A2 BIOLOGY CORE PRACTICAL SUMMARYName of practicalIndependent &dependentvariablesOther variablesto be controlledequipmentMethodandoutcomePossibleevaluationissuesObserving patternsby EcologicalsamplingRandom samplingSystemic samplingAbiotic factorse.g. light,temperature,soilwater, humidity,O2concentration,pH, aspect, slopeangleGridded QuadratTape measurePoint quadratPitfall trapSweep NetPooterTullgren funnelBaermann funnelSeveral methods.1random sampling= set up gridusing tape measure, use random numbers to generate points to place quadrat tocollect data.2systemic sampling= line transect often used especially to study zonation. Atape measure is laid along several zones to belooked at and quadrats are used to recorddata at regular intervals3 Measuring abundanceDensity = presence of organisms per quadratFrequency = percentage of quadratsquares containing organismPercentage cover = percentage of ground covered with organism ina quadrat (usually for plants)Pitfall trap = to collectinvertebratesSweep net = to collect invertebrates in long grassesPooter = to collect invertebrates into a containerTullgren funnel = to collect organisms fromsoil or leaf litterBaermann funnel = to collect living organisms fromwaterconstant changing of abioticconditionsMovement of organismsSampling taken within a smallamount of timeLimitations of only 1 studyConsideration for safety oforganismsDisruption to normal habitatEthics of measuring wildorganismsThe effect oftemperature on thehatching success ofbrine shrimpIndependent =temperatureDependent =number of hatchedshrimpLight intensitypHsalt contentpresence ofchlorine fromtap wateroxygenconcentrationBrine shrimp eggcysts2 g sea salt for eachtreatmentde-chlorinated waterfor eachtreatmentbeakersWater baths orincubatorsForcepsBright lightpipetteDecide on a range of temperatures from 5 C to 35 C to be tested.Place 2 g ofsea salt into a 100 cm3 beaker. Add 100 cm3 ofde-chlorinated water and stiruntil the salt completely dissolves. Label the beaker with sea salt andthe temperature at which itwill be incubated. Place a tiny pinch of egg cysts onto a large sheet of white paper. Wet the piece of graph paper using afewdrops of salt water. Dab thepaper onto the white sheet to pick upapproximately 40 eggs. Use a magnifying glass to count theeggs.Put the paper with the 40 eggs into the beaker (eggs-side down). After 3 minutes, use a pair of forceps to gently removethe paper, making sure that all the eggcysts have washed off into the water.If possible replicate the treatments.Incubate thebeakers at the appropriate temperatures, controlling exposure to light asfar as possible. The nextday count the number ofhatched larvae in each of thebeakers. To do this, place abright light next to thebeaker. Any larvae will swim towards the light.Using a fine glasspipette catch the brine shrimps and place them ina small beaker ofsalt water. Brine shrimps are verydelicate and care must be taken when handling them. Record thenumber of larvae that have successfully hatched at eachtemperature.OutcomeThe majority of the shrimp should hatch at the optimum temperature between 25 and 30C. (optimum at 28C). Statstests could be used to showevidence for data.Difference = student t test or mann whitney UCorrelation = spearmans rankethics of hatching shrimp underdifferent conditionsuse of animals in experimentseffect of light intensity, may be adifference in light in each samplefluctuatingtemperaturesnot accurate saltmeasurementsmay not have counted exactly 40eggsmay miss seeing some of thebaby shrimpsome eggs may not beviableanymore and wont hatchDNA gelelectrophoresisselected restrictionenzymesagar gelgel tankelectrical supplymicropipettesDNA sampleLoading dyeUV lightCameraBuffer solutionDNA restrictionladderMix DNA with desired restriction enzyme and loading dye. Prepare agarand pour into electrophoresis mould. Once set, fillelectrophoresis tank with buffer solution. Usemicropipette to load restriction ladder into first well then DNAsamples cut withrestriction enzyme into the other wells. Connect to electrical supply, turn on andleave until the dye has moved tothe oppositeend of the geltank. Switch off and disconnect electrical supply. Carefully remove the gelfrom the tank and view under UVlight. Take picture if desired.OutcomeDNA will be separated out through the agargel, with the heaviest (biggest) DNA strands near the wellsand thelightest (smallest) will be at the opposite end. The DNA restriction ladder can be used as aruler to measure the size of thedifferent fragments.DNA amplificationusing PCRThermocyclerDNA sampleTaq polymeraseNucleotidesprimersDNA sample is placed into tube inthermocycler with nucleotides, primers and polymerase. Step 1: denaturation = DNAheatedfor 1min at 94Cto denature it. This breaks the Hbonds between nucleotides and makes the double stranded DNA, singlestranded.Step 2: annealing = temperature reduced to 54C.Bonds form between primers and the template strands .This willallow the polymerase enzyme to start to copy the template.Step 3: extension = carried out at72C. This isthe optimum for taq polymerase enzyme. The bases are placed intheir correctposition, extending the strand fromthe primer.The amount of DNA doubleseach cycle (steps 1-3) thereforea considerably amount of copiedDNA can be made for use in DNAfingerprinting etc.35 cycles ( a few hrs)= 34 billioncopies

A2 BIOLOGY CORE PRACTICAL SUMMARYName of practicalIndependent &dependentvariablesOther variablesto be controlledequipmentMethodandoutcomePossibleevaluationissuesObserving patternsby EcologicalsamplingRandom samplingSystemic samplingAbiotic factorse.g. light,temperature,soilwater, humidity,O2concentration,pH, aspect, slopeangleGridded QuadratTape measurePoint quadratPitfall trapSweep NetPooterTullgren funnelBaermann funnelSeveral methods.1random sampling= set up gridusing tape measure, use random numbers to generate points to place quadrat tocollect data.2systemic sampling= line transect often used especially to study zonation. Atape measure is laid along several zones to belooked at and quadrats are used to recorddata at regular intervals3 Measuring abundanceDensity = presence of organisms per quadratFrequency = percentage of quadratsquares containing organismPercentage cover = percentage of ground covered with organism ina quadrat (usually for plants)Pitfall trap = to collectinvertebratesSweep net = to collect invertebrates in long grassesPooter = to collect invertebrates into a containerTullgren funnel = to collect organisms fromsoil or leaf litterBaermann funnel = to collect living organisms fromwaterconstant changing of abioticconditionsMovement of organismsSampling taken within a smallamount of timeLimitations of only 1 studyConsideration for safety oforganismsDisruption to normal habitatEthics of measuring wildorganismsThe effect oftemperature on thehatching success ofbrine shrimpIndependent =temperatureDependent =number of hatchedshrimpLight intensitypHsalt contentpresence ofchlorine fromtap wateroxygenconcentrationBrine shrimp eggcysts2 g sea salt for eachtreatmentde-chlorinated waterfor eachtreatmentbeakersWater baths orincubatorsForcepsBright lightpipetteDecide on a range of temperatures from 5 C to 35 C to be tested.Place 2 g ofsea salt into a 100 cm3 beaker. Add 100 cm3 ofde-chlorinated water and stiruntil the salt completely dissolves. Label the beaker with sea salt andthe temperature at which itwill be incubated. Place a tiny pinch of egg cysts onto a large sheet of white paper. Wet the piece of graph paper using afewdrops of salt water. Dab thepaper onto the white sheet to pick upapproximately 40 eggs. Use a magnifying glass to count theeggs.Put the paper with the 40 eggs into the beaker (eggs-side down). After 3 minutes, use a pair of forceps to gently removethe paper, making sure that all the eggcysts have washed off into the water.If possible replicate the treatments.Incubate thebeakers at the appropriate temperatures, controlling exposure to light asfar as possible. The nextday count the number ofhatched larvae in each of thebeakers. To do this, place abright light next to thebeaker. Any larvae will swim towards the light.Using a fine glasspipette catch the brine shrimps and place them ina small beaker ofsalt water. Brine shrimps are verydelicate and care must be taken when handling them. Record thenumber of larvae that have successfully hatched at eachtemperature.OutcomeThe majority of the shrimp should hatch at the optimum temperature between 25 and 30C. (optimum at 28C). Statstests could be used to showevidence for data.Difference = student t test or mann whitney UCorrelation = spearmans rankethics of hatching shrimp underdifferent conditionsuse of animals in experimentseffect of light intensity, may be adifference in light in each samplefluctuatingtemperaturesnot accurate saltmeasurementsmay not have counted exactly 40eggsmay miss seeing some of thebaby shrimpsome eggs may not beviableanymore and wont hatchDNA gelelectrophoresisselected restrictionenzymesagar gelgel tankelectrical supplymicropipettesDNA sampleLoading dyeUV lightCameraBuffer solutionDNA restrictionladderMix DNA with desired restriction enzyme and loading dye. Prepare agarand pour into electrophoresis mould. Once set, fillelectrophoresis tank with buffer solution. Usemicropipette to load restriction ladder into first well then DNAsamples cut withrestriction enzyme into the other wells. Connect to electrical supply, turn on andleave until the dye has moved tothe oppositeend of the geltank. Switch off and disconnect electrical supply. Carefully remove the gelfrom the tank and view under UVlight. Take picture if desired.OutcomeDNA will be separated out through the agargel, with the heaviest (biggest) DNA strands near the wellsand thelightest (smallest) will be at the opposite end. The DNA restriction ladder can be used as aruler to measure the size of thedifferent fragments.DNA amplificationusing PCRThermocyclerDNA sampleTaq polymeraseNucleotidesprimersDNA sample is placed into tube inthermocycler with nucleotides, primers and polymerase. Step 1: denaturation = DNAheatedfor 1min at 94Cto denature it. This breaks the Hbonds between nucleotides and makes the double stranded DNA, singlestranded.Step 2: annealing = temperature reduced to 54C.Bonds form between primers and the template strands .This willallow the polymerase enzyme to start to copy the template.Step 3: extension = carried out at72C. This isthe optimum for taq polymerase enzyme. The bases are placed intheir correctposition, extending the strand fromthe primer.The amount of DNA doubleseach cycle (steps 1-3) thereforea considerably amount of copiedDNA can be made for use in DNAfingerprinting etc.35 cycles ( a few hrs)= 34 billioncopies

As Biology With Stafford Practical Workbook Marking Schemes (3) (1)Ratings:(0)|Views:409|Likes:0Published byAnji Zareerbio 6b marking schemeSee More

Marking scheme for AS Biology with Stafford, Unit Three Practical Workbook. Book available athttp://www.amazon.com/gp/aw/s/ref=is_s_?k=AS+A2+Biology+with+staffordAS Biology with Stafford.Unit Three: Practical Workbookanswers/ Unit three paper BIO7Page1Marking schemes forAdvanced Level BiologyAS Biology with StaffordUnit Three: Practical WorkbookPaper reference: 6BIO7The book is available at thefollowing linkhttp://www.amazon.com/gp/aw/s/ref=is_s_?k=AS+A2+Biology+with+staffordA copy of this marking scheme and many other resources can be downloaded from thefollowing linkhttp://www.facebook.com/groups/biologywithstafford/

Marking scheme for AS Biology with Stafford, Unit Three Practical Workbook. Book available athttp://www.amazon.com/gp/aw/s/ref=is_s_?k=AS+A2+Biology+with+staffordAS Biology with Stafford.Unit Three: Practical Workbookanswers/ Unit three paper BIO7Page2Copyright Stafford Valentine ReddenUnauthorized duplication contravenes applicable laws.Typeset & layouts byThe effect oftemperature on thehatching success ofbrine shrimpIndependent =temperatureDependent =number of hatchedshrimpLight intensitypHsalt contentpresence ofchlorine fromtap wateroxygenconcentrationBrine shrimp eggcysts2 g sea salt for eachtreatmentde-chlorinated waterfor eachtreatmentbeakersWater baths orincubatorsForcepsBright lightpipetteDecide on a range of temperatures from 5 C to 35 C to be tested.Place 2 g ofsea salt into a 100 cm3 beaker. Add 100 cm3 ofde-chlorinated water and stiruntil the salt completely dissolves. Label the beaker with sea salt andthe temperature at which itwill be incubated. Place a tiny pinch of egg cysts onto a large sheet of white paper. Wet the piece of graph paper using afewdrops of salt water. Dab thepaper onto the white sheet to pick upapproximately 40 eggs. Use a magnifying glass to count theeggs.Put the paper with the 40 eggs into the beaker (eggs-side down). After 3 minutes, use a pair of forceps to gently removethe paper, making sure that all the eggcysts have washed off into the water.If possible replicate the treatments.Incubate thebeakers at the appropriate temperatures, controlling exposure to light asfar as possible. The nextday count the number ofhatched larvae in each of thebeakers. To do this, place abright light next to thebeaker. Any larvae will swim towards the light.Using a fine glasspipette catch the brine shrimps and place them ina small beaker ofsalt water. Brine shrimps are verydelicate and care must be taken when handling them. Record thenumber of larvae that have successfully hatched at eachtemperature.OutcomeThe majority of the shrimp should hatch at the optimum temperature between 25 and 30C. (optimum at 28C). Statstests could be used to showevidence for data.Difference = student t test or mann whitney UCorrelation = spearmans rankethics of hatching shrimp underdifferent conditionsuse of animals in experimentseffect of light intensity, may be adifference in light in each samplefluctuatingtemperaturesnot accurate saltmeasurementsmay not have counted exactly 40eggsmay miss seeing some of thebaby shrimpsoThe effect oftemperature on thehatching success ofbrine shrimpIndependent =temperatureDependent =number of hatchedshrimpLight intensitypHsalt contentpresence ofchlorine fromtap wateroxygenconcentrationBrine shrimp eggcysts2 g sea salt for eachtreatmentde-chlorinated waterfor eachtreatmentbeakersWater baths orincubatorsForcepsBright lightpipetteDecide on a range of temperatures from 5 C to 35 C to be tested.Place 2 g ofsea salt into a 100 cm3 beaker. Add 100 cm3 ofde-chlorinated water and stiruntil the salt completely dissolves. Label the beaker with sea salt andthe temperature at which itwill be incubated. Place a tiny pinch of egg cysts onto a large sheet of white paper. Wet the piece of graph paper using afewdrops of salt water. Dab thepaper onto the white sheet to pick upapproximately 40 eggs. Use a magnifying glass to count theeggs.Put the paper with the 40 eggs into the beaker (eggs-side down). After 3 minutes, use a pair of forceps to gently removethe paper, making sure that all the eggcysts have washed off into the water.If possible replicate the treatments.Incubate thebeakers at the appropriate temperatures, controlling exposure to light asfar as possible. The nextday count the number ofhatched larvae in each of thebeakers. To do this, place abright light next to thebeaker. Any larvae will swim towards the light.Using a fine glasspipette catch the brine shrimps and place them ina small beaker ofsalt water. Brine shrimps are verydelicate and care must be taken when handling them. Record thenumber of larvae that have successfully hatched at eachtemperature.OutcomeThe majority of the shrimp should hatch at the optimum temperature between 25 and 30C. (optimum at 28C). Statstests could be used to showevidence for data.Difference = student t test or mann whitney UCorrelation = spearmans rankethics of hatching shrimp underdifferent conditionsuse of animals in experimentseffect of light intensity, may be adifference in light in each samplefluctuatingtemperaturesnot accurate saltmeasurementsmay not have counted exactly 40eggsmay miss seeing some of thebaby shrimpsome eggs may not beviableanymore and wont hatcAnother tableDNA gelelectrophoresisselected restrictionenzymesagar gelgel tankelectrical supplymicropipettesDNA sampleLoading dyeUV lightCameraBuffer solutionDNA restrictionladderMix DNA with desired restriction enzyme and loading dye. Prepare agarand pour into electrophoresis mould. Once set, fillelectrophoresis tank with buffer solution. Usemicropipette to load restriction ladder into first well then DNAsamples cut withrestriction enzyme into the other wells. Connect to electrical supply, turn on andleave until the dye has moved tothe oppositeend of the geltank. Switch off and disconnect electrical supply. Carefully remove the gelfrom the tank and view under UVlight. Take picture if desired.OutcomeDNA will be separated out through the agargel, with the heaviest (biggest) DNA strands near the wellsand thelightest (smallest) will be at the opposite end. The DNA restriction ladder can be used as aruler to measure the size of thedifferent fragments.

Another tableDNA amplificationusing PCRThermocyclerDNA sampleTaq polymeraseNucleotidesprimersDNA sample is placed into tube inthermocycler with nucleotides, primers and polymerase. Step 1: denaturation = DNAheatedfor 1min at 94Cto denature it. This breaks the Hbonds between nucleotides and makes the double stranded DNA, singlestranded.Step 2: annealing = temperature reduced to 54C.Bonds form between primers and the template strands .This willallow the polymerase enzyme to start to copy the template.Step 3: extension = carried out at72C. This isthe optimum for taq polymerase enzyme. The bases are placed intheir correctposition, extending the strand fromthe primer.The amount of DNA doubleseach cycle (steps 1-3) thereforea considerably amount of copiedDNA can be made for use in DNAfingerprinting etc.35 cycles ( a few hrs)= 34 billioncopiesEffects of differentantibiotics onbacteriaIndependen =antibioticDependent =diameter ofinhibition zoneConcentrationof antibioticAmount ofantibioticDisc sizeBacterialspeciesTemperatureRulerSamples of differentantibiotics on mastring or filter paperdiscsPetri dishesAgar gelDisinfectantBunsen burnerForcepsMarker penAdhesive tapeincubatorWash hands. For this practical you willneed to work in sterile conditions (aseptictechnique) i.e. you will need to flametheforceps in the Bunsen after every use. Prepare anagar plate seeded with bacteria.Label the Petri dish on the base at the edgewith your name, the date and the typeof bacterium it is inoculated with. Flamethe forceps and then use them topick up anantibiotic disc or Mast ring. Raise the lid of the Petri dish and place the Mast ring firmly in the centre of the agar; ifindividualdiscs are used they will needto be spaced evenly around the dish. Tapethe dish securely with two pieces ofadhesive tape (butdo not seal it completely), then keep itupside down at 30Cfor 48 hours. Afterincubation, look carefully at the plate butdonot open it. Where bacteria have grown the plate willlook opaque, but where the antibiotics have inhibited growth, clearzones called inhibition zones will be seen. Measure the diameter ofthe inhibition zones in millimetres and use this informationto decide which antibiotic is most effective at inhibiting the growth of the bacterium.Outcome: dependent on bacterial species used and antibiotics used. E.g. E.coliis gram negative and notoften susceptible topenicillin which is effective mainly with grampositive species. The larger the inhibition zone, the more effective the antibioticagainst that species.Ensuring that the discs areplaced evenly on the Petri dishHaving good aseptictechniqueto prevent platecontaminationAge of antibiotic, if theantibioticused is out of date it is likely tobe less effectiveRepeatsAccuracy of incubationtemperature and timeAnother tableMeasuring the rateof oxygen uptakeNo oforganismsTemperatureTimeAmount ofsoda limeRespirometerSoda limeColoured liquid5g Organisms e.g.maggots,germinating peas,woodliceCotton woolStop clockMarker penPlace 5g of organism (maggots) into the tube and replace the bung. Introduce a drop of dye into the glass tube. Opentheconnection (three-way tap) to the syringe and move the fluid toa convenient place on the pipette (i.e. towards theend of thescale that is furthest from the testtube). Mark the starting position of thefluid on the pipette tube with apermanent OHT pen.Isolate the respirometer by closing the connection to the syringe and theatmosphere and immediately start the stop clock.Mark the position of the fluid on the pipette at 1 minute intervals for 5 minutes. 6. At the end of 5 minutes open theconnection to the outside air. Measure the distance travelled by the liquid duringeach minute (the distance from one mark tothe next on your pipette).If your tube does not havevolumes marked onto it you will need toconvert the distance moved intovolume of oxygen used. (Remember the volume used = r2 distance moved, where r = the radius ofthe hole in the pipette.)Record your results in a suitable table. Calculate the mean rateof oxygen uptake during the 5minutes.Outcome: Oxygen molecules are absorbed by the organism and used in respiration. The same number of carbon dioxidemolecules are released but these are absorbed by the soda lime. This reduces the pressure inside the test tube (fewer molecules =lower pressure). Atmospheric pressure pushes the liquid along the tube, until the pressure in and outside the tube is equal.Oxygen isthe final electron acceptor, and it eventually combines with hydrogen to make water. The carbon dioxide comes fromthe carbon dioxide released in the link reaction and the Krebs cycle as the carbohydrate is broken down.Simplerespirometerdisadv. =does not allow you to reset; itneeds a control tube usedalongside it; no scale someasurements likely to be lessaccurate.Adv= very simple toset up; minimal number ofconnections makes a good sealeasier to obtain.U-tuberespirometerdisadv. =tendency for the connections toleak in elderly school/collegemodels (making the equipmentuseless); expense.Adv. = doesnot need to have an additionalcontrol as the second tubebalances out the effects ofchanges in temperature oratmospheric pressure; the syringeallows you to move the liquid inthe U to reset theapparatus.Another tableEffects of exerciseon tidal volume andbreathing rateSpirometerKymographDisinifectantEye protectionSoda limeThe general principle behind a spirometer is simple. It iseffectively a tank of water withan air-filled chamber suspended in thewater. It is set up so that adding air to the chamber makes the lid of the chamber rise in the water, and removing air makes itfall. Movements of the chamber are recorded usinga kymograph (pen writing on arotating drum). Tubes run from thechamber to a mouthpiece and back again. Breathing inand out through the tubes makes the lidof the chamber fall andrise.The volume of air the personinhales and exhales can be calculated from thedistance the lid moves. The apparatus can becalibrated so that the movement of the lid corresponds to agiven volume. A canister containing soda limeis inserted betweenthe mouthpiece and the floating chamber. This absorbs the CO2 that thesubject exhales. In which direction will thepen movewhen the subject inhales. After calibration, the spirometer is filled with oxygen.A disinfected mouthpiece is attached to thetube, with the tap positioned so that the mouthpiece is connected to theoutside air. The subject to betested puts a nose clipon, places the mouthpiece in their mouth and breathes the outside air untilthey are comfortable with breathing through thetube. Switch on the recording apparatus and at theend of an exhaled breath turn the tapso that the mouthpiece is connectedto the spirometer chamber. The trace will move down asthe person breathes in. After breathing normally the subject shouldtake as deep a breath aspossible and then exhale as much airas possible before returning to normal breathing. Seetraceexample below.Outcome: The tidal volume is the volume of air breathed in and out in one breath at rest. The tidal volume for most adults isonly about 0.5 dm3. Vital capacity isthe maximum volume of air that can bebreathed in or out ofthe lungs in oneforcedbreath. Breathing rate is the number of breaths taken per minute. Minute ventilation is the volume ofair breathed into (andout of) the lungs inone minute. Minute ventilation = tidal volume rate ofbreathing (measured in number of breaths perminute). Some air (about 1 dm3) always remains inthe lungs as residual airand cannot be breathed out. Residual air preventsthe walls of the bronchioles and alveoli fromsticking together. Any air breathed in mixes with this residual air.

Another tableAnother tablenvestigatinghabituation to astimulusIndependentvariable = numberof pokesDependent variable= retraction timeReplicationusing snails ofapprox samesize and ageEqual handlinghistoryDrying out1 giant African landsnail1 dampened cottonwool budClean firm surfaceStop watchCollect one giant African land snail, and place it on a clean, firm surface. Allow the snail to get used to itsnew surroundings fora few minutes until it hasfully emerged from its shell. Dampen acotton wool bud with water. Firmly touchthe snail betweenthe eye stalks with the dampened cotton wool bud and immediately start the stopwatch. Measure the length oftime betweenthe touch and the snail being fullyemerged from its shell once again,with its eye stalks fully extended. Repeat the procedure instep 3 for a total of 10 touches, timing how long the snail takes to re-emerge each time.Record your results in a suitable table.Present your results in an appropriate graph.Outcome: spearmans rank stats test to look for correlation in data.There is anegative correlationas the number of stimuliincrease the time taken for the snail tore-emerge decreases. Students should make areference to the data. With repeatedstimulation, Ca2+ channels inthe presynaptic membrane become less responsive. Less Ca2+ crosses the membrane into thepresynaptic (sensory) neurone. As aresult less neurotransmitter is released intothe synaptic cleft. This means that an actionpotential across the postsynaptic membrane is lesslikely. Fewer action potentials areproduced in thepostsynaptic motorneurone so less of aresponse is observed.Snails already handled beforethe experiment may not react inthe same wayDetermining when a snail hasfully emergedLack of moisture may encouragesnail to stay more in its shellMeasuring eye stalk lengthinstead

: Mohamed SobirCover designed by: Mohamed SobirPrinted in Maldives by: Copier RepairPublished by: Author publisherAll rights reserved.No part of this publicationmay beReproduced, stored in a database orretrieval system, or transmitted in anyform or by any means, electronic,mechanical, photocopying, recording,or otherwise, without the priorwritten permission of the authorISBN:978-81-910705-2-1Note: A few graphs have been drawn to give students an idea on how to find the scaleand plot range or variability. Other graphs have not been drawn as students need topractice the graph drawing. Do post your graphs on my FB group and I can give afeedback on the graphs.Any other queries on any aspect of the practical paper can be clarified on myFB grouphttp://www.facebook.com/groups/biologywithstafford/I have also included additional notes on referencing, citation or bibliography at the endof the document. Evaluation of references is also dealt with in detail.Cheers and all the best.Stafford Valentine Redden(M.A; M.Sc.; M.Ed.; (Ph.D))Head of Department (Biology)Villa International School,Male, Republic of MaldivesEmail: staffordv@yahoo.comMobile: +960 7765507

Observing Mitosis1. Heat2cm3of1 mole HCl acidin a60oC waterbath.2. Cut off1-2cmgarlic root tips.3. Put the garlic root tips in a watch glass containing2cm3ofacetic alcoholfor12 minutes.4. Remove the tips from the acetic acid and place them into a different watch glass containing5cm3of ice cold distilled water.5. After5 minutes remove themand leave them todry.6. Then place the tips into thewarmed HClacid for 5 minutes.7. Repeat 1-6 to make the tips even more fragile.8. Transfer a tip to amicroscope slideand then cut 5mm off the end of the tip.9. Macerateusing amounted needle.10. Stain using1 drop of toludine blueand leave root tips for 2 minutes.11. Add coverslip andblot with filter paper.12. View under a microscope and identify thestages of mitosis.(Overview of treatment to 1-2cm tips:2cm3acetic alcohol->5cm3ice cold water->dry->2cm360oC HCl acid->repeat->Cut 4-5mm tip off root tip->macerate using mounted needle->stain with toludine blue->blot with filter paper->view)

Source:LostWacky'sMint or Garlic in Toothpaste1. Seed agar plates using aseptic techniques.2. Crush 3g of mint leaves using a pestle and mortar in 10cm3of methylated spirit.3. Pipette 0.1cm3of the mint leaf solution onto a paper disc.4. Repeat 1-3 using garlic leaves instead of mint leaves.5. Allow the discs to dry for 10 minutes.6. Using sterilised forceps place the discs onto a petri dishes.7. Use a blank disc as a control in the petri dish.8. Tape the lid onto the petri dish, leaving a sufficient air supply so that dangerous anaerobes do not grow.9. Incubate the petri dish for 24 hours at 25oC.10. Measure the diameter of the rings of affect around the different discs and record the data in a table.11. Repeat 1-10 at least 3 times and calculate mean averages.12. Create a graph in order to better see the differences between the antibacterial effects of mint and garlic.13. Larger diameters of the rings of affect suggest more antibacterial strength.For a more in-depth (not tailored to SNAB) version of this experiment, see:Garlic and Mint Experiment

McCartney BottleSource:Aliimg.comTotipotency and Tissue Culture1. Acquire seeds that are starting to unfold theircotyledons.2. Cut the tops of the seeds just below theshoot apexusingsharp scissors.3. Place thestemof the newexplantsintoagar gelinMcCartney bottles.4. Cover theMcCartney bottleswithcling filmand place on asunny windowsill.Factors that may affect the results: Agar gel may become contaminated with pathogens (which kill the cotyledons) because of the nutritious and moist environment it provides. The wrong part of the plant may be cut off and placed into the agar gel.

Plant cross section (should remember from previous unit)Source:BBCThe Strength of Plant Fibres1. Soak plant material in water for at least one week to soften the fibres for easier extraction.2. Retthe plant material for its fibres.3. Clamp a fibre between twoclamp standsand add mass to the centre of the fibre until it snaps (record the weight at which it does so).4. Repeat at least 3 times and calculate the average.5. Repeat using other plant fibres6. Plot data in a bar graph to compare fibre strengths.7. Ensure that the lengths of the fibres are equal each time.8. Ensure that the plants are the same age at the time of extraction as older fibres will be more brittle than younger counterparts.

A tomato plant deprived of magnesium.Source:Plantphys.netInvestigating Plant Mineral Deficiencies1. Prepare bottles of varying mineral content starting from a control ofdistilled water(lacking all nutrients) and ending with a solution containingall nutrients(with no potassium, no phosphorus, no magnesium etc. in other bottles).2. Cover bottle openings with foil and then perforate the centre of the foil lids.3. Place a plant of the same species in each bottle by putting its roots through the opening that was perforated so that the roots may absorb the solution.4. Place on a sunny windowsill.5. Record observations.Note: see photo below for major roles of each nutrient.

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Major Functions of Mineral Deficiencies