Photosynthesis: Edexcel International A Level Biology questions

Every Edexcel International A Level Biology exam question on Photosynthesis (specification points 5.1–5.8), 2019–2025, with its mark scheme and examiner’s report.

All 111 questions on Photosynthesis, as a list

June 2025, Unit 4, Q7(b)(i) (1 mark): Which is the Rf value for beta-carotene in this chromatogram? (1) A 0.75 B 0.87 C 1.16 D 1.33
June 2025, Unit 4, Q7(b)(ii) (2 marks): Explain why chromatography can be used to identify beta-carotene. (2)
June 2025, Unit 4, Q9(b)(i) (1 mark): Suggest why wavelengths of light between 400 nm and 900 nm were used in this investigation. (1)
June 2025, Unit 4, Q9(b)(ii) (2 marks): Explain why the scientists thought that there would be a difference in the reflection spectra for healthy leaves and leaves infected with RYMV. (2)
June 2025, Unit 4, Q9(b)(iii) (3 marks): Discuss the extent to which the results shown in the graph could be useful to farmers in identifying infected plants. (3)
January 2025, Unit 4, Q4(a)(i) (1 mark): Which row of the table shows where the light‑dependent reactions and the light‑independent reactions take place? (1) Light-dependent reactions Light-independent
January 2025, Unit 4, Q4(a)(ii) (1 mark): Where do hydrogen ions (protons) accumulate? (1) A Q B R C S D W
January 2025, Unit 4, Q4(a)(iii) (3 marks): The diagram is 16 000 times larger than an actual chloroplast. Calculate the surface area of the actual chloroplast. Use the formula: Surface area = 4 πr2 Give
January 2025, Unit 4, Q4(a)(iv) (2 marks): Explain the advantages of thylakoids in a chloroplast having a large surface area. (2)
January 2025, Unit 4, Q4(b)(i) (1 mark): Which describes how ATP is generated in the light‑dependent reactions? (1) A by hydrolysis of ADP releasing energy B by hydrolysis of ADP requiring energy C by
January 2025, Unit 4, Q4(b)(ii) (2 marks): When one molecule of glucose is made in the light‑independent reactions, the ratio of ATP used to reduced NADP used is 1.5 : 1. Show how this ratio can be calcu
January 2025, Unit 4, Q4(b)(iii) (2 marks): Explain why only a small proportion of the GALP produced is used to make the glucose. (2)
October 2024, Unit 4, Q1(a) (2 marks): Suggest two reasons why very little of the light energy is absorbed by plants. (2)
October 2024, Unit 4, Q7(a) (4 marks): Explain how infection with these bacteria results in the death of the leaf cells and eventually the whole plant. (4)
October 2024, Unit 4, Q9(a) (3 marks): Explain the role of light in the light‑dependent reactions in photosynthesis. (3)
October 2024, Unit 4, Q9(b)(i) (1 mark): Which would have been the most appropriate light to use as a positive control? (1) A green B mixture of green, blue and red light C ultraviolet D sunlight
October 2024, Unit 4, Q9(b)(ii) (4 marks): The graphs show the results for the mean rate of photosynthesis and mean leaf biomass. 4 3 Mean rate of photosynthesis 2 / a.u. 1 0 control blue amber red Light
October 2024, Unit 4, Q9(b)(iii) (3 marks): The table shows the results for the pigment content of the leaves. Mass of pigment / µg per g of leaf biomass Pigment Control light Blue light Amber light Red l
October 2024, Unit 4, Q9(b)(iv) (3 marks): Plants treated with blue light had an increase in photosynthesis caused by an increase in the transcription of some genes in the leaves. Suggest two genes whose
October 2024, Unit 6, Q4(a) (2 marks): Describe the preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (2)
October 2024, Unit 6, Q4(b) (9 marks): Devise a detailed method, including how you would control and monitor important variables. (9)
October 2024, Unit 6, Q4(d) (2 marks): Suggest two limitations of your proposed method. (2)
June 2024, Unit 4, Q1(a) (1 mark): Which process can be used to separate chloroplast pigments according to their solubility? (1) A chromatography B dendrochronology C gel electrophoresis D polyme
June 2024, Unit 4, Q1(b)(i) (3 marks): Compare and contrast the types of chloroplast pigment found in the seaweeds with those found in the spinach. Use the information in the diagram to support your
June 2024, Unit 4, Q1(b)(ii) (3 marks): Describe how the student could identify pigment P using this method. (3)
June 2024, Unit 4, Q1(c)(i) (1 mark): Which row of the table shows the light that green seaweed can absorb? (1) Green light Red light A can absorb can absorb B can absorb cannot absorb C cannot abso
June 2024, Unit 4, Q1(c)(ii) (2 marks): Explain the positions of the brown and red seaweeds on the submerged rock. (2)
June 2024, Unit 4, Q7(a) (3 marks): Describe how carbon becomes incorporated into plant biomass. (3)
June 2024, Unit 4, Q7(b)(i) (2 marks): Explain why air temperature affects the CO2 fertilisation effect. (2)
June 2024, Unit 4, Q7(b)(ii) (2 marks): Suggest why soil temperature affects the CO2 fertilisation effect. (2)
June 2024, Unit 4, Q7(c) (3 marks): Explain why a lack of water availability in the leaves would decrease the CO2 fertilisation effect. (3)
June 2024, Unit 4, Q7(d) (4 marks): The roots of most land plants are associated with microscopic fungi called mycorrhizal fungi. These fungi provide the plants with nitrate ions. The effect of tw
January 2024, Unit 4, Q2(a)(i) (1 mark): Which row of the table shows the products of the light‑dependent reactions that are used in the light‑independent reactions? (1) ATP produced by NADP A cyclic p
January 2024, Unit 4, Q2(a)(ii) (2 marks): Simple sugars have the formula CnH2nOn. Name the inorganic molecule that provides each element in a simple sugar. (2) C H . O
January 2024, Unit 4, Q2(b)(i) (3 marks): Describe three conclusions that can be made about the differences in the effect of temperature on the rate of photosynthesis in these two types of plant. (3)
January 2024, Unit 4, Q2(b)(ii) (2 marks): Calculate the Q10 for the enzymes in C4 plants. Use the formula: R Q t 10 10 R t where Rt is the initial rate of reaction at 10 °C. Give your answer as a whole
October 2023, Unit 4, Q1(a) (1 mark): Which is the site of photolysis? (1) A P B R C T D V
October 2023, Unit 4, Q1(b) (1 mark): Which contains a gene coding for RUBISCO? (1) A P B Q C S D V
October 2023, Unit 4, Q1(c) (1 mark): Where do hydrogen ions accumulate for use in photosynthesis? (1) A Q B R C S D V
October 2023, Unit 4, Q5(b)(i) (1 mark): Which type of bond is broken in a water molecule? (1) A covalent B glycosidic C hydrogen D ionic
October 2023, Unit 4, Q5(b)(ii) (1 mark): Which is a fuel that stores hydrogen in plants and seaweeds? (1) A ATP B glucose C glycogen D RUBISCO
October 2023, Unit 4, Q5(b)(iii) (1 mark): Which row of the table shows the reactions that combine hydrogen with carbon dioxide and release oxygen into the atmosphere? (1) Hydrogen is combined with Oxyge
October 2023, Unit 6, Q4(a) (2 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (2)
October 2023, Unit 6, Q4(b) (9 marks): Devise a detailed method, including how you would control and monitor important variables. (9)
October 2023, Unit 6, Q4(d) (2 marks): Suggest two limitations of your proposed method. (2)
June 2023, Unit 4, Q1(a) (2 marks): Explain the importance of magnesium ions to a plant. (2)
June 2023, Unit 4, Q5(a)(i) (3 marks): Calculate the rate of production of oxygen at 1 200 seconds for C. pyrenoidosa with PBF attached. (3) Answer nmol secs–1
June 2023, Unit 4, Q5(a)(ii) (3 marks): Explain the effect PBF has on the production of oxygen. (3)
June 2023, Unit 4, Q5(b) (3 marks): These scientists also measured the mass of C. pyrenoidosa, with and without PBF attached, after a 20-day period. They found that the increase in mass of C. pyre
June 2023, Unit 4, Q7(a)(ii) (2 marks): Nitrates contain nitrogen. Describe the importance of nitrates to plants. (2)
January 2023, Unit 4, Q2(a)(ii) (1 mark): Where do the light‑dependent reactions take place? (1) A Q B S C T D U
January 2023, Unit 4, Q2(a)(iii) (1 mark): Where do the light‑independent reactions take place? (1) A Q B S C T D U
January 2023, Unit 4, Q2(b) (2 marks): The graphs show the absorption spectrum of the photosynthetic pigments in a plant and in a bacterium. Plant 0.9 0.8 0.7 0.6 0.5 Absorbance / a.u. 0.4 0.3 0.2 0.
January 2023, Unit 4, Q2(c) (3 marks): Photosynthetic pigments can be identified using chromatography. The diagram shows part of a chromatogram. pigment direction of movement of solvent front origin
January 2023, Unit 4, Q4(b) (4 marks): Rubber is synthesised by specialised cells in the trunks of rubber trees. The diagram shows the structure of one molecule that these cells use to synthesise rub
January 2023, Unit 6, Q1(a) (6 marks): Describe an experiment to investigate the effect of nitrate ion concentration on the rate of growth of these plants. (6)
January 2023, Unit 6, Q1(b) (3 marks): Explain the roles of nitrate ions in cell division to produce daughter plants. (3)
October 2022, Unit 4, Q3(a) (1 mark): Which row of the table is correct for these two reactions? (1) Light-dependent Light-independent reactions reactions ADP is phosphorylated, ATP is hydrolysed, A
October 2022, Unit 4, Q3(b)(i) (3 marks): Complete this diagram to show three other labelled structures found in a chloroplast. (3)
October 2022, Unit 4, Q3(b)(ii) (4 marks): Compare and contrast the structure of the outer membrane of a chloroplast with that of a thylakoid membrane. (4)
October 2022, Unit 4, Q9(b) (4 marks): Describe how GALP, produced in the leaves, becomes incorporated into biomass in the roots. (4)
October 2022, Unit 4, Q9(c) (3 marks): Inorganic ions are used by plants to make molecules. The table shows some molecules made by plants. For each molecule, put one cross in the appropriate box, in
October 2022, Unit 6, Q1(a) (5 marks): Describe an experiment to investigate the effect of temperature on the rate of photosynthesis in Cabomba caroliniana. (5)
October 2022, Unit 6, Q1(b) (3 marks): Describe how oxygen is produced during photosynthesis. (3)
January 2022, Unit 4, Q2(a)(i) (2 marks): Draw the action spectrum for this plant on the axes below. (2) Rate of photosynthesis / a.u. 400 450 500 550 600 650 700 Wavelength of light / nm
January 2022, Unit 4, Q2(a)(ii) (1 mark): Calculate how many times greater the percentage of light absorbed by chlorophyll b is than that absorbed by chlorophyll a, at their maximum absorptions. . (1) A
January 2022, Unit 4, Q2(a)(iii) (2 marks): Thylakoid membranes contain different types of chlorophyll pigment. Explain the advantage of this for a plant. (2)
January 2022, Unit 4, Q2(b)(ii) (2 marks): Products of the light‑independent reactions are used to synthesise amino acids. Describe how plants synthesise amino acids. (2)
January 2022, Unit 4, Q6(a)(i) (1 mark): Where in the chloroplast is RUBISCO active? (1) A P B Q C R D S
January 2022, Unit 4, Q6(a)(ii) (1 mark): What is stored in S? (1) A GALP B lipid C starch D sucrose
January 2022, Unit 4, Q6(a)(iii) (1 mark): Where is GP formed? (1) A P B Q C R D S
January 2022, Unit 4, Q6(b)(i) (1 mark): Which could be the units for rate of photosynthesis? (1) A mg CO2 produced mm–2 hr–1 B mg CO2 produced mm–1 hr–2 C mg CO2 used mm–2 hr–1 D mg CO2 used mm–1 hr–2
January 2022, Unit 4, Q6(b)(ii) (3 marks): Compare and contrast the rate of photosynthesis of these two species of plant, at different temperatures. (3)
January 2022, Unit 4, Q6(b)(iii) (2 marks): Describe how a Q10 value for the rate of photosynthesis can be calculated, using this graph. (2)
January 2022, Unit 4, Q6(b)(iv) (3 marks): The graph shows the maximum temperature, for each month, in two regions of North America: Wheatland and Pole Mountain. 35 30 25 Maximum 20 temperature / °C 15 1
October 2021, Unit 4, Q1(a)(i) (1 mark): Which row in the table identifies the structures labelled P, Q and V? (1) P Q V A DNA starch grain ribosome B starch grain DNA ribosome C starch grain ribosome
October 2021, Unit 4, Q1(a)(ii) (1 mark): Which structure contains GALP? (1) A Q B R C U D V
October 2021, Unit 4, Q1(a)(iv) (3 marks): Structures T and U are membranes. Compare and contrast the structure of these two membranes. (3)
October 2021, Unit 4, Q1(b) (2 marks): An investigation studied the effect of periods of light and dark on the levels of chloroplast DNA in one species of a single-celled organism. One group of these
October 2021, Unit 4, Q6(b) (2 marks): Explain the role of chlorophyll in the light-dependent reactions of photosynthesis. (2)
October 2021, Unit 4, Q6(c)(i) (6 marks): Discuss the effectiveness of these extraction methods in the identification of these species. Use the information in the graphs to support your answer. (6)
October 2021, Unit 4, Q6(c)(ii) (2 marks): Suggest why different concentrations of chlorophyll were obtained using these two different solvents. (2)
October 2021, Unit 6, Q1(a) (5 marks): Describe an experiment to investigate the effect of different wavelengths of light on the rate of photosynthesis in Elodea canadensis. (5)
October 2021, Unit 6, Q1(b) (3 marks): Explain how the features of the grana in a chloroplast enable photosynthesis to occur. (3)
June 2021, Unit 4, Q2(b)(i) (3 marks): The diagram shows cyclic photophosphorylation. Complete the diagram by writing the correct word or words on the dotted lines, labelled D, E, F, G and H. (3) E F
June 2021, Unit 4, Q2(b)(ii) (1 mark): Name one molecule that is produced in non-cyclic photophosphorylation that is not produced in cyclic photophosphorylation. (1)
June 2021, Unit 4, Q2(b)(iii) (2 marks): Describe the role of photolysis in non-cyclic photophosphorylation. (2)
January 2021, Unit 4, Q5(a)(i) (2 marks): Explain why light energy is converted into energy stored in ATP. (2)
January 2021, Unit 4, Q5(a)(ii) (2 marks): An equation can summarise the production and breakdown of ATP. Complete this equation, by writing the names of the substrates and the type of reaction on the th
January 2021, Unit 4, Q5(a)(iii) (3 marks): Explain the role of light energy in the light-dependent reactions. (3)
January 2021, Unit 4, Q5(b)(i) (1 mark): Which row of the table shows the products of the light-dependent reactions that are used in the light-independent reactions? (1) ATP produced by NADP A cyclic p
January 2021, Unit 4, Q5(b)(ii) (2 marks): Simple sugars have the formula CnH2nOn. Name the inorganic molecule from which each element in a simple sugar originated. (2) C H . O
January 2021, Unit 4, Q5(b)(iii) (3 marks): Simple sugars are used in the synthesis of new biological molecules. Which row of the table shows the inorganic ions that are needed to synthesise these new bio
January 2021, Unit 4, Q6(a)(i) (3 marks): Explain how flies evolve resistance to new chemicals. (3)
October 2020, Unit 4, Q1(a) (1 mark): Which row of the table shows where the light-dependent reactions and light‑independent reactions take place? (1) Light-dependent reactions Light-independent rea
October 2020, Unit 4, Q1(b) (3 marks): The diagram shows the outline of a chloroplast. Draw three labelled features on this diagram that are found in a chloroplast, other than the stroma and the thyl
October 2020, Unit 4, Q1(c) (1 mark): An absorption spectrum shows how much light is absorbed by chloroplasts at different wavelengths of light. The table shows the colour of light at four wavelengt
October 2020, Unit 4, Q1(d) (1 mark): State what is meant by the term action spectrum. (1)
October 2020, Unit 4, Q1(e)(i) (1 mark): Which process can be used to separate chloroplast pigments? (1) A chromatography B dendrochronology C osmosis D PCR
October 2020, Unit 4, Q1(e)(ii) (1 mark): The diagram shows separated chloroplast pigments, J and K. 1.0 cm solvent front 1.5 cm J 2.5 cm K direction of 3.5 cm movement origin 1.5 cm What is the Rf valu
October 2020, Unit 4, Q3(a)(i) (1 mark): In photolysis, one of the bonds in each water molecule is broken. Using the equation for photosynthesis, calculate how much energy is released by photolysis in
October 2020, Unit 4, Q3(a)(ii) (4 marks): Explain how light energy is converted into chemical energy in the form of ATP. (4)
October 2020, Unit 4, Q3(b)(i) (1 mark): State what other information is needed in the table of bond energies for this value to be calculated. (1)
October 2020, Unit 4, Q3(b)(ii) (1 mark): Where in the chloroplasts are these bonds formed? (1) A cytoplasm B matrix C stroma D thylakoid membrane
October 2020, Unit 6, Q3(b) (3 marks): Describe the preliminary practical work that you might undertake to ensure your proposed method would provide meaningful data. . (3)
October 2020, Unit 6, Q3(c) (10 marks): Devise a detailed method, including an explanation of how you would control and monitor important variables. (10)
October 2020, Unit 6, Q3(e) (3 marks): Suggest three limitations of your proposed method. (3) 1 2 3
January 2020, Unit 4, Q7(a)(i) (1 mark): Which row of the table shows the colour of each of these seaweeds? (1) U. fasciata S. linifolium C. officinalis A green brown red B green red green C red brown
January 2020, Unit 4, Q7(a)(ii) (2 marks): Explain the role of chloroplast pigments in the light-dependent reactions of photosynthesis. (2)
January 2020, Unit 4, Q7(b)(i) (3 marks): Describe how GALP, produced in chloroplasts, is converted into protein. (3)
January 2020, Unit 4, Q7(b)(ii) (6 marks): These seaweeds are considered to be a healthy, environmentally-friendly and economic food source. Comment on this statement. Use the information in the table an

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