Question 1
The source of the oxygen released during oxygenic photosynthesis is required.
A.
Glucose oxidized during respiration in chloroplasts
B.
Mineral ions absorbed from the soil solution
C.
Carbon dioxide fixed in the Calvin cycle
D.
Water split during the light-dependent reactions
Question 2
A photosynthetic pigment moved from the origin during paper chromatography. The solvent front moved from the origin.
What is the value of the pigment?
A.
24.0
B.
0.67
C.
1.67
D.
0.60
Question 3
The absorption spectrum that best represents chlorophyll in the visible range is required.
A.
B.
C.
D.
Question 4
A student investigates the effect of carbon dioxide concentration on the rate of photosynthesis in pondweed by using different concentrations of sodium hydrogen carbonate solution.
The controlled variable in this investigation is required.
A.
Concentration of sodium hydrogen carbonate solution
B.
Volume of oxygen produced per minute
C.
Rate of photosynthesis in the pondweed
D.
Distance between the lamp and the pondweed
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Question 5
The diagram that best represents a photosystem is required.
A.
B.
C.
D.
Question 6
The products of photolysis of water in photosystem II are required.
A.
Carbon dioxide, protons and ATP
B.
RuBP, electrons and glycerate 3-phosphate
C.
Reduced NADP, oxygen and glucose
D.
Oxygen, protons and electrons
Question 7
The reduction of NADP in the light-dependent reactions is described correctly by one statement.
A.
NADP is phosphorylated by ATP synthase in the thylakoid membrane.
B.
NADP donates two electrons to photosystem II and releases oxygen.
C.
NADP accepts carbon dioxide and becomes glycerate 3-phosphate.
D.
NADP accepts two electrons from photosystem I and a hydrogen ion from the stroma.
Question 8
Photosynthesis supplies most of the chemical energy entering many ecosystems.
State the energy transformation that occurs during photosynthesis.
[1]
Outline how this energy transformation supports consumers in an ecosystem.
[2]
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Question 9
Glucose is often used as the named product in the simple equation for photosynthesis.
State the simple word equation for photosynthesis.
[1]
State the source of the hydrogen used to convert carbon dioxide into glucose.
[1]
State the source of the oxygen released during photosynthesis.
[1]
Question 10
Photosynthesizing algae were exposed to different wavelengths of light of equal intensity. Oxygen production was measured for the same time interval at each wavelength.
The graph shows the results.
A.
This is an absorption spectrum because it shows the amount of light absorbed by isolated pigment.
B.
This is a chromatogram because it separates pigments by movement through a solvent.
C.
This is an action spectrum because it shows the rate of photosynthesis at different wavelengths.
D.
This is a limiting-factor graph because it shows the effect of temperature on enzyme activity.
Question 11
The main reason for using free-air carbon dioxide enrichment experiments rather than enclosed greenhouses to predict future plant growth in ecosystems is required.
A.
They keep temperature and water supply under stricter control than a greenhouse.
B.
They allow carbon dioxide to be completely excluded from control plants.
C.
They expose plants to more realistic field conditions and ecological interactions.
D.
They remove the need for untreated control plots in an experiment.
Question 12
A toxin blocks proton movement through ATP synthase in thylakoid membranes but does not directly stop electron transport.
The immediate effect on the light-dependent reactions is required.
A.
Rubisco fixes carbon dioxide faster.
B.
ATP synthesis in the stroma decreases.
C.
NADP is reduced by accepting protons from the thylakoid space.
D.
Photolysis produces glucose instead of oxygen.
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Question 13
The reaction catalysed by Rubisco in the Calvin cycle is required.
A.
Triose phosphate combines with NADP to produce carbon dioxide.
B.
Water combines with reduced NADP to produce oxygen.
C.
Glycerate 3-phosphate combines with oxygen to regenerate RuBP.
D.
Carbon dioxide combines with RuBP to form glycerate 3-phosphate.
Question 14
The absorption spectrum of a mixture of photosynthetic pigments was obtained from a leaf extract.
Identify the region of the visible spectrum in which the pigments absorb least strongly.
[1]
Explain why chlorophyll-containing leaves usually appear green.
[2]
State what happens to an electron in a pigment molecule when a suitable photon is absorbed.
[1]
Question 15
Photosystems are located in membranes of cyanobacteria and in chloroplast thylakoid membranes of photosynthetic eukaryotes.
State what is meant by a photosystem.
[2]
Explain one advantage of arranging different pigment molecules in a photosystem rather than using a single chlorophyll molecule.
[2]
Question 16
Photolysis of water occurs in photosystem II during the light-dependent reactions of photosynthesis.
State the products of photolysis of water in photosystem II.
[2]
Outline the roles of these products in photosynthesis.
[2]
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Question 17
An aquatic alga was grown in sealed vessels supplied with either isotope-labelled water or isotope-labelled carbon dioxide. The oxygen gas released during illumination was analysed for the labelled isotope.
Treatment | Labelled released / % |
|---|---|
Isotope-labelled water | 91 |
Isotope-labelled carbon dioxide | 3 |
Identify the treatment that provides evidence for the source of oxygen released in photosynthesis.
[1]
Calculate the difference in the percentage of labelled oxygen gas released between the labelled-water treatment and the labelled-carbon-dioxide treatment.
[1]
Explain how the results support the conclusion that oxygen is a by-product of oxygenic photosynthesis.
[2]
Question 18
Pondweed was placed in sodium hydrogen carbonate solutions of different concentrations. Light intensity and temperature were kept constant. Oxygen production was measured using an oxygen probe.
Describe the effect of increasing sodium hydrogen carbonate concentration on oxygen production.
[2]
Deduce which factor is no longer limiting photosynthesis in the plateau region.
[1]
State one variable that should be controlled to make this investigation valid.
[1]
Question 19
A chloroplast is illuminated but supplied with no carbon dioxide.
The reason photosystem II eventually stops functioning normally is required.
A.
ATP synthase stops because protons are no longer produced from water.
B.
The thylakoid membrane breaks down because oxygen cannot diffuse into the stroma.
C.
Photolysis cannot occur because carbon dioxide is the direct source of replacement electrons.
D.
Rubisco cannot fix carbon, so NADP is not regenerated fast enough to accept electrons.
Question 20
A student separated photosynthetic pigments from a leaf extract by paper chromatography. The solvent front was marked immediately after the paper was removed.
Feature | Band colour | Distance from origin / mm |
|---|---|---|
Orange pigment band | orange | 70 |
Solvent front | colourless | 80 |
Calculate the value for the orange pigment band.
[2]
Suggest why the solvent level must be below the origin line at the start of chromatography.
[1]
Identify one type of evidence, other than distance moved, that can help identify a pigment separated by chromatography.
[1]
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Question 21
An investigation measured oxygen production by algae exposed to different wavelengths of light. Each wavelength was supplied at the same light intensity.
Wavelength / nm | Oxygen produced / in 6.0 min |
|---|---|
430 | 3.5 |
550 | 1.0 |
660 | 3.6 |
Determine the rate of photosynthesis at the red-light wavelength from the oxygen data.
[2]
Outline why an action spectrum is expected to have peaks at wavelengths that are strongly absorbed by photosynthetic pigments.
[2]
Question 22
A student used pondweed in sodium hydrogen carbonate solution to investigate the effect of light intensity on photosynthesis. The distance between a lamp and the pondweed was changed.
Identify the independent variable and the dependent variable in this investigation.
[2]
Suggest one controlled variable and one reason why it should be controlled.
[2]
Question 23
ATP is produced in chloroplasts by chemiosmosis in thylakoids.
State two processes that help generate the proton gradient across the thylakoid membrane.
[2]
Explain how the proton gradient is used to synthesize ATP.
[2]
Question 24
NADP is reduced during the light-dependent reactions of photosynthesis.
State the source of the electrons and hydrogen ion used to reduce NADP.
[2]
Explain why the reduction of NADP occurs on the stroma side of the thylakoid membrane.
[2]
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Question 25
A student separated pigments from a leaf extract using paper chromatography. The solvent front and the centres of four pigment bands were marked immediately after the chromatogram was removed from the chamber.
Calculate the value of the orange pigment.
[2]
Deduce the identity of the orange pigment using the chromatogram and the reference table.
[1]
Explain why the pigments separated into different bands.
[1]
Question 26
Leaf discs were infiltrated with sodium hydrogen carbonate solution so that they sank. The discs were then illuminated by a lamp at different distances. The time for half of the discs to rise was recorded.
Identify the independent variable and the dependent variable in this investigation.
[2]
Calculate the relative light intensity at a lamp distance of 0.25 m using .
[1]
Suggest why the discs took longer to rise when the lamp was further away.
[2]
Question 27
An artificial photosystem was constructed in a membrane using either one type of chlorophyll molecule or a structured array of chlorophyll and accessory pigments around a reaction centre. Electron emission from the reaction centre was measured under different wavelengths of light.
Identify the part of the photosystem from which the excited electron is emitted.
[1]
Explain two advantages of a structured array of different pigment molecules in a photosystem.
[2]
Use the graph to explain why chlorophyll alone would not perform photosynthesis effectively in the artificial membrane.
[2]
Question 28
Isolated chloroplasts were illuminated with either abundant NADP or very little NADP available. Oxygen production, ATP production and reduced NADP production were measured.
Deduce which condition shows more cyclic photophosphorylation.
[1]
State what NADP accepts when it is reduced in photosynthesis.
[2]
Suggest why reduced NADP production decreases when little NADP is available.
[1]
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Question 29
The Calvin cycle occurs in the stroma of chloroplasts and begins with carbon fixation.
State the substrates and product of the carbon fixation reaction catalysed by Rubisco.
[2]
Outline why ATP is required in two different parts of the Calvin cycle.
[2]
Question 30
The light-dependent reactions and the Calvin cycle are interdependent parts of photosynthesis.
Explain why the Calvin cycle stops soon after a plant is placed in darkness.
[2]
Explain why a lack of carbon dioxide can prevent photosystem II from functioning normally.
[2]
Question 31
An absorption spectrum for a mixture of photosynthetic pigments was compared with an action spectrum measured from oxygen production by the same species of alga.
Compare the absorption spectrum and the action spectrum shown.
[2]
Calculate the percentage decrease in oxygen production from blue light at 450 nm to green light at 550 nm.
[2]
Suggest why green light gives a lower rate of photosynthesis than blue light in this investigation.
[1]
Question 32
Researchers compared the effect of carbon dioxide enrichment on wheat growth in an enclosed greenhouse and in a free-air carbon dioxide enrichment (FACE) field experiment. Each system included plots with adequate nitrogen and plots with low nitrogen.
System | Nitrogen availability | Biomass increase under elevated / % |
|---|---|---|
Greenhouse | Adequate N | 28 |
Greenhouse | Low N | 10 |
FACE | Adequate N | 16 |
FACE | Low N | 5 |
Compare the effect of carbon dioxide enrichment in the greenhouse and FACE experiments.
[2]
Suggest why low nitrogen reduced the biomass response to carbon dioxide enrichment.
[1]
Evaluate one advantage of using FACE experiments rather than only greenhouse experiments to predict future plant growth.
[1]
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Question 33
Isolated thylakoids were illuminated under different conditions. Oxygen production and electron flow from photosystem II were recorded.
Treatment | Oxygen production / a.u. | Electron flow from PSII / a.u. |
|---|---|---|
Dark treatment | 2 | 2 |
Illuminated control | 24 | 18 |
Illuminated + PSII inhibitor | 8 | 6 |
Calculate how many times greater oxygen production was in the illuminated control than in the dark treatment.
[1]
State the products of photolysis that are used in photosynthesis and the product that diffuses away as waste.
[2]
Explain why the photosystem II inhibitor reduced both electron flow and oxygen production.
[2]
Question 34
Chloroplast thylakoids were isolated and illuminated. A pH probe measured the thylakoid space and the surrounding stroma. ATP production was measured before and after adding a compound that allows protons to cross the thylakoid membrane without passing through ATP synthase.
Time / min | Stroma pH | Thylakoid space pH | ATP production rate / a.u. |
|---|---|---|---|
0.0 | 7.0 | 7.0 | 0 |
2.0 | 7.3 | 6.3 | 4 |
4.0 | 7.6 | 5.6 | 9 |
5.0 | 7.8 | 5.2 | 12 |
5.5 | 7.6 | 6.1 | 3 |
7.0 | 7.4 | 6.6 | 1 |
Calculate the pH difference between the stroma and thylakoid space immediately before the compound was added.
[1]
Explain how the proton gradient across the thylakoid membrane is generated during illumination.
[2]
Explain why ATP production fell after the compound was added.
[2]
Question 35
A student measured the absorption of light by a leaf pigment extract and the rate of photosynthesis in leaf discs exposed to different wavelengths of light.
I.
Using the graph, identify the colour region in which the rate of photosynthesis is lowest.
[1]
II.
Calculate the rate of photosynthesis as a percentage of the maximum rate for one wavelength shown on the graph.
[2]
Compare and contrast the absorption spectrum and the action spectrum.
[2]
Explain why photosynthetic pigments absorb only some wavelengths of visible light and how this begins the transformation of energy.
[2]
Question 36
A class separated pigments from spinach leaves by paper chromatography. The solvent front and several coloured pigment bands were marked immediately after the paper was removed from the solvent.
I.
State the formula used to calculate the retention factor, , for a pigment.
[1]
II.
Using the chromatogram, calculate the value for the yellow-green band.
[2]
Explain why pigments separate during chromatography.
[2]
Evaluate two aspects of technique that are important for obtaining reliable pigment identification.
[2]
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Question 37
A culture of green algae was supplied with water containing a tracer isotope of oxygen. The oxygen gas released during photosynthesis contained the tracer.
I.
Write the simple word equation for photosynthesis with glucose as the product.
[1]
II.
Deduce the source of the oxygen gas released by the algae.
[1]
III.
State the name of the process that splits water during photosynthesis.
[1]
Explain how carbon dioxide is converted into glucose using hydrogen obtained from water.
[2]
Discuss the importance of oxygenic photosynthesis for ecosystems.
[2]
Question 38
In a shaded woodland, plants differ in leaf pigment composition and in the amount of biomass produced each year.
I.
State the energy transformation that occurs in photosynthesis.
[1]
II.
State one group of organisms, other than plants, that carries out oxygenic photosynthesis.
[1]
Explain how pigments allow photosynthesis to occur in shaded habitats.
[2]
Discuss how photosynthesis links energy flow and carbon cycling in a woodland ecosystem.
[2]
Question 39
A suspension of chloroplasts was supplied with radioactive carbon dioxide. The quantities of Calvin cycle intermediates were measured after changing the carbon dioxide concentration while light intensity remained high.
Identify the substrates and product of the Rubisco-catalysed carbon fixation reaction shown.
[2]
A chloroplast produces 12 molecules of TP during a period of photosynthesis. Calculate how many TP molecules must be recycled to regenerate RuBP if glucose is the net product.
[1]
Explain why high concentrations of Rubisco are needed in chloroplast stroma.
[2]
Question 40
Intact chloroplasts were kept in bright light with adequate carbon dioxide. The light was then switched off for several minutes and restored. In a second trial, carbon dioxide was removed while bright light was maintained.
Describe the effect of switching off the light on ATP and reduced NADP concentrations.
[1]
Explain why the Calvin cycle soon stops in darkness.
[2]
Explain why removal of carbon dioxide can eventually prevent photosystem II from functioning normally, even though light is still present.
[2]
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Question 41
Leaf discs from the same plant were placed in sodium hydrogen carbonate solution and exposed to lamps at different distances. The time taken for half of the discs to float was recorded.
I.
Identify the independent variable and the dependent variable in this investigation.
[2]
II.
State a testable hypothesis for this investigation.
[1]
Explain why leaf discs float after photosynthesis has occurred.
[2]
Discuss how the design could be improved to test the effect of light intensity more reliably.
[3]
Question 42
Researchers compared tomato plant growth under ambient carbon dioxide and enriched carbon dioxide in two systems: enclosed greenhouse chambers and free-air carbon dioxide enrichment (FACE) plots.
System | CO2 treatment | Mean photosynthesis rate / mol | Harvest dry biomass / plant |
|---|---|---|---|
Greenhouse | ambient | 12 | 150 |
Greenhouse | enriched | 18 | 156 |
FACE | ambient | 10 | 145 |
FACE | enriched | 13 | 148 |
I.
Identify one controlled variable that should be kept similar between ambient and enriched carbon dioxide treatments.
[1]
II.
Using the table, compare the effect of carbon dioxide enrichment on photosynthesis rate in the two systems.
[2]
Explain why increased carbon dioxide may increase photosynthesis but not lead to a proportional increase in dry biomass.
[2]
Evaluate greenhouse experiments and FACE experiments as methods for predicting future plant growth under rising atmospheric carbon dioxide.
[3]
Question 43
A photosystem contains many pigment molecules arranged around a reaction centre in a membrane.
I.
State where photosystems are located in photosynthetic eukaryotes.
[1]
II.
Describe what is emitted from the reaction centre after light has been absorbed.
[1]
III.
State one type of organism, other than photosynthetic eukaryotes, in which photosystems occur.
[1]
Explain two advantages of having different pigment molecules in a structured photosystem array.
[2]
Discuss why a single isolated chlorophyll molecule cannot perform photosynthesis.
[2]
Question 44
The diagram shows part of a thylakoid membrane during the light-dependent reactions of photosynthesis.
I.
Write the equation summarizing photolysis of water in photosystem II.
[1]
II.
State the fate of the electrons produced by photolysis.
[1]
III.
State the fate of the oxygen produced by photolysis.
[1]
Explain how a proton gradient is generated across the thylakoid membrane.
[2]
Explain how chemiosmosis in thylakoids produces ATP.
[3]
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Question 45
Photosystem I can participate in non-cyclic and cyclic electron flow. The availability of NADP influences which pathway operates.
I.
State where reduction of NADP occurs relative to the thylakoid membrane.
[1]
II.
State what NADP accepts when it is reduced.
[2]
Compare and contrast cyclic and non-cyclic photophosphorylation.
[3]
Suggest why cyclic electron flow may increase when most NADP is already reduced.
[1]
Question 46
A hydroponic crop received adequate light and carbon dioxide but was grown either with complete mineral nutrients or with nitrate omitted from the nutrient solution.
Treatment | Shoot dry mass / g plant | Starch / mg g dry mass | Protein / mg g dry mass |
|---|---|---|---|
Complete nutrients | 18.0 | 96 | 172 |
Nitrate omitted | 11.4 | 95 | 58 |
I.
State the Calvin cycle product that can be used to synthesize carbohydrates.
[1]
II.
Identify the mineral nutrient missing from the nitrate-deficient treatment and the element it supplies.
[2]
Explain why photosynthesis alone is not sufficient for synthesis of all plant biomass.
[2]
Discuss how the table supports the idea that all carbon compounds in photosynthesizing organisms can be traced back to the Calvin cycle, but growth also depends on mineral nutrition.
[2]
Question 47
The Calvin cycle fixes carbon dioxide and produces triose phosphate in the stroma of chloroplasts.
I.
Identify the substrate that accepts carbon dioxide in the Calvin cycle and the enzyme that catalyses this reaction.
[2]
II.
State the first stable product formed after carbon fixation.
[1]
Explain how GP is converted into TP.
[2]
Explain why RuBP must be regenerated and how this affects the net yield of triose phosphate.
[3]
Question 48
Isolated chloroplasts were supplied with carbon dioxide in the light. At two different times, either the light was switched off or carbon dioxide was removed. Concentrations of ATP, reduced NADP, GP and RuBP were monitored.
I.
State the products of the light-dependent reactions that are used by the Calvin cycle.
[2]
II.
State the products returned by the Calvin cycle to the light-dependent reactions.
[1]
Explain the expected effect of switching off the light on the Calvin cycle.
[2]
Evaluate the claim that removal of carbon dioxide can eventually prevent photosystem II from functioning normally.
[3]
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