Sci (bio) syllabus notes 2024

1. Cell StructureandOrganisationContent ● PlantandAnimalCells ● CellSpecialisation LearningOutcomes Candidatesshouldbeableto: (a) identifyandstatethefunctionsofthefollowingcellstructures(includingorganelles)oftypicalplantandanimalcellsfromdiagrams,lightmicrographsandasseenunderthelightmicroscopeusingpreparedslidesandfreshmaterialtreatedwithanappropriatetemporarystainingtechnique: ● cellwall-fullypermeable;givesthecellitsfixedshapeandprotectsitfrominjury ● cellmembrane-partiallypermeable;controlsthesubstancesgoinginandoutofthecell ● cytoplasm-containscellorganellesandenzymes;wheremostcellactivitiesoccur ● nucleus-controllscellactivitiessuchascellgrowthandrepairofworn-outparts;essentialforcelldivision ● cellvacuoles(large,sap-filledinplantcells,small,temporaryinanimalcells)-storesdissolvedsubstances ● chloroplasts-containschlorophyllwhichabsorbslightenergyandconvertsittochemicalenergytomanufactureglucosewithcarbondioxideandwaterduringphotosynthesis.oxygenisproduced. (b) identifyandstatethefunctionsofthefollowingorganellesfromdiagramsandelectronmicrographs: ● mitochondria-siteforaerobicrespirationwhereglucoseisoxidisedtoreleaseenergyforcellularactivities ● ribosomes-synthesisofproteins(c) comparethestructureoftypicalanimalandplantcells plantcell animalcell havecellwall nocellwall hasalargecentralvacuole havenumeroussmallvacuoles havechloroplasts(leafcells) nochloroplasts (d) explainhowthestructuresofspecialisedcellsareadaptedtotheirfunctions(e.g.musclecell–manymitochondriatosupplymoreenergy,roothaircell–largesurfaceareaofcellmembraneforgreaterabsorption,redbloodcell–lackofnucleusallowingittotransportmoreoxygen) roothaircell- long,narrowprotrusiontoincreasesurfaceareatovolumeratioforincreasedrateofabsorptionofwateranddissolvedmineralsalts- uniformlythincellwalltodecreasediffusiondistancetoincreaserateofabsorptionofwatermoleculesandmineralions redbloodcell- circularbiconcaveshapetoincreasesurfaceareatovolumeratioforincreasedrateoftransportofoxygen- absenceofnucleustoallowforpackingofmorehaemoglobintoincreasecarryingcapacityofoxygenmolecules- containshaemoglobinwhichbindsirreversiblywithoxygentoformoxyghaemiglobintotransportitaroundthebody

musclecell- numerousmitochondriatoreleasemoreenergyviaaerobicrespirationforcontractionofmusclecell

2. Movement of SubstancesContent ● Diffusion ● Osmosis LearningOutcomes Candidatesshouldbeableto: (a) definediffusionanddescribeitsroleinnutrientuptakeandgaseousexchangeinplantsandhumans-netmovementofparticlesfromaregionofhigherconcentrationtoaregionoflowerconcentrationdownaconcentrationgradient (b) defineosmosis,investigateanddescribetheeffectsofosmosisonplantandanimaltissues-netmovementofwatermoleculesfromaregionofhigherwaterpotentialtoaregionoflowerwaterpotentialacrossapartiallypermeablemembrane 3. Biological MoleculesContent ● Carbohydrates,FatsandProteins ● Enzymes LearningOutcomes Candidatesshouldbeableto: (a) statethemainrolesofcarbohydrates,fatsandproteinsinlivingorganisms: ● carbohydratesasanimmediatesourceofenergy ● fatsforinsulationandlong-termstorageofenergy ● proteinsforgrowthandrepairofcells (b) describeandcarryouttestsfor: ● starch(usingiodineinpotassiumiodidesolution)-iodineremainsbrown:starchabsent,iodineturnsblue-black:starchpresent ● reducingsugars(usingBenedict’ssolution)-remainsblue:absent,bluetogreenppt:traces,bluetoyellow/orangeppt-moderate,bluetobrickredppt:largeamount ● protein(usingbiuretsolution)-bluetoviolet:present,remainsblue:absent ● fats(usingethanol)-cloudywhiteemulsion:fatspresent,remainsclear:absent (c) statethatlargemoleculesaresynthesisedfromsmallerbasicunits: ● cellulose,glycogenandstarchfromglucose ● polypeptidesandproteinsfromaminoacids ● lipidssuchasfatsfromglycerolandfattyacids

(d) explainthemodeofactionofenzymesintermsofanactivesite,enzyme-substratecomplexandenzymespecificityusingthe‘lockandkey’hypothesisenzymeisthelock,substrateisthekey.substratebindstotheactivesiteoftheenzymetoformenzyme-substratecomplex.whilesubstrateisattachedtotheactivesite,chemicalreactionstakeplace,andsubstrateisconvertedintoproducts,butenzymeremainschemicallyunchangedattheendofthereaction.enzymes- biologicalcatalystsmadeupofproteins- formanenzyme-substratecomplex- requiredinminuteamountsastheycanbereusedoverandoveragain- remainchemicallyunchangedattheendofthereaction- speeduporalterrateofreaction (e) investigateandexplaintheeffectsoftemperatureandpHontherateofenzymecatalysedreactionsincreasingtemperature:particlegainkineticenergy,enzymeismoreactive.beyondoptimumpHandtemperature-enzymesaredenatured,activesiteofenzymeislostoptimumpHandtemperature-enzymesaremostactive,rateofreactionishighest

4. NutritioninHumansContent ● HumanDigestiveSystem ● PhysicalandChemicalDigestion 5. AbsorptionandAssimilation LearningOutcomes Candidatesshouldbeableto: (a) describethefunctionsofthevariouspartsofthedigestivesystem:mouth,salivaryglands,oesophagus,stomach,duodenum,pancreas,gallbladder,liver,ileum,colon,rectum,anus,inrelationtoingestion,digestion,absorption,assimilationandegestionoffood,asappropriate mouth:chewingtobreakfoodintosmallerpiecesforincreasedrateofdigestionbysalivaryamylase salivaryglands;secretesalivacontainingsalivaryamylaseviasalivaryduct,softensfoodforfasterdigestionbysalivaryamylase oesophagus:longnarrowmusculartubemadeupoflongitudinalandcircularmuscles stomach:thickdistenisble,peristalsistochurn,breakupandmixwithgastricjuice,containshydrochlorideacid(pH2),tokillharmfulmicroorganismsinfood,acidictostoptheactionofsalivaryamylase.provideacidicmediumforproteasesmallintestine(duodenum&ileum):peristalsistochurnandbreakuplargepiecesoffoodintosmallerpieces,ileum-absorption,hasvilli(tinyfinger-likeprotrusions)toincreasesurfaceareatovolumeratioforfasterrateofabsorptionofdigestedfood.thesmallintestineislongtoallowmoretimeforabsorption,richlysuppliedwithbloodcapillariestomaintainasteepconcentrationgradientforfasterrateofabsorption. largeintestine:nodigestion,absorbwaterandmineralsaltsfromundigestedfood. rectum:storesfaecestemporarily anus:wherefaecesareexpelledthrough (b) describethefunctionsofenzymes(e.g.amylase,maltase,protease,lipase)indigestion,listingthesubstratesandend-productsamylasedigestsstarchintomaltose(salivaryamylasefoundinmouthandpancreaticamylasefoundinsmallintestine)maltasedigestsmaltoseintoglucose(foundinsmallintestine)stomachandpancreaticproteasedigestsproteinsintopolypeptide,intestinalproteasedigestspolypeptideintoaminoacidslipasedigestsfatsintofattyacidsandglycerol(bothintestinal&pancreaticlipasefoundinsmallintestine) (c) statethefunctionofthehepaticportalveinasthetransportofbloodrichinabsorbednutrientsfromthesmallintestinetotheliver (d) statetheroleoftheliverin: ● conversionofglucosetoglycogenandviceversa(regulatebloodglucoseconcentration)-whenBGCincreasesaboveorbelownormal,moreinsulinorglucagonissecretedbyisletsofLangerhansinthepancreastoregulateBGC ● fatdigestion(productionofbile)-bileemulsifieslargefatglobulesintosmallfatdropletstoincreasesurfaceareatovolumeratioforicreasedrateofdigestionoffatsbylipaseintofattyacidsandglycerol ● metabolismofaminoacidsandformationofurea(deaminationofexcessaminoacids)-excessaminoacidsarebroughttotheliverforitsaminogroupstoberemoved,andconvertedtourea,removedviaurine ● breakdownofalcohol-harmfulsubstancesaretransportedtothelivertobeconvertedintoharmlesssubstances

● breakdownofhormones-onceahormoneasserveditsfunction,itisbroughttothelivertobebrokendown (e) defineahormoneasachemicalsubstance,producedbyagland,carriedbytheblood,whichalterstheactivityofoneormorespecifictargetorgans

(f) outlinehowbloodglucoseconcentrationisregulatedbyinsulinandglucagon whenBGCincreasesabovenormal(afteraheavymeal),isletsofLangerhansarestimulatedtoproducemoreinsulinintothebloodstream,insulinistransportedbybloodtotheliverwhereitstimulatesthelivertoconvertexcessglucoseintoglycogenforstorage.BGCdecreasesbacktonormal. whenBGCdecreasesbelownormal(starving/fasting/afterexercise),isletsofLangerhansarestimulatedtoproducemoreglucagonintothebloodstream,glucagonistransportedbybloodtotheliverw