hormones.docx

hormones.docx

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hormones

Question

1989Paper1Question4

4.Withtheaidofgraphs,relatetheeventsofthehumnmenstrualcycletochangesinhormonelevel.

（8marks）

Ans

1989Paper2Question5（c）

5.（c）ExplainTWOfunctionaldifferencesbetweenthenervousandhormonalcoordinatingsystems.

（4marks）

Ans

1990Paper1Question5

5.Statepreciselyasourceofeachofthefollowinghormonesandgiveabriefaccountoftheirfunctions:

（a）testosterone

（b）progesterone（6marks）

Ans

1990Paper1Question8

8.Theconcentrationsofglucoseandtwopancreatichormones（AandB）inthebloodofamammalweremonitoredbefore,duringandafteranormalcarbohydrate-richmeal.Thefollowingtableshowsthetypicalchangesinthelevelsofbloodglucoseandthesetwohormonesduringtheexperiment:

Time（min）

Concentrationinblood

Glucose

（10-5g/ml）

hormoneA

（10-6internationalunits/ml）

hormoneB

（10-12g/ml）

60minutesbeforemeal

89

16

127

Meal

0

87

17

125

Aftermeal

30

60

120

180

240

300

125

134

105

94

89

88

100

140

89

38

19

18

103

92

77

114

126

125

（a）Plottheaboveresultsintheformofagraph.（6marks）

（b）Howdothetwohormonesdifferintheirresponsetochangesinbloodglucoselevel?

Namethetwohormones.（2marks）

（c）DrawaflowdiagramtoindicatetherelationshipbetweentheincreaseinbloodglucoselevelandthesecretionofhormonesAandB.Indicateinyourdiagram,foreachhormone,itssiteofsecretionandonemajoreffectonthetargettissuesconcerned.（4marks）

（d）If,insteadofthecarbohydratemeal,anequivalentamountofglucoseisadministereddirectlyintothebloodstream,howwouldthisaffecttheobservedchangesinbloodglucoselevel?

Giveareasonforyouranswer.（2marks）

（e）（i）Inasimilarexperiment,thebloodglucosewasmonitoredasintheaboveexperiment.Threehoursafterthemeal,theadrenalmedullaoftheanimalwasbrieflystimulatedtosecretealargeamountofanadrenomedullaryhormone,theeffectofwhichdisappearedwithinanhour.Sketchacurveinyouranswerbookbasedonthecurveplottedin（a）,butmodifiedtoshowthepossiblechangesinbloodglucoselevelafterthestimulation.（3marks）

（ii）Namethisadrenomedullaryhormone.Whatisthebiologicalsignificanceofthechangeinbloodglucoselevelcausedbythesecretionofthisadrenomedullaryhormone?

（3marks）

Ans

1991Paper1Question9

9.Theautoradiographsbelowshowfreshlydetachedleavesoftobacco,eachofwhichhasbeentreatedwithaspotofaradioactiveaminoacid.Theregionscircledbywhitedottedlinesshowtheareaswheretheradioactiveaminoacidwasapplied.Therelativeagesoftheleavesareshown.ThelefthalfofleafCandtherighthalfofleafDwerepaintedwiththeplanthormonecalledkinetin.

（a）HowdoesthemovementoftheaminoaciddifferbetweentheyoungleafAandthematureleafB?

Suggestareasonforthisdifference.（5marks）

（b）ComparingleavesBandC,whatistheeffectofthekinetinonthemovementoftheaminoacid?

（1mark）

（c）ComparingleavesBandD,howdoesthekinetinaffectthemovementoftheaminoacid?

（1mark）

（d）ComparingleafAwithleavesB,CandD,suggestapossibleroleforkinetinincellularactivities.Explainyouranswer.（3marks）

（e）Suggestwhere,inwholeplants,kinetinismostlikelytobeproduced.（3marks）

（f）Explainwhy,inthisexperiment,itisimportanttousefreshlydetachedleavesratherthandetachedleaveswhichhavebeenstoredforsometime.（3marks）

（g）Brieflydescribetheeffectsofkinetinonthegrowthanddevelopmentofplants.（3marks）

（h）SuggestONEcommercialuseforkinetin.（1mark）

Ans

1992Paper2Question7

7.Discusstherolesofhormonesinthelifeoffloweringplants.（20marks）

Ans

1993Paper1Question9

9.Inanexperimenttostudytheeffectofplanthormonesonthegrowthofpeaseedlings,etiolatedpeaseedlingsweredecapitated.Theapicalregionofeachepicotylwasmarkedoffintoa10mm'segment'asshownbelow:

Theseedlingswerethenseparatedinto3batcheseachof120.TwoofthebatchesweretreatedwithplanthormoneAorBasshowninthetablebelow.

Thedifferentbatcheswerethenallowedtogrowintotaldarknessfor5days.Atdailyintervals,20'segments'fromeachbatchwerecutoffandtheirmeanlength（L）andmeanfreshweight（W）determined.

foreachbatchwasalsocalculated.Theresultsareshowninthefollowingtable:

Day

Control

+HormoneA

+HormoneB

L

（mm）

W

（mg）

（mg/mm）

L

（mm）

W

（mg）

（mg/mm）

L

（mm）

W

（mg）

（mg/mm）

0

10.0

20.5

2.05

10.0

21.0

2.10

10.0

21.5

2.15

1

10.2

21.0

2.06

10.3

27.5

2.67

12.5

25.0

2.00

2

10.8

21.5

1.99

10.9

42.5

3.90

15.5

36.0

2.32

3

11.0

22.0

2.00

11.2

60.0

5.36

22.0

49.5

2.25

4

11.5

22.0

1.91

11.4

69.5

6.10

29.5

59.0

2.00

5

11.4

22.5

1.97

11.3

60.5

5.35

30.0

60.0

2.00

（a）Withreferencetothedataonmeanlength（L）,whatconclusionscanbedrawn?

（2marks）

（b）Whatdoesthemeanfreshweightofthe'segments'（W）tellyouaboutthecellvolumeoftheseedlings?

Explainyouranswer.

（4marks）

（c）Followingyourreasoninginpart（b）,whatdoes

mean?

（2marks）

（d）Plotagraphtoshowhow

changeswithtimeforboththecontrolandthoseseedlingstreatedwithhormoneA.（4marks）

（e）Whatconclusionscanbedrawnfromthegraph?

（2marks）

（f）NameaplanthormonewhichmayhavecharacteristicssimilartohormoneB.（1mark）

（g）Suggestapossibleexplanationforthedecreasein

onday5relativetothatofday4inthebatchofseedlingstreatedwithhormoneA.（1mark）

（h）Explainthereasonsbehindthefollowingexperimentalprocedures:

（i）decapitationofthepeaseedlings

（ii）growingofseedlingsintotaldarkness（4marks）

Ans

1994Paper1Question12

12.（a）Juvenilefishareusuallysexuallyundifferentiatedwithinacertainperiodafterhatching.Thesexofjuvenilefishatthisstagecanbemanipulatedbytheexternalapplicationofhormones.

Anexperimentwasconductedusingthreedifferentsizegroups（A,BandC）ofjuvenilefishofthesamespecies.Thefishineachsizegroupwasthenallocatedto10tanksandfedwithadietcontainingvariousconcentrationsofhormoneXfor30days.Attheendofthe30-dayperiod,theproportionofmalesineachtankwasdeterminedandplottedasshowninFigure1.

Sizegroup

Initialsizeoffish（mm）

A

B

C

5–10

11–15

16-20

Figure1

（i）WithreferencetoFigure1,describetheeffectsofhormoneapplicationininducingmalefishinthe3groupsofjuvenilefish.（5marks）

（ii）Calculatethemaletofemaleratioforthe3groupsatahormoneconcentrationof30mgkg-1diet.Whatsizeoffishwouldyouusetoproducemalefishonlywithhormonetreatment?

Explainyourchoice.（4marks）

（iii）NameahormonewhichcouldexertsimilarphysiologicaleffectstoX.（1mark）

（b）Inanotherexperiment,juvenilefishofthesamespecieswereculturedinthreeseparatetanks.Eachtankcontainedthesamenumberoffish.Tank1containedmixedsexes,tank2containedmalefishonlyandtank3containedfemalefishonly.Theywereculturedforaperiodof6monthsbeforeharvest.Thefollowingtableshowstheexperimentaldata:

Tank1

Tank2

Tank3

Start

Harvest

Start

Harvest

Start

Harvest

Meanweight

perfish/g

Malefish

5

95

5

110

－

－

Femalefish

5

80

－

－

5

85

Inwhichtankwasthegreatestyieldoffishobtained?

Whatistheratioofthemeanweightperfishatharvesttotheinitialvalueinthistank?

（2marks）

（c）Basedontheinformationderivedfromtheexperimentsdescribedin（a）and（b）,whatspecificconditionswouldberequiredtomaximizetheyieldofthisspeciesoffishinaquaculture?

（3marks）

（Total:

15marks）

Ans

1995Paper1Question4（b）

4.Distinguishbetween

（b）theactionsofantidiuretichormone（ADH）andaldosteroneinosmoregulation

Ans

1997Paper1Question9

9.ThefollowinggraphsshowthechangesinthelevelsofhormonesA,B,CandDintheplasmaduringonemenstrualcycleofahealthywoman.Thechanginghormonelevelsalsoshowtheinteractionofthesefourhormoneswhichbringsabouteventsinthemenstrualcycle.

（a）（i）Basedonthechanginghormonelevelsshowninthegraphs,deducetheeffectofhormoneAonhormonesCandDfromday2today11.Duringwhatothertimeperiod（s）inthemenstrualcycleisthereasimilarrelationshipbetweenthesehormones?

（2marks）

（ii）Immediatelyafterday12,theeffectofhormoneAonhormonesCandDchangesabruptly.Fromthegraphs,readoffthedayswhenhormonesA,CandDreachtheirmaximumlevels.Usingthisinformation,deducetheeffectofhormoneAonhormonesCandDduringthistimeperiod.Suchaneffectbringsaboutanimportanteventinthemenstrualcycle.Whatisthisevent?

（3marks）

（b）HormoneBisanimportantingredientincontraceptivepills.Whatevidencefromthegraphssupportsthis?

Statethecontraceptiveprincipleinvolved.（3marks）

（c）Menstruationisbroughtaboutbydramatichormonalchanges.Usinginformationfromthegraphs,describethesehormonalchanges.（1marks）

（d）Partofthehypothalamusofthewomanwasdamagedinanaccident.Shetoldherdoctorthatshehadnotmenstruatedformonths.HerpregnancytestwasnegativeandherplasmalevelsofhormonesCandDwerefoundtobeverylow.AccountforherlowlevelsofhormonesCandD.Whatisthelikelyconsequenceoftheaccidentonthewoman'schancesofgettingpregnant?

（3marks）

Total:

13marks

Ans

Solution

1989Paper1Question4Solution

4.Onemarkforeachcurve:

1