!reasing herenergy re4irements.

/-/2 identiy sour$es and des$ri&e un$tions o $ar&o!ydrate, protein,lipid (ats and oils, 'itamins , C and %, and t!e mineral ions $al$iumand iron, *ater and dietary 5&re as $omponents o t!e diet

Car&o!ydrateimmediate energybananas" brown ri!e" whole meal foods and potatoes.

Protein

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Gro*t!< repairsea food" eggs" por# and soy.

4ipidslong term energy store< insulation< prote$tion7sh" eggs" mil# and beef.

=itamin maintaining normal reprodu$tion< good 'ision9 formation and maintenan!eof healthy s#in" teeth and soft tisses of the body9 immne fn!tion (has antio3idant properties+.il#" !heese" eggs" fatty 7sh" yelloworange vegetables and frits s!h as!arrots" pmp#in" mango" apri!ots" and other vegetables s!h as spina!h"bro!!oli.

=itamin C

aiding a&sorption o iron and $opper< !ealt!y &ones< !elps 5g!tine$tion.Jla!#!rrants" orange" grapefrit" gava" #iwi frit" raspberries" sweet peppers(Capsi!m+" bro!!oli" sprots

=itamin %immune un$tion< !ealt!y skin< mus$le strengt!0nlight on s#in allows the body to prod!e Fitamin ;. ew foods !ontainsigni7!ant amonts however main dietary sor!es are forti7ed margarine"salmon" herring" ma!#erel" and eggs.

Cal$iumde'elopment and maintenan$e o &ones and teeth9 good fn!tioningms!les and nerves9 heart fn!tionil#" !heese" yoghrt" bony 7sh" legmes" forti7ed soy beverages and forti7edbrea#fast !ereals.

>ron:aemoglo&in in red blood !ells (important for transport of o3ygen totisses+9 !omponent of myoglobin (ms!le protein+.Ked meats = beef" lamb" veal" por#" 7sh" !hi!#en and wholegrain !ereals

%ietary 5&re

?eeping t!e &o*els un$tioning well9 red!es the ris# of bowl !an!erCereals" bread" ri!e" beans and nts.

@aterC!emi$al rea$tions in $ells need *ater< respiration< $ytoplasm< &loodplasma

/-10 des$ri&e t!e stru$ture o a 'illus and explain !o* t!is !elpsa&sorption o t!e produ$ts o digestion in t!e small intestine

The villi are in the small intestine" and are small protrsions that trap and absorb

bro#en down food mole!les.

They have mi!rovilli on their srfa!es to in!rease srfa!e area frther.

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They have very thin walls" only one !ell thi!#9 this enables mole!les to passthrogh easily in a short di>sion pathway.

They also in!rease the srfa!e area of the small intestine wall meaning thatthere is a lot of srfa!e for di>sion to happen throgh.

On the otside of villi there are !apillaries whi!h pi!# p the di>sed food intothe blood stream" and they get a great spply of blood to maintain a high!on!entration gradient.

/-1A understand t!at t!e li'er produ$es &ile and stores it in t!e gall&ladder, and understand t!e role o &ile in neutrali)ing stoma$! a$idand emulsiying lipids

Jile is prod!e by the li'er and stored in the gall &ladder.En-ymes in the small intestine wor# best in al#aline !onditions" their optimmpH level is arond IB" bt the food is a!idi! after being in the stoma!h. Jile isal#aline and so when it is released into the small intestine it enables the

en-ymes to wor# on the $!ime &y neutrali)ing it.Jile also emulsi5es at9 this gives it a larger srfa!e area" whi!h means that itis easier for lipases to wor#.

.!e a&sorption o atty a$ids and gly$erol rom t!e small intestine

ollowing the !hemi!al and me!hani!al brea#down of food in the digestive tra!t"most ntrients are absorbed into the blood throgh intestinal !apillaries. anydigested fats" however" are too large to enter the blood !apillaries and areinstead absorbed into lymphati! !apillaries by intestinal la!teals. ats are addedto the blood when lymph Goins the bloodstream.

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/-/

understand

t!e role o digesti'e en)ymes, toin$lude t!e digestion o star$! toglu$ose &y amylase and maltase,t!e digestion o proteins to aminoa$ids &y proteases and t!e

digestion o lipids to atty a$idsand gly$erol &y lipases

En-ymes brea# down food into simpler mole!les that !an di>se throgh thethin ilem lining and are solble in blood plasma for transportation. 6lso" thesesimple mole!les are ne!essary for essential pro!esses li#e respiration orma#ing ne* tissue" bt also to synt!esi)e ne* long $!ain mole!les,tissefor di>erent prposes = li#e gly$ogen or $ellulose or star$! or su$rose =hen!e these simple mole!les are the bilding blo!#s.

mylase and maltase !onvert star$! to glu$ose and maltose

Proteases !onvert proteins to amino a$ids

4ipases !onvert lipids to (1 atty a$ids and gly$erol.

Enzymes and reactions

any !hemi!al rea!tions !an be speeded p by sbstan!es !alled !atalysts.&ithin living organisms" these rea!tions (metaboli! rea!tions+ are !ontrolled by!atalysts !alled en-ymes. En-yme mole!les are proteins that !ataly-emetaboli! pro!esses by lowering the a!tivation energy bt not being sed p per

se. Their a!tive sites lo!# onto spe!i7!sbstrates" brea#ing them down into theprod!ts.

En-ymes and rea!tions:

Temperatre" pH and en-ymes:

The a!tivity of en-ymes is a>e!ted bytemperatre and pH.

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E>e!t of temperatre on en-ymes

The optimm (best+ temperatre for en-yme!ontrolled rea!tions is LC (body temperatre+.

6s the temperatre in!reases" the rate of rea!tion in!reases. Jt very high temperatresdenatre en-ymes.

The graph shows the typi!al !hange in anen-yme%s a!tivity with in!reasing temperatre.

The en-yme a!tivity gradally in!reases withtemperatre p to arond oC" or bodytemperatre. Then" as the temperatre!ontines to rise" the rate of rea!tion fallsrapidly as heat energy denatres the en-yme.

ost en-ymes are denatred above *LLC. ;enatring is where the e3tremetemperatre !ases the en-yme8s a!tive site to brea# down and deform"thereby ma#ing it m!h less eM!ient at lat!hing onto sbstrate and s!!essfllybrea#ing it down.

E>e!t of pH on en-ymes

Changes in pH also alter an en-yme8s shape and slow down its a!tivity" bt this!an sally be reversed if the optimm pH is restored.

6n e3treme pH !an denatre en-ymes = the a!tive site is deformed permanently.

Enzymes - 'Lock and key' model

En-ymes are very spe!i7!" ea!h #ind of en-yme !ataly-e one #ind of rea!tiononly. To !ataly-e a rea!tion" en-yme mole!le and sbstrate mole!le need tomeet

and Goint together by a temporary bond.

Ea!h mole!le has a spe!ial shape and an a!tive site into whi!hits sbstrate mole!le 7ts e3a!tly.

This en-yme is amylase" and its a!tive site is Gst the right si-e and shapefor a sbstrate mole!le (star!h in this !ase+.

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The star!h slots into thea!tive site.

The star!h is split into maltose mole!les.

The en-yme is naltered" and ready to a!!ept another part of the star!hmole!le. 0aliva starts the !hemi!al brea#down of food bt also ma#es food intobols" so is lbri!ated and moves down oesophags smoothly and higher srfa!earea ma#e is easier for en-ymes.

/-/ explain !o* and *!y ood is mo'ed t!roug! t!e gut &y peristalsis

ood is moved throgh the gt by peristalsis" whereby in the oesophags" it!ontra!ts and rela3es in s!!ession to for!e food down the digestive system.s!les move food be!ase me!hani!al a!tion is needed to get food throgh thesystem.

/-/D understand t!e pro$esses o ingestion, digestion, a&sorption,assimilation and egestion

>ngestion: ta#ing food into the body" i.e. eating throgh yor moth.%igestion: pro!ess in whi!h large insolble mole!les of food are bro#en downinto smaller ones.

&sorption: the pro!ess by whi!h solble mole!les prod!ed by digestion areta#en from the gt (o!!rs mostly in the small intestine.+ The solble prod!ts of digestion are then transported to the varios tisses by the !ir!latory system.

ssimilation: the !ells of the tisses absorb the mole!les for se.

Egestion: removal of waste ndigested prod!ts as fae!es.

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/-/6 des$ri&e t!e stru$tures o t!e !uman alimentary $anal anddes$ri&e t!e un$tions o t!e mout!, oesop!agus, stoma$!, smallintestine, large intestine and pan$reas

The mothe!hani!al digestion happens here yor Gaw a!tion.6 bols is !reated9 this is a ball of food !overed in saliva. This is help fll as thefood is lbri!ated to enable swallowing and en-ymes in the saliva !an begin tobrea# down the food. (amylase+

The oesophags This tbe !onne!ts yor moth and stoma!h. $t is ne3t to the tra!hea.Peristalsis or ms!lar !ontra!tions moves the food downward.

The stoma!h

Chrning me!hani!ally digests whilst protease (pepsin+ does so !hemi!ally.Chyme is the name for li4id food e3isting in the stoma!h.

The hydro!hlori! a!id #ills ba!teria that are ta#en into the gt with the food.

The small intestine$n the dodenm" bile se!reted from gall bladder netrali-es !hyme andemlsi7es lipids so lipases will have a larger srfa!e area to wor# on = amylase"lipase and protease 7nish brea#ing down the ingested food. These were made bythe pan!reas.

6t the $lem" digested mole!les are absorbed into the blood stream throghthin walls.Filli !over the inside giving it a large srfa!e area whi!h many mole!les !andi>se throgh into the blood.

arge intestine This absorbs water from ndigested food" prod!ing fae!es.

Pan!reas This prod!es the en-ymes lipase" amylase and protease and inslin.

Bile is prod!ed in the li'er and stored in the Gall Bladder" before beingse!reted into the dodenm on the !hyme.

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Ileumadapted as:

• $t has folds

• Fery long (mts+ so in!reased srfa!earea

• reat blood spply to maintain high!on!entration gradient

• Thin lining for short di>sion pathway

Villi adapted as:

• One !ell thi!# epidermis

• Capillaries have great blood spply

• i!rovilli in!rease srfa!e area

/-1/ des$ri&e an experiment to in'estigate t!e energy $ontent in aood sample

Hold a pie!e of food nder a tbe of water" brn the food. &hen it is flly brned!ompare the heat of the temperatre before and after and mltiply by


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0HC Energy re4ired to raise temperatre of 1g of a sbstan!e by 1LC $nH2O" this is


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/-6 des$ri&e t!e stru$ture o $ar&o!ydrates, proteins and lipids aslarge mole$ules made up o smaller &asi$ units+ star$! and gly$ogenrom simple sugar< protein rom amino a$ids< lipid rom atty a$ids andgly$erol

0imple sgars e.g. gl!ose" maltose" la!tose 0tar!h" and gly!ogen" et!6mino a!ids Proteinatty a!ids 5 gly!erol ipids

/-D des$ri&e t!e tests or glu$ose and star$!

.est or glu$ose

Jenedi!t%s soltionble soltion.

Benedi$ts test+

6dd 2 !m of Jenedi!t%s soltion to 2 !m of gl!ose soltion in a test tbe andsha#e the mi3tre. eave the test tbe in a bea#er of boiling water for 7vemintes.

6s a !ontrol e3periment" repeat step 1 sing 2 !m of distilled water in pla!e of gl!ose soltion.

The !olor !hange after 7ve mintes is the ble Jenedi!t%s soltion trningbri!#red or orangered pre!ipitate" proving the e3isten!e of l!ose.

.est or star$!

>odine test:0tar!h !an be dete!ted by the iodine test. 6 few drops of iodine soltion addedto any sbstan!e !ontaining star!h will prod!e a blebla!# !olor.

6dd a few drops of iodine soltion to a pie!e of potato on a white plotting tile.

&hat do yo observe'

Plants store gl!ose in the form of star!h.

Fariegated leaves don8t have !hloroplasts at the otside of leaves" and so nogl!ose is prod!ed here" nor is any star!h stored here. This !an be seen as astar!h test wold show the !entre to be ble bla!#" while the oter edges"orange brown.

The importan!e of light !an be shown in photosynthesis by leaving a leaf in thedar# for a long time. &ith no light" no photosynthesis" and ths" no more gl!oseand then star!h" !an be prod!ed. To respire" star!h stored is !onverted ba!# togl!ose and respired. This diminishes star!h amont" so iodine test may styorangebrown and not go blebla!#.

/- understand t!e role o en)ymes as &iologi$al $atalysts in meta&oli$

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rea$tions

En-ymes are biologi!al !atalysts made of proteins that speed p !hemi!alrea!tions withot being sed p,!hemi!ally altered. They lower a!tivationenergy.

/- understand !o* t!e un$tioning o en)ymes $an &e a#e$ted &y$!anges in temperatures

Colder temperatres mean that the mole!les aren8t moving arond as fast" sothe metaboli! rea!tions o!!r slower.

However" an en-yme has an optimm temperatre wherein the en-ymesperform the best they !an as the warm temperatre means the rate of rea!tionis high" bt the temperatre isn8t too high as we shall see below.

Fery high temperatres denatre en-ymes so they do not fn!tion anymore.

This is be!ase en-ymes8 a!tive sites" where they lat!h onto sbstrate to formen-ymesbstrate!omple3es" are deformed by very high temperatres and!annot easily brea# down more mole!les.

/-00 des$ri&e !o* to $arry out simple $ontrolled experiments toillustrate !o* en)yme a$ti'ity $an &e a#e$ted &y $!anges intemperature

.!e e#e$t o temperature on en)yme a$ti'ity, example9amylase

$ will have * water baths of temperatres LR" 2LR"


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These !omple3 organisms need a lot of energy to srvive.

/-12 des$ri&e t!e di#eren$es &et*een aero&i$ and anaero&i$respiration

6erobi! respiration is with o3ygen" anaerobi! respiration is withot it. Jasi!ally"yor ms!le !ells !an respire anaerobi!ally for short periods of time when thereis a shortage of o3ygen.6nd aerobi! respiration releases more energy" bt the good thing with anaerobi!respiration is that it8s almost instant" it8s 4i!# whi!h is why events s!h as a1LLm sprint whi!h re4ires a 4i!# brst of energy is anaerobi!. Jt anaerobi!respiration leads to the prod!tion of la!ti! a!ida poison" whi!h bilds p in yorms!les. The la!ti! a!id !on!entrations bild p slowly in the ms!les and mayeventally be!ome high enogh to !ase fatige" ms!lar pains and !ramps tostop yo from !ontining.

This is why yo !ontine to breathe hard after anaerobi! e3er!ise for a while" as

yo are repaying yor o$ygen debt " whi!h is the o3ygen re4ired to o3idi-e and!onvert the harmfl la!ti! a!id into harmless prod!ts li#e !arbon dio3ide andwater.

/-18 re$all t!e *ord equation and t!e &alan$ed $!emi$al sym&olequation or aero&i$ respiration in li'ing organisms

Glu$ose F oxygen $ar&on dioxide F *ater F energy (.P

C6:0/O6 F 6O/ 6CO/ F 6:/O F .P

$N )E60T (EKENT6T$ON+: yeast F sugar al$o!ol F $ar&on dioxide

/-16 re$all t!e *ord equation or anaero&i$ respiration in plants and inanimals

Glu$ose la$ti$ a$id F less energy

C6:0/O6 /C1:6O1 F 4ess energy

Experiment to demonstrate t!e e'olution o CO/ and !eat rom

respiring seeds+:eat rom respiration 0et p two va!m @as#s" one with germinating peasand one with boiled peas. $nsert a thermometer" srronded by !otton wool toallow CO2 to es!ape bt not heat" and re!ord the !hange in temperatre after 2hors. erminating peas are living and so respire" giving of heat" ths heat!hange will be m!h higher whereas the @as# with boiled peas have notemperatre !hange as they are dead and do not respire.CO/ e'ol'ed Pt peas to respire in a !oni!al @as#" with a bng on top with apipe leading to a test tbe of Hydrogen !arbonate indi!ator (orangered+ whi!hwill yellow from CO2 evolved" whereas with dead peas it will remain orangeredas no e3!ess !arbon dio3ide is prod!ed for dead peas !annot respire" in!reasingthe !on!entration of CO2 above L.L


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$ts fn!tions:

o To transport ntrients and o3ygen to the !ells.

o To remove waste and !arbon dio3ide from the !ells.

o To provide for eM!ient gas e3!hange. The right side of the heart!olle!ts deo3ygenated blood form the body and pmps it to the lngs.

The left side !olle!ts o3ygenated blood from the lngs and pmps it to thebody.

/-66 understand t!e general stru$ture o t!e $ir$ulation system toin$lude t!e &lood 'essels to and rom t!e !eart, t!elungs, t!e li'er and t!e kidneys-

The doble !ir!lationJeginning at the lngs" blood @ows into the lefthand side of the heart" and then ot to the rest of the body. $t is broghtba!# to the rightside of the heart" before going ba!# to thelngs again.

This is !all a doble !ir!lation system" be!ase the bloodtravels throgh the heart twi!e on one !omplete Gorneyarond the body:

o One !ir!it lin#s the heart and lngs (plmonary !ir!it+

o The other !ir!it lin#s the heart with the rest of the body (systemi!!ir!it+.

The importan!e of a doble !ir!lation

o O3ygenated blood is #ept separate from deo3ygenated blood. The septmin the heart ensres this !omplete separation. O3ygenated blood @owsthrogh the left side of the heart while deo3ygenated blood @ows throghthe right.

o The blood pressre in the systemi! !ir!lation is #ept higher than that inthe plmonary !ir!lation. The left ventri!le" with a thi!#er wall" pmpsblood nder higher pressre to the body and delivers o3ygenated bloode>e!tively to all parts of the body. The right ventri!le has a thinner wall andpmps blood to the lngs nder lower pressre" thereby avoiding any lngdamage.

Fein to the heart6rtery away from heartng plmonaryiver hepati!idney renal

Jetween the gt and liver is the !epati$ portal 'ein.

/-68 des$ri&e t!e stru$ture o arteries, 'eins and $apillaries andunderstand t!eir roles

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6rteries• Ta#e blood away from the heart

• Jlood in them is nder high pressre

• They are delivering blood to an organ

• Thi!#" ms!le wall9 small lmen• 6rteries get smaller the frther away they are" de to lower volme and

pressre away from heart.

Feins• Ta#e deo3ygenated blood to the heart

• Jlood is nder low pressre

• Their blood is retrning from an organ

• Kelatively thin wall9 large lmen (to give low blood pressre+

• Falves stop blood @owing ba!# in the wrong dire!tion

Capillaries• E3!hange of o3ygen and !arbon dio3ide is ta#en pla!e here

• Fery thin !ell walls (one !ell thi!#+ so that sbstan!es !an di>se easily withshort di>sion pathway.

$n arteries" lmen is smaller be!ase: with a higher pressre of blood !oming inwaves at every heart beat" the arteries mst have a thi!# elasti! layer to stret!hand e3pand nder stress" as !ompared to veins. rthermore" blood pmpedfrom the thi!#er left ventri!le is m!h thi!#er be!ase it mst rea!h all parts of the systemi! !ir!it" i.e. most body !ells" ths there is greater ris# of rptre"ths a thi!#er otside ms!lar layer is ne!essary as this !an be fatal. 6lso"

given the fa!t that the maGority of the pressre is given by the heart" as perP,6" having a smaller !ross se!tional area for !onstant for!e given by theheart reslts in greater pressre far from the heart so the whole body !an berea!hed. /nli#e veins" there are no infolding valves to prevent ba!# @ow.

$n veins" lmens !an be bigger as the blood @ow throgh is more !onstant andnot in waves it does8t have to adapt to !hanges in pressre and volme of blood as m!h " ths it doesn8t need a thi!# elasti! layer. 6lso" as it is so far fromthe heart that initiates blood @ow" blood pressre throgh veins is less" ths ris#of rptre is less and a thi!# ms!lar wall is not ne!essary. Feins" nli#earteries have valves that prevent ba!# @ow and so do not need to maintain highpressre. They are often lo!ated !lose to ms!les9 when they !ontra!t" they

for!e blood in veins onward.

/-62 explain !o* t!e !eart rate $!anges during exer$ise and under t!einuen$e o adrenaline

;ring e3er!ise ms!les re4ire more energy" whi!h is !reated throghrespiration. That re4ires more o3ygen to be broght to !ells and more !arbondio3ide to be ta#en away" this means the heart needs to in!rease its speed sothat more blood is sent to ms!les.

/-61 des$ri&e t!e stru$ture o t!e !eart and !o* it un$tions

The heart !an be thoght of in for se!tions: the right atrim9 the right ventri!le9the left atrim9 the left ventri!le. 6 des!ription of the wor#ings of the heart:

The right atrim 7lls with blood (from the vena !ava+ and the valve is !losed9

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This area is s4ee-ed for!ing the blood throgh an tri!spid valve into the rightventri!le9 This area !ontra!ts for!ing the blood throgh semilnar valves pthrogh the plmonary artery where it is o3ygenated at the lngs9 theplmonary vein 7lls the left atrim with o3ygenated blood pon retrn9 This!ontra!ts" for!ing the blood throgh the bi!spid valve into the left ventri!le9when the left ventri!le !ontra!ts the blood is for!ed ot throgh the aorta"having gone throgh the semilnar valves. The septm prevents o3ygenatedblood mi3ing with deo3ygenated blood.

.!ings to remem&er+o %eins lead to the heart& arteries lead away.

o 'trium means entrance hall in atin& hence the atrium is where blood enters

the heart.

o )he left side is bigger than the right as it has to pump blood through the

whole body, and the right ventricle pumps blood at a low pressure to prevent

pulmonary damage.

o #oronary arteries and veins supply the heart with its own blood, and if these

get blocked, you could have a heart attack or a blood clot in your heart.

o *ou talk about the heart from right to left, as if you

were e$amining someone+s heart and using his or her own left and right.

o )he 'tria are wider and more thin-walled as they only pump the blood a short

way to the ventricles.

o )he Septum separates the deo$ygenated blood from the o$ygenated blood.

o )he pulmonary artery splits into two to go to each lung.

o )endon connects muscle to bone.

o igament connects bone to bone – synovial uids in oints between bones,

synovial membrane and capsule.

/-6/ understand t!at platelets are in'ol'ed in &lood $lotting, *!i$!pre'ents &lood loss and t!e entry o mi$roorganisms

&hen yo have a wond yo are at ris# of losing blood andPlatelets are prod!ed in the bone marrow they are fragments of !ells. The!hemi!als in platelets trn 7brigen in the blood into a solid !alled 7brin. 6networ# of 7brin !reates inherits red blood !ells and platelets9 it will then dryover to form a s!ab" beneath whi!h the tisse !an begin to repair.

/-6A des$ri&e !o* t!e immune system responds to disease using *!ite&lood $ells, illustrated &y p!ago$ytes ingesting pat!ogens andlymp!o$ytes releasing anti&odies spe$i5$ to t!e pat!ogen

&hite blood !ells are spe!iali-ed !ells that !an stop pathogens in yor body.

Phago!ytes They !an dete!t the presen!e of pathogens be!ase of !hemi!als they give o>.

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The !ell then englfs the pathogen. $f then destroys the !ell with digestiveen-ymes = phago!ytosis.

ympho!ytes&hen a lympho!yte meets its spe!i7! pathogen it divides: one !ells it !reatesbeing a memory !ell9 the other being the !ell" whi!h will !reate antibodiesspe!i7! to the pathogen.

One type of antibody !lmps pathogens together for easier digestion for thephago!ytes" whilst one other netrali-es the pathogen8s antigen" the other!ase the !ells to brst" or pt labels on the pathogens to ma#e them morevisible to the phago!ytes.$f the memory !ells every meet the pathogen again they will!reate the antibodies more 4i!#ly and in greater 4antity.

P!ago$ytosis

Phago!ytes have the ability to move ot of !apillaries to thesite of an infe!tion. They then englf (ingest+ the infe!tingpathogens and #ill them by digesting them.

/-60 understand t!at 'a$$ination results in t!e manua$ture o memory$ells, *!i$! ena&le uture anti&ody produ$tion to t!e pat!ogen to o$$ursooner, aster and in greater quantity

Fa!!ination is when a harmless or ina!tive form of a pathogen is inGe!ted into

the body. $t stimlates a response from the immne system with ot ptting thebody at ris#.&hen the pathogen will meet the lympho!yte that has the ability to get rid of it"it will be disposed of. The #ey thing is" thogh" that when the lympho!yte dividesit will !reate memory !ells. $f the same pathogen is ever in the blood streamagain (in the !ase of a real harmfl infe!tion+ the memory !ells will meet it andprod!e the appropriate antibodies ma#ing the immne rea!tion o!!r soonerand faster meaning a greater 4antity of antibodies will be prod!ed from whenthe pathogen enters the body" dealing with the pathogen before yo a!tallyfeel its e>e!ts (i.e. !olds" snee-ing from in@en-a+.

/-8D des$ri&e t!e $omposition o t!e &lood+ red &lood $ells, *!ite &lood$ells, platelets and plasma

The blood has several di>erent !omponents.o **S of the blood is plasma: hay !olored li4id !ontaining water with

di>erent things dissolved in it.o There are many red blood !ells (Erythro!ytes.+o There are fewer white blood !ells: Phago!ytes9 lympho!ytes.o Platelets (dead !ells+ play an important role in !lotting" !asing the !hemi!al

!alled 7brigen to trn into a solid !alled ibrin that inherits red blood !ellsand platelets to dry over the wond as a s!ab" allowing for repair to o!!r

below.

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/-8 understand t!e role o plasma in t!e transport o $ar&on dioxide,digested ood, urea, !ormones and !eat energy

o &ater whi!h is the main !omponent of plasma is a solvent and a li4id9 soplasma !arries these di>erent things arond the body dissolved in water:

o

Carbon Hydrogen !arbonateo ;ig

ested

food solble sgars and amino a!idso /reao Hormones.o &ater" a good inslator" also !arries heat" whi!h is important in the

reglation of body temperatre.

E3tension (not te!hni!ally on syllabs" bt not sreU+ Plasma !arries CO2arond the body. How' CO2 5 H2O V HCO 5 H 5 The CO2 rea!ts with watermole!les to prod!e the Hydrogen Carbonate ion. $n the lngs the rea!tionreverses to prod!e CO2 again. CO2 is" therefore" !arried as an a4eos ion inthe plasma

/-8 explain !o* adaptations o red &lood $ells, in$luding s!ape,stru$ture and t!e presen$e o !aemoglo&in, make t!em suita&le or t!etransport o oxygen

Ked blood !ells !arry o3ygen arond the body. $n order to do this theyhave haemoglobin whi!h is made from iron that !an bond to o3ygen to ma#eo3yhaemoglobin.Ked blood !ells are en!leate (they have no n!les+ to ma#e room for thehaemoglobin. There are no mito!hondria as the !ells respire anaerobi!ally so the!ells don%t se any o3ygen. They are bi!on!ave9 they are a @at dis# with a dip inthe middle. The shape and @e3ibility of a @at dis# enables them to pass throghnarrow !apillaries.

They have a dip in the middle to in!rease the srfa!e area to volme ratio andde!rease the distan!e for di>sion meaning that di>sion of o3ygen happens

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4i!#ly. They have very thin walls also for a short di>sion pathway.

Gas ex$!ange in :umans

/-1 understand t!e role o di#usion in gas ex$!ange

;i>sion is the movement of parti!les from an area of high density to an area of low density. $n this way gasses will move from an area dense with gas to an areaof low density.

$n the !ir!latory system o3ygen enters the blood and !arbon dio3ide leaves theblood via gaseos e3!hange. asses move a!ross the walls of alveoli to an areaof lower !on!entration than they are in: O3ygen moves into the blood as there isa low density of o3ygen in the blood9 Carbon dio3ide moves into the lngs as it isan area of lower !on!entration.

/-26 explain !o* al'eoli are adapted or gas ex$!ange &y di#usion&et*een air in t!e lungs and &lood in $apillaries

The alveoli have are thin" this allows gasses to di>se throgh them easily. They are small and there are millions of them meaning there is a large srfa!earea to volme ratio" throgh whi!h m!h gas !an di>se at on!e.6lveoli have a moist lining for gasses to dissolve into.Capillaries have a ri!h blood spply throgh the plmonary artery from theheart" to maintain high !on!entration gradient.

%es$ri&e t!e stru$ture o t!e t!orax, in$luding t!e ri&s, inter$ostalmus$les, diap!ragm, tra$!ea, &ron$!i, &ron$!ioles, al'eoli and pleuralmem&ranes

The thora3 is the part of yor body that lies between yor ne!# and yorabdomen (arond yor stoma!h+" and it in!ldes all of the above. They are vitalfor gas e3!hange.

6ir enters yor body throgh yor nose throgh yor two e3ternal nostrilswhose walls bear a fringe of hairs. The nostrils lead into two nasal passageswhi!h are lined with moist m!os membrane. Jreathing throgh the nose hasthe following advantages:

. /ust and foreign particles, including bacteria in the air, are trapped by the hairs in the nostrils, ciliated epithelial cells, or as well as by themucus on the mucous membrane. #ilia beat back and forward,sweeping the mucous out toward the mouth.

. 'ir is warmed and moistened before it enters the lungs.

1. 2armful chemicals may be detected by small sensory cells in themucous membrane.

The air in yor nasal passages enters the p!arynx" then to the larynx" and theninto yor tra!hea. The tra$!ea lies in front of yor oesop!agus. $t e3tendsdownwards from the laryn3 into the !hest !avity. The lower end of the tra!hea

divides into two tbes" the bron!hi (singlar: bron!hs+" one to ea!h lng. Ea!h&ron$!us divides repeatedly and ends in very small" 7ne bron!hioles. Ea!h&ron$!iole ends in a !lster of air sa!s !alled al'eoli.

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Ea!h lng lies in the pleural $a'ity" within whi!h the lng e3pands. The pleral!avity is lined by two transparent elasti! membranes !alled the plera (singlar:pleron+ or pleural mem&ranes. The inner pleron !overs the lng. The oterpleron is in !onta!t with the walls of the thora3 and the diap!ragm. 6 thinlayer of lbri!ating @id between the plera allows the membranes to glide overea!h other easily when the lngs e3pand and !ontra!t dring breathing.

&ithin the lngs" the bron!hial tbes divide repeatedly" giving rise to smallertbes !alled bron!hioles as mentioned earlier. They ea!h end in a !lster of airsa!s or al'eoli (singlar: al'eolus+. Thosands of alveoli are fond in the lngs"providing a very large srfa!e area for gas e3!hange.

)or !hest wall is spported by the ribs. They are atta!hed dorsally to theba!#bone in s!h a way that they !an move p and down. The ribs are atta!hedventrally to the !hest bone or sternum. Two sets of ms!les"the external and internal inter$ostal mus$les" !an be fond between the

ribs. They are antagonisti! ms!les. &hen the e3ternal inter!ostal ms!les!ontra!t" the internal inter!ostal ms!les rela3 and vi!e versa.

The diaphragm" whi!h is a domeshaped sheet of ms!le and elasti! tisse"separates the thora3 from the abdomen. &hen the diaphragm ms!les !ontra!t"the diaphragm @attens downwards and whey they rela3" the diaphragm ar!hespwards again.

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/-28 understand t!e role o inter$ostal mus$les and t!ediap!ragm in 'entilation

;ring inhalation,inspiration:

1 )or diaphragm !ontra!ts and @attens to ma#e more volme of air insidethora3.

. )or e3ternal inter!ostal ms!les !ontra!t while yor internal inter!ostalms!les rela3" again in!reasing the volme.


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I. 6tmospheri! pressre (pressre of air otside+ is now higher than thepressre within yor lngs. This !ases air to rsh into yor lngs fromotside.

;ring e3halation,e3piration:W )or diaphragm rela3es and ar!hes pwards.

W )or internal inter!ostal ms!les !ontra!t while yor e3ternal inter!ostalms!les rela3.

W )or ribs move downwards and inwards. )or sternm also moves down toits original position.

W The volme of yor thora!i! !avity de!reases.

W )or lngs are !ompressed and air pressre inside them in!reases as thevolme de!reases.

6ir pressre within the lngs is now higher than atmospheri! pressre. The air isfor!ed ot of yor lngs to the e3terior.

R>CE and ER>C

&hen yo inhale" yo...

Rela3 yor

>nternal inter!ostal ms!les and

Contra!t yor

E3ternal inter!ostal ms!les

&hen yo e3hale" yor...

E3ternal inter!ostal ms!lesRela3 and yor

>nternal inter!ostal ms!les

Contra!t

Hnderstand t!e &iologi$al $onsequen$es o smoking on t!e lungs and$ir$ulatory systems+

4ung $an$er The tar in smo#e has many !an!er !asing !ar!inogens.

Bron$!itis

Tar in smo#e severely damages the !iliated epithelial !ells in thelining of the bron!hi and tra!hea !ilia !annot now sweep p m!os" leading to!oghing.Emp!ysema The smo#e damages and !ases the walls of the alveoli tobrea# down and fse together" forming ineM!ient irreglar airspa!es" so gase3!hange is very ineM!ient and so less o3ygen is re!eived" ths simple tas#s li#ewal#ing are made diM!lt.Car&on monoxide in smoke CO bonds more tightly with hemoglobin thanwith O2 ths eventally many red blood !ells form tight bonds with the CO"red!ing the amont of O2 rea!hing !ells = this ma#es physi!al a!tivity verydiM!lt.

3a$tors t!at limit t!e rate o p!otosynt!esis

0 .emperature

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6 low temperatre will limit the rate as the mole!les will move less andtherefore the rea!tion happens slower

/ Car&on dioxide

6 shortage of the rate as fewer mole!les will be available for the rea!tion.

1 4ig!t intensity6 shortage of light means there is less energy to power the rea!tion.

4imiting a$tors explained+

ight" temperatre and the availability of !arbon dio3ide intera!t and in pra!ti!eany one of them may be the fa!tor that limits photosynthesis.

$f one of these fa!tors is !losest to its minimm vale it will limit the rate.$n!reasing this fa!tor will in!rease the rate.

The rate will !ontine to in!rease ntil another fa!tor be!omes limiting.6ny frther in!rease in the original fa!tor will now not in!rease the rate.&ith no limiting fa!tors" in!reasing a fa!tor above a !ertain level will not

in!rease the rate. 6ll !hlorophyll mole!les are being sed.

Gas Ex$!ange in t!e lea 9 key points+

W The srfa!e area of leaves is in!reased by the @attened shape and internal airspa!es.

W ost photosynthesis ta#es pla!e in the palisade !ells.

W Carbon dio3ide needs to rea!h the palisade !ells.

W Plants have stomata to obtain !arbon dio3ide from the atmosphere.

W This !arbon dio3ide is sed in photosynthesis.

W The si-e of stomata is !ontrolled by gard !ells" whi!h srrond them.

W 0tomata open dring daylight hors" to enable !arbon dio3ide to di>se in.

.ranspiration

W The pro!ess by whi!h plants lose water vapor from the srfa!e of theirleaves.

W $t evaporates into the air spa!es in the leaf" and then di>ses ot throgh thestomata.

W Transpiration is more rapid in hot" dry and windy !onditions: Page *

O Heat !ases the water to evaporate 4i!#er.

O ;ry !onditions in!reases the water vapor !on!entration gradient. &indmoves the water vapor away from the leaf" maintaining the !on!entrationgradient.

W ost of the water lost by transpiration leaves throgh the stomata.

W 0tomata !lose when it is dar#" when !arbon dio3ide is not re4ired.

W This red!es the amont of water lost by the plant at a time when it is notneeded for photosynthesis.

W $f plants lose water faster than the roots repla!e it" the stomata !an !lose toprevent wilting.

/-0D des$ri&e t!e pro$ess o p!otosynt!esis and understand itsimportan$e in t!e $onser'ation o lig!t energy to $!emi$al energy

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Photosynthesis is the pro!ess in whi!h energy from the snlight is sed to!reate gl!ose and then energy.

ight energy is absorbed by !hlorophyll in plants leaves. $t is then sed to!onvert !arbon dio3ide (fsrom the air+ and water (from the grond+ into gl!ose9whi!h is sed for respiration. O3ygen is a byprod!t of this pro!ess.

This is sing light energy" from the sn" to !reate !hemi!al energy (gl!ose+9whi!h !onserves the energy from the sn.

3a$tors limiting p!otosynt!esis

Three fa!tors !an limit the speed of photosynthesis: light intensity" !arbondio3ide !on!entration and temperatre.

4ig!t intensity-

&ithot enogh light" a plant !annot photosynthesise very 4i!#ly" even if there is plenty of water and !arbon dio3ide.$n!reasing the light intensity will boost the speed of

photosynthesis.

Car&on9dioxide $on$entration-

0ometimes photosynthesis is limited by the !on!entrationof !arbon dio3ide in the air. Even if there is plenty of light" a

plant !annot photosynthesise if there is insM!ient !arbon dio3ide.

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.emperature 9

$f it gets too !old" the rate of photosynthesis will de!rease. Plants!annot photosynthesise if it gets too hot as its en-ymes denatre.

$f yo plot the rate of photosynthesis against the levels of thesethree limiting fa!tors" yo get graphs li#e the ones to the left.

/-/A des$ri&e t!e stru$ture o t!e lea and explain!o* it is adapted or p!otosynt!esis

eaves have a large srfa!e area9 this allows them toabsorb more snlight. They are also thin" meaning that !arbon

dio3ide has a shorter way to travel. $n addition the stomata allow the entran!e of !arbon dio3ide. &a3y !ti!le red!es e3!ess water loss throghtranspiration.

The more !omple3 adaptations are of theinternal leaf str!tre. Theepidermis is thin and it8stransparent this means thatmore light !an rea!hthe palisade !ells nderneaththe pper epidermis.

The palisade !ellsthemselves are to the top of the leaf so they !an

absorb more if the light9they !ontain !hloroplasts so that they !anabsorb the light.

The spongy layer has air spa!es in: these allow for !arbon dio3ide to di>sethrogh the leaf" and they in!rease the srfa!e area.

/-/0 understand t!at plants require mineral ions or gro*t! and t!atmagnesium ions are needed or $!lorop!yll and nitrate ions are neededor amino a$ids

6s well as water and snlight" plants re4ire mineral ions to grow. ;i>erentmineral ions do di>erent things" two #ey e3amples of this are that: magnesim

ions are needed for !hlorophyll9 nitrate ions are needed for amino a!ids. 6 la!#of nitrates reslt in stnted growth and a la!# of magnesim ions reslts inyellowed leaves.

2t! 3orm iGCSE Biology Notes0-1 re$all t!e term Ipat!ogen 7 and kno* t!at pat!ogens may &e ungi,&a$teria, proto$tists or 'iruses-Pathogens are mi!roorganisms that !ase disease.

Ja!teria" fngi" virses and Proto!tists all !ase disease in a variety of ways.or e3ample" ba!teria release to3ins. 6nother sefl e3ample of pathogens!asing disease is virses destroying host !ells. Pathogeni! proto!tista in!ldeplasmodim" whi!h !ases malaria.

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• E3amples in!lde a!toba!ills blgari!s (sed in the prod!tion of yoghrtfrom mil#+ and Pnemo!o!!s (pathogen !asing pnemonia+

• Co$$us = rond shaped

• Ba$illus = rod shaped

Proto$tists• These are mi!ros!opi! single$elled organisms

Eukaryoti$

• 0ome" li#e moe&a" that live in pond water" have featres li#ean animal !ell

• 0ome li#e C!lorella" have !hloroplasts and are more li#e plants

• 6 pathogeni! e3ample is Plasmodium" responsible for !asing malaria

6lgae are normally de7ned as proto-oa be!ase most algae are ni!elllarnits wor#ing !losely with one another and those that are mlti!elllar arevery simplisti! str!tres" la!#ing the !omple3ity and organs of plants

=iruses

• These are ma!ro parti!les" proteins" smaller than ba!teria

• $ellular

• They are parasiti$ and $an reprodu$e only inside li'ing $ells Jreprodu$tion is the only thing it !an do from Mrs C Gren

• They ine$t e'ery type o li'ing organism

• They have a wide variety of shapes and si-es

• They have $ellular str!tre bt have a protein $oat srronding !ontainone type of nu$lei$ a$id" either ;N6 or KN6" of only a few genes" that areall that it is re4ired to reprod!e

• 0ometimes" they may inherit stolen membrane from a host !ell !alled anen'elope may srrond the virs parti!le

• E3amples in!lde the in@en-a virs (!ases D@8+ and H$F virs (!ases6$;0+

0-0 Hnderstand t!at li'ing organisms s!are t!e ollo*ing$!ara$teristi$s+

• they re4ire nutrition

• they respire

• they ex$rete their waste

•

they respond to their surroundings • they mo'e

• they $ontrol their internal !onditions

• they reprodu$e

• they gro* and develop.

MRS C GREN

K=iruses are interesting as t!ey $an onlyreprodu$e, and t!at too only inside a li'ing $ell

rom *!i$! t!ey may in!erit an en'elope

3eeding relations!ips

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2-2 explain t!e names gi'en to di#erent trop!i$ le'els to in$ludeprodu$ers, primary, se$ondary and tertiary $onsumers andde$omposers

;i>erent trophi! levels di>erent feeding levels

Prod!er (trns light energy into !hemi!al energy (photosynthesise food =atotrophi!+vPrimary !onsmer (feeds on the prod!er and gains its energy = heterotrophi!+v0e!ondary !onsmersv

Tertiary !onsmers

(;e!omposers feed at every level+N.J. The arrows in the food !hain follow the dire!tion of energy,biomass transfer.

The top consumer is known as the: ‘Top Carnivore

:a&itat+ pla!es in an e!osystem where one type of organism live (this !old beanother organism itself" li#e for parasites or de!omposers+Population+ how many organisms of the same spe!ies live in the samehabitat,e!osystemCommunity+ poplation of all spe!ies3ood *e&+ diagram showing interrelations between food !hains>ntera$tions *it!in a ood $!ain+ 0- 3eeding (Predation

/- Cy$les (e-g- Nitrogen Cy$le

1- Competition or resour$eseaning they feed on othersSaprotrop!i$+ a sbset of heterotrophi!" feeding only on dead things" de!ayingthem = fngi andutotrop!i$+ self feeding" ma#ing food via photosynthesising: plants" ba!teriaor Proto!tists.:eterotrop!i$+ animals are heterotrophi!" m some ba!teria do thisBio9mass+ the dry mass of organi! material

2-8 understand t!e $on$epts o ood $!ains, ood *e&s, pyramids o

num&er, pyramids o &iomass and pyramids o energy transer

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6 food !hain shows the transfer of energy p a!ross many trophi!levels" beginning with the prod!ers then the primary !onsmers and so forth.

6 food web lin#s several animals within a habitat showing what !onsmes whatand is !onsmed by what. $t shows the feeding intera!tions between food webs.

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6 pyramid of nmber progresses throgh the trophi! levels of a food !hainrepresenting the nmber of ea!h spe!ies by the area of the pyramid blo!#.

'll pyramids of bio-mass are in a true pyramid shape as energy and bio-massac3uired from the trophic level below is used or lost (typically about 40!" at

each trophic level, so the level above will always have less bio-mass to feed onand actually conserve. 5nly 0! of the biomass of an organism fed upon will

become part of the biomass of the predating organism.

pyramid o &iomass represents t!e dry &iomass o ea$! trop!i$ le'el&y t!e area o a pyramid &lo$k-

2-D explain *!y only a&out 0AL o energy is transerred rom one

trop!i$ le'el to t!e next-

The reason why not all of the energy will ma#e it to the ne3t tropi! level is thatsome of it will be sed p on the level it is at.

• The energy is sed for the life pro!esses of the animal that it is in = if a

mammal" a lot of energy is sed for maintaining a high" !onstant bodytemperatre.

• Energy !an be sed for respiration and movement.

• 0ome of the biomass is egested,e3!reted.

• Things li#e bones or stal#s may not be eaten.

2-6 understand t!e transer o su&stan$es and o energy along a ood$!ain

6s one thing !onsmes another" the energy and other things inside it = fore3ample fat and vitamins = get transferred to the !onsmer" absorbed throgh

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the ilem and assimilated by !ells. l!ose mole!les not immediately neededfor respiration !an be sed to ma#e gly!ogen for storage" bilding p biomass.$f yo eat a fatty pie!e of beef yo get the fat from the !ow.

Nitrogen Cy$le

n-&- N/ and O/ gas $an $om&ine under intense !eat in lig!tening to

produ$e nitrates t!at all to eart!

n-&-.!e :a&er Pro$ess is an industrial pro$ess &y *!i$! ertilisers like

N:2NO1 are produ$ed

Car&on $y$le+

Car&on Cy$le+

=as$ular &undlesylem and p!loem tisses are fond in grops !alled 'as$ular &undles. Theposition of these bndles varies in di>erent parts of the plant. $n a leaf" fore3ample" the phloem is sally fond !loser to the lower srfa!e.

Root

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Xylem vessels are togh and strong" so the vas!lar bndles are in the !entre ofthe root to resist for!es that !old pll the plant ot of the grond.

Stem The stem has to resist !ompression (s4ashing+ and bending for!es !ased by

the plant8s weight and the wind. The vas!lar bndles are arranged near theedge of the stem" with the phloem on the otside and the 3ylem on the inside.

/-80 des$ri&e t!e role o

p!loem in transportingsu$rose and amino a$ids&et*een t!e lea'es andot!er parts o t!e plant

• The phloem is!omposed of li'ing$ells" with !ell wallsof $ellulose and aretained $ytoplasm

• 6t the end of ea!h

!ell is a !ross se!tional sie'e plate, throgh whi!h the living !ytoplasme3tends" forming a long sie'e tu&e• $t transports prod!ts of photosynthesis" li#e su$rose (disa!!haride of

isomers r!tose and l!ose+ and amino a$ids rom lea'es to pla$es

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t!at need t!em in the form of sap" li#e young lea'es or roots thatmst grow and synthesise proteins

• Phloem !ells do not !a'e nu$lei9 rather" they are !ontrolled by$ompanion $ells in order to dire!t the !ontents to their destinations

• Phloem translo$ation is the name given to the movement of sap arond

the phloem networ#

l!ose and similar prod!ts of photosynthesis are transported as su$rosebe!ase:

• 0!rose is solu&le" ma#ing it easy to transport

• $t is nonred!ing9 it does not rea!t li#e gl!ose so easily

/-8/ des$ri&e t!e role o t!e xylem in transporting *ater and mineralsalts rom t!e roots to ot!er parts o t!e plant

• Xylem is a $ontinuous vessel of dead !ells lined end to end" !ontainingno $ytoplasm

• $nstead" they have a !ollo* lumen

• The walls !ontain a *oody" strong material !alled lignin" that ma#esthem strong enogh to support t!e *eig!t o t!e plant" andimpermea&le to *ater so it does not de!ompose" wea#en or lea#

• The !ells begin life as normal $ells" bt gradally the !elllose !ell wallsbe!ome impregnated *it! lignin in a pro$ess $alled ligni5$ation

• $n the Xylem as opposed to the Phloem" the @id (*ater and inorgani!mineral salts li#e Nitrates, P!osp!ates, Magnesium" et!+ only @owfrom the roots p to the leaves de to the for!es of ad!esion and$o!esion pon water" the pressure from the phloem itself" and also thetranspiration stream whi!h allows water to di>se p easily.

Co!esion ad!esion tension t!eory

This theory however des!ribes the movement of water from roots to the

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leaves of a plant. Je!ase of osmosis water from soil rea!h the 3ylem of roots of a plant. &ater mole!les are bonded to ea!h other by hydrogenbonding" hen!e water form a string of mole!les dring its movementtoward 3ylem. The water mole!les sti!# together ($o!esion and getplled p by the for!e !alled tension. This for!e is e3erted be!ase of the

evaporation atthe srfa!e of the leaf. 6lso"the partialattra!tion of thewater to the3ylem(ad!esionaids this.

.!e t!eory is &asedon t!e ollo*ingeatures+

• Cohesive and adhesive properties of water mole!les to form annbro#en !ontinos water !olmn in the 3ylem.

• Transpiration pll or tension e3erted on this water !olmn.Xylem vessels are tblar str!tres e3tending from roots to the top of the plants. Cells are pla!ed one above the other" with their end wallsperforated forming a !ontinos tbe. These are spported by 3ylemtra!heids whi!h are !hara!terised by having pores in their walls .one end

of 3ylem tbe is !onne!ted with the root hairs via peri!y!le" endodermisand !orte3 and another end is !onne!ted with the sb stomatal !avity inthe leaves via mesophyll !ells. This tbe is 7lled with water.

The water is 7lled inside the 3ylem !apillaries and de to !ohesion andadhesion properties of water" it forms a !ontinos water !olmn. Thewater !olmn !annot be bro#en or plled away from the 3ylem wallsbe!ase of !ohesion and adhesion of water.

/-81 explain !o* *ater is a&sor&ed &y root !air $ells&ater enters root hair !ells by osmosis from a higher water potential inthe soil to a lower water potential inside the root hair !ells throgh apartially permeable membrane. The roots are fll of minerals" whi!h

arti7!ially lower the !on!entration of water inside the root !ells" so wateris always drawn into them from the soil. This enables transpiration to

happen even if the soil is very dry. The roots ta#e theminerals p against the !on!entration gradient throgh asele!tively permeable membrane and is" therefore" an

e3ample of a!tive transport(transport against the!on!entration gradient be sing

energy throgh a sele$ti'ely permea&le mem&rane*it! $arrier proteins-

Koot hair !ells in!rease the root8s srfa!e area at a !elllar level" whereasthe bran!hing of roots in!reases srfa!e area to volme ratio at a tisselevel. $n!reasing the srfa!e area means it is easier for water to di>sethrogh the partially permeable membrane and into the transpiration

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Pagesion. To red!e loss the leaf is !oated in a wa3 !ti!le to stop the

water vapor es!aping throgh the epidermis. eaves sally have fewerstomata on their top srfa!e to red!e this water loss.

.urgidity

)o shold be able to e3plain why most plants will wilt if they get @ooded by seawater. (Hint: sea water !ontains many !hemi!als in soltion" s!h as salt.Osmosis will move water a!ross the plant !ell membrane" from the wea#er to thestronger soltion.+

/-88 explain !o* t!e rate o transpiration is a#e$ted &y $!anges in!umidity, *ind speed, temperature and lig!t intensity

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Pagen'estigating transpiration The rate of transpiration o> a leaf from spe!i7! sides !an be investigated bymeasring the de!rease in mass de to water loss" or by measring the volmeof water absorbed.

%e$rease in mass+Ct the leaves from the plant" and one or both srfa!es may be !oated withgrease to prevent transpiration. The table shows some typi!al reslts:

eaf 1 eaf 2 eaf eaf <

0rfa!e !oated with grease None Hpper only 4o*er only Bot!

S de!rease in mass 2A 16 2 /

The reslts show that most transpiration happens from the lower srfa!e of theleaf:

• !oating the pper srfa!e !ased water loss similar to !oating no srfa!eat all (leaf 2 vs leaf 1+

• !oating the lower srfa!e !ased water loss similar to !oating bothsrfa!es (leaf vs leaf


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Pagespring may inherit bene7!ial 4alities fromboth parents" and that ths there are more alleles (gene variants+" geneti!variation among the o>spring" in!reasing the ability for an organism poplationto !olle!tively adapt to environmental !hanges. eneti! variation in!reases the!han!es of a spe!ies8 srvival as some individal organisms will be betteradapted to !hanges in the environment. The disadvantages of se3alreprod!tion are that two parents are re4ired" so it will ta#e more time andenergy to reprod!e = this may be diM!lt in barren s!enarios.

'se$ual reproduction" on the other hand" does not involve gametes as theo>spring arise from one parent throgh !ell division = the o>spring are !lones.

Ths the advantages of ase3al reprod!tion are that only one parent isre4ired" and that bene7!ial 4alities are more li#ely to be passed on to theo>spring sin!e all o>spring are geneti!ally identi!al to the parent. However" thedisadvantage of having geneti!ally identi!al o>spring is that there is lessvariation" so the organism will be less adapted to !hanges in the environment.

• Keprod!tion is the prod!tion of new organisms. Keprod!tion isne!essary to ensre the !ontinity of spe!ies.

• 6se3al reprod!tion prod!es geneti$ally identi$al o#spring fromone parent by mitosis or simple 7ssion is ba!teria. eneti!ally identi!alo>spring are !alled $lones.

0e3al reprod!tion involves the usion o t*o !aploid gametes toform a diploid )ygote" prod!ing geneti!ally dissimilar o>spring from twoparents. Gametes are spe$ial reprodu$ti'e $ells produ$edt!emsel'es &y meiosis (a type o $ell di'ision t!at redu$es$!romosomes &y !al-

•

The pro!ess by whi!h the n!les of the male gamete fses with then!les of the female gamete to form a -ygote is !alled ertilisation.• $n sexual Reprodu$tion" before the !ell divides" the n!les divides

and ea!h !hromosome is !opied into two identi!al n!lei.• The only variation or alleles prod!ible in sexual Reprodu$tion are via

mtation.• Genders are only present in organisms prod!ed via Sexual

Reprodu$tion.• Male Gametes are Sperm

• 3emale Gametes are O'a

3ertilisation+• 6 male8s !ell will be a diploid as it has the fll nmber of

!hromosomes (


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Pagespring are geneti!allyidenti!al so !an srvive in the same!onditions as the parents. $f parentis well adapted" so will theo>spring.

:umanreprodu$tion+

1- des$ri&e t!e stru$ture and explain t!e un$tion o t!e male andemale reprodu$ti'e systems

ale reprod!tive system

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Pagesion to o!!r.

;i>se from foets to mother CO2" water" rea;i>se from mother to foets O2" gl!ose" amino a!ids" minerals

The pla!enta is adapted for di>sion in m!h the same way as other e3!hangeorgans" i.e. it has9

Hge srfa!e area (it has lots of villili#e proGe!tions+ Only a few !ells thi!#" short di>sion pathway Jlood spplies #eep the !on!entration gradients high

• O3ygen di#uses from mother%s blood to foetalblood9

• Carbon dio3ideand rea di>se

fromfoetal

blood tomother%s

blood9• l!ose"

aminoa!ids andvitaminsmoveby a$ilitated

di#usion into the foetal blood9• 0odim" potassim and !al!im are a$ti'ely transported into the foetal

blood.

6ntibodies also pass from mother to foets to give the foets passive immnitydring the pregnan!y and for a few months after birth.

Throghot pregnan!y" the pla!enta releases oestrogen" progesterone" HP(Hman Pla!ental a!togen+" and C (Chorioni! onadotrophin+.

&aste sbstan!es from the foets are !arried by the mbili!al artery. Theydi>se into the blood7lled spa!e and into the mother%s vein to be !arried away.

Ntrients are !arried by the mother%s artery to the pla!enta. They di>se intothe !apillaries of the foets. They are ta#en to the foets by the mbili!al vein.

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$ontra$epti'es like I.!e Pill79 Causes maturation o 'agina9 Causes &reasts to gro*9 Causes gro*t! o pu&i$ and armpit !air9 Causes !ips to *iden, rounded s!ape appears

Plant reprodu$tion+

3lo*erslowers are important in the se3al reprod!tion of plants. They prod!e malese3 !ells (pollen grains+ and female se3 !ells (!ontained in the ovles+. Thesemst meet for reprod!tion to begin a pro!ess !alled pollination.

Parts o a o*erStru$tur

e3un$tion

0epal Prote!ts the nopened @ower

Petal ay be brightly !olored to attra!t inse!ts

0tamen The male part of the @ower" !omprising an anther atta!hed toa 7lament

6nther Prod!es the male se3 !ells (pollen+ by meiosis

0tigma The top of the female part of the @ower" whi!h !olle!ts pollengrains

OvaryProd!es the female se3 !ells (!ontained in the ovles+ bymeiosis

Ovle Here" the one ovm is stored per ovle

ilament Provides spport for the anthers

0tyle

Throgh this" the pollen tbe grows and digests in order to

rea!h the ovle" go throgh the mi!ropyle and into the ovleso the pollen n!les !an fse with the ovm8s n!les infertilisation

i!ropyle

0mall hole,wea#ened part of ovle throgh whi!h pollen tbe!an travel to the ovm (the tip of the pollen tbe dissolveshere+ so the n!lei !an fse in fertilisation

Ke!epta!le Jase Gst below the sepal that provides spport to the @ower

Carpel The female parts of the @ower" that after fertilisation mayform the seed and frit

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>nse$t9pollinated o*erslowers with brightly!olored petals are sally inse$t9pollinated

@owers. $nse!ts !arry pollen from one @ower to another.

Cross se!tion throgh an inse!tpollinated @ower = the ne!tary prod!essgary ne!tar to attra!t inse!ts

@ind9pollinated o*ersrasses have *ind9pollinated @owers. They have small petals" andtheir stamens and stigmas hang otside the @ower.

Crossse!tion throgh a windpollinated @ower

Pollination and o*ers

3lo*ers are adapted or pollination &y inse$ts or &y t!e *ind-

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1-2 understand t!at t!e gro*t! o t!e pollen tu&e ollo*ed &y

ertilisation leads to seed and ruit ormation

Pollination: the deposition of pollen from the anther of one @ower onto thestigma of a di>erent @ower of the same spe!ies. &hen pollination o!!rs" thepollen grows a pollen tbe whi!h digests down the stigma of the @ower. Thepollen tbe !arries the n!les of the pollen throgh the ovary" and then throgha small wea#ened hole in the ovle !alled the mi$ropyle9 the n!les of themale gamete then fses with the n!les of the female gamete" the ovm fertilisation.

&hen fertili-ation has happen the @ower will !hange in the following ways:

1. The petals may die and fall away" as they are now redndant

2. The -ygote will begin to divide my mitosis and spe!ialise into an em&ryoplant J this has a radi$al (small root+ and plumule (small shoot+

. The other !ontents of the ovle develop into $otyledons, *!i$! areseed lea'es (some plants may have two and so one !an split the seedsof these di$otleydons or some have one mono$otyledons+. TheCotyledons provide the !arbohydrate and lipid energy and food store forthe seed prior to" and dring" germination


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*. The mi$ropyle remains" in order to allow some water to enter the seedwhen !onditions are met for germination

?. The seed as a whole is essentially the ovle and its !ontents

. The srronding ovary may 7ll p with sgars li#e fr!tose and s!roseand e3pand to form ruits

I. The ovary wallthenbe!omes theruit $oat"whi!h !anta#e many

forms

1-8 understand t!e $onditions needed or seed germination$n order to germinate (grow into a new plant+ seeds need the following!onditions9 Presen!e of water (all en-yme a!tivities re4ire a4eos media+ Presen!e of O3ygen (seed needs to respire to live+ &armth,Corre!t temperatre (re!all en-ymes wor# at optimm temp+

or e3periments" pyrogailol in sodium !ydroxide solution a&sor&s oxygen

N-B- @!en dormant, seeds are ex$eptionally dry in order to lo*ermeta&olism and sur'i'e or many years *it!out e'en germinating, untilt!e $onditions are rig!t

&hen a seed germinates the !ells inside it start to grow rapidly and form thenew shoot and root. The seed !ontains a limited store of !arbohydrate and lipid"

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whi!h it ses as a fel for respiration to provide the energy for growth. ;ringthis stage the seed mst prod!e leaves so it !an begin to photosynthesi-e. Thedanger is that the seed will rn ot of stored energy before it ma#es leaves. $f this happens it will die. Ths" before germination and the growth of roots andshoots in order to begin photosynthesising its own energy sor!e (gl!ose+ forrespiration" it mst !ontine to se p the !arbohydrate and lipid sor!e of the$otyledons.

Plants must disperse t!eir seeds so t!at t!e germinating seeds do not!a'e too mu$! $ompetition t!at may redu$e num&ers- .!ere are ourmet!ods o dispersal+

1. &ind2. 6nimal. e!hani!al a bran!h from the parent plant2. remove the lower leaves and plant the stem in damp !ompost. plant rooting !ormones in rooting powder !an be sed to en!orage

new roots to develop


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sexual reprodu$tion in plants0in!e there is only one parent involved in asexual reprodu$tion" theo>spring are geneti!ally identi!al to the parent and to ea!h other = theyare !lones.

Runners0ome plants natrally prod!e side bran!hes with plantlets on them. Thespider plant does this. Other plants" s!h as strawberries" prod!erunners with plantlets on them.

0trawberry plant with rnners = stems growing sideways

Bul&sany plants natrally develop ndergrond food storage organs that laterdevelop into the following year8s plants potato tbers and da>odil blbsare e3amples of this.

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These !omponds go down into the soil and are ta#en p from the rootstr!tre" and move in the transpiration stream p to the leave.

Potassium J essential or plant mem&ranesNitrate J essential or making plant proteinsP!osp!ate J essential or %N and mem&ranes(Magnesium 9 to make $!lorop!yll

ertilisers !an be divided into two grops:

1. Organi$ ertili)ersProd!ed from animal waste on farm

This sally ta#e the forms li#e Cow fae!es" !olle!ted by the farmer$t often goes throgh the pro!essof de$omposition and ermentation and form a sbstan!e #nownas slurry-

This gives !rop plant a spply of nitrate and phosphate to promote

growth.

2. rti5$ial ertili)ers Ta#e the forms of !hemi!alsPotassim nitrate6mmonim nitrate6pply to the 7eld" they will go into soltion in the soil water. This willrelease nitrates and promote growth in the same way as it wold do at the!ompond.

Pro&lems *it! ertili)ers+ Eutrop!i$ation+

1. Kainwater !an dissolve nitrates from farmers8 fertili-ers2. The nitrates are lea$!ed into rivers. $n!reased !on!entration of nitrates !ases algal &looms where algae

grow and mltiply very fast light to the riverbed plants" ma#ing photosynthesis harder9

they then die*. %e$omposition Ba$teria t!at de$ay plants use up t!e ri'er7s

oxygen, and no oxygen is put &a$k into t!e ri'er as plants $annotp!otosynt!esise and die

?. The la!# of o3ygen the water is anoxi$ !ases sealife li#e 7sh to die

8-2 understand t!e reasons or pest $ontrol and t!e ad'antages anddisad'antages o using pesti$ides and &iologi$al $ontrol *it! $ropplants

&hen all the !rops are of the same type in (say" a 7eld+ we !all this amono$ulture:ono!ltres are typi!ally ss!eptible to pests due to a&undan$e, presen$eoten or large amounts o time per year, and also la$k o 'ariation- .!is$an lead to 5nan$ial losses on t!e &e!al o t!e armer-

To over!ome this farmers have two soltions:

Biologi$al Control+

6iological control = introd!ing a biologi!al organism whi!h will eat the pest" btnot the !rop plant (e.g. birds are sometimes en!oraged inside greenhosesbe!ase they eat !aterpillars+

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d'antages. No to3i! !hemi!als" no bioa!!mlation et!. ess impa!t on the wildlife" or hmans

%isad'antages-

Not 1LLS e>e!tive-

Can be diM!lt to !ontrol" there is a danger that the introd!ed spe!ieswold start preying on an alternative prey so it will not die ot

-

$t is diM!lt to mat!h a predator to prey" and so !an Gst 7nd alternativeprey instead" being detrimental to environment

-

$t !an ta#e a long time

Pesti$ides+

Pesti!ides are $!emi$als designed to #ill the pest bt not the !rop.

d'antages+- Pesti!ides are !hemi!als so they are easy to obtain

- Easy to apply

- Fery e>

igcse biology notes updated april 2016 copy

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