plumiCell transport mechanisms: Edexcel A‑Level Biology B questions
Every Edexcel A-Level Biology B exam question on 4.2 Cell transport mechanisms, 2016–2025, with its mark scheme and examiner’s report.
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All 114 questions on Cell transport mechanisms, as a list
- June 2025, Paper 1, Q1(a) (1 mark): What happens during active transport? (1) A ATP is hydrolysed releasing energy B ATP is hydrolysed using energy C ATP is phosphorylated releasing energy D ATP i
- June 2025, Paper 1, Q1(b) (1 mark): Which substance is transported against a concentration gradient by active transport? (1) A hydrophilic molecule B large hydrophobic molecule C small hydrophobic
- June 2025, Paper 1, Q1(c) (2 marks): The graph shows the change in concentration of molecule A and molecule B, as they are transported into the cytoplasm of a cell. molecule A Concentration of mole
- June 2025, Paper 1, Q4(a)(ii) (2 marks): Draw part of a cell surface membrane that has twelve phospholipids, one channel protein and one cholesterol molecule. Use the components shown in the diagram. (
- June 2025, Paper 1, Q4(a)(iii) (2 marks): Describe the role of channel proteins in cell transport. (2)
- June 2025, Paper 1, Q4(b)(i) (2 marks): Analyse the data to give two conclusions that can be made from this graph. (2)
- June 2025, Paper 1, Q4(b)(ii) (2 marks): Explain the effect of temperature on membrane permeability at point P. (2)
- June 2025, Paper 2, Q7(b)(i) (1 mark): The diagram shows three plant cells with different water potentials. Draw arrows on the diagram to show the direction of water movement between the cells. (1) φ
- June 2025, Paper 2, Q7(b)(ii) (2 marks): Explain why some plant species make inulin with fewer fructose molecules in dry weather and inulin with more fructose molecules in wet weather. (2)
- June 2025, AS Paper 2, Q1(a)(i) (1 mark): Which of the following labelled structures is cholesterol? (1) A P B Q C S D V
- June 2025, AS Paper 2, Q1(a)(ii) (1 mark): Which of the following labelled structures is an integral protein? (1) A Q B R C S D U
- June 2025, AS Paper 2, Q1(a)(iii) (1 mark): Which structure allows water molecules into the cell? (1) A P B Q C T D V
- June 2025, AS Paper 2, Q1(b) (4 marks): Explain how the properties of oxygen and of sodium ions determine how they enter a cell. (4) Oxygen Sodium ions
- June 2025, AS Paper 2, Q6(a) (2 marks): State what is meant by the term osmosis. (2)
- June 2025, AS Paper 2, Q6(b)(ii) (3 marks): The table shows the results of this investigation. Initial mass Final mass Percentage Change Mean percentage Temperature of potato of potato change in Standard
- June 2025, AS Paper 2, Q6(b)(iii) (5 marks): The graph shows the effect of increasing temperature on the viscosity of water. Viscosity is a measure of how quickly liquids flow. A liquid with low viscosity
- June 2024, Paper 3, Q3(a)(ii) (2 marks): Describe the structure of a membrane in a plant cell. (2)
- June 2024, Paper 3, Q3(b)(i) (2 marks): Describe the relationship between temperature and absorbance, as shown by these results. (2)
- June 2024, Paper 3, Q3(b)(ii) (2 marks): Explain the results of this investigation. (2)
- June 2024, Paper 3, Q3(c) (4 marks): Group 1 results were excluded from the calculations of the means as they were so different from the other groups. Identify four errors this group may have made
- June 2024, Paper 3, Q5(a)(i) (2 marks): Describe how you would prepare 10 cm3 of a solution of sucrose with a concentration of 0.6 mol dm–3 from the stock solution. (2)
- June 2024, Paper 3, Q5(a)(ii) (3 marks): The table shows the mean results. Concentration of sucrose 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 solution / mol dm–3 Mean percentage of 0.0 1.3 4.0 31.9 59.6 76.3
- June 2024, Paper 3, Q5(a)(iii) (1 mark): Determine the concentration of the cell sap of the onion epidermal cells, using your graph. (1) Answer mol dm–3
- June 2024, Paper 3, Q5(a)(iv) (1 mark): This conversion graph can be used to convert the concentration of cell sap into osmotic potential. 0 –200 –400 –600 –800 Osmotic potential –1000 / kPa –1200 –14
- June 2024, Paper 3, Q5(a)(v) (1 mark): Write the equation that is used to calculate the water potential of a plant cell. (1)
- June 2024, Paper 3, Q5(a)(vi) (1 mark): State the water potential of the cell sap of the onion epidermal cells when 50% of the cells are plasmolysed. (1) Answer kPa
- June 2024, Paper 3, Q5(b) (3 marks): The students modified the method and repeated the investigation. The changes are shown in italics. Step 2: all pieces of onion epidermis were cut from a single
- June 2024, AS Paper 1, Q1(b) (2 marks): The graph shows the uptake of nitrate ions by a plant in the presence and absence of oxygen. 60 with oxygen 50 40 Uptake of nitrate ions 30 / arbitrary without
- June 2024, AS Paper 2, Q8(a) (3 marks): Describe three named methods of passive transport by which substances can enter or leave a cell. (3)
- June 2024, AS Paper 2, Q8(b)(i) (1 mark): State why the discs were washed in Step 1. (1)
- June 2024, AS Paper 2, Q8(b)(ii) (2 marks): Explain the purpose of Step 2. (2)
- June 2024, AS Paper 2, Q8(b)(iii) (3 marks): Calculate the standard deviation (s) for the results at 60% ethanol. Give your answer to two decimal places. (3) Use the formula: x 2 x s n 1 Answer
- June 2024, AS Paper 2, Q8(b)(iv) (1 mark): State which ethanol concentration shows the lowest range of absorbance. (1)
- June 2024, AS Paper 2, Q8(b)(v) (2 marks): Explain why standard deviation is a better measure of variation than range. (2)
- June 2024, AS Paper 2, Q8(b)(vi) (3 marks): Explain the effect of increasing ethanol concentration on membrane permeability. (3)
- June 2023, Paper 1, Q1(b) (4 marks): The uptake of potassium ions by plant seedlings in anaerobic and aerobic conditions was investigated. The seedlings were grown in a mineral ion solution contain
- June 2023, Paper 3, Q6(a)(i) (1 mark): Calculate the water potential (ψ) of this cell. (1) Answer kPa
- June 2023, Paper 3, Q6(a)(ii) (2 marks): Explain the direction of net movement of water for this plant cell when it is placed in a sucrose solution with a water potential (ψ) of –400 kPa. (2)
- June 2023, Paper 3, Q6(b)(i) (3 marks): Plot a suitable graph of these results. Join the points with straight lines. (3)
- June 2023, Paper 3, Q6(b)(ii) (1 mark): Determine the concentration of sucrose solution that causes no change in mass, using your graph. (1) Answer mol dm–3
- June 2023, Paper 3, Q6(b)(iii) (5 marks): Evaluate whether the method used in this investigation would provide valid results for the water potential of potato cells. (5)
- June 2023, AS Paper 2, Q6(a) (2 marks): State what the terms P and π represent. (2) P π
- June 2023, AS Paper 2, Q6(b) (7 marks): Students carried out an investigation to determine the osmotic potential and therefore water potential of plant epidermal cells. Plant cells were placed in salt
- June 2023, AS Paper 2, Q6(c) (2 marks): Explain how finding the point of incipient plasmolysis allows the students to determine the water potential of the epidermal cells. (2)
- June 2022, Paper 1, Q6(c)(i) (1 mark): Calculate the mean percentage of branched‑chain fatty acids in bacteria whose optimum growth temperature is <20 °C. (1) Answer %
- June 2022, Paper 1, Q6(c)(ii) (2 marks): Analyse the data to describe two conclusions that can be drawn from this investigation. (2)
- June 2022, Paper 1, Q6(d) (3 marks): A change in temperature can affect the permeability and fluidity of the membrane. Explain why it is important that the lipid composition of the membrane of prok
- June 2022, Paper 1, Q7(a)(iii) (2 marks): Explain why water flows into the part of the cell where the soluble components are located (Step 3). (2)
- June 2022, Paper 3, Q7(a)(i) (3 marks): Describe how mineral (inorganic) ions are taken up by active transport. (3)
- June 2022, AS Paper 2, Q5(a)(i) (1 mark): A small ion is in high concentration outside a cell. By which method is the ion most likely to enter the cell? (1) A active transport B diffusion C facilitated
- June 2022, AS Paper 2, Q5(a)(ii) (1 mark): Which of the following are required for active transport? (1) 1 ATP 2 carrier proteins 3 cell membrane A 1 only B 1 and 2 only C 1 and 3 only D 1, 2 and 3
- June 2022, AS Paper 2, Q5(a)(iii) (1 mark): Which is a description of exocytosis? (1) A a form of active transport in which large particles move into cells B a form of active transport in which large part
- June 2022, AS Paper 2, Q5(b)(i) (2 marks): Explain which temperature above 30 °C shows the most variation in absorbance. (2)
- June 2022, AS Paper 2, Q5(b)(ii) (3 marks): Calculate the standard deviation for the results at 20 °C. Use the formula x 2 x s n 1 (3) Answer
- June 2022, AS Paper 2, Q5(b)(iii) (3 marks): Explain the effect of increasing temperature on membrane permeability. (3) (Total for Question 5 =11 marks)
- November 2021, Paper 2, Q9(b) (2 marks): Auxin is an uncharged molecule when it diffuses through the cell surface membrane. When inside the cytoplasm, auxin develops a negative charge. Auxin leaves cel
- November 2021, Paper 3, Q3(a) (5 marks): Describe how you would investigate the effect of temperature on the permeability of the membranes in the root cells of these purple carrots. (5)
- November 2021, Paper 3, Q3(b) (2 marks): The anthocyanins in purple carrots are used as antioxidants in the food industry. Purple Haze carrots with a mass of 750g contain 1265.25 mg of anthocyanin. Cal
- November 2021, Paper 3, Q7(a) (4 marks): Analyse the data to comment on the effect of the concentration of sodium chloride solution on blood. (4)
- November 2021, Paper 3, Q7(b) (3 marks): The student then investigated the effect of using glucose solutions and sucrose solutions, instead of sodium chloride solutions. The appearance of the solutions
- November 2021, AS Paper 2, Q4(a)(i) (1 mark): Which of these processes requires energy from respiration? (1) A diffusion B endocytosis C facilitated diffusion D osmosis
- November 2021, AS Paper 2, Q4(a)(ii) (1 mark): Which of these processes can occur against a concentration gradient? (1) A active transport B diffusion C facilitated diffusion D osmosis
- November 2021, AS Paper 2, Q4(a)(iii) (1 mark): The graph shows the effect of increasing oxygen concentration on the rate of uptake of a substance other than oxygen. Rate of uptake Oxygen concentration Which
- November 2021, AS Paper 2, Q4(a)(iv) (1 mark): Which substance can enter a cell by diffusion? (1) A amino acid B carbon dioxide C glucose D protein
- November 2021, AS Paper 2, Q4(b)(i) (1 mark): Draw a suitable line on this graph. (1)
- November 2021, AS Paper 2, Q4(b)(ii) (1 mark): Give the sucrose concentration that has the same water potential as the cells in these potato samples. (1) Answer mol dm−3
- November 2021, AS Paper 2, Q4(b)(iii) (4 marks): The water potential (ψ) of plant cells can be calculated using the equation: ψ = P + π Explain the changes in the water potential of cell (ψ), turgor pressure (
- November 2021, AS Paper 2, Q4(b)(iv) (2 marks): Explain why it is more difficult to determine the osmotic potential (π) than the water potential (ψ) of plant cells. (2)
- October 2020, Paper 2, Q3(b)(i) (1 mark): Which of the following statements about facilitated diffusion are correct? (1) 1. substances move through membrane proteins 2. substances move against a concent
- October 2020, Paper 3, Q9(e) (5 marks): A student thought that the age of a plant affects the water potential of its tissue. The student used potatoes of different ages to test this hypothesis. Justif
- October 2020, AS Paper 2, Q2(a)(i) (1 mark): Which of these mechanisms moves substances against a concentration gradient? (1) A active transport B diffusion C facilitated diffusion D osmosis
- October 2020, AS Paper 2, Q2(a)(ii) (1 mark): Which of these mechanisms enables non-polar molecules to pass through cell membranes? (1) A diffusion B facilitated diffusion C osmosis D transpiration
- October 2020, AS Paper 2, Q6(a)(i) (3 marks): Plot a suitable graph to display the results of this investigation. (3)
- October 2020, AS Paper 2, Q6(a)(ii) (2 marks): Calculate the mean change in the distance S in mm as the sucrose concentration changes from 0.2 to 0.4 mol dm–3. (2) Answer mm per mol dm–3
- October 2020, AS Paper 2, Q6(a)(iii) (4 marks): Analyse the data to explain the relationship between the concentration of sucrose and turgor in the pieces of potato. (4)
- October 2020, AS Paper 2, Q6(b) (2 marks): Criticise the method used to determine turgor in this investigation. (2)
- June 2019, Paper 1, Q8(d)(i) (1 mark): What happens when hydrogen ions are actively transported out of the guard cells? (1) A ADP and phosphate ions are converted into ATP by a hydrolysis reaction B
- June 2019, Paper 1, Q8(d)(ii) (1 mark): Which of the following explains why water moves into the guard cells? (1) A malate lowers the water potential of the cytoplasm B malate raises the water potenti
- June 2019, Paper 3, Q1(a) (1 mark): The student was given a 1.0 mol dm–3 sucrose solution. State how the student used this solution to make a 0.8 mol dm–3 sucrose solution. (1)
- June 2019, Paper 3, Q1(b) (2 marks): Sketch a graph you could use to identify the water potential of potato cells. (2)
- June 2019, Paper 3, Q1(c) (3 marks): The method used by the student could be improved to obtain a more accurate value for the water potential of these potato cells. Justify three improvements that
- June 2019, AS Paper 2, Q2(a) (1 mark): The part labelled X (1) A allows facilitated diffusion to take place B is absent in animal cells C is made of phospholipid D prevents lipid soluble molecules fr
- June 2019, AS Paper 2, Q2(b) (1 mark): The part labelled Y (1) A allows active transport to take place B allows polar molecules to pass into the cell C makes the membrane more fluid D makes the membr
- June 2019, AS Paper 2, Q2(c) (3 marks): Explain how the properties of molecules affect their transport through the cell membrane. (3)
- June 2019, AS Paper 2, Q2(d)(i) (1 mark): Give a reason why the beetroot discs were placed in the same volume of ethanol solution. (1)
- June 2019, AS Paper 2, Q2(d)(ii) (2 marks): Explain why the boiling tubes were kept in a water bath. (2)
- June 2019, AS Paper 2, Q2(d)(iii) (2 marks): Calculate the standard deviation for absorption at the ethanol concentration of 20% using the formula (2) ∑( x − x 2 ) s = n − 1 Answer
- June 2019, AS Paper 2, Q2(d)(iv) (1 mark): State why the standard deviation is a better measure of variation than the range. (1)
- June 2019, AS Paper 2, Q2(d)(v) (2 marks): Explain the effect of increasing ethanol concentration on membrane permeability. (2)
- June 2018, Paper 2, Q1(a) (1 mark): Name the parts labelled A and B. (1)
- June 2018, Paper 2, Q1(b) (4 marks): Explain how the structure of the membrane controls the transport of polar molecules. (4)
- June 2018, AS Paper 2, Q2(a)(i) (1 mark): Which of the following will occur? (1) A more water will leave the tissue than enter B the cells will become turgid C the tissue will become flaccid D the cells
- June 2018, AS Paper 2, Q2(a)(ii) (1 mark): When the plant tissue is placed in distilled water the value of (1) A P will decrease B π will decrease C P will increase D ψ will not change
- June 2018, AS Paper 2, Q2(a)(iii) (1 mark): Which row of the table correctly identifies the values of P and π if the value of ψ is 0 kPa? (1) P / kPa π / kPa A 0 0 B –4.6 4.6 C 4.6 –4.6 D 4.6 0
- June 2018, AS Paper 2, Q2(a)(iv) (1 mark): Which liquid has the lowest water potential (ψ)? (1) A distilled water B 1.0 mol dm–3 sodium chloride solution C 0.1 mol dm–3 sodium chloride solution D 0.1 mol
- June 2018, AS Paper 2, Q2(b)(i) (3 marks): Analyse the data in the graph and in the table to explain how the osmotic potential of these onion cells could be determined. (3)
- June 2018, AS Paper 2, Q2(b)(ii) (2 marks): Explain why the plant tissue was left in sucrose solution for 10 minutes before the cells were observed. (2)
- June 2018, AS Paper 2, Q8(b)(i) (3 marks): Explain how the properties of herbicide molecules affect their ability to pass through plant cell membranes. (3)
- June 2017, Paper 2, Q6(d) (3 marks): Calcium ions are needed for the secretion of enzymes from pancreatic cells. The graph shows the effect of increasing calcium ion concentration on the uptake of
- June 2017, Paper 3, Q7(c)(i) (2 marks): Explain why only the fine spray of 7.0% salt solution resulted in mucus that contained more water. (2)
- June 2017, Paper 3, Q7(c)(ii) (2 marks): Explain why the control group inhaled a fine spray of 0.9% salt solution, rather than a fine spray of pure water. (2)
- June 2017, Paper 3, Q8(a)(ii) (2 marks): Explain the absorbance value at 0 minutes. (2)
- June 2017, Paper 3, Q8(a)(iii) (2 marks): Explain the effect of ethanol on plant cell membranes. (2)
- June 2017, Paper 3, Q8(b) (2 marks): The student also carried out a control, using water instead of 40% ethanol. Draw a line on the graph to show the results for this control. (2) 0.7 – 0.6 – 0.5 –
- June 2017, Paper 3, Q8(c) (5 marks): The student then investigated the effect of ethanol concentration on leaves from different plant species. Justify the modifications to the procedure in part (a)
- June 2017, Paper 3, Q10(a) (5 marks): Devise an experiment, which uses changes in mass, to compare the water potential of carrot tissue with the water potential of potato tissue. (5)
- June 2017, Paper 3, Q10(b) (3 marks): The photograph shows Salicornia, a plant growing on salt marshes close to the sea. Salicornia colonises bare mud containing seawater. A student sampled Salicorn
- June 2017, AS Paper 2, Q2(c)(i) (1 mark): The water leaves the contractile vacuole by (1) A endocytosis B exocytosis C osmosis D facilitated diffusion
- June 2017, AS Paper 2, Q2(c)(ii) (2 marks): A student investigated the effect of mineral ions in pond water on the rate at which the contractile vacuole emptied. The student placed different specimens of
- June 2017, AS Paper 2, Q3(a)(i) (1 mark): Give the ratio of sodium ions in the soil to those in the cytoplasm. (1)
- June 2017, AS Paper 2, Q3(a)(ii) (1 mark): Which of the following describes how these mineral ions are transported into the cytoplasm of plant root cells? (1) A active transport through carrier proteins
- June 2016, AS Paper 1, Q4(b)(i) (2 marks): Describe the relationship between membrane fluidity and temperature as shown by this graph. (2)
- June 2016, AS Paper 2, Q1(a) (2 marks): The photograph shows part of one epithelial cell from the wall of the small intestine. This cell is adapted to absorb substances by active transport. State what
- June 2016, AS Paper 2, Q1(b) (3 marks): The bacteria that cause cholera release a toxin. This toxin affects the CFTR protein found in the membrane of intestinal epithelium cells. The toxin causes the
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