triple biology required practicals · a bacterial cell is 40 times smaller. calculate the diameter...

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TripleBiologyRequiredPracticalActivities

RequiredPractical–Followeachofthelinksforavideotowatchonthepractical!

Pages

Usealightmicroscopetoobserve,drawandlabelaselectionofplantandanimalcells.Amagnificationscalemustbeincludedhttps://www.youtube.com/watch?v=XKPdnE6BGewhttps://www.youtube.com/watch?v=DyL6s15WeqYhttps://www.youtube.com/watch?v=GXqrpb91JPghttps://www.youtube.com/watch?v=J3HfSss5YPs

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Investigatetheeffectofantisepticsorantibioticsonbacterialgrowthusingagarplatesandmeasuringzonesofinhibition.https://www.youtube.com/watch?v=6SblFQHRnRY&list=PLyLdDAgC3ROjaTKJF1sORxcSZSdxvczq9&index=2https://www.youtube.com/watch?v=sZueyuUQeFc

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Investigatetheeffectofarangeofconcentrationsofsaltorsugarsolutionsonthemassofplanttissue.https://www.youtube.com/watch?v=oieXYuQm_xEhttps://www.youtube.com/watch?v=aA_UvVeQbww&t=32s

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Usequalitativereagentstotestforarangeofcarbohydrates,lipidsandproteins.Toinclude:Benedict’stestforsugars;iodinetestforstarch;andBiuretreagentforprotein.https://www.youtube.com/watch?v=sLP8dcnWnJghttps://www.youtube.com/watch?v=81SpohOUHjA

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InvestigatetheeffectofpHontherateofreactionofamylaseenzyme.StudentsshoulduseacontinuoussamplingtechniquetodeterminethetimetakentocompletelydigestastarchsolutionatarangeofpHvalues.Iodinereagentistobeusedtotestforstarchevery30seconds.Temperaturemustbecontrolledbyuseofawaterbathorelectricheater.https://www.youtube.com/watch?v=7wJItifm9Wshttps://www.youtube.com/watch?v=8Yqbu56ImXk&t=11s

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Investigatetheeffectoflightintensityontherateofphotosynthesisusinganaquaticorganismsuchaspondweed.https://www.youtube.com/watch?v=yg8vqsBOFMw&t=6shttps://www.youtube.com/watch?v=6xEEDZAiTME

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Planandcarryoutaninvestigationintotheeffectofafactoronhumanreactiontime.https://www.youtube.com/watch?v=81lPJtAp5Schttps://www.youtube.com/watch?v=3XM-4Qavh5k

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Investigatetheeffectoflightorgravityonthegrowthofnewlygerminatedseedlings.Recordresultsbothaslengthmeasurementsandasaccurate,labelledbiologicaldrawingstoshowtheeffects.https://www.youtube.com/watch?v=2TCu8GHS2nchttps://www.youtube.com/watch?v=pCFstSMvAMI

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Measurethepopulationsizeofacommonspeciesinahabitat.Usesamplingtechniquestoinvestigatetheeffectofafactoronthedistributionofthisspecies.https://www.youtube.com/watch?v=UDp3I07Wcrghttps://www.youtube.com/watch?v=lKyj7gEAAS8&t=53s

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InvestigatetheeffectoftemperatureontherateofdecayoffreshmilkbymeasuringpHchange.https://www.youtube.com/watch?v=FVrOIMmmBQE

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GCSEBiologyrequiredpracticalactivity:Microscopy

Requiredpracticalactivity Apparatusandtechniques

Usealightmicroscopetoobserve,drawandlabelaselectionofplantandanimalcells.Amagnificationscalemustbeincluded.

AT1,AT7

Usingalightmicroscopetoobserve,drawandlabelcellsinanonionskin

Prepareamicroscopeslidetoshowthecontentsofcellsfromonionskin.

Useanopticalmicroscopetoobserveanddrawtheonioncells.Youwillalsoneedtoidentifystructureswithinthecells.

Method

Youareprovidedwiththefollowing:

• asmallpieceofonion

• aknife

• awhitetile

• forceps

• amicroscopeslide

• acoverslip

• amicroscope

• iodinesolutioninadroppingbottle

• prepared animal and plant cells

Readtheseinstructionscarefullybeforeyoustartwork.1. Useadroppingpipettetoputonedropofwaterontoamicroscopeslide.2. Separateoneofthethinlayersoftheonion.3. Peeloffathinlayerofepidermaltissuefromtheinnersurface.4. Useforcepstoputthisthinlayerontothedropofwaterthatyouhaveplacedonthemicroscopeslide.5. Makesurethatthelayerofonioncellsisflatontheslide.6. Puttwodropsofiodinesolutionontotheoniontissue.7. Carefullyloweracoverslipontotheslide.Dothisby:

• placing one edge of the coverslip on the slide • use the forceps to lower the other edge onto the slide.

8. Theremaybesomeliquidaroundtheedgeofthecoverslip.Useapieceofpapertosoakthisliquidup.9. Puttheslideonthemicroscopestage.

Usingthemicroscopetolookatanimalandplantcells

Thediagramshowsatypicalmicroscope.

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Thismicroscopehasamirrortoreflectlightupthroughtheslide.Somemicroscopeshaveabuilt-inlightinsteadofamirror.

10. Usethelowestpowerobjectivelens.Turnthenosepiecetodothis.11. Theendoftheobjectivelensneedstoalmosttouchtheslide.Dothisbyturningthecoarseadjustmentknob.

Lookfromtheside(notthroughtheeyepiece)whendoingthis.12. Nowlookingthroughtheeyepiece,turnthecoarseadjustmentknobinthedirectiontoincreasethedistance

betweentheobjectivelensandtheslide.Dothisuntilthecellscomeintofocus.13. Nowrotatethenosepiecetouseahigherpowerobjectivelens.14. Slightlyrotatethefineadjustmentknobtobringthecellsintoaclearfocusandusethehigh-powerobjectiveto

lookatthecells.15. Makeaclear,labelleddrawingofsomeofthesecells.Makesurethatyoudrawandlabelanycomponentparts

ofthecell.16. Writethemagnificationunderneathyourdrawing.

Questions1. Explainwhyiodineisaddedtotheslide

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2. LabelpartsA–Cofthediagrambelow

Q1.Figure 1 shows a human cheek cell viewed under a light microscope.

Figure 1

© Ed Reschke/Photolibrary/Getty Images

(a) Label the nucleus and cell membrane on Figure 1. (2)

(b) Cheek cells are a type of body cell.

Body cells grow through cell division.

What is the name of this type of cell division? Tick one box.

Differentiation

Mitosis

Specialisation

(1)

A

B

C

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(c) Ribosomes and mitochondria are not shown in Figure 1.

What type of microscope is needed to see ribosomes and mitochondria?

............................................................................................................................. (1)

(d) What is the advantage of using the type of microscope you named in part (c)?

Tick one box.

Cheaper

Higher magnification

Lower resolution

(1)

(e) The cheek cell in Figure 2 is magnified 250 times.

The width of the cell is shown by the line D to E.

Figure 2

Calculate the width of the cheek cell in micrometres (µm).

Complete the following steps.

Measure the width of the cell using a ruler .......................................... mm

Use the equation to work out the real width of the cell in mm:

real size = ............................................ mm

Convert mm to µm ............................................. µm (3)

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(f) A red blood cell is 8 µin diameter.

A bacterial cell is 40 times smaller.

Calculate the diameter of the bacterial cell.

Tick one box.

0.02 µm

0.2 µm

2.0 µm

20.0 µm

(1)

(Total 9 marks)

Q2.Living organisms are made of cells.

(a) Animal and plant cells have several parts. Each part has a different function.

Draw one line from each cell part to the correct function of that part.

(3)

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(b) The diagram below shows a cell from a plant leaf.

Which two parts in the diagram above are not found in an animal cell?

1 ....................................................................................................................

2 .................................................................................................................... (2)

(Total 5 marks)

GCSEBiologyrequiredpracticalactivity:Microbiology


Investigatetheeffectofantisepticsorantibioticsonbacterialgrowthusingagarplatesandmeasuringzonesofinhibition.

AT1,AT3,AT4,AT8

Investigatingtheeffectofantisepticsonthegrowthofbacteria

Measure the diameter of the ‘clear zone’ around the disc. This is where there is no bacteria growing. The larger the clear zone, the more effective the antiseptic. Riskassessment

• Ensure that your work spaces and hands are thoroughly cleaned before and after the experiment.

• Care must be taken when handling microorganisms such as bacteria. You will use techniques called

aseptic techniques during this experiment to avoid contamination.

• Contamination can occur when microorganisms from: o the surroundings get into your experiment and spoil your results o your experiment get into the surroundings and cause a potential health hazard.

Method


• anutrientagarplate

• aheatproofmat

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• filterpaperdiscs

• threeantiseptics(suchasmouthwash,TCP,andantisepticcream)

• disinfectantbenchspray

• 1%VirKondisinfectant

• forceps

• cleartape

• handwash

• awaxpencil

• accesstoanincubator(setto25oC).

Read these instructions carefully before you start work. 1. Spraying the bench where you are working with disinfectant spray. Then wipe with paper towels. 2. Mark the underneath of a nutrient agar plate (not the lid) with the wax pencil

as follows (make sure that the lid stays in place to avoid contamination): • divide the plate into three equal sections and number them 1, 2 and 3 around the edge • placeadotintothemiddleofeachsection• around the edge write your initials, the date and the name of the bacteria (E. coli)

3. Wash your hands with the antibacterial hand wash.

4.Putdifferentantisepticsontothethreefilterpaperdiscs.Thiscanbedonebyeithersoakingthemintheliquidorspreadingthecreamorpasteontothem.

5. Carefullyliftthelidoftheagarplateatanangle.Donotopenitfully.

6.Useforcepstocarefullyputeachdiscontooneofthedotsdrawnonwiththewaxpencil.

7.Makeanoteofwhichantisepticisineachofthethreenumberedsectionsoftheplate

8.Securethelidoftheagarplateinplaceusingtwosmallpiecesofcleartape.

Do not seal the lid all the way around as this creates anaerobic conditions. Anaerobic conditions will prevent the E. coli bacteria from growing and can encourage some other very nasty bacteria to grow.

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9.Incubatetheplateat25°Cfor48hours.

10.Measurethediameteroftheclearzonearoundeachdiscbyplacingtheruleracrossthecentreofthedisc.

Measureagainat90°tothefirstmeasurementsothatthemeandiametercanbecalculated.

11.Recordyourresultsinatablesuchastheonehere.

Type of antiseptic Diameter of clear zone in mm

1 2 Mean

Mouthwash(1)

TCP (2)

Antiseptic cream (3)

Questions

1 What is the independent variable? Is this categoric or continuous, explain your answer. 2 What is the dependent variable? 3 What does the term anaerobic conditions mean? 4 Why does the plate need to be incubated for 48 hours? 5 Human body temperature is around 37 oC, explain why the bacteria are incubated at 25 oC. 6 Explain why you must not lift the lid of the agar dish fully when adding the antiseptic discs.

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Q1.Students in a school investigated the effect of five different antibiotics, A, B, C, D and E, on one type of bacterium.

The students:

• grew the bacteria on agar jelly in a Petri dish

• soaked separate paper discs in each of the antibiotics

• put the paper discs onto the bacteria in the Petri dish

• put the Petri dish into an incubator.

The diagram shows what the Petri dish looked like after 3 days.

(a) (i) What is the maximum temperature the incubator should be set at in the school?

Draw a ring around your answer.

10°C 25°C 50°C (1)

(ii) Draw a ring around the correct answer to complete the sentence.

The incubator should not be set at a higher temperature because the higher

pathogens.

temperature might help the growth of toxins.

viruses.

(1)

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(b) Which antibiotic, A, B, C, D or E, would be best to treat a disease caused by this type of bacterium?

Write your answer in the box.

Give the reason for your answer.

........................................................................................................................

........................................................................................................................ (2)

(c) Antibiotics cannot be used to treat diseases caused by viruses.

Why?

Tick ( ) one box.

Viruses are not pathogens

There are too many different types of virus

Viruses live inside cells

(1)

(Total 5 marks)

Q2. An investigator placed paper discs containing different concentrations of an antibiotic onto a culture of bacteria in a petri dish.

After an incubation period of two days, the dish looked like this.

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(a) Explain why there are areas around some of the paper discs where no bacteria are growing.

.....................................................................................................................................

..................................................................................................................................... (2)

(b) The concentration of the antibiotic on the paper discs is given in the table, along with the diameter of the circles where no bacteria are growing.

Disc Concentration of the antibiotic in units

Diameter of circle where no bacteria are growing, in mm

A 0 0

B 2 8

C 4 14

D 6 26

E 10 26

What effect does an increase in the concentration of the antibiotic have on the growth of the bacteria?

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

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(c) When students carry out this experiment, they need to take several safety precautions.

The precautions include:

• passing inoculating loops through a flame

• sealing the lid of the petri dish with tape

• incubating at a maximum temperature of 25 °C.

Explain why each of these precautions is necessary.

To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific word.

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....................................................................................................................................

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....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (5)

(d) Scientists are concerned that many bacteria are developing resistance to antibiotics.

Suggest two ways by which this problem could be limited.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 11 marks)

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GCSEBiologyrequiredpracticalactivity:Osmosis


Investigatetheeffectofarangeofconcentrationsofsaltorsugarsolutionsonthemassofplanttissue.

AT1,AT3,AT5

Investigatingosmosisinpotatotissue

Osmosisisthemovementofwaterthroughaselectivelypermeablemembrane.Thewatermovesfromanareaofhighconcentrationofwatertoanareaoflowerconcentrationofwater.

Planttissuescanbeusedtoinvestigateosmosis.Thisexperimentusespotato,butothertissuesuchassweetpotato,carrotorbeetrootcanbeused.

Potatotissueiscutintoequalsizedcylinders.Thepotatotissueisleftovernightinsugarsolutionanddistilledwater.Thechangesinlengthandmasscanthenbeaccuratelycompared.

Method


• apotato

• acorkborerorpotatochipper/vegetablestickcutter

• aruler

• a10cm3measuringcylinder

• labels

• threeboilingtubes

• atesttuberack

• papertowels

• asharpknife

• awhitetile

• arangeofsugarsolutions

• distilledwater

• atop-panbalance. Read these instructions carefully before you start work. 1. Use a cork borer to cut five potato cylinders of the same diameter. 2. Trim the cylinders so that they are all the same length (about 3 cm). 3. Accurately measure and record the length and mass of each potato cylinder. 4. Measure 10 cm3 of the 1.0 M sugar solution and put into the first boiling tube. Label boiling tube as:

1.0. M sugar.

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5. Repeat step 4 to produce the additional labelled boiling tubes containing solutions of 0.75 M, 0.5 M. and 0.25 M.

6. Measure 10 cm3 of the distilled water and put into the fifth boiling tube. Label boiling tube as water. 7. Add one potato cylinder to each boiling tube. Make sure you know the length and mass of each potato

cylinder in each boiling tube. 8. Record the lengths and masses of each potato cylinder in a table such as the one below.

1.0Msugarsolution

0.75sugarsolution

0.5Msugarsolution

0.25Msugarsolution

Distilledwater

Initiallength(mm)

Finallength(mm)

Changeinlength(mm)

Initialmass(g)

Finalmassin(g)

Changeinmassin(g)

9. Leave the potato cylinders in the boiling tubes overnight in the test tube rack. 10. Remove the cylinders from the boiling tubes and carefully blot them dry with the paper towels. 11. Re-measure the length and mass of each cylinder (make sure you know which is which). Record your measurements in the table. Then calculate the changes in length and mass of each

potato cylinder. 12. Plot a graph with:

• ‘Change in mass in g’ on the y-axis • ‘Concentration of sugar solution’ on the x-axis.

13. Plot another graph with:

• ‘Change in length in mm’ on the y-axis • ‘Concentration of sugar solution’ on the x-axis. Compare the two graphs that you have drawn.

Questions

1.Defineosmosis

2.Whatistheindependentvariable?

3.Whatistherangeoftheindependentvariableinthismethod?

4.Whatarethedependentvariables?

5.Giveatleast2controlvariables.

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6.Whatwillhappentothemassandlengthofthepotatoinpurewater?Explainyouranswerintermsofosmosis.

Q1.Cells, tissues and organs are adapted to take in different substances and get rid of different substances.

The table shows the concentration of four ions outside cells and inside cells.

Ion Concentration

outside cells in mmol per dm3

Concentration inside cells in mmol per dm3

Sodium 140 9

Potassium 7 138

Calcium 2 27

Chloride 118 3

(a) Use information from the table above to complete the following sentences.

Sodium ions will move into cells by the process

of .................................................................. .

Potassium ions will move into cells by the process

of .................................................................. . (2)

(b) Some students investigated the effect of the different concentrations of sugar in four drinks, A, B, C and D, on the movement of water across a partially permeable membrane.

The students:

• made four bags from artificial partially permeable membrane

• put equal volumes of 5% sugar solution in each bag

• weighed each bag containing the sugar solution

• placed one bag in each of the drinks, A, B, C and D

• after 20 minutes removed the bags containing the sugar solution and weighed them again.

The diagram below shows how they set up the investigation.

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(b) (i) The bag in drink A got heavier after 20 minutes.

Explain why.

...................................................................................................................

...................................................................................................................

...................................................................................................................

................................................................................................................... (3)

(ii) In which drink, A, B, C or D, would you expect the bag to show the smallest change in mass?

Tick (✔) one box.

A

B

C

D

(1)

(iii) Explain why you think the bag you chose in part (b)(ii) would show the smallest change.

...................................................................................................................

...................................................................................................................

...................................................................................................................

................................................................................................................... (2)

(Total 8 marks)

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Q2.A student investigated the effect of different sugar solutions on potato tissue.

This is the method used.

1. Add 30 cm3 of 0.8 mol dm−3 sugar solution to a boiling tube.

2. Repeat step 1 with equal volumes of 0.6, 0.4 and 0.2 mol dm−3 sugar solutions.

3. Use water to give a concentration of 0.0 mol dm−3.

4. Cut five cylinders of potato of equal size using a cork borer.

5. Weigh each potato cylinder and place one in each tube.

6. Remove the potato cylinders from the solutions after 24 hours.

7. Dry each potato cylinder with a paper towel.

8. Reweigh the potato cylinders.

The table below shows the results.

Concentration of sugar

solution in mol dm−3

Starting mass in g

Final mass in g

Change of mass in g

Percentage (%) change

0.0 1.30 1.51 0.21 16.2

0.2 1.35 1.50 0.15 X

0.4 1.30 1.35 0.05 3.8

0.6 1.34 1.28 −0.06 −4.5

0.8 1.22 1.11 −0.11 −9.0

(a) Calculate the value of X in the table above.

.............................................................................................................................

.............................................................................................................................

Percentage change in mass = ........................................ % (2)

(b) Why did the student calculate the percentage change in mass as well as the change in

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grams?

.............................................................................................................................

............................................................................................................................. (1)

(c) Complete the graph using data from the table above.

• Choose a suitable scale and label for the x-axis.

• Plot the percentage (%) change in mass.

• Draw a line of best fit.

(4)

(d) Use your graph to estimate the concentration of the solution inside the potato cells.

Concentration = ............................................... mol dm−3

(1)

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(e) The results in the table above show the percentage change in mass of the potato cylinders.

Explain why the percentage change results are positive and negative.

.............................................................................................................................

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............................................................................................................................. (3)

(f) Suggest two possible sources of error in the method given above.

1...........................................................................................................................

.............................................................................................................................

2...........................................................................................................................

............................................................................................................................. (2)

(Total 13 marks)

GCSEBiologyrequiredpracticalactivity:Enzymes


InvestigatetheeffectofpHontherateofreactionofamylaseenzyme.

StudentsshoulduseacontinuoussamplingtechniquetodeterminethetimetakentocompletelydigestastarchsolutionatarangeofpHvalues.Iodinereagentistobeusedtotestforstarchevery30seconds.

Temperaturemustbecontrolledbyuseofawaterbathorelectricheater.

AT1,AT2,AT5,AT8

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InvestigatingtheeffectofpHontheenzymeamylase

Theenzymeamylasecontrolsthebreakdownofstarchinourdigestivesystem.Weareabletosimulatedigestionusingsolutionsofstarchandamylaseintesttubes.Wecanalsodeterminetheoptimumconditionsrequired.

Thepresenceorabsenceofstarchcanbedeterminedusingiodinesolution.Inthisexperiment,wecanmeasurehowlongtheamylasetakestobreakdownthestarchatdifferentpHs.


• testtubes

• atesttuberack

• waterbath(electricalorBunsenburnerandbeakers)

• spottingtiles

• 5cm3measuringcylinder

• syringes

• astopclock

• starchsolution

• amylasesolution

• bufferedsolutionscoveringarangeofpH,eachwithalabelledsyringe/plasticpipette

• iodinesolution

• syringes.

1. Placeonedropofiodinesolutionintoeachdepressiononthespottingtile.2. PlacelabelledtesttubescontainingthebufferedpHsolutions,amylasesolutionandstarchsolutionsintothe

waterbath3. Allowthesolutionstoreach25°C4. Add2cm3ofoneofthebufferedsolutionstoatesttube.5. Usethesyringetoplace2cm3ofamylaseintothebufferedpHsolution.6. Useanothersyringetoadd2cm3ofstarchtotheamylase/buffersolution.7. Immediatelystartthestopclockandleaveitonthroughoutthetest.8. Mixusingaglassrod.9. After30seconds,removeonedropofthemixturewithaglassrod.

Placethisdroponthefirstdepressionofthespottingtilewiththeiodinesolution. The iodine solution should turn blue-black.

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10.Rinsetherod.

11.Usetheglassrodtoremoveonedropofthemixtureevery30seconds.Puteachdropontotheiodinesolutioninthenextdepressiononthespottingtile.Rinsetheglassrodwithwateraftereachdrop.Continueuntiltheiodinesolutionandtheamylase/buffer/starchmixtureremainorange.

12.RepeattheprocedurewithsolutionsofotherpHs

13.Recordyourresultsinatablesuchastheonehere.

pHofsolutionTimetakenforamylasetocompletelybreakdownthestarchin

seconds(s)

Questions 1. What is the independent variable in this investigation? 2. What is the dependent variable? 3. Temperature is an example of a control variable, what piece of equipment is used in this investigation to control the temperature? 4. What is the name of the enzyme in this reaction? 5. What is the name of the substrate in this reaction? 6. What is Iodine used for in this experiment?

Q1.Catalase is an enzyme.

Catalase controls the following reaction:

hydrogen peroxide water + oxygen

A student did an investigation on catalase activity.


1. Put 1 cm3 hydrogen peroxide solution in a test tube.

2. Add 1 cm3 of catalase solution.

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• Bubbles of oxygen are produced.

• Bubbles cause foam to rise up the tube.

3. Measure the maximum height of the foam.

The diagram below shows the experiment.

The experiment is carried out at 20 °C.

The table below shows some results from the investigation.

Temperature in °C

Maximum height of foam in cm

Test 1 Test 2 Test 3 Mean

10 1.3 1.1 0.9 1.1

20 0.0 3.3 3.1 3.2

30 5.2 5.0 5.3 5.2

40 4.2 3.5 4.4 4.0

50 2.1 1.9 2.3 2.1

60 0.0 0.0 0.0 0.0

(a) Why did the student carry out the experiment three times at each temperature?

Tick one box.

To make the experiment more accurate

To prove the experiment was correct

To show the experiment was more repeatable

(1)

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(b) The student thought one result was an anomaly.

Circle the anomaly in the table above. (1)

(c) What did the student do with the anomalous result?

.............................................................................................................................

............................................................................................................................. (1)

(d) Look at the table above.

What conclusion can be made as the temperature increases?

Tick one box.

Decreases the rate of reaction up to 30 °C

Decreases the rate of reaction up to 40 °C

Increases the rate of reaction up to 30 °C

Increases the rate of reaction up to 40 °C

(1)

(e) At which temperature was catalase denatured?

Tick one box.

10 °C

30 °C

40 °C

60 °C

(1)

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(f) The student thought the optimum temperature for catalase activity was between 30 °C and 40 °C.

How could the investigation be improved to find a more precise value for the optimum temperature?

Tick one box.

Do the experiment at 70 °C and 80 °C

Do the experiment at 30 °C, 35 °C and 40 °C

Use less hydrogen peroxide solution

Use more catalase solution

(1)

(g) Amylase is the enzyme that controls the breakdown of starch to glucose.

Describe how the student could investigate the effect of pH on the breakdown of starch by amylase.

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............................................................................................................................. (4)

(Total 10 marks)

Q2.Catalase is an enzyme found in many different tissues in plants and animals.It speeds up the rate of the following reaction.

hydrogen peroxide water + oxygen

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Figure 1 shows a 25-day-old broad bean seedling.

Some students investigated whether different parts of bean seedlings contained different amounts of catalase.

The students: • put hydrogen peroxide into five test tubes

• added a different part of a bean seedling to each tube

• recorded the results after half a minute.

If there was catalase in part of the seedling, oxygen gas was given off. When oxygen gas is given off, foam is produced in the tubes.

Figure 2 shows the results.

The students made the following conclusions: • most parts of a bean seedling contain catalase

• the seed contains a lot of catalase

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• stems and roots have quite a lot of catalase

• the leaves have a little bit of catalase

• the seed coat has hardly any catalase.

The students’ teacher said that the students needed to improve their investigation in order to make valid conclusions.

(a) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

Describe how you would carry out an investigation to compare the amounts of catalase in different parts of bean seedlings.

You should include details of how you would make sure your results give a valid comparison of the amounts of catalase.

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........................................................................................................................

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........................................................................................................................ (6)

(b) Scientists investigated the effect of pH on the activity of the enzyme catalase in a fungus.

The table below shows the scientists’ results.

pH Enzyme activity in arbitrary units

Test 1 Test 2 Test 3 Test 4 Test 5 Mean

3.0 0 0 0 0 0 0

4.0 6 5 8 4 7 6

5.0 38 65 41 42 39

5.5 80 86 82 84 88 84

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6.0 100 99 96 103 102 100

6.5 94 92 90 93 91 92

7.0 61 63 61 62 63 62

8.0 22 22 21 24 21 22

(i) Calculate the mean enzyme activity at pH 5.0.

...............................................................................................................

...............................................................................................................

Mean = ......................... arbitrary units (2)

(ii) On the graph paper in Figure 3, draw a graph to show the scientists’ results.

Remember to: • add a label to the vertical axis

• plot the mean values of enzyme activity

• draw a line of best fit.

Figure 3

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(4)

(iii) At what pH does the enzyme work best?

........................................ (1)

(iv) Predict the activity of the enzyme at pH 9.0.

........................................ arbitrary units (1)

(v) Suggest why the enzyme’s activity at pH 3.0 is zero.

...............................................................................................................

............................................................................................................... (1)

(Total 15 marks)

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GCSEBiologyrequiredpracticalactivity:Foodtests1.Testingforcarbohydrates

Inthisexperimentyouwilltestoneormorefoodstuffsforthepresenceofcarbohydrates.

Method


• foodtobetested

• apestleandmortar

• astirringrod

• filterfunnelandfilterpaper

• 2´beaker,250ml

• aconicalflask

• 2´testtube

• Benedict’ssolution

• iodinesolution

• kettleforboilingwater

• athermometer

• safety goggles. 1. Useapestleandmortartogrindupasmallsampleoffood.2. Transferthegroundupfoodintoasmallbeaker.Thenadddistilledwater.3. Stirthemixturesothatsomeofthefooddissolvesinthewater.4. Filterusingafunnelwithfilterpapertoobtainasclearasolutionaspossible.

Thesolutionshouldbecollectedinaconicalflask.

5. Halffillatesttubewithsomeofthissolution.6. Add10dropsofBenedict’ssolutiontothesolutioninthetesttube.7. Puthotwaterfromakettleinabeaker.Thewatershouldnotbeboiling. Putthetesttubeinthebeakerforaboutfiveminutes.8. Noteanycolourchange. Ifareducingsugar(suchasglucose)ispresent,thesolutionwillturngreen,yellow,orbrick-red.Thecolour

dependsonthesugarconcentration.9. Take5mlofthesolutionfromtheconicalflaskandputitintoacleantesttube.10. Addafewdropsofiodinesolutionandnoteanycolourchange. Ifstarchispresent,youshouldseeablackorblue-blackcolourappear.11. Recordyourresultsinatablesuchastheonebelow,

NameoffoodtestedColourproducedwithBenedict’s

solutionColourproducedwithiodine

solution

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Testingforlipids

Inthisexperimentyouwilltestoneormorefoodstuffsforthepresenceoflipids(fats).


• foodtobetested


• astirringrod

• 2´beaker,250ml

• atesttube

• SudanIIIstainsolution.

• safetygoggles.1. Useapestleandmortartogrindupasmallsampleoffood.2. Transferthegroundupfoodintoasmallbeaker.Thenadddistilledwater.3. Stirthemixturesothatsomeofthefooddissolvesinthewater.Donotfilter.4. Halffillatesttubewithsomeofthissolution.5. Add3dropsofSudanIIIstaintothesolutioninthetesttube.Shakegentlytomix.6. If fat is present: a red-stained oil layer will separate out and float on the water surface.

Alternatively

1. Add the sample to a test tube, then add alcohol and shake, 2. Then add water and shake 3. If the solution turns milky, lipids are present

3.Testingforproteins

Inthisexperimentyouwilltestoneormorefoodstuffsforthepresenceofprotein


• foodtobetested


• astirringrod

• afilterfunnelandfilterpaper

• 2´beaker,250ml

• atesttube

• Biuretsolution

• safetygoggles.

1. Useapestleandmortartogrindupasmallsampleoffood.2. Transferthegroundupfoodintoasmallbeaker.Thenadddistilledwater.3. Stirthemixturesothatsomeofthefooddissolvesinthewater.

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4. Filterusingafunnelwithfilterpapertoobtainasclearasolutionaspossible.Thesolutionshouldbecollectedinaconicalflask.

5. Put2cm3ofthissolutionintoatesttube.6. Add2cm3ofBiuretsolutiontothesolutioninthetesttube.Shakegentlytomix.7. Noteanycolourchange.Proteinswillturnthesolutionpinkorpurple.Questions

Completethetablebelow

Food type Chemical used Test result Reducing sugar Benedicts Turns green/orange brick red when heated with

Benedicts starch

protein

Lipids method 1

Lipids method 2

GCSEBiologyrequiredpracticalactivity:PhotosynthesisRequiredpracticalactivity Apparatusandtechniques

Investigatetheeffectofafactorontherateofphotosynthesisusinganaquaticorganismsuchaspondweed.

AT1,AT3,AT4,AT5

Investigatingtheeffectoflightintensityonphotosynthesisinpondweed

Plantsusecarbondioxideandwatertoproduceglucoseandoxygen.Thisprocessiscalledphotosynthesis.Therateofphotosynthesisisaffectedbymanyfactors,suchas:

• light intensity • light wavelength.

Aquaticplantsproducevisiblebubblesofoxygengasintothesurroundingwaterwhentheyphotosynthesise.Thesebubblescanbecountedasameasureoftherateofphotosynthesis.Pondweedisanexampleofanaquaticplant.

Theeffectoflightintensitycanbeinvestigatedbyvaryingthedistancebetweenpondweedandalightsource.Thecloserthelightsource,thegreaterthelightintensity.

Riskassessment:

Careshouldbetaken:

• when handling glassware • with the use of lamps that may get hot • with the presence of water and the electrical power supply for the lamp.

34

Method


• aboilingtube

• freshlycut10cmpieceofpondweed

• alightsource

• aruler

• atesttuberack

• astopwatch

• 0.2%solutionofsodiumhydrogencarbonate

• a glass rod.

Readtheseinstructionscarefullybeforeyoustartwork.

1. Set up a test tube rack containing a boiling tube at a distance of 10 cm away from the light source 2. Fill the boiling tube with the sodium hydrogen carbonate solution. 3. Put the piece of pondweed into the boiling tube with the cut end at the top. Gently push the pondweed

down with the glass rod. 4. Leave the boiling tube for 5 minutes. 5. Start the stop watch and count the number of bubbles produced in one minute.

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6. Record the results in a table such as the one here.

Distancebetweenpondweedandlightsourceincm

Numberofbubblesperminute

1 2 3 Mean

10

20

30

40

7. Repeat the count twice more. Then use the data to calculate the mean number of bubbles per minute. 8. Repeat steps 1‒7 with the test tube rack and boiling tube at distances of 20 cm, 30 cm and 40 cm from

the light source.

Questions

1. What is the independent variable? 2. What is the range of the independent variable in this method? 3. What is the dependent variable? 4. Give at least 3 examples of control variables? 5. What gas is the bubbles that are being counted? 6. By what process is the gas in question 5 produced? 7. When the lamp is closer to the pondweed light intensity is higher, what relationship would you expect to see

between light intensity and the number of bubbles produced? Can you explain this relationship. 8. An efficient bulb which transfers very little energy as waste is used in this experiment explain why. 9. A heat shield such as a piece of clear plastic or a beaker of water is often placed between the lamp and the

pondweed, suggest why.

Q1.In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

Light intensity, carbon dioxide concentration and temperature are three factors that affect the rate of photosynthesis.

How would you investigate the effect of light intensity on the rate of photosynthesis?

The image below shows some of the apparatus you might use.

36

You should include details of:

• how you would set up the apparatus and the materials you would use

• the measurements you would make

• how you could make this a fair test.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (Total 6 marks)

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Q2.This question is about photosynthesis.

(a) Plants make glucose during photosynthesis. Some of the glucose is changed into insoluble starch.

What happens to this starch?

Tick ( ) one box.

The starch is converted into oxygen.

The starch is stored for use later.

The starch is used to make the leaf green. (1)

(b) A student investigated the effect of temperature on the rate of photosynthesis in pondweed.

The diagram shows the way the experiment was set up.

(i) The student needed to control some variables to make the investigation fair.

State two variables the student needed to control in this investigation.

1.............................................................................................................

2............................................................................................................. (2)

(ii) The bubbles of gas are only produced while photosynthesis is taking place.

What two measurements would the student make to calculate the rate of photosynthesis?

1.............................................................................................................

38

2............................................................................................................. (2)

(c) The graph shows the effect of temperature on the rate of photosynthesis in the pondweed.

Temperature in °C

(i) Name the factor that limits the rate of photosynthesis between the points labelled A and B on the graph.

............................................................................................................... (1)

(ii) Suggest which factor, carbon dioxide, oxygen or water, might limit the rate of photosynthesis between the points labelled C and D on the graph.

............................................................................................................... (1)

(Total 7 marks)

Q3.(a) Complete the equation for photosynthesis. Draw a ring around each correct answer.

hydrogen alcohol

Carbon dioxide + nitrogen light energy glucose + oxygen

water methane

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(2)

Some students investigated the effect of light intensity on the rate of photosynthesis in pondweed.

The diagram shows the apparatus the students used.

The closer the lamp is to the pondweed, the more light the pondweed receives.

The students placed the lamp at different distances, d, from the pondweed.

They counted the number of bubbles of gas released from the pondweed in 1 minute for each distance.

(b) A thermometer was placed in the glass beaker.

Why was it important to use a thermometer in this investigation?

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (3)

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(c) The students counted the bubbles four times at each distance and calculated the correct mean value of their results.

The table shows the students’ results.

Distance d in cm

Number of bubbles per minute

1 2 3 4 Mean

10 52 52 54 54 53

20 49 51 48 52 50

30 32 30 27 31 30

40 30 10 9 11

(i) Calculate the mean number of bubbles released per minute when the lamp was 40 cm from the pondweed.

...............................................................................................................

...............................................................................................................

Mean number of bubbles at 40 cm = ............................................ (2)

(ii) On the graph paper below, draw a graph to show the students’ results:

• add a label to the vertical axis • plot the mean values of the number of bubbles • draw a line of best fit.

41

Distance d in cm (4)

(iii) One student concluded that the rate of photosynthesis was inversely proportional to the distance of the lamp from the plant.

Does the data support this conclusion?

Explain your answer.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(d) Light intensity, temperature and concentration of carbon dioxide are factors that affect the rate of photosynthesis.

Scientists investigated the effects of these three factors on the rate of photosynthesis in tomato plants growing in a greenhouse.

42

The graph below shows the scientists’ results.

Light intensity in lux

A farmer in the UK wants to grow tomatoes commercially in a greenhouse.

The farmer read about the scientists’ investigation.

During the growing season for tomatoes in the UK, natural daylight has an intensity higher than 30 000 lux.

The farmer therefore decided to use the following conditions in his greenhouse during the day:

• 20°C

• 0.1% CO2

• no extra lighting.

Suggest why the farmer decided to use these conditions for growing the tomatoes.

You should use information from the scientists’ graph in your answer.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

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........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (4)

(Total 17 marks)

GCSEBiologyrequiredpracticalactivity:ReactionTime Investigatingwhetherpracticereduceshumanreactiontimes

Messagestravelveryquicklyaroundyourbodythroughthenervoussystem.Thisissothatyouareabletorespondtochangesintheenvironment.Thetimeittakesforyoutorespondtosuchachangeiscalledyourreactiontime.

Athletesspendhourspractisingtotrytoreducetheirreactiontime.Thisistohelpthemimprovetheirperformanceintheirparticularsport.Respondingquickertothestarter’spistolinaracecangainyoutheadvantageoverotherrunners.

Youwillconductasimple,measurableexperimentcalledtherulerdroptest.Fromthisyoucandeterminewhetheryourreactiontimecanbereducedwithpractice.


• ametreruler

• achair

• atable

• a partner.

1. Useyourweakerhandforthisexperiment.Ifyouarerighthandedthenyourlefthandisyourweakerhand.2. Sitdownonthechairwithgooduprightpostureandeyeslookingacrosstheroom.3. Placetheforearmofyourweakerarmacrossthetablewithyourhandoverhangingtheedgeofthetable.4. Yourpartnerwillholdarulerverticallywiththebottomend(theendwiththe0cm)inbetweenyourthumband

firstfinger. Practiceholdingtherulerwiththosetwofingers.5. Yourpartnerwilltakeholdoftherulerandaskyoutoremoveyourfingers.6. Yourpartnerwillholdtherulersothezeromarkislevelwiththetopofyourthumb.Theywilltellyouto

preparetocatchtheruler.7. Yourpartnerwillthendroptherulerwithouttellingyou.8. Youmustcatchtherulerasquicklyasyoucanwhenyousensethattherulerisdropping.9. Aftercatchingtheruler,lookatthenumberlevelwiththetopofyourthumb. Recordthisinatablesuchastheonehere.

44

DroptestattemptsRulermeasurementsincm Reactiontimesinseconds

Person1 Person2 Person1 Person2

1

2

3

4

5

6

7

8

9

10

10. Haveashortrestandthenrepeatthetest.Recordthenumberontherulerasattempt2.11. Continuetorepeatthetestseveraltimes.12. Swapplaceswithyourpartner.Repeattheexperimenttogettheirresults.13. Useaconversiontabletoconvertyourrulermeasurementsintoreactiontimes.

Q1.Two students investigated reflex action times.


1. Student A sits with his elbow resting on the edge of a table.

2. Student B holds a ruler with the bottom of the ruler level with the thumb of Student A.

3. Student B drops the ruler.

4. Student A catches the ruler and records the distance.

5. Steps 1 to 4 are then repeated.

The same method was also used with Student A dropping the ruler and Student B catching the ruler.

(a) Give two variables the students controlled in their investigation.

1 ..........................................................................................................................

2 .......................................................................................................................... (2)

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(b) Figure 1 shows one of the results for the Student A.

Figure 1

What is the reading shown in Figure 1?

.............................................................................................................................

Reading on ruler = ...................................................... cm (1)

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(c) Table 1 shows the students’ results.

Table 1

Test number

Distance ruler dropped in cm

Student A Student B

1 9 12

2 2 13

3 6 13

4 7 9

5 7 8

Mean 7 X

Circle the anomalous result in Table 1 for Student A. (1)

(d) What is the median result for Student B?

Tick one box.

8

11

12

13

(1)

(e) Calculate the value of X in Table 1.

.............................................................................................................................

Mean distance ruler dropped = .................................... cm (1)

(f) Figure 2 shows the scale used to convert distance of the ruler drop to reaction time.

Figure 2

47

Calculate how much faster the reaction time of Student A was compared to Student B.

Use Figure 2 and Table 1.

.............................................................................................................................

Answer = .......................... s (2)

(g) What improvement could the students make to the method so the results are more valid?

Tick one box.

Use alternate hands when catching the ruler

Carry out more repeats

Use a longer ruler for catching

Use more than two students to collect results

(1)

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(h) Student A carried out a second investigation to see the effect of caffeine on the reflex action.

Table 2 shows his results.

Table 2

Test

number

Distance ruler dropped in cm

Without caffeine With caffeine

1 9 5

2 6 5

3 9 4

4 6 7

5 10 4

Mean 8 5

Give one conclusion about the effect of caffeine on reflex actions.

.............................................................................................................................

............................................................................................................................. (1)

(Total 10 marks)

Q2.Car drivers need quick reactions to avoid accidents.

A student uses a computer program to measure reaction time.

The computer screen shows a traffic light on red. The traffic light then changes to green.

The diagram below shows the change the person sees on the computer screen.

When the traffic light changes to green the person has to click the computer mouse as quickly

49

as possible.

The computer program works out the time taken to react to the light changing colour.

(a) Special cells detect the change in colour.

(i) What word is used to describe special cells that detect a change in the environment?

Draw a ring around the correct answer.

(1)

(ii) Where in the body are the special cells that detect the change in colour of the traffic lights?

................................................................................................................... (1)

(b) The student used the computer program on one computer to measure the reaction times of people of different ages.

(i) Give one variable the student should control so that a fair comparison can be made between the people of different ages.

...................................................................................................................

................................................................................................................... (1)

(ii) The student did each measurement three times to calculate a mean value.

The table shows the results.

Age in years

Mean reaction time in

milliseconds

15 242

30

45 221

60 258

75 364

90 526

50

The reaction times for the 30-year-old person were 192, 174 and 180 milliseconds.

Calculate the mean reaction time of the 30-year-old person.

...................................................................................................................

...................................................................................................................

Mean reaction time = ..................................... milliseconds (1)

(iii) Which one of the following is an advantage of repeating each test three times and not doing the test just once?

Tick (✔) one box.

Any anomalies can be identified.

The results will be more precise.

There will be no errors.

(1)

(iv) Some people think that old people should not be allowed to drive a car.

Why is it more dangerous for old people to drive cars?

Use information from the table above to support your answer.

...................................................................................................................

...................................................................................................................

...................................................................................................................

................................................................................................................... (2)

(Total 7 marks)

Q3.Two students investigated reflex action times.


1. Student A sits with her elbow resting on the edge of a table.

2. Student B holds a ruler with the bottom of the ruler level with the thumb of Student A.

3. Student B drops the ruler.

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4. Student A catches the ruler and records the distance, as shown in the diagram below.

5. Steps 1 to 4 were then repeated.

(a) Suggest two ways the students could improve the method to make sure the test would give valid results.

1 .....................................................................................................................

........................................................................................................................

2 .....................................................................................................................

........................................................................................................................ (2)

(b) The table below shows Student A’s results.

Test Number Distance ruler dropped in mm

1 117

2 120

3 115

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4 106

5 123

6 125

7 106

What is the median result?

Tick one box.

106

115

116

117

123

(1)

(c) The mean distance the ruler was dropped is 116 mm.

Calculate the mean reaction time.

Use the equation:

reaction time in s =

Give your answer to 3 significant figures

........................................................................................................................

........................................................................................................................

........................................................................................................................

Mean reaction time = ............................................ s (3)

(d) The students then measured Student A’s reaction time using a computer program.


1. The computer shows a red box at the start.

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2. As soon as the box turns green the student has to press a key on the keyboard as fast as possible.

3. The test is repeated five times and a mean reaction time is displayed.

Student A’s mean reaction time was 110 ms.

Using a computer program to measure reaction times is likely to be more valid than the method using a dropped ruler.

Give two reasons why.

1 .....................................................................................................................

........................................................................................................................

2 .....................................................................................................................

........................................................................................................................ (2)

(e) A woman has a head injury.

Her symptoms include:

• finding it difficult to name familiar objects

• not being able to remember recent events.

Suggest which part of her brain has been damaged.

........................................................................................................................ (1)

(f) A man has a head injury.

He staggers and sways as he walks.

Suggest which part of his brain has been damaged.

........................................................................................................................ (1)

(Total 10 marks)

54

GCSEBiologyrequiredpracticalactivity:Plantresponses


Investigatetheeffectoflightorgravityonthegrowthofnewlygerminatedseedlings.Recordresultsasbothlengthmeasurementsandascarefully,labelledbiologicaldrawingstoshowtheeffects.

AT1,AT3,AT4,AT7

Investigatingtheeffectoflightintensityonthegrowthofmustardseedlings

Lightaffectsthedistributionofauxinswithinthestemsofnewlygerminatedseeds.Theeffectoflightonthisgrowthcanbedeterminedbymeasuringtheheightofshootswitharuler.

Method


• whitemustardseeds

• petri-dishes

• cottonwool

• aruler

• water

• accesstoalightwindowsillandadarkcupboard.


1. Set up three petri dishes containing cotton wool soaked in equal amounts of water. 2. Put ten mustard seeds in each petri dish. 3. Put the petri dishes in a warm place. They must not be disturbed or moved. 4. Allow the mustard seeds to germinate. Add more water if the cotton wool gets dry (equal amounts of water to each petri dish). 5. Each petri dish should have the same number of seedlings after the seeds have geminated. Remove

excess seedlings from any dish that has too many. For example, one dish has eight seedlings which are the fewest compared to the other petri dishes.

Therefore, remove seedlings from the other petri dishes so that each dish has eight. 6. Move the petri dishes into position.

• One should be placed on a windowsill in full sunlight. • One should be placed in partial light. • The third should be placed in darkness.

7. Measure the height of each seedling. Do this every day, for at least a week.

55

Record the heights in a table such as the one here. You will need a table each for: • full sunlight • partial light • darkness.

DayHeightofseedlinginfullsunlightinmm

1 2 3 4 5 6 7 8 Mean

1

2

3

4

5

6

7

8. Calculate the mean height of the seedlings each day. 9. Plot a graph with:

• ‘Mean height in mm’ on the y-axis • ‘Day’ on the x-axis.

The graph should include data for full sunlight, partial light and darkness. Compare the data.

Questions 1.Whatistheindependentvariable?

2.Whatisthedependentvariable?

3.Giveatleast3examplesofcontrolvariables

Q1.(a) When a seed starts to grow, the young root grows downwards towards gravity. The young shoot grows upwards, away from gravity.

(i) Name this type of plant response to gravity.

............................................................................................................... (1)

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(ii) Give two reasons why it is useful for a young root to grow towards gravity.

1 ............................................................................................................

...............................................................................................................

2 ............................................................................................................

............................................................................................................... (2)

(iii) The root grows towards gravity due to the unequal distribution of a substance in the root.

Draw a ring around the correct answer to complete the sentence.

This substance is

auxin.

chlorophyll.

sugar.

(1)

(b) The drawings show some apparatus and materials.

57

In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

Describe how the students could use some or all of the apparatus and materials shown in the drawings to investigate the growth response of maize seedlings to light shining from one side.

You should include a description of the results you would expect.

........................................................................................................................

........................................................................................................................

........................................................................................................................

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........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

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........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (6)

(Total 10 marks)

58

Q2.(a) A student investigated the effect of a plant hormone on the growth of roots by plant cuttings.

The student took six stem cuttings from the same plant. He put the cuttings in test tubes containing hormone solutions of different concentrations.

The image below shows the six cuttings after 2 weeks.

(i) What is the best concentration of hormone for encouraging root growth?

........................................ arbitrary units (1)

(ii) Give two functions of plant roots.

1 ............................................................................................................

...............................................................................................................

2 ............................................................................................................

............................................................................................................... (2)

(iii) Draw a ring around the correct answer to complete the sentence.

Taking cuttings to produce new plants is an example of

asexual reproduction.

genetic engineering.

sexual reproduction.

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(1)

(b) Another student investigated the effect of light, shining from one side, on the growth of plant shoots.

The diagram below shows how the student treated the shoots and the results she obtained after 12 hours.

(i) What is the response to light shown by Seedling A called?

Tick (✓) one box.

cloning

a reflex

a tropism

(1)

(ii) The student concluded that the shoot tip is sensitive to light.

What evidence is there in the diagram above for this conclusion?

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

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(2)

(c) The seedling produces a hormone which helps to control its response to light.

(i) What is the name of the hormone?

Tick (✓) one box.

auxin

glucagon

glycerol

(1)

(ii) How does the hormone control the response of Seedling A to light shining from one side?

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (4)

(Total 12 marks)

GCSEBiologyrequiredpracticalactivity:Fieldinvestigations


Measurethepopulationsizeofacommonspeciesinahabitat.Usesamplingtechniquestoinvestigatetheeffectofafactoronthedistributionofthisspecies.

AT1,AT3,AT4,AT6,AT8

Thisinvestigationhastwoparts:

1.Investigatingthepopulationsizeofaplantspeciesusingrandomsampling

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2.Investigatingtheeffectofafactoronplantdistributionusingatransectline.

Method


• a25cmx25cmquadrat

• 2x30mtapemeasure

• aclipboard

• apen

• paper.

1.Investigatingthepopulationsizeofaplantspeciesusingrandomsampling.

Yourteacherwillhavepreparedasurveyareaforyouandwillshowyouhowtoidentifyplantainplants.Youwillneedtoworkinthrees.

1. Collecttwonumbers,onefromeachbag.2.Usethenumbersandthetapemeasurestolocatethefirstpositionforyourquadrat.

3.Laythe25cmx25cmquadratontheground.

4.Replacethenumbersinthebags.

5.Countandrecordthenumberofplantaininsidethequadrat.

6.Collecttwomorenumbersfromthebagsandusethemtolocatethenextsite.

7.Replacethenumbersinthebagsforotherstudentstouse.

8.Countandrecordthenumberofplantaininsidethequadrat.Repeatsteps1–5untilyouhaverecordedthenumbersofplantainin10quadrats.

10.Yourteacherwillshowyouhowtoestimatethepopulationofplantainusingtheequation:

estimatedpopulationsize= areasampledtotalarea

xnumberofplantaincounted

2.Investigatingtheeffectofafactoronplantdistributionusingatransectline

Yourteacherwillhelpyouidentifyaspeciesofplanttoidentify.

1. Laythe30mtapemeasureinalinefromthebaseofatreetoanopenareaofground.2. Putthe25cmx25cmquadratagainstthetransectline.Onecornerofthequadratshouldtouchthe0mmarkon

thetapemeasure.3. Countthenumberofplantswithinthequadratandrecordtheminatable.

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Distancealongthetransectlineinm

Numberofplants Lightintensity

0

5

10

15

20

25

30

4.Movethequadrat5mupthetransectlineandcountthenumberofplantsagain.Recordinthetable.

5.Continuetoplacethequadratat5mintervalsandcountthenumberofplantsineachquadrat.

6.Gatherdatafromyourclasstoproduceagraphofplantnumbersagainstlightintensity.

Q1.A student was asked to estimate how many clover plants there are in the school field.

The image below shows the equipment used.


1. Throw a quadrat over your shoulder.

2. Count the number of clover plants inside the quadrat.

3. Repeat step 1 and step 2 four more times.

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4. Estimate the number of clover plants in the whole field.

(a) What is the tape in the image above used for in this investigation?

.............................................................................................................................

............................................................................................................................. (1)

(b) The teacher told the student that throwing the quadrat over his shoulder was not random.

The method could be improved to make sure the quadrats were placed randomly.

Suggest one change the student could make to ensure the quadrats were placed randomly.

.............................................................................................................................

............................................................................................................................. (1)

(c) How could the student improve the investigation so that a valid estimate can be made?

Tick two boxes.

Weigh the clover plants

Compare their results with another student’s results

Count the leaves of the clover plants

Place more quadrats

Place the quadrats in a line across the field

(2)

(d) The table below shows the student’s results.

Quadrat number

Number of clover plants

counted

1 11

2 8

64

3 11

4 9

5 1

Total 40

The area of the school field was 500 m2.

The quadrat used in the table above had an area of 0.25 m2.

Calculate the estimated number of clover plants in the school field.

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Estimated number of clover plants = ................................. (3)

(e) What was the mode for the results in the table above?

Tick one box.

1

8

11

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(1)

(f) Suggest which quadrat could have been placed under the shade of a large tree.

Give one reason for your answer.

Quadrat number ....................................

Reason ...............................................................................................................

............................................................................................................................. (1)

(Total 9 marks)

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Q2.A grassy field on a farm measured 120 metres by 80 metres.

A student wanted to estimate the number of buttercup plants growing in the field.

The student found an area where buttercup plants were growing and placed a 1 m × 1 m quadrat in one position in that area.

Figure 1 shows the buttercup plants in the quadrat.

The student said, 'This result shows that there are 115 200 buttercup plants in the field.'

(a) (i) How did the student calculate that there were 115 200 buttercup plants in the field?

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(ii) The student’s estimate of the number of buttercup plants in the field is probably not accurate. This is because the buttercup plants are not distributed evenly.

How would you improve the student’s method to give a more accurate estimate?

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(b) Sunlight is one environmental factor that might affect the distribution of the buttercup plants.

(i) Give three other environmental factors that might affect the distribution of the buttercup plants.

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2...............................................................................................................

3............................................................................................................... (3)

(ii) Explain how the amount of sunlight could affect the distribution of the buttercup plants.

(3)

(c) Figure 2 is a map showing the position of the farm and a river which flows through it.

Every year, the farmer puts fertiliser containing mineral ions on some of his fields.When there is a lot of rain, some of the fertiliser is washed into the river.

(i) When fertiliser goes into the river, the concentration of oxygen dissolved in the water decreases.

Explain why the concentration of oxygen decreases.

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(ii) There is a city 4 km downstream from the farm.

Apart from fertiliser, give one other form of pollution that might go into the river as it flows through the city.

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(d) Three sites, A, B and C, are shown in Figure 2.

Scientists took many samples of river water from these sites.

The scientists found larvae of three types of insect in the water: mayfly, stonefly and caddisfly. For each type of insect the scientists found several different species.

The scientists counted the number of different species of the larvae of each of the three types of insect.

Figure 3 shows the scientists’ results.

(i) How many more species of mayfly were there at Site B than at Site A?

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(ii) Suggest what caused this increase in the number of species of mayfly.

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(iii) The scientists stated that the number of species of stonefly was the best indicator of the amount of oxygen dissolved in the water.

Use information from Figure 3 to suggest why. (1)

(Total 19 marks)

Q3.Some students investigated the distribution of dandelion plants in a grassy field. The grassy field was between two areas of woodland.

Figure 1 shows two students recording how many dandelion plants there are in a 1 metre x 1 metre quadrat.

Figure 1

© Science Photo Library

Figure 2 shows a section across the area studied and Figure 3 shows a bar chart of the students’ results.

Figure 2

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Distance in m

Figure 3

Distance in m

(a) How did the students use the quadrat and the 30-metre tape measure to get the results in Figure 3?

Use information from Figure 1.

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(b) (i) Suggest one reason why the students found no dandelion plants under the trees.

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(ii) Suggest one reason why the students found no dandelion plants at 16 metres.

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(c) The teacher suggested that it was not possible to make a valid conclusion from these results.

Describe how the students could improve the investigation so that they could make a valid conclusion.

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(Total 7 marks)

Q4. Some students investigated the distribution of some of the plants growing in and around a shallow stream. They sampled along a transect line.

The diagram shows their results.

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(a) (i) Name the one species that grew only in the driest conditions.

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(ii) Only one species grew in the marsh, the swamp and in the aquatic zones.

Which species?

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(iii) Duckweed grows floating in water. What evidence is there for this in the students’ results?

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........................................................................................................................ (1)

(b) In this question you will be assessed on using good English, organising information

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clearly and using specialist terms where appropriate.

Describe how you would use a -metre × -metre quadrat frame and a 30-metre tape measure to obtain data similar to the data shown in the diagram.

You should include details of how you would make sure that you would obtain valid results.

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(Total 9 marks)

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GCSEBiologyrequiredpracticalactivity:Decay


InvestigatetheeffectoftemperatureontherateofdecayoffreshmilkbymeasuringpHchange.

AT1,AT3,AT4,AT5

InvestigatingtheeffectoftemperatureontherateofdecayoffreshmilkbymeasuringpHchange

Youwilluseanalkalinesolutionofmilk.Whenlipaseisaddedtothemilkthefatinthemilkisbrokendownintofattyacids.ThismakesthepHlower.

CresolredisanindicatorthatispurpleinalkalinesolutionsofaboutpH8.8.WhenthepHdropsbelowpH7.2Cresolredbecomesyellow.

Method


• asmallbeakercontainingfullfatmilkorsinglecream

• asmallbeakercontainingsodiumcarbonatesolution

• asmallbeakercontaininglipasesolution

• 250cm3beakers,tobeusedaswaterbaths

• testtubes

• atesttuberack

• amarkerpen

• 10cm3plasticsyringes

• astirringthermometer

• astopclock

• Cresolred,inadropperbottle

• anelectrickettle,forheatingwater

• ice,forinvestigatingtemperaturesbelowroomtemperature.


1. Halffilloneofthe250cm3beakerswithhotwaterfromthekettle.Thiswillbethewaterbath.2. Labeltwotesttubes:

• one ‘lipase’ • one ‘milk’

3. Inthe‘lipase’testtubeput5cm3oflipasesolution.4. Inthe‘milk’testtubeputfivedropsofCresolredsolution.

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5. Useacalibrateddroppingpipettetoadd5cm3ofmilktothe‘milk’testtube.6. Useanotherpipettetoadd7cm3ofsodiumcarbonatesolutiontothe‘milk’testtube.

Thesolutionshouldbepurple.

7. Putathermometerintothe‘milk’testtube.8. Putbothtesttubesintothewaterbath.Waituntilthecontentsreachthesametemperatureasthewaterbath.9. Useanotherdroppingpipettetotransfer1cm3oflipaseintothe‘milk’testtube. Immediatelystarttiming. 10. Stirthecontentsofthe‘milk’testtubeuntilthesolutionturnsyellow.11. Recordthetimetakenforthecolourtochangetoyellow,inseconds.12. Repeatsteps1‒11fordifferenttemperaturesofwaterbath. Youcanobtaintemperaturesbelowroomtemperaturebyusingiceinthebeakerinsteadofhotwater.13. Recordyourresultsinatablesuchastheonehere.Plotagraphofyourresults.

Temperatureofmilkin°CTimetakenforsolutiontoturnyellow,inseconds

Trial1 Trial2 Trial3 Mean

1. What is the independent variable in this experiment? 2. What is the dependent variable in this experiment? 3. Suggest at least 3 control variables.

Q1.Students investigated decomposition.

The students: • put some decaying grass cuttings into a vacuum flask • put a carbon dioxide sensor and a temperature sensor in the flask • attached the sensors to a data logger • closed the flask with cotton wool.

A vacuum flask was used to reduce the loss of thermal energy.

Figure 1 shows the investigation.

Figure 1

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(a) Give one advantage of using a temperature sensor attached to a data logger instead of a thermometer.

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(b) Figure 2 shows the results from the data logger for carbon dioxide concentration in the flask for the next 25 days.

Figure 2

(i) Why did the concentration of carbon dioxide in the flask increase?

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(ii) Suggest what has happened in the flask to cause the carbon dioxide concentration to level off after 20 days.

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(Total 5 marks)

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Q2.A gardener investigates if turning over the waste in a compost heap makes the waste decay more quickly.

The gardener: • makes two separate heaps of garden waste, heap A and heap B

• turns over the material in heap A every 2 weeks

• does not turn over the material in heap B

• estimates the amount of decay in the two heaps after 6 months.

The diagram shows the two heaps of garden waste at the beginning of the investigation.

(a) Suggest two factors, other than time, the gardener should control to make the investigation fair.

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(b) Name one type of living thing that causes decay.

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(c) The gardener’s results are shown in the table.

Compost heap Estimated amount of decay

A A lot

B Very little

(i) Why does turning over the material in heap A make the material decay more quickly?

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(ii) The gardener puts decayed material around his plants to help them grow.

Suggest why the plants in a woodland grow well each year without material from compost heaps being added.

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(Total 6 marks)

triple biology required practicals · a bacterial cell is 40 times smaller. calculate the diameter...

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