IB 150 ALL PRACTICE HOMEWORK QUESTIONS AND COR
What cis cone creason cthat corganisms chave cto cmaintain chomeostasis c(maintaining ca crelatively cs
cdiffers cfrom cthe cexternal cenvironment)? c- cCORRECT cANS✔✔Organisms chave cto cperpetually c
cequilibrium cwith cthe cenvironment.
What ccan cyou cconclude cabout can corganism cthat chas creached cequilibrium cwith cits cexternal cen
cANS✔✔The corganism cis cdead.
Which cof cthe ccell cshapes cin cthe cprevious cquestion cdo cyou cexpect cto cmake cup cthe clining cof cy
cCORRECT cANS✔✔Sheet
Match cthe cfollowing cconcepts cto ctheir cappropriate crelationships cand cfunctions cwith crespect cto c
cANS✔✔the cFick's cLaw cequation c→ cmodels cthe crate cof cdiffusion
metabolic crate cof corganism c→ cdetermines c(in cpart) cP1
each cof cthe cfour cvariables cin cFick's cLaw c→ caffects cthe clikelihood cof crespiratory cgas cmolecule
cpoint cB cvia crandom cmotions
Second cLaw cof cThermodynamics c→ cshows cthat cthe cprocess cof cdiffusion cis cexergonic
surface carea cto cvolume cratio c(SA/V) c→ cexplains cthe crelationship cbetween cthe crate cof csupply c
crespiratory cgases
The cfigure cbelow cshows cthe csimplified cdiagram cof cthe cinsect crespiratory csystem cthat cwe cused
coxygen cto cits ccells cvia cdiffusion.
Why cdid cwe chave cto cdivide cthe centire clength cthat can coxygen cmolecule chas cto ctraverse cvia cd
catmosphere cto cinside cthe cmitochondria cof ca cbody ccell cinto ctwo cdistances, cand ccalculate cthe c
cthe cdistance cX-Y cand cY-Z? c- cCORRECT cANS✔✔D cdiffers cfor cthe ctwo cdistances
In cclass, cwe cdetermined cthat cthe clarger cinsect cwas cnot cable cto cachieve ca csufficient crate cof cd
cY cin cits ctracheal csatisfy cthe coxygen cdemand cof cits ccells cwithout cincreasing cthe ccross-sectiona
The cvariables cof cFick's cLaw cthat cwe cdetermined cfor cour clarger cinsect cwith cthin ctrachea cis csho
Assuming cthat cthe ccells cof cthe cinsect crequire can coxygen csupply cof c2.0 c* c10-6 cmL/min c(= c0.0
cdetermine cwhat cthe ccross-sectional carea c(A) cof cthis clarger cinsect chas cto cminimally cbe cin cµm2
cof cdiffusion cof coxygen cof c2.0 c* c10-6 cmL/min.
Round cyour canswer cto cthe cnearest cfull cµm2. c- cCORRECT cANS✔✔110
,For cexample, cas cin cany crespiratory corgan, cthe cactual crespiratory csurfaces cwhere cthe ctips cof ct
cwith cindividual ccells cof cthe cinsect care cmoist cand cfilled cwith cwater.
When cthe cinsect cbecomes cactive cand cits cmuscle ccells chave ca cgreater cdemand cfor coxygen cas
cpulls cout cof cthe ctracheoles cand cinto cthe cmuscle ccells cagain c(see cfigure cabove). cWhat cmight c
cinsect? c- cCORRECT cANS✔✔Decreases cthe cpart cof cthe cdistance cfilled cwith ca cmedium cthat ch
cto cincrease cthe cdiffusion crate cat ctimes cof chigh cmetabolic cdemand cfor coxygen.
There care cmany cdifferent cspecies cof cmarine cannelid cworm. cSome care cvery csmall, conly ca cfew
csuch cas clugworms, care cmuch clarger. cLugworms clive cin cU-shaped cburrows cthat cthey cbuild cin c
cmarine cintertidal czones.
Ignoring csurface carea cof cgills, cwhich cof cthe cfollowing cvariables cDECREASES cas ca clugworm cg
cANS✔✔SA/V
There care cmany cdifferent cspecies cof cmarine cannelid cworm. cSome care cvery csmall, conly ca cfew
csuch cas clugworms, care cmuch clarger. cLugworms clive cin cU-shaped cburrows cthat cthey cbuild cin c
cmarine cintertidal czones.
Which cvariable cdoes cpresence cof cgills cmost caffect cin clugworms? c- cCORRECT cANS✔✔A
Blue cwhales care cmammals cand cjust clike cus chave clungs cwith calveoli cand ctransport coxygen cin c
csystem. cHowever, cin ccontrast cto cus, cblue cwhales care cthe cbiggest canimals cthat chave cever clive
Compared cto ca chuman, cthe ctotal cdistance cthat coxygen chas cto cdiffuse cto creach ccells cin cblue cw
cdistance cof cbulk cflow cfor coxygen cin cblue cwhales cis cblank c. c- cCORRECT cANS✔✔roughly cthe
larger.
What cis ca cprerequisite c(requirement) cfor ccounter-current cexchange cto cfunction? c- cCORRECT cA
cthe coutside cmedium c(air cor cwater)
bulk cflow c(mass cflow) cof cblood cand cexternal cmedium c(air cor cwater)
Mammalian clungs cwith cthe crespiratory csurfaces cin cthe cshape cof cdead-end calveoli crequire ctidal
cis cnot cconducive cto ccounter-current cexchange. cThe cnext ctwo cquestions cask cyou cto cexplore cw
When casked cto cdemonstrate cwhy csomething ccannot cwork, can ceffective cstrategy cis cto cmodel ct
cexplore cwhat cthe cconsequences cwould cbe. cBelow cis ca cdiagram cof cwhat cour calveoli cmight cloo
cenable ccounter-current cflow cduring cinhalation:
First, cidentify cthe cconcentration cgradient cfor cboth cinhalation cand cfor cexhalation cin cthe chypothe
cplumbed cfor ccounter-current cexchange cduring cinhalation. c- cCORRECT cANS✔✔blood cduring ce
blood cduring cinhalation c→ cPlow
air cduring cexhalation c→ cPlow
air cduring cinhalation c→ cPhigh
Based con cyour canswer cto cthe cprevious cquestion, cwhat cproblem cprevents cmammalian clungs cfr
current cdesign?
If cmammalian calveoli chad crespiratory ccapillaries cdirected cto cengage cin ccounter-current cexchan
cCORRECT cANS✔✔the cconcentration cgradient cwould creverse cduring cexhalation cand ccause cdi
cto cthe cair.
There care cmany cdifferent cspecies cof cmarine cannelid cworm. cSome care cvery csmall, conly ca cfew
csuch cas clugworms, care cmuch clarger. cLugworms clive cin cU-shaped cburrows cthat cthey cbuild cin c
cmarine cintertidal czones.
Lugworms ccreate ca cunidirectional cwater ccurrent cthat cruns cthrough ctheir cU-shaped cburrows. cW
cto cestablish ca ccountercurrent coxygen cexchange cin ctheir cgills? c- cCORRECT cANS✔✔Capillaries
cdirected cto crun cblood cin cthe copposite cdirection cas cexternal cwater cflow
How cis/are cthe crelevant cvariable(s) cof cFick's cLaw coptimized cby cthe ccountercurrent coxygen cexc
cCORRECT cANS✔✔The ccorrect canswer cis: c(Phigh-Plow) cis cre-established
, For cplants, cobtaining cCO2 cby cdiffusion cthrough cstomata cinto cthe cleaf cis cdirectly clinked cto cwat
cand csubsequent cdiffusion cthrough cstomata cout cof cthe cleaf. cPlants ccan cprevent cwater closs cby
cstomatal copening cusing cthe cguard ccells cthat csurround cthe copenings. cHowever, cthis csets cup ca
cbecause cclosing cstomata calso creduces cdiffusion cof cCO2 cinto cthe cleaf, cand chence creduces cth
cphotosynthesis c& cgrowth. cThe crelationship cis cimportant cto cunderstand cin clight cof congoing cclim
cimpact cof cchanges cin cCO2 cconcentration cin cour catmosphere cdue cto cburning cof cfossil cfuels ca
cdrought cconditions con cour cability cto cgrow cenough cfood cfor ca cgrowing cworld cpopulation.
Prof. cLisa cAinsworth cis ca cplant cphysiologist cand cgeneticist cin cIntegrative cBiology. cDr. cAinswort
crecognition cfor che c- cCORRECT cANS✔✔Increased cdrought cconditions cforced cplants cto creduce
cLaw cto cavoid cwater closs cto ca cdegree cthat creduced cdiffusion crates cof cCO2 cbelow ctoday's cval
catmospheric cCO2 cconcentrations.
When cmeasuring cthe crespiratory csurface carea cof cgills cin cbrook ctrout, cAbigail cnotices cthat cthe c
cwhen ccompared cto cthe cvolume cof cthe cfish cas cthe cfish cgrew:
What crelationship cdo cthe cdata cin cthe cgraph creveal cas cthe ctrout cgrow clarger? c- cCORRECT cAN
crespiratory csurface carea cto cbody cvolume cis cconstant c(stays cthe csame)
Based con cher cdata, cwhat cdid cAbigail cconclude cenabled cthe cfish cto cmaintain cthis crelationship c
cbody cvolume cduring cthe cfish's cgrowth? c- cCORRECT cANS✔✔As cthe cbody cof cthe cfish cgrows,
cincrease cmuch cfaster cthan cpredicted cfor cthe cSA/V cratio cof ca cbody cof cthe csame cshape cso cth
cwhen cits cbody cvolume cdoubles cduring cgrowth.
Alessandro cstarts ca cproject cto cbetter cunderstand ccarp cgill canatomy. cHe cknows cthat cthe cbrook
clive cin chighly coxygenated cmountain cstreams. cIn ccontrast, ccarp care cbottom-dwelling cfish cin clak
ca cmuch clower coxygen cconcentration.
Alessandro cwould clike cto cuse cAbigail's cdata con cbrook ctrout cto cmake csome cpredictions cabout c
cdata.
Knowing cthe cdifference cin coxygen cconcentration cin ctheir cenvironment, cand cassuming ceverythin
cbrook ctrout cexample, cwhich cof cthe cdotted clines cshows cthe cpredicted crelationship cof cbody cvolu
ccarp cin ccomparison cto cthe cbrook ctrout crelationship c(thin csolid cline)? c- cCORRECT cANS✔✔Lin
After cAlessandro ccollected csome cdata, che cfinds cthat cthe ccarp cdata care cmost csimilar cto cLine cB
cthat cthe crelationship cof cgill csurface carea cand cvolume cin ccarp cis csimilar cto cthat cof ctrout.
Which cof cthe cfollowing chypotheses cmay cbe cpossible cexplanations cthat care cconsistent cwith cthe
ccan cset cout cto ctest cnext cin chis ccarp cstudy csystem? c- cCORRECT cANS✔✔Carp chave ca chighe
cin ctheir cblood cthan ctrout cdo., cCarp chave ca clower cmetabolic cenergy crequirement cthan ctrout cdo
coxygen cconcentrations cin ctheir cenvironment cthan cpreviously cassumed.
Prof. cChris cCheng cis ca cmolecular cphysiologist cin cIntegrative cBiology cwho cstudies ca cgroup cof c
cSome cspecies cin cthis cgroup care cunique cin cthat cthey care cthe conly cvertebrates cknown cwho clac
crespiratory cpigment chemoglobin.
Below care csome cadditional cobservations cabout cicefish. cMatch ceach cof cthese cobservations cto c
cthat ccould chelp cexplain chow cthese ccurious cfish ccan cmaintain csufficient coxygen csupply cto csati
cdespite cthe clack cof crespiratory cpigments. c- cCORRECT cANS✔✔Cold cwater ccan cdissolve cmore
chigh cPhigh c(high cconcentration)
Icefish chave cno cscales cin ctheir cskin, cand ccan chence cuse ctheir cskin cas ca crespiratory csurface. c
Ice cfish chave can cunusually chigh cvolume cof cblood ccompared cto ctheir cbody cweight. c→ chigh crat
cflow
Icefish conly clive cin cwater cnear cthe cfreezing cpoint. c→ clow cmetabolic cdemand cfor coxygen
Ice cfish ccontain ca cprotein cin ctheir cblood cthat cacts cas can cantifreeze. c→ cdoes cnot cexplain cmee
coxygen
Some cspecies cof cicefish care cnearly ctransparent cbecause cthey calso clost cthe cmuscle cpigment cm
cmeeting cmetabolic cdemand cfor coxygen
Birds cengage cin ccounter-current cexchange, cmammals cdo cnot. cSimply cbased con cwhat cyou ckno
What cis cone creason cthat corganisms chave cto cmaintain chomeostasis c(maintaining ca crelatively cs
cdiffers cfrom cthe cexternal cenvironment)? c- cCORRECT cANS✔✔Organisms chave cto cperpetually c
cequilibrium cwith cthe cenvironment.
What ccan cyou cconclude cabout can corganism cthat chas creached cequilibrium cwith cits cexternal cen
cANS✔✔The corganism cis cdead.
Which cof cthe ccell cshapes cin cthe cprevious cquestion cdo cyou cexpect cto cmake cup cthe clining cof cy
cCORRECT cANS✔✔Sheet
Match cthe cfollowing cconcepts cto ctheir cappropriate crelationships cand cfunctions cwith crespect cto c
cANS✔✔the cFick's cLaw cequation c→ cmodels cthe crate cof cdiffusion
metabolic crate cof corganism c→ cdetermines c(in cpart) cP1
each cof cthe cfour cvariables cin cFick's cLaw c→ caffects cthe clikelihood cof crespiratory cgas cmolecule
cpoint cB cvia crandom cmotions
Second cLaw cof cThermodynamics c→ cshows cthat cthe cprocess cof cdiffusion cis cexergonic
surface carea cto cvolume cratio c(SA/V) c→ cexplains cthe crelationship cbetween cthe crate cof csupply c
crespiratory cgases
The cfigure cbelow cshows cthe csimplified cdiagram cof cthe cinsect crespiratory csystem cthat cwe cused
coxygen cto cits ccells cvia cdiffusion.
Why cdid cwe chave cto cdivide cthe centire clength cthat can coxygen cmolecule chas cto ctraverse cvia cd
catmosphere cto cinside cthe cmitochondria cof ca cbody ccell cinto ctwo cdistances, cand ccalculate cthe c
cthe cdistance cX-Y cand cY-Z? c- cCORRECT cANS✔✔D cdiffers cfor cthe ctwo cdistances
In cclass, cwe cdetermined cthat cthe clarger cinsect cwas cnot cable cto cachieve ca csufficient crate cof cd
cY cin cits ctracheal csatisfy cthe coxygen cdemand cof cits ccells cwithout cincreasing cthe ccross-sectiona
The cvariables cof cFick's cLaw cthat cwe cdetermined cfor cour clarger cinsect cwith cthin ctrachea cis csho
Assuming cthat cthe ccells cof cthe cinsect crequire can coxygen csupply cof c2.0 c* c10-6 cmL/min c(= c0.0
cdetermine cwhat cthe ccross-sectional carea c(A) cof cthis clarger cinsect chas cto cminimally cbe cin cµm2
cof cdiffusion cof coxygen cof c2.0 c* c10-6 cmL/min.
Round cyour canswer cto cthe cnearest cfull cµm2. c- cCORRECT cANS✔✔110
,For cexample, cas cin cany crespiratory corgan, cthe cactual crespiratory csurfaces cwhere cthe ctips cof ct
cwith cindividual ccells cof cthe cinsect care cmoist cand cfilled cwith cwater.
When cthe cinsect cbecomes cactive cand cits cmuscle ccells chave ca cgreater cdemand cfor coxygen cas
cpulls cout cof cthe ctracheoles cand cinto cthe cmuscle ccells cagain c(see cfigure cabove). cWhat cmight c
cinsect? c- cCORRECT cANS✔✔Decreases cthe cpart cof cthe cdistance cfilled cwith ca cmedium cthat ch
cto cincrease cthe cdiffusion crate cat ctimes cof chigh cmetabolic cdemand cfor coxygen.
There care cmany cdifferent cspecies cof cmarine cannelid cworm. cSome care cvery csmall, conly ca cfew
csuch cas clugworms, care cmuch clarger. cLugworms clive cin cU-shaped cburrows cthat cthey cbuild cin c
cmarine cintertidal czones.
Ignoring csurface carea cof cgills, cwhich cof cthe cfollowing cvariables cDECREASES cas ca clugworm cg
cANS✔✔SA/V
There care cmany cdifferent cspecies cof cmarine cannelid cworm. cSome care cvery csmall, conly ca cfew
csuch cas clugworms, care cmuch clarger. cLugworms clive cin cU-shaped cburrows cthat cthey cbuild cin c
cmarine cintertidal czones.
Which cvariable cdoes cpresence cof cgills cmost caffect cin clugworms? c- cCORRECT cANS✔✔A
Blue cwhales care cmammals cand cjust clike cus chave clungs cwith calveoli cand ctransport coxygen cin c
csystem. cHowever, cin ccontrast cto cus, cblue cwhales care cthe cbiggest canimals cthat chave cever clive
Compared cto ca chuman, cthe ctotal cdistance cthat coxygen chas cto cdiffuse cto creach ccells cin cblue cw
cdistance cof cbulk cflow cfor coxygen cin cblue cwhales cis cblank c. c- cCORRECT cANS✔✔roughly cthe
larger.
What cis ca cprerequisite c(requirement) cfor ccounter-current cexchange cto cfunction? c- cCORRECT cA
cthe coutside cmedium c(air cor cwater)
bulk cflow c(mass cflow) cof cblood cand cexternal cmedium c(air cor cwater)
Mammalian clungs cwith cthe crespiratory csurfaces cin cthe cshape cof cdead-end calveoli crequire ctidal
cis cnot cconducive cto ccounter-current cexchange. cThe cnext ctwo cquestions cask cyou cto cexplore cw
When casked cto cdemonstrate cwhy csomething ccannot cwork, can ceffective cstrategy cis cto cmodel ct
cexplore cwhat cthe cconsequences cwould cbe. cBelow cis ca cdiagram cof cwhat cour calveoli cmight cloo
cenable ccounter-current cflow cduring cinhalation:
First, cidentify cthe cconcentration cgradient cfor cboth cinhalation cand cfor cexhalation cin cthe chypothe
cplumbed cfor ccounter-current cexchange cduring cinhalation. c- cCORRECT cANS✔✔blood cduring ce
blood cduring cinhalation c→ cPlow
air cduring cexhalation c→ cPlow
air cduring cinhalation c→ cPhigh
Based con cyour canswer cto cthe cprevious cquestion, cwhat cproblem cprevents cmammalian clungs cfr
current cdesign?
If cmammalian calveoli chad crespiratory ccapillaries cdirected cto cengage cin ccounter-current cexchan
cCORRECT cANS✔✔the cconcentration cgradient cwould creverse cduring cexhalation cand ccause cdi
cto cthe cair.
There care cmany cdifferent cspecies cof cmarine cannelid cworm. cSome care cvery csmall, conly ca cfew
csuch cas clugworms, care cmuch clarger. cLugworms clive cin cU-shaped cburrows cthat cthey cbuild cin c
cmarine cintertidal czones.
Lugworms ccreate ca cunidirectional cwater ccurrent cthat cruns cthrough ctheir cU-shaped cburrows. cW
cto cestablish ca ccountercurrent coxygen cexchange cin ctheir cgills? c- cCORRECT cANS✔✔Capillaries
cdirected cto crun cblood cin cthe copposite cdirection cas cexternal cwater cflow
How cis/are cthe crelevant cvariable(s) cof cFick's cLaw coptimized cby cthe ccountercurrent coxygen cexc
cCORRECT cANS✔✔The ccorrect canswer cis: c(Phigh-Plow) cis cre-established
, For cplants, cobtaining cCO2 cby cdiffusion cthrough cstomata cinto cthe cleaf cis cdirectly clinked cto cwat
cand csubsequent cdiffusion cthrough cstomata cout cof cthe cleaf. cPlants ccan cprevent cwater closs cby
cstomatal copening cusing cthe cguard ccells cthat csurround cthe copenings. cHowever, cthis csets cup ca
cbecause cclosing cstomata calso creduces cdiffusion cof cCO2 cinto cthe cleaf, cand chence creduces cth
cphotosynthesis c& cgrowth. cThe crelationship cis cimportant cto cunderstand cin clight cof congoing cclim
cimpact cof cchanges cin cCO2 cconcentration cin cour catmosphere cdue cto cburning cof cfossil cfuels ca
cdrought cconditions con cour cability cto cgrow cenough cfood cfor ca cgrowing cworld cpopulation.
Prof. cLisa cAinsworth cis ca cplant cphysiologist cand cgeneticist cin cIntegrative cBiology. cDr. cAinswort
crecognition cfor che c- cCORRECT cANS✔✔Increased cdrought cconditions cforced cplants cto creduce
cLaw cto cavoid cwater closs cto ca cdegree cthat creduced cdiffusion crates cof cCO2 cbelow ctoday's cval
catmospheric cCO2 cconcentrations.
When cmeasuring cthe crespiratory csurface carea cof cgills cin cbrook ctrout, cAbigail cnotices cthat cthe c
cwhen ccompared cto cthe cvolume cof cthe cfish cas cthe cfish cgrew:
What crelationship cdo cthe cdata cin cthe cgraph creveal cas cthe ctrout cgrow clarger? c- cCORRECT cAN
crespiratory csurface carea cto cbody cvolume cis cconstant c(stays cthe csame)
Based con cher cdata, cwhat cdid cAbigail cconclude cenabled cthe cfish cto cmaintain cthis crelationship c
cbody cvolume cduring cthe cfish's cgrowth? c- cCORRECT cANS✔✔As cthe cbody cof cthe cfish cgrows,
cincrease cmuch cfaster cthan cpredicted cfor cthe cSA/V cratio cof ca cbody cof cthe csame cshape cso cth
cwhen cits cbody cvolume cdoubles cduring cgrowth.
Alessandro cstarts ca cproject cto cbetter cunderstand ccarp cgill canatomy. cHe cknows cthat cthe cbrook
clive cin chighly coxygenated cmountain cstreams. cIn ccontrast, ccarp care cbottom-dwelling cfish cin clak
ca cmuch clower coxygen cconcentration.
Alessandro cwould clike cto cuse cAbigail's cdata con cbrook ctrout cto cmake csome cpredictions cabout c
cdata.
Knowing cthe cdifference cin coxygen cconcentration cin ctheir cenvironment, cand cassuming ceverythin
cbrook ctrout cexample, cwhich cof cthe cdotted clines cshows cthe cpredicted crelationship cof cbody cvolu
ccarp cin ccomparison cto cthe cbrook ctrout crelationship c(thin csolid cline)? c- cCORRECT cANS✔✔Lin
After cAlessandro ccollected csome cdata, che cfinds cthat cthe ccarp cdata care cmost csimilar cto cLine cB
cthat cthe crelationship cof cgill csurface carea cand cvolume cin ccarp cis csimilar cto cthat cof ctrout.
Which cof cthe cfollowing chypotheses cmay cbe cpossible cexplanations cthat care cconsistent cwith cthe
ccan cset cout cto ctest cnext cin chis ccarp cstudy csystem? c- cCORRECT cANS✔✔Carp chave ca chighe
cin ctheir cblood cthan ctrout cdo., cCarp chave ca clower cmetabolic cenergy crequirement cthan ctrout cdo
coxygen cconcentrations cin ctheir cenvironment cthan cpreviously cassumed.
Prof. cChris cCheng cis ca cmolecular cphysiologist cin cIntegrative cBiology cwho cstudies ca cgroup cof c
cSome cspecies cin cthis cgroup care cunique cin cthat cthey care cthe conly cvertebrates cknown cwho clac
crespiratory cpigment chemoglobin.
Below care csome cadditional cobservations cabout cicefish. cMatch ceach cof cthese cobservations cto c
cthat ccould chelp cexplain chow cthese ccurious cfish ccan cmaintain csufficient coxygen csupply cto csati
cdespite cthe clack cof crespiratory cpigments. c- cCORRECT cANS✔✔Cold cwater ccan cdissolve cmore
chigh cPhigh c(high cconcentration)
Icefish chave cno cscales cin ctheir cskin, cand ccan chence cuse ctheir cskin cas ca crespiratory csurface. c
Ice cfish chave can cunusually chigh cvolume cof cblood ccompared cto ctheir cbody cweight. c→ chigh crat
cflow
Icefish conly clive cin cwater cnear cthe cfreezing cpoint. c→ clow cmetabolic cdemand cfor coxygen
Ice cfish ccontain ca cprotein cin ctheir cblood cthat cacts cas can cantifreeze. c→ cdoes cnot cexplain cmee
coxygen
Some cspecies cof cicefish care cnearly ctransparent cbecause cthey calso clost cthe cmuscle cpigment cm
cmeeting cmetabolic cdemand cfor coxygen
Birds cengage cin ccounter-current cexchange, cmammals cdo cnot. cSimply cbased con cwhat cyou ckno
