Biology f4 Chap 7

8/17/2019 Biology f4 Chap 7

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7.1 THE RESPIRATORY PROCESS

1. Living organisms require energy to carry out all living processes such as:

(a) Movement

(b) Growth

(c) Reproduction

(d) Response

(e) reathing

(!) "igestion

(g) #$cretion

%. #nergy is required !or the various processes in the cell such as:

(a) &ell division

(b) 'ormation o! gamete !or reproduction

(c) ransmission o! nerve impulses

(d) &ontraction o! muscles

(e) ynthesis o! protein* hormones* lipid and en+ymes

,. Respiration is the o$idation o! !ood substances in the mitochondria o! thecells to release energy.

-. Glucose is the main substrate !or energy production. Glucose is obtained!rom:

(a) he digestion o! carbohydrate in humans and animals

(b) he process o! photosynthesis in plants

7.1.1 Types of respiration

1. here are two type o! respiration:

(a) erobic respiration

/ erobic respiration is the brea0ing down o! glucose in the presence o!

o$ygen to release chemical energy

/ a0es place in all living cells o! plants* animals and in certainmicroorganisms

/ ccurs in the mitochondria and cytoplasm

/ ccurs slowly and in stages controlled by en+ymes

/ he glucose is completely o$idi+ed to release all the chemical energy inthe glucose

/ ome o! the energy released is changed into body heat while the rest is

stored in the !orm o! adenosine triphosphate (2)


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3hen body cells need energy* 2 molecules will be hydrolysed to yield energy*a molecule o! "2 and an inorganic phosphate

2 "2 4 2 4 energy

/ "uring aerobic respiration* ,5 molecule o! 2 or %565 07 o! energy isreleased.

/ erobic respiration can be represented by the !ollowing equation:

Glucose 4 $ygen &arbon dio$ide 4 3ater 4 #nergy

&891%8 4 8% 8&% 4 89% 4 energy (%565 07)

(a) naerobic respiration

/ naerobic respiration is the brea0down o! glucose to produce energy inthe absence o! o$ygen

/ Glucose is not completely bro0en down* only small amount o! energy isreleased

/ ccurs only in the cytoplasm

/ ccurs both in animal cells and plant cells

(i) naerobic respiration in human muscles; ccurs in human muscles during vigorous e$ercise or activities

; "uring vigorous e$ercise*

/ he breathing rate and heart beat are increased to supply o$ygen to themuscle !or rapid muscular contraction

/ 9owever* the supply o! o$ygen to the muscles is still insu


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/ $ygen is required to pay o> the o$ygen debt by rapid breathing a!ter thevigorous e$ercise

/ $ygen o$idi+es the lactic acid to carbon dio$ide* water and energy

(i) naerobic respiration in yeast

; naerobic respiration in yeast is called !ermentation

; "uring !ermentation* yeast secretes the en+yme +ymase which hydrolysesglucose in the absence o! o$ygen to !orm ethanol* carbon dio$ide and energy

Glucose ethanol 4 carbon dio$ide 4 energy (1=07)

&891%8 %&%9=94 %&% 4 energy (1= 07 or two molecules o! 2)

; ?n the !ermentation* only small amount o! energy is released. largeamount o! energy is still stored in the ethanol as chemical energy. his isbecause glucose is not completely bro0en down in anaerobic respiration

1. &omparison between aerobic respiration and anaerobic respiration

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"?''#R#@

erobic respiration naerobic respiration


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A.1 R#2?RRB RC&CR# @" R#9?@G M#&9@?M ?@ 9CM@ @"@?ML

1. reathing:

/ ?s the e$change o! gases between the organism and the environment

/ ?nvolves the process o! ta0ing o$ygen and removing carbon dio$ide

%. he common characteristics o! respiratory sur!ace !or gaseous e$change:

(a) Large total surface area

/ o enhance the eusion !or gaseous e$change

(b) Moist respiratory surfaces

/ he respiratory sur!aces has a layer o! moisture to !acilitate the di>usion o!o$ygen and carbon dio$ide

(a) Thin wall of respiratory surface


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/ he wall o! respiratory sur!ace is only one cell thic0 to !acilitate thedi>usion o! gases across the sur!ace

(b) Has a network of blood capillaries

/ networ0 o! blood capillaries beneath the respiratory sur!ace (e$cept !or

proto+oa and insects)

7.1.1 Protozao

/ @o special respiratory structure

/ Gases e$change by simple di>usion occurs rapidly across the thin plasmamembrane

7.1.2 Fish

1. Respiratory structure: Gills. Gaseous e$change occurs at the gill Flaments.

%. he adaptation o! gill Flaments !or gaseous e$change:

(a) Many lamella at the gill Flaments

/ o increase the D E ratio !or the absorption o! dissolved o$ygen in thewater

(b) hin epithelial walls o! the gill Flaments

/ o allow the o$ygen to di>use easily into the blood capillaries o! the gillFlaments

(c) networ0 o! capillaries in the gill Flaments

/ o increase the rate o! gaseous e$change by di>usion

,. he breathing mechanism


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1. "issolves o$ygen di>uses through the gill epithelium into the bloodcapillaries at the gill Flaments. &arbon dio$ide di>uses !rom the blood capillariesinto the surrounding water.

%. he direction o! water ow over the gill lamella is opposite to the ow o!blood in order to ma$imise the rate o! di>usion !rom the water into the bloodcapillaries

7.1.1 Insects

1. he respiratory system o! insects is called the tracheal system.

%. 'or insects* gases are not transported by blood.

,. piracles:

/ ir enters the body through spiracles

/ piracles are located on the both sides o! thora$ and abdomen.


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-. racheae and tracheoles:

/ he spiracles lead into a system o! large tubes called tracheae* which are0ept open by chitin.

/ he tracheae branch into a networ0 o! smaller tracheoles.

/ he tracheoles end on the plasma membrane o! every body cell in thebody cells o! insects.

=. Gases e$change at the respiratory sur!ace:

/ $ygen enters through the spiracles to tracheae and tracheoles* thendi>uses into muscle cells.

/ &arbon dio$ide di>uses !rom the cells into tracheoles and tracheae* andeliminated through spiracles.

7.1.2 Aphi!ians

1. n amphibian e$changes gases in three di>erent ways:

(a) &utaneous respiration

(b) uccal respiration

(c) 2ulmonary respiration

%. &utaneous respiration

; he amphibianHs s0in is thin* moist and is well supplied with bloodcapillaries.

; tmospheric o$ygen dissolves into the moist sur!ace o! the s0in to theblood capillaries.

,. uccal respiration

; he buccal carvity and the pharyn$ are covered with a thin epithelium*which has an underlying networ0 o! blood capillaries.

; Eentilation o! the buccal cavity:

/ he mouth closes* the buccal oor lower to reduce air pressure.

/ Low buccal cavity pressure suc0s in the atmospheric air through thenostrils.

/ $ygen !rom the buccal air dissolves in the epithelial moisture* anddi>uses across the thin epithelium into the underlying blood capillaries.

/ &arbon dio$ide !rom the blood capillaries di>uses into the buccal air.

/ he buccal oor rises* with the glottis closed* increases air pressure in thebuccal carvity !orces the used air out through the nostrils.

-. 2ulmonary respiration

; 2ulmonary respiration is carried out only when the need o! o$ygen is great*li0e when a !ood is Iumping or swimming.


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; he !rog has a pair lungs connected to a short bronchus. #ach lung ismoist and has several hundreds o! tiny alveoli. #ach alveolus has a networ0 o!blood capillaries.

; Eentilation o! the lungs

/ he nostrils close* the glottis opens* the oor o! the mouth rises to !orceair into the lungs.

/ ?n the lungs* o$ygen dissolves in the moisture on the epithelium anddi>uses through the thin epithelium into the blood capillaries.

/ &arbon dio$ide di>uses out !rom the blood capillaries into the lungs.

/ he glottis open* air ow out o! the lungs. he nostrils open* the used airis eliminated through the nostrils

7.1." H#an

1. he human respiratory system consists o!:

(a) @ose and nasal cavity

(b) 2haryn$

(c) Laryn$

(d) rachea

(e) ronchi and bronchioles

(!) Lungs

%. reathing mechanism

?nspiration #$piration

1. he e$ternal intercostalmuscles JJJJJJJJJJJ* internalintercostal muscles JJJJJJJJJJ*raising the ribs JJJJJJJJJJ and

JJJJJJJJJJ.%. t the same time* the

1. he e$ternal intercostalmuscles JJJJJJJJJJJ* internalintercostal muscles JJJJJJJJJJ*lowering the ribs JJJJJJJJJJ

and JJJJJJJJJJ.%. t the same time* the


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diaphragm muscles JJJJJJJJJ and JJJJJJJJJJJ.

,. hese JJJJJJJJJJJJ thevolume o! thoracic cavity*causing the pressure to

JJJJJJJJJJJ.

-. ince atmospheric pressureis JJJJJJJJJJJ* air is JJJJJJJJJJJJJthe lungs.

diaphragm muscles JJJJJJJJJand JJJJJJJJJJJ.

,. hese JJJJJJJJJJJJ thevolume o! thoracic cavity*causing the pressure to

JJJJJJJJJJJ.

-. ince atmosphericpressure is JJJJJJJJJJJJ* air is

JJJJJJJJJJJJJ the lungs.

1. &omparison between inspiration and e$piration

&hanges ?nspiration #$piration

#$ternal intercostalmuscles

?nternal intercostalmuscles

Rid cage

"iaphragm

Eolume o! thoraciccavity

2ressure in lungs

Movement o! air

1. Models the e$plain the breathing mechanism in human

(?) ell 7ar Lung Model


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(??) Rib &age Model

A.1.1 &omparison between di>erent respiratory system

?M?LR??#


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&haracteristics

2roto+oa ?nsect 'ish mphibian 9uman

Respiratorysystem

Respiratoryorgan

Respiratorystructures

9igh DEratioachieved

by


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Respiratoryopening

@etwor0 o!bloodcapillaries

2assage o!respiratorygases

ransport o!


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blood

7.1 $ASEO%S E&CHA'$E ACROSS THE RESPIRATORY S%RFACE A'(TRA'SPORT OF $ASES I' H%)A'S

A.1.1 #$change o! o$ygen and carbon dio$ide between the blood and thealveolus.

1. ?n human lungs* there are about A million alveoli* giving a total respiratorysur!ace area o! A K 5m,.

%. he characteristics o! respiratory sur!ace in the alveoli.

(a) large sur!ace area !or gaseous e$change

(b) thin one/cell thic0 epithelial sur!ace which is moist and permeable to gas.

(c) n underlying capillary networ0* which is also one/cell thic0* that carrieso$ygen away and bring carbon dio$ide to be eliminated.

,. he e$change o! gases at the respiratory sur!ace is by di>usion !rom a placeo! high partial pressure to a place o! low partial pressure down its partialpressure gradient.

?n the alveoli:

G 2R?L 2R#CR# ?@ #''#&

lveolar ir lood &apillaries

BG#@

&R@ "??"#

?n the body cells:


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G 2R?L 2R#CR# ?@ #''#&

lveolar ir lood &apillaries

BG#@

&R@ "??"#

7.1.1 The transport of respiratory *ases an+ the process of *aseo#se,chan*e

A.1.1.1 ransport o! $ygen !rom the lungs to the body cells and gaseous

e$change1. $ygen is transported !rom the lungs to the body cells in two ways:

(a) 66 o! o$ygen is transported as o$yhaemoglobin in the red blood cells

(b) 1 o! o$ygen is transported as dissolved gas molecules in the plasma.

%. $ygen di>uses into the blood capillaries will combine with haemoglobin to!orm o$yhaemoglobin.

,. Red blood cells transport o$ygen as o$yhaemoglobin to respiring body cellswhere partial pressure o! o$ygen is low.

-. t low partial pressure o! o$ygen* the o$yhaemoglobin dissociates itsel! torelease o$ygen molecules.


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A.1.1.% ransport o! &arbon dio$ide !rom the body cells to the lungs and gaseouse$change

1. Respiring body cells produce carbon dio$ide.

%. &arbon dio$ide di>uses into the blood capillaries and is carried to the lungsin three ways:

(a) 5= o! carbon dio$ide is carried as bicarbonate ions (9&,/)* dissolved inblood plasma.

(b) 1 o! carbon dio$ide is combined with amino groups o! haemoglobin in redblood cells to !orm carbaminohaemoglobin.

(c) = o! carbon dio$ide is transported as dissolved gas molecules in theplasma.

,. 3hen blood carrying carbon dio$ide reaches the lungs:

(a) 9ydrogen carbonate ions (9&,/) convert bac0 to carbon dio$ide moleculewhich di>uses into alveolar air.

(b) &arbaminohaemoglobin brea0s down to release carbon dio$ide moleculewhich di>uses into alveolar air.


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(c) "issolved carbon dio$ide molecule in the plasma di>uses !rom the bloodcapillaries into alveolar air.

7.1 THE RE$%-ATORY )ECHA'IS) I' RESPIRATIO'

A.-.1 "uring a vigorous e$ercise*

/ muscle cells need more o$ygen and glucose to release energy during cellular

respiration./ 9ence

N he rate o! respiration increase

N he % content decrease

N he &% content increase

/ s a result :

N he breathing rate increase

/ to supply more % to the muscles and discharge more &% !rom the lungs.

N he heartbeat rate increase

/ to pump more blood into the blood circulation.

/ more &% and glucose can be supplied !or cellular respiration.

/ more &% can be removed !orm the cells.

N he ventilation rate increases

/ the rate o! gaseous e$change between alveoli and blood capillaries becomes!aster.

A.-.% 9# R#GCLR M#&9@?M ' % @" &% &@#@ ?@ 9# "B

• Respiratory centre


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O a group o! cells situated in the medulla ablongata to regulate the rhythm o!breathing by controlling the intensity and !requency o! contracrion o! theintercostal muscles and diaphragm.

•

&hemoreceptorsO are sensory receptors in the body that responds to chemical stimuli.

/ % sets o! chemoreceptors

(a) &entral chemoreceptors

/ located in the medulla oblongata

/ detect the increase o! &% in blood indirectly through the !ormation o!hydrogen ion (94).

(b) 2eripheral &hemoreceptors

/ consist o! the carotid bodies on the carotid arteries *and the aortic bodies onthe aorta

/ sensitive to p9 levels and the very low level o! % in the blood.

Regulation o! Respiration by the central &hemoreceptor

A.-.%.% Regulation o! respiration by the peripheral chemoreceptor

.


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/ 2eripheral chemoreceptors are only activated when o$ygen levels dropreal low* this can happen at high altitudes where atmosphere o$ygen is very thin.

• he % content in the blood usually has little e>ect on the respiratorycentre.

• Csually* a rise in &% concentration is a better indication o! a drop in%concentration* because both the &% and % concentrations are a>ectedby cellular respiration.

%.-., 9uman Respiration ?n "i>erent ituations.

) R#L?@G

/he rate o! breathing : 1- / % timesDminute

/he rate o! heartbeat : 8 K A beatsDminute

/ @ormal* at optimal levels su


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/to increase the supply o! %

N he rate o! heartbeat increases

/to transport more % to the muscle cells

N he rate o! cellular respiration increases

/to produce su


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7.0 RESPIRATIO' I' P-A'TS

A.8.1 #nergy requirement in plants

/ 2lants carry out cell respiration to produce energy.

A.8.% he inta0e o! $ygen by 2lants !or Respiration

1. Gaseous e$change between plant cells and the environment occurs bydi>usion * mainly through

(a) tomata

/ #ach stoma consists o! a pore surrounded by two guard cells.

/ he guard cells contain a large number o! chloroplast in whichphotosynthesis ta0es place.

/ tomata allow the e$change o! gases between atmospheric air and the internaltissues o! a lea!.

/ he stomata open when there is light and the close in the dar0.

(b) Lenticels

/ Lenticels are raised pores !ound on the stems and the roots.


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/ he cells around the lenticels are arranged loosely to allow the di>usion o!gases into and out o! the plant tissues.

(a) Roots

/ $ygen di>uses !rom the air spaces between the soil particles into the roottissues by di>usion.

%. ?nta0e o! o$ygen during the day

/ "uring day time* where there is sunlight* photosynthesis ta0es place.

/ tomata open. &arbon dio$ide di>uses into the leaves and is used inphotosynthesis. $ygen is produced.

/ s the rate o! photosynthesis e$ceeds the rate o! respiration* moreo$ygen is produced that can be used up by the respiring cells.

/ ome o$ygen di>uses !rom the chloroplasts to the mitocondria !or cellularrespiration the rest di>uses into the substomatal air spaces* and intercellular airspaces.

,. ?nta0e o! o$ygen during the night

/ t night* photosynthesis does not occurs. tomata are closed.

/ $ygen cannot enter the lea!.

/ Respiration is carried out by using

(i) o$ygen !rom the air trapped in the substomatal air spaces* and intercellularair spaces.

(ii) $ygen ta0en through the lenticels and root hairs o! plants.

A.8., erobic nd naerobic Respiration ?n 2lants

• erobic respiration

/ is usually carried out by plants throughout the day and night.

C0 H12 O0 0O2 0CO2 0H2O ener*y.

$3#cose O,y*en


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• naerobic respiration

/ is carried out under certain conditions !or short periods

/ e$ample :/ in a ood

/ during the initial stages o! seed germination.

C0 H12 O0 2C2HOH 2CO2

*3#cose ethano3 car!on +io,i+e

A.8.1 &ompare and contrast the processes o! 2hotosynthesis and Respiration

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"?''#R#@

2hotosynthesis Respiration


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A.8.1 he relationship between the percentage composition o! carbon dio$idein the air with photosynthesis and cell respiration

1. &ell respiration

/ ta0es place all the time

/ using o$ygen and producing carbon dio$ide into the air

%. 2hotosynthesis

/ ta0es place only in day light

/ using carbon dio$ide and producing o$ygen into the air

,. 2ercentage composition o! carbon dio$ide in the air among plantsthroughout the day


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.

(a) 'rom morning to noon

/ he rate o! photosynthesis increases.

/ &oncentration o! carbon dio$ide in the air drops because more carbondio$ide is used !or photosynthesis

(b) t noon

/ he rate o! photosynthesis is the highest./ 2ercentage composition o! carbon dio$ide reaches the lowest level.

(c) 'rom noon until sunset

/ he rate o! photosynthesis decreases gradually.

/ &oncentration o! carbon dio$ide in the air increases because less carbondio$ide is used !or photosynthesis

(d) t midnight


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/ @o photosynthesis is carried out.

/ 2ercentage composition o! carbon dio$ide reaches the pea0* o! which alarge portion o! carbon dio$ide is contributed by cell respiration.

-. &ompensation point

/ &ompensation point is the point o! light intensity where there is no nete$change o! carbon dio$ide and o$ygen.

/ his means it is a point where all the released o$ygen (by photosynthesis)is used up in the cell respiration and all the released carbon dio$ide (by cellrespiration) is used up in the photosynthesis.

/ ?! the rate o! photosynthesis and the rate o! respiration is remained at thecompensation point:

(a) here will be no growth and development in green plants

Gradually* as the o$ygen in the air is used up but not replenished byphotosynthesis* all o$ygen breathing living organisms would die o! su>ocation.

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Biology f4 Chap 7