9.2 - maintaining a balance

8/12/2019 9.2 - Maintaining a Balance

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HSC - Stage 6 2 Unit Biology

9.2 - Maintaining a Balance:

1. Most organisms are active within a limited temperature range:

Identify the role of enzymes in metabolism, describe their chemical

composition and use a simple model to describe their specificity in

substrates:

Role of enzymes in metabolism:

Metabolism refers to all the chemical reactions occurring in organisms

nzymes are biological catalysts !hich increase the rate of chemical reactions

"ithout enzymes# metabolism !oul$ be too slo! to su%%ort life

Chemical com%osition of enzymes:

&ll enzymes are ma$e of %rotein

'roteins consist of one or more %oly%e%ti$e chain(

)hese are com%ose$ of long chains of amino aci$s *oine$ together by %e%ti$e

bon$s

Structure of enzymes:

+n enzymes# the %oly%e%ti$e chain is fol$e$ into a ,-$imensional globular

sha%e

'art of the enzyme is calle$ the actie site( )his %art attaches to the substrate

)he substrate are the molecules the enzymes acts u%on

S%ecificity of enzymes:

nzymes are highly s%ecific in their action. this means that each enzyme acts

on one substrate only

)his is because the sha%e of the actie site of the enzyme matches the sha%e of

the substrate material

)he molecules the enzyme act u%on are calle$ the substrate

)he substrate molecules bin$ to the actie site an$ a chemical reaction occurs

)he %ro$ucts are the substances that the substrate/s0 become( 1ne substrate

can be s%lit# or t!o substrates can be *oine$

Mo$els to e%lain s%ecificity:

Co%yright 3 2445. &hma$ Shah +$il


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)he oc7 an$ 8ey Mo$el suggests that the substrate fits eactly into the

actie site of the enzyme li7e a 7ey fits into a loc7( +t assumes that the enzyme

ha$ a rigi$ an$ unchanging sha%e(

)he +n$uce$ 9it Mo$el states that the bin$ing of the substrate to the enzymein$uces; a tem%orary change in sha%e of the enzyme( )he ne! sha%e of the

enzyme better accommo$ates the sha%e of the substrate an$ a reaction occurs(

Identify the pH as a way of describing the acidity of a substance:

)he substance that ma7es a solution aci$ic is hy$rogen ions

%H is a measure of the aci$ity or the al7alinity of a substance

%H is a measure of the concentration of hy$rogen ions %er litre of solution

)he %H scale is from 4 to is neutral /%ure !ater0. aboe > is al7alinean$ belo! > is aci$ic

Identify the effect of increased temperature, change in pH and change in

substrate concentrations on the activity of enzymes:

nzyme function is affecte$ by many factors# inclu$ing:

)em%erature :

Sensitiity to tem%erature relates to the %rotein structure of enzymes

&s tem%erature increases# enzyme actiity increases# u% to the o%timum

tem%erature

)his is because the enzyme an$ substrate molecules are moing faster

/more 7inetic energy0 an$ therefore more collisions bet!een enzyme an$

substrate occur

&t high tem%eratures# the sha%e of the enzyme changes# an$ some of the

enzymes can no longer accommo$ate the substrate( &ctiity $ecreases(

Ho!eer# if the tem%erature cools $o!n# actiity !ill start again

&t ?R@ high tem%eratures# the enzyme is denatured. i(e( the chemical

bon$s hol$ing the %rotein molecule together are bro7en an$ the sha%e is

%ermanently change$( )he enzyme is $estroye$# can no longer

accommo$ate the substrate# an$ !ill remain inactie een if the

tem%erature returns to the o%timum



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%H :

nzymes !or7 best at an o%timum %H

)his is usually !ithin a ery narro! range

tremes of aci$ity or al7alinity can affect the bon$s hol$ing the ,A

globular sha%e of the enzyme# $enaturing the enzyme(

Substrate concentration :

&n increase in substrate concentration !ill increase the reaction until all

enzyme actie sites are occu%ie$( )hen the reactions !ill %rocee$ at a

maimum rate(

Explain why the maintenance of a constant internal environment is

important for optimal metabolic efficiency:

nzymes are essential for %ro%er metabolic function in an organism

Ho!eer# enzyme efficiency is affecte$ greatly by certain factors

)hese inclu$e temperature# pHan$ substrateconcentration:

nzymes !or7 best !ithin a limite$ range of enironmental con$itions

)herefore# a constant an$ stable internal enironment is nee$e$ so that enzymes

!ill al!ays be !or7ing at an o%timum rate# an$ thus metabolism !ill be ao%timum efficiency

Describe homeostasis as the process by which organisms maintain a

relatively stable internal environment:

A9++)+1: Homeostasis is the %rocess by !hich organisms maintain a

relatiely stable internal enironment

)he internal enironment of cells are 7e%t !ithin certain limits by the

coor$inating systems of the bo$y )hese systems monitor all the actiities of cells# their reuirements an$ the !astes

they %ro$uce this is to maintain health(

)his is calle$ homeostasis(

Explain that homeostasis consists of two stages



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Detecting changes from the stable state;

ounteracting changes from the stable state:

Aetecting Changes:

)he bo$y nee$s to maintain a stable state; in or$er to function %ro%erly

Changes# or $eiations# from the stable state are cause$ by the eternal an$

internal enironment

&ny change# or information# that %roo7es a res%onse is calle$ a S)+MUUS

RC')1RS $etect stimuli. organisms then react to the change

am%les of eternal stimuli: light# $ay length# soun$# tem%erature# o$ours

am%les of internal stimuli: leels of C12# oygen leels# !ater# !astes# etc(

Rece%tors can range from a %atch of sensitie cells# to com%le organs li7e the

eyes an$ ears of mammals

Counteracting Changes:

&fter rece%tors $etect changes# organisms can then react to the change

)his ty%e of res%onse !ill counteract the change to ensure the stable state is

maintaine$

99C)1RS bring about res%onses to stimuli

ffectors can either be muscles or glan$s:

Muscles bring about change by moement

Dlan$s bring about change by secreting chemical substances

!ather, process and analyse information from secondary sources and use

available evidence to develop a model of a feedbac" mechanism:

Homeostasis inoles the $etection of the change in the enironment an$ the

res%onse to that change

)hemechanismthat brings about this change is calle$ 9AB&C8

+n fee$bac7 systems# the res%onse alters the stimulus

+n liing organisms# the fee$bac7 system has , main %arts:

Rece%tors: & ty%e of sensor that constantly monitors the internal enironment

Control Centre: Receies info from the rece%tors an$ $etermines the res%onse



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ffector: Restores the set alue( 8ee%s enironments stable(

&n eam%le of a fee$bac7 system !oul$ be the control of bo$y tem%erature

)hese rece%tors sen$ their information to the control centre

)he tem%erature control centre in mammals is the hypothalamus )he hy%othalamus res%on$s by initiating res%onses to increase or $ecrease

tem%erature# until it goes bac7 to the set alue /!hich is ,>EC0

)em%erature control res%onses:

Keeping Warm Keeping ool

Shier to generate heat S!eating. ea%oration loses heat

Hair muscles erect. insulation Bloo$ essels $ilate. increase$ bloo$

su%%le# more heat lost

+ncrease$ a%%etite Hair relaes# less insulation

Bloo$ essels constrict. less bloo$ flo!#

less heat loss

Aecrease in metabolism

+ncrease in metabolism ess eercise

Aiagram of 9AB&C8:

#utline the role of the nervous system in detecting and responding to

environmental changes:

)he nerous system !or7s to regulate an$ maintain an animal;s internal

enironment an$ res%on$ to the eternal enironment

)he nerous system is ma$e u% of t!o %arts# the central nerous system# an$ the

%eri%heral nerous system:

Central erous System: )his %art acts as the C1)R1 C)R for all of

the bo$y;s res%onses( +t coor$inates all the res%onses( +t is ma$e u% of the

brain an$ the s%inal cor$( +t receies information# inter%rets it an$ initiates a

res%onse(



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'eri%heral erous System: )his is a branching system of neres that

connects rece%tors an$ effectors( )his system transmits messages from the

central nerous system an$ bac7( +t acts as a communication channel(

Identify the broad range over which life is found compared with the narrow

limits for individual species:

$mbient temperatureis the tem%erature of the enironment

)he range of tem%eratures oer !hich life is foun$ is broa$ com%are$ to the

narro! limits for in$ii$ual s%ecies

1rganisms on arth life in enironments !ith ambient tem%eratures ranging from

less than 4EC /such as arctic animals0 to more than


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Hibernation : )he bogong mothsFhibernateG in hot !eather /this is calle$

aestiation0( Auring summer# they gather in caes# their metabolism slo!s an$

the bo$y tem%erature $ro%s()his is to maintain bo$y tem%erature(

Shelter : )he central netted dragonstays in sheltere$ areas to aoi$ etremeheat( )hey can $ig burro!s or see7 shelter in caes or creices( )his re$uces

the effect of heat on their bo$y(

octurnal &ctiity : Brown sna&escan change into nocturnal animals !hen

the tem%erature becomes ery hot( Many $esert animals slee% in burro!s

$uring the $ay an$ are actie at night# to esca%e the heat(

"'($#H"%MRS'1SS )1 CH&D+D )M'R&)UR:

Migration : )he short-tailed shearwatermigrates to euatorial regions $uring

the !inter months( )his is to aoi$ the col$ !eather# as the bir$ only bree$s in

!arm !eather(

+nsulation : )he superb parrot contracts the muscles controlling its feather in

col$ con$itions# fluffing u% its coat( )his maintains a later of tra%%e$ air as

insulation( )his air re$uces heat echange !ith the enironment(

a%oration :)he red &angaroolic7s its arms to cool itself( )he ea%oration

of the salia cools its s7in(

octurnal Behaiour : Hopping mice# an$ many other &ustralian en$otherms#

are nocturnal( )his is to %reent oerheating# an$ to re$uce moisture loss(

Identify some responses of plants to temperature change:

'lants res%on$ to tem%erature change by altering their gro!th rate (D( Some

ucaly%tus trees gro! more in s%ring than in !inter(

+n etreme heat or col$# %lants can $ie# but leae behin$ $ormant see$s(

'lants may $ie aboe the groun$# but leae bulbs# roots# rhizomes or tubers to

surie un$ergroun$( )hese then s%rout !hen faourable con$itions return

Some %lants can change the orientation of their leaes in relation to the sun at

$ifferent times of the sun# thus controlling tem%erature

eaes hang $o!n ertically to re$uce sun e%osure



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2. )lants and animals transport dissolved nutrients and gases in a !luid

medium:

Identify the forms in which each of the following is carried in mammalian

blood:

arbon Dioxide

#xygen

%ater

&alts

'ipids

(itrogenous wastes

#ther products of digestion

#ransporting *ubstances +n #he Blood:

C&RB1 A+1+A:

+t is %ro$uce$ as a !aste %ro$uct of res%iration in bo$y cells( &fter

entering the bloo$stream it may:


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,( Be $issole$ $irectly in the %lasma ,onl 0 o! the carbon dioide(

1@D:

1ygen is nee$e$ in the bo$y for res%iration( +t is brought in across the

res%iratory surfaces of the lungs(

+t bin$s !ith haemoglobin in re$ bloo$ cells# forming oxyhaemoglobin)

"&)R:

"ater is the solent of %lasma it ma7es u% the bul7 of bloo$ olume

+t ma7es u% 64J of the olume of bloo$

S&)S:

)hese are trans%orte$ $irectly $issole$ in the %lasma

(D( so$ium# %otassium# magnesium# etc

+'+AS:

Aigeste$ li%i$s are change$ into triglycerides /this ha%%ens in the lining of

the small intestine0(

i%i$s are trans%orte$ as chlomicrons these are clusters of

triglyceri$es# %hos%holi%i$s an$ cholesterol# !ra%%e$ in a coat of %rotein(

)hese are release$ into the lym%h an$ eentually %ass into the eins

+)R1D1US "&S)S:

"astes such as ammonia are change$ in urea

Urea is trans%orte$ $issole$ in the %lasma

1)HR 'R1AUC)S 19 A+DS)+1:

+nclu$es amino aci$s# sugars# glycerol an$ itamins

)hey are mainly !ater soluble an$ trans%orte$ in the %lasma

Explain the adaptive advantage of haemoglobin:

&$a%tie &$antage:

+f bloo$ carrie$ oygen withouthaemoglobin# the oygen !oul$ hae to be

$issole$ $irectly into the %lasma /into !ater0(



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1ygen is not ery soluble in !ater

+f oygen !as carrie$ only by being $issole$ in bloo$ %lasma#


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Ca%illaries are only one cell thic7# an$ are so narro!# that only one re$ bloo$

cell can %ass at a time(

Ca%illaries surroun$ all tissue cells

)hus# they %roi$e a ery large surface area oer !hich echange of materials

bet!een bloo$ an$ bo$y cells can occur(

?+S:

?eins carry bloo$ bac7 to the heart

?eins are not un$er a lot of stress - bloo$ %ressure is lo!

)his is !hy they hae thinner walls than arteries, less muscle and a wider

diameter/large lumen0(

Since there are no thic7 muscular !alls to 7ee% the bloo$ %ulsing along# theeins hae a series of ales !hich %reent the bloo$ from bac7-flo!ing on its

!ay bac7 u% to the heart(

)he eins also run through muscles# such as your leg muscles# an$ as you use

these muscles# they %ress on the eins# %ushing bloo$ through the eins(

Describe the main changes in the composition of the blood as it moves

around the body and identify tissues in which these changes occur:

'UM1&R@ C+RCU+) /ungs0:

Bloo$ enters the right atrium of the heart ia the ena caa /ma*or ein0:

)he bloo$ is $eoygenate$# an$ high in carbon $ioi$e

+t is lo! in glucose an$ other nutrients. it is also high in urea# other

nitrogenous !astes an$ arious %oisons(

&s the heart beats# the right entricle %um%s the bloo$ through the %ulmonary

artery# to the lungs:

Here the bloo$ gains oygen# an$ loses its carbon $ioi$e(

)he bloo$ then enters the left atrium ia the %ulmonary ein(

S@S)M+C C+RCU+) /Bo$y0:

)he left entricle %um%s oygenate$ bloo$ to the bo$y through the aorta(

+n the bo$y# arious changes occur to the bloo$(



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)he bloo$ loses oygen an$ gains carbon $ioi$e in all bo$y cells# as

res%iration occurs( Dlucose leels also $ro%(

+n the 4+5"%:

eels of glucose are regulate$ ecess glucose is change$ to glycogen#

or glycogen stores are change$ to glucose /if nee$e$0

cess amino aci$s are change$ to ammonia# an$ then to urea

'oisons are also re$uce$# as the lier changes them to less toic forms

+n the +'#"*#+'"*:

eels of nutrients from $igestion increase(

Dlucose# amino aci$s# ions# li%i$s an$ other substances from foo$ enter thebloo$( )he increase is through the small intestines reabsor%tion of foo$

+n the K+('"6*:

Salt an$ !ater leels are regulate$

&ll urea is remoe$# toins are ecrete$ into the urine

)he change$ bloo$# again highly $eoygenate$# then flo!s bac7 to the

%ulmonary circuit(

#utline the need for oxygen in living cells and explain why the removal of

carbon dioxide from cells is essential:

&ll liing cells nee$ oygen for res%iration(

&s a result of res%iration# carbon $ioi$e is %ro$uce$

"hen carbon $ioi$e $issoles in !ater# it ma7es carbonic aci$(

)his means that if a lot of carbon $ioi$e is %ro$uce$# the bo$y cells /an$ the

bloo$ an$ lym%h0 !ill become acidic(

&s stu$ie$ before# enzymes can only function !ithin a s%ecific %H range

So an increase in carbon $ioi$e !ill result in a lo!ering of %H# !hich !ill affect

the oerall metabolism of the bo$y(

Describe current theories about processes responsible for the movement of

materials through plants in xylem and phloem tissue:



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@M:

)rans%ort of !ater is %assie an$ $e%en$s on transpirationan$ the %hysical

%ro%erties of !ater:

)rans%iration: a%oration of !ater from the leaf cells through the

stomates initiates the %ull of the )R&S'+R&)1 S)R&M( "ater is

then $ra!n u% the ylem tubes to re%lace this loss( )he lo! concentration

of !ater at the roots allo!s $iffusion of !ater in(

Cohesion: "ater molecules ten$ to bin$ together# forming a continuous

column in the ylem# !hich re%laces any loss

&$hesion: "ater molecules stic7 to the si$es of the ylem tubes /cellulose

!alls0# %ulling the !ater u% the tubes(

)he moement of !ater through narro! tubes is calle$ C&'+&R+)@

+t is cause$ by the t!o forces of C1HS+1 an$ &AHS+1

'H1M:

Moement of organic molecules# eg sugars# amino aci$s an$ hormones# in the

%hloem is calle$ translocation)

Materials are trans%orte$ both u% an$ $o!n the stem( Materials are $istribute$

es%ecially to the growing points an$ reproductive structures# inclu$ing$eelo%ing fruits an$ see$s

9lo! of materials in the %hloem is an actie %rocess that reuires energy

+t is thought to occur by a mechanism calle$ the source-%ath-sin7 system an$

is $rien by a gra$ient generate$ osmotically

)hesource*path*sin" )H1R@:

+n the %lants# there are S1URCS of nutrients# e(g( leaf cells are the

sources of glucose( &s the glucose buil$s u%# the cells trans%ort theglucose by actie trans%ort into the %hloem tubes# by 2 !ays:

S@M'&S)+C 1&A+D: Sugars an$ nutrients moe in the

cyto%lasm from the meso%hyll cells to the siee elements through

%lasmo$esmata *oining a$*acent cells /1): 'lasmo$esmata hae

not been foun$ in all %lants0



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&'1'&S)+C 1&A+D: Sugar an$ nutrients moe along the cell

!alls to the siee tube( )hen they cross the cell membrane by actie

trans%ort(

&s sugars enter the %hloem the concentration of %hloem sa% increases an$

the( )his causes the entry of !ater by osmosis from the surroun$ing cells(

)his resulting %ressure causes !ater an$ $issole$ solutes to flo! to!ar$s

a S+8(

& sin7 is a region of the %lant !here sugars an$ other nutrients are actiely

begin remoe$ from the %hloem( &s sugars moe out of the %hloem# !ater

flo!s out !ith them( )his re$uces the %ressure in the siee cells at the sin7

region(

+se the light microscope to estimate the size of red and white blood cells

and draw scaled diagrams of each:

RA B11A CS /rythrocytes0:

*i7e:6- Nm

*hape:Bi-concae $iscs

8unction:)rans%ort of oygen(

)hey hae no nuclei. they only lie for , months(

&fter this they are $estroye$ in the lier or s%leen(

5-6 million in eery millilitre of bloo$(

)hey are %ro$uce$ in the bone marro!

"H+) B11A CS /eucocytes0:

*i7e:


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)hey are %ro$uce$ in the lym%h glan$s(

$nalyse information from secondary sources to identify current

technologies that allow measurement of oxygen saturation and carbon

dioxide concentrations in blood and describe the conditions under which

these technologies are used:

#echnolog How it Wor&s #he onditions +t +s sed

'ulse

oimeter

Measures

12 leels

Aeice li7e

a %eg sits on the finger an$

measures the transmission oflight through tissues

Measures

the amount of oygen in arterial

bloo$

)here is a

large $ifference bet!een re$

light absorbe$ by haemoglobin

com%are$ to oyhaemoglobin

Use$ in many con$itions this is

because it is %ainless# easy to

a%%ly an$ uic7 to gie results(

Can be use$ as a general chec7-u%

%roce$ure to analyse 12leels &lso use$ $uring surgeries# to

monitor %atients un$er anaesthesia

&lso use$ to monitor %remature

babies that are in neo-natal !ar$s(

&rterial

bloo$ gas

/&BD0

analysis

Measures 12an$ C12 leels(

Uses electrochemical metho$s

Measures %artial %ressure /or

the concentration0 of 12 an$

C12 in the bloo$

Measures saturation of oygen

/!hich is the amount of oygen

combine$ to haemoglobin

com%are$ to the maimum0

Measures leels of bicarbonate

an$ %H /to sho! C12leels0

Use$ !hen there are signs of

$angerously lo! oygen or high

carbon $ioi$e leels

Hel%s for $iagnosing as !ell as

monitoring %atients

Hel%ful for monitoring %atients

un$er anaesthesia# in intensie

care# in acci$ent or emergency

facilities an$ for %remature babies

g# a %atient in a coma can hae

their bloo$ gases regularly



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)his analysis ealuates ho!

effectiely the lungs are

$eliering oygen an$ remoing

carbon $ioi$e

monitore$

$nalyse information from secondary sources to identify the products

extracted from donated blood and the uses of these products:

RA B11A CS: Use$ to increase the amount of oygen that can be carrie$

to the bo$y;s tissues. gien to anaemic %atients# or %eo%le !hose bone marro! $o

not ma7e enough re$ bloo$ cells

'&))S: Use$ to ma7e the bloo$ clot. is gien to %eo%le !ith cancer of the

bloo$ /leu7aemia or lym%homa0( 'atients un$ergoing chemothera%y# !hose bloo$$oes not ma7e enough %latelets# are gien this(

'&SM&: )his liui$ %ortion of the bloo$# is gien to %eo%le !ith clotting

$isor$ers /such as haemo%hilia0# an$ also use$ to a$*ust the osmotic %ressure of

the bloo$ /to %ull flui$s out of tissues0(

"H+) B11A CS: +nfection fighting com%onent of the bloo$( ?ery rarely

gien# but are use$ !hen cell count is ery lo!

+MMU1D1BU+S: &lso calle$ gamma globulins# immune serum# or

antibo$ies# these are also infection fighting %arts of the bloo$ %lasma( Dien to

%eo%le !ho hae $ifficulty fighting infections# eg &+AS sufferers(

$nalyse and present information from secondary sources to report progress

in the production of artificial blood and use available evidence to propose

reasons why such research is needed:

)he %roblems of using real bloo$:

Shortage of real bloo$

+t has to be cross-matche$;( )his is because# if you receie the !rong ty%e of

bloo$# it can be fatal( )his is a great $isa$antage in emergency situations(

+t has to be free of infectious agents( 1nly bloo$ that is free of bacteria an$

infectious agents /such as H+?0 can be use$( )esting the bloo$ is costly(



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+t has a short shelf-life( Because re$ bloo$ cells only surie for , months# the

bloo$ has a short life s%an /bloo$ can only surie for ,-= !ee7s0(

Some %ro%ose$ re%lacements for bloo$:

'erflurochemicals /%erflurocarbons0:

Synthetic an$ inert# are com%letely sterile

Chea% to %ro$uce# com%are$ to using real bloo$(

Can $issole 5 times more oygen than bloo$(

9ree of biological materials# therefore no ris7 of infections

BU) - must be combine$ !ith other materials to mi in !ith the

bloo$stream /eg lecithin0(

Haemoglobin Base$ 1ygen Carriers /HB1Cs0:

Ma$e from haemoglobin etracte$ from re$ bloo$ cells

Haemoglobin is not containe$ in membrane - cross matching unnecessary

Can be store$ for a long time

BU) - haemoglobin ten$s to oi$ise to a $ifferent form# brea7 $o!n# an$

can no longer carry oygen(

Aetrose Solution:

Ma$e of =J glucose solution in a flui$ !ith eual salinity to bloo$

1nly use$ to restore bloo$ %ressure after acci$ents(

Draw transverse and longitudinal sections of phloem and xylem tissue:

'H1M:



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@M:



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3. )lants and animals regulate the concentration o! gases water and waste

products o! metabolism in cells and in interstitial !luid:

Explain why the concentration of water in cells should be maintained within

a narrow range for optimal function:

"ater ma7es u% aroun$ >4-4J of liing things. it is essential for life

"ater is the solent of all metabolic reactions in liing cells# an$ sometimes

$irectly ta7es %art in it /eg( Res%iration0

RC&:

Isotonic: Concentration of solutes outsi$e the cell is the same as insi$e the

cell( o oerall moement of !ater(

Hypertonic: Concentration of solutes is greater outsi$e the cell than insi$e(

"ater ten$s to moe out of the cell(

Hypotonic: Concentration of solutes is greater insi$e the cell than out( "ater

ten$s to moe insi$e the cell(

iing cells !or7 best in an isotonic enironment

)he leels of !ater in cells nee$s to be 7e%t relatiely constant

&ny change in the concentration of solutes !ill result in a change in the leels of

!ater in cells !hich usually results in $eath /either $ehy$ration or cell bursting0 nzymes also reuire s%ecific con$itions of functioning# some of !hich coul$

relate to the leels of !ater an$ solutes in cells(

)his is !hy the concentration of !ater must be 7e%t constant: )o ensure the

%ro%er functioning of liing cells(

Explain why the removal of wastes is essential for continued metabolic

activity:

&s a result of metabolism# many !aste %ro$ucts are forme$ /e(g( C120 +f these !ere allo!e$ to accumulate# they !oul$ slo! $o!n metabolism an$ 7ill

the cells /e(g( ecess C12increases %H# affecting enzyme function0

)his is !hy they nee$ to uic7ly be remoe$# or conerte$ into a less toic form(

"hen %roteins an$ amino aci$s are bro7en $o!n /in a %rocess calle$

$eamination0# a nitrogenous !aste calle$ ammonia# is %ro$uce$



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&mmonia is highly toic an$ must be remoe$ or change$ to a less toic form

Identify the role of the "idney in the excretory system of fish and mammals:

)he %rimary role is osmoregulation(

)his is the regulation of salt an$ !ater leels in the bo$y

9ish $o not ecrete nitrogenous !astes through the 7i$neys. they use their gills

)heir urine contains mainly ecess !ater an$ salts

Mammals; urine contains urea as !ell as !ater an$ salts

)he 7i$neys ensure that the concentration of bloo$ an$ interstitial flui$ is constant

Explain why the processes of diffusion and osmosis are inadeuate in

removing dissolved nitrogenous wastes in some organisms:

Aiffusion an$ osmosis are both eam%les of %assie trans%ort# relying on ran$om

moements of molecules(

Aiffusion is too slo! for the normal functioning of the bo$y an$ is not able to

selectiely reabsorb useful solutes(

1smosis only $eals !ith the moement of !ater an$ thus !oul$ only allo! !ater

to moe out of the bo$y# not the nitrogenous !astes(

+n the 7i$ney# some useful %ro$ucts are reabsorbe$ into the bo$y this !oul$ not

be %ossible !ith $iffusion /actie trans%ort nee$e$0

1smosis !ithout actie reabsor%tion of !ater !oul$ result in ecess !ater loss

)he 7i$ney functions by using ecreting all the bloo$ substances in the ne%hron

outsi$e; the bo$y an$ then selectiely /actiely0 reabsorbing useful materials

Distinguish between active and passive transport and relate these to

processes occurring in the mammalian "idney:

&ctie trans%ort uses energy to trans%ort substances across a membrane it !oul$

normally not be able to cross $ue to a $iffusion gra$ient or its o!n %ro%erties

'assie trans%ort is the moement of substances across a membrane !ithout

energy e%en$iture /this is di!!usionan$ osmosis0 com%letely ran$om(

& 7i$ney is ma$e u% of aroun$ a million ne%hrons( +t is !ithin the ne%hrons that

the %rocesses of !iltration# reabsorptionan$ secretionoccur(



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)he S)RUC)UR of a ne%hron:

+t is a long t!iste$ tubule ma$e

u% of sections: a Bowman;s

capsule# connecte$ to /


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Explain how the processes of filtration and reabsorption in the mammalian

nephron regulate body fluid composition:

)he ne%hron is a regulatory unit. it absorbs or secretes substances in or$er to

maintain homeostasis(

)his regulation maintains the constant com%osition of bo$y !luids(

Salts an$ !ater are a$*uste$ to maintain flui$ concentration

Aifferent ions also a$*uste$ to maintain %H(

)hese $ifferent %rocesses ha%%en in the $ifferent sections of the ne%hron(

'roimal )ubule :

Bicarbonate ions are reabsorbe$ into the ca%illaries into the bloo$ from the

ne%hron# hy$rogen ions are secrete$ out( )his maintains the %H of the bloo$( Arugs# such as as%irin# %enicillin an$ %oisons are secrete$ out of the bloo$

Regulation of salts also occurs here( So$ium ions are actiely reabsorbe$ an$

chlorine ions follo! %assiely( 'otassium ions are also reabsorbe$

)he oo% of Henle : +t has a descendinglimb an$ an ascendinglimb

+n the $escen$ing limb# it ispermeable to water# not salt(

"ater %asses out of the ne%hron an$ into the ca%illaries by osmosis

+n the ascen$ing limb# the !alls arepermeable to salt# but not !ater &scen$ing limb is thin-!alle$ at the bottom# an$ thic7-!alle$ at the to%(

Salt %assiely %asses out into the ca%illaries at the bottom# thin-!alle$ section#

but is actiely %asse$ out in the to%# thic7-!alle$ section(

)he Aistal )ubule :

Selectie reabsor%tion of so$ium ions an$ %otassium ions occurs here again#

to regulate the %H of the bloo$# an$ the concentration of salts(

)he Collecting Auct :

)his is the en$ of the ne%hron# an$ connects to the ureters(

)he !alls are %ermeable to !ater only# an$ !ater is trans%orte$ out

accor$ingly to the nee$s of the bo$y

)he final filtrate is calle$ urine(



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Identify the regions of the mammalian "idney involved in the excretion of

waste products:

)he 7i$ney is ma$e u% of three sections# the

%elis# the me$ulla an$ the corte

)he corte contains the glomeruli( +t is ery $ar7

re$ $ue to the ca%illaries

)he corte is inole$ in the !iltrationof bloo$

)he me$ulla contains the ne%hron tubules# as can

be obsere$ by the stri%e$ a%%earance of the

me$ulla

)his section is inole$ in the reabsor%tion an$secretion of substances

)he %elis is !here all the collecting $ucts

connect to

)he collecting $ucts reabsorb !ater

)he renal artery# renal ein an$ ureters are all connecte$ to the %elis(

ompare the process of renal dialysis with the function of the "idney:

'eo%le !ith $ysfunctional 7i$neys are not able to remoe !astes such as urea

)hey hae to un$ergo renal $ialysis to regulate their bloo$

)he %rocess:

)he bloo$ is etracte$ from the bo$y from a ein an$ %asse$ into a $ialyser#

!hich is a bun$le of hollo! fibres ma$e of a %artially %ermeable membrane

)he $ialyser is in a solution of $ialysing flui$# !hich has similar

concentrations of substances as bloo$

)he $ialyser only allo!s !astes to %ass through# an$ not bloo$ cells an$

%roteins( +n this !ay it is similar to the filtrations stage of the ne%hron

)he !astes $iffuse into the solution# an$ it is constantly re%lace$

)he anti-clotting agent# he%arin# is also a$$e$ to %reent clotting

)he bloo$ is then returne$ to the bo$y

Com%arison of $ialysis an$ normal 7i$ney function:



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Kidnes %enal (ialsis

- &ctie an$ %assie trans%ort is use$

throughout the ne%hron(

- Uses a series of membranes /ne%hrons0

!hich are selectiely %ermeable

- Continuous %rocess. ery efficient

- Useful substances are reabsorbe$

actiely by the 7i$ney

- 1nly %assie trans%ort is use$

- &lso uses membranes /but artificial0

!hich are selectiely %ermeable

- Slo! %rocess# occurs a fe! times a

!ee7 for %atients

- Useful substances $iffuse into bloo$

from $ialysing flui$# no reabsor%tion

#utline the role of the hormones, aldosterone and $DH -anti*diuretic

hormone. in the regulation of water and salt levels in blood:

&AH /&nti-Aiuretic Hormone0:

&lso calle$ aso%ressin

Controls the reabsor%tion of !ater by a$*usting the %ermeability of the

collecting $ucts an$ the $istal tubules(

+t is ma$e in the hy%othalamus in the brain# but store$ in the %ituitary glan$

Rece%tors in the hy%othalamus monitor the concentration of the bloo$:

High &alt oncentration: &AH leels increase$# collecting $ucts an$

$istal tubules become more %ermeable to !ater# more !ater reabsorbe$#

concentration returns to normal( /Concentrate$ urine0

'ow &alt oncentration:&AH leels re$uce$# collecting $ucts an$ $istal

tubules less %ermeable# less !ater absorbe$# concentration returns to stable

state( /Ailute urine0

&AH $oes not control the leels of salt in the bloo$( +t only controls the

concentrationof salt through !ater retention(

&l$osterone :

'ro$uce$ an$ release$ by the a$renal glan$s# !hich sit aboe the 7i$neys

Controls the amount of salt in the bloo$ by regulating the reabsor%tion of salt

in the ne%hrons

High &alt 'evels:

High bloo$ olume an$ bloo$ %ressure $ue to !ater $iffusing in(



25/28


eels of al$osterone $ecrease$(

ess salt reabsorbe$# less !ater $iffusing in

Salt leel $ecrease$# bloo$ olume an$ %ressure $ecreases

'ow &alt 'evels:

o! bloo$ olume an$ bloo$ %ressure $ue to !ater $iffusing out(

eels of al$osterone increase$(

More salt reabsorbe$# more !ater $iffusing in

Salt leels increase# bloo$ olume an$ %ressure increase

Define enantiostasis as the maintenance of metabolic and physiological

functions in response to variations in the environment and discuss its

importance to estuarine organisms in maintaining appropriate salt

concentrations:

A9++)+1: nantiostasis is the maintenance of metabolic an$ %hysiological

functions in res%onse to ariations in the enironment(

&n estuary is !here a rier meets the sea# an$ fresh!ater mies !ith salt!ater

+n such an enironment# the salinity leels are al!ays changing $ramatically(

9rom lo! ti$e to high ti$e# !ater can flo! in from either the salty ocean# or from

fresh!ater riers this causes great ariation in the leels of salt in the !ater(

1rganisms liing in such an enironment nee$ to hae mechanisms to co%e !ith

such changes in or$er to surie( )he mechanisms are all collectiely calle$

enantiostasis

&nimals /li7e fish0 can moe to aoi$ changes /or shellfish o%ening an$ closing0#

'lants must hae mechanisms to hel% them co%e !ith these changing

enironmental con$itions(

Describe adaptations of a range of terrestrial $ustralian plants that assist

in minimising water loss:

*pini!e grass has etensie root systems that can reach un$ergroun$ !ater(

)heir leaes are also long an$ thin to re$uce !ater loss# an$ can roll u% to hi$e

their stomates# !hich %reents !ater loss(



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"ucalptus trees are har$ !ith !ay cuticles this re$uces the amount of !ater

loss through trans%iration( )heir leaes also hang ertically to re$uce sun

e%osure(

Ban&sia leaes hae sun7en stomates this re$uces trans%iration Wattleleaes are small an$ hairy the small size means less ea%oration of

!ater# an$ the hairy leaes re$uce the trans%iration by tra%%ing !ater(


27/28


Role of 8i$ney : Continually $rin7s !ater( 8i$neys reabsorb !ater# !hile

actiely secreting salts( Small amounts of concentrate$ urine( Salt is also

ecrete$ across gills(

Urine : Small# concentrate$ amount(

#errestrial Mammals:

1smotic 'roblem : "ater nee$s to be consere$(

Role of 8i$ney : Regulates concentration of bloo$# !hile at the same time

ecretes urea an$ conseres !ater(

Urine : Concentration changes !ith the aailability of !ater# as !ell as

tem%erature an$ !ater loss through s!eat( "ater leels in bloo$ rise# urine

amount rises# an$ concentration $ecreases an$ ice ersa( Explain the relationship between the conservation of water and the

production and excretion of concentrated nitrogenous wastes in a range of

$ustralian insects and terrestrial animals:

=mmonia is the $irect result of amino aci$ brea7$o!n /$eamination0 an$ is a

!aste %ro$uct of all organisms( +t is ery !ater soluble# but ?R@ toic# an$

must be remoe$ uic7ly# or change$ to a less toic form(

)he remoal of ammonia !oul$ reuire large olumes of !ater# an$ this is not%ossible for animals or insects that see7 to consere !ater

=>uatic =nimals and 8ish:)hese organisms $irectly release &MM1+& into

the enironment( )his uses a lot of !ater# but they hae no nee$ to consere it(

&mmonia is ery !ater soluble an$ is ecrete$ through the gills(

#errestrial =nimals:Releasing ammonia !oul$ be im%ossible $ue to lac7 of

!ater( +nstea$# lan$-$!ellers change ammonia into less toic forms an$ release it

%erio$ically( Mammals change it into UR& an$ release it as urine( /(D(

8angaroos# !allabies# ho%%ing mice# 7oalas# etc(0 &ustralian animals release ery

concentrate$ urine# an$ are able to tolerate high leels of urea in their bo$ies(

Birds: Bir$s change ammonia into UR+C &C+A# a !hitish %aste !hich uses

har$ly any !ater( )his is lighter than using urea# an$ hel%s in flight(

+nsects: +nsects also change ammonia to UR+C &C+A /(D( &cacia %sylli$s0



28/28


/rocess and analyse information from secondary sources and use available

evidence to discuss processes used by different plants for salt regulation in

saline environments:

Halo%hytes are %lants that can tolerate high salt leels

)hey are commonly foun$ in areas such as estuaries(

Drey Mangroes :

&alt Exclusion:S%ecial glan$s in the mangroes can actiely eclu$e the salt

from the !ater# so that the !ater absorbe$ has a lo!er salt concentration than

the !ater in the enironment(

&alt $ccumulation:Salt is accumulate$ in ol$ leaes that $ro% off# so that the

salt is out of the %lant;s system

&alt Excretion:Salt can be ecrete$ from the un$ersi$e of the leaes of the

mangroe %lants. salt crystals form un$er the leaes(

Saltbushes :

&alt $ccumulation: )his %lant stores its ecess salt in s!ollen leaf bases#

!hich $ro% off# ri$$ing the %lant of salt(

Describe structures in plants that assist in the in the conservation of water:

"ucalptus:

"ay# har$ leaes: Re$uces !ater loss by re$ucing the rate of trans%iration

from the leae surface

)he leaes hang ertically# an$ this re$uces the !ater loss# consering !ater

Ban&sia:

eaes hae sun7en stomates this re$uces trans%iration

Wattle:

eaes are small an$ hairy the small size means less ea%oration of !ater#an$ the hairy leaes re$uce the trans%iration by tra%%ing !ater(

9.2 - maintaining a balance

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