Biological membranes: OCR A‑Level Biology A questions

Every OCR A-Level Biology A exam question on 2.1.5 Biological membranes, 2016–2025, with its mark scheme and examiner’s report.

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Q6
June 2025 · Paper 2
1 mark2.1.5 Biological membranes
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Q5(a)
June 2025 · Paper 3
1 mark2.1.5 Biological membranes
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Q5(b)
June 2025 · Paper 3
1 mark2.1.5 Biological membranes
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Q5(c)
June 2025 · Paper 3
1 mark2.1.5 Biological membranes
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Q5(d)
June 2025 · Paper 3
2 marks2.1.5 Biological membranes
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Q6
June 2025 · AS Paper 1
1 mark2.1.5 Biological membranes
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Q7
June 2025 · AS Paper 1
1 mark2.1.5 Biological membranes
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Q8
June 2025 · AS Paper 1
1 mark2.1.5 Biological membranes
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Q24(b)(i)
June 2025 · AS Paper 1
2 marks2.1.5 Biological membranes
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Q24(b)(ii)
June 2025 · AS Paper 1
1 mark2.1.5 Biological membranes
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Q24(b)(iii)
June 2025 · AS Paper 1
3 marks2.1.5 Biological membranes
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Q2(a)(i)
June 2025 · AS Paper 2
2 marks2.1.5 Biological membranes
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Q2(a)(ii)
June 2025 · AS Paper 2
2 marks2.1.5 Biological membranes
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Q2(a)(iii)
June 2025 · AS Paper 2
2 marks2.1.5 Biological membranes
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Q2(b)
June 2025 · AS Paper 2
2 marks2.1.5 Biological membranes
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Q2(c)
June 2025 · AS Paper 2
3 marks2.1.5 Biological membranes
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Q2(d)
June 2025 · AS Paper 2
2 marks2.1.5 Biological membranes
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Q3
June 2024 · Paper 1
1 mark2.1.5 Biological membranes
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Q4
June 2024 · Paper 1
1 mark2.1.5 Biological membranes
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Q21(c)(iii)
June 2024 · Paper 1
2 marks2.1.5 Biological membranes
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All 110 questions on Biological membranes, as a list

June 2025, Paper 2, Q6 (1 mark): Some students are conducting an osmosis investigation using cylinders of potato. They cut cylinders of potato 50 mm long using the ruler shown in the diagram. 0
June 2025, Paper 3, Q5(a) (1 mark): The student makes sucrose solutions of different concentrations by diluting a stock solution. State a piece of equipment, with a higher resolution than a measur
June 2025, Paper 3, Q5(b) (1 mark): The student controls temperature and the time that the pepper pieces are in the sucrose solution. State one other variable that the student should control durin
June 2025, Paper 3, Q5(c) (1 mark): The student calculates the change in mass of each piece of pepper during the experiment and converts these values to percentage change in mass. Explain why the
June 2025, Paper 3, Q5(d) (2 marks): The graph shows the results of the experiment. 15 10 Percentage change in mass 5 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Sucrose concentration (mol dm–3) Use the
June 2025, AS Paper 1, Q6 (1 mark): Which component acts as a transport protein? Your answer [1]
June 2025, AS Paper 1, Q7 (1 mark): Which component is made in the smooth endoplasmic reticulum? Your answer [1]
June 2025, AS Paper 1, Q8 (1 mark): Which option describes a role of membranes inside a cell? A The cell surface membrane acts as a barrier between the cell and its environment. B The inner membra
June 2025, AS Paper 1, Q24(b)(i) (2 marks): State two variables that were not controlled in this experiment. 1 2 [2]
June 2025, AS Paper 1, Q24(b)(ii) (1 mark): One of the students suggests using a red filter in the colorimeter because this is what they had used for a Benedict’s test. Suggest why the student is incorrec
June 2025, AS Paper 1, Q24(b)(iii) (3 marks): Explain how the students can process their data to assess repeatability. [3]
June 2025, AS Paper 2, Q2(a)(i) (2 marks): Identify the independent variable and the dependent variable in this experiment. Independent variable Dependent variable [2]
June 2025, AS Paper 2, Q2(a)(ii) (2 marks): Suggest two improvements to this experiment to increase the accuracy of the results. Improvement 1 Improvement 2 [2]
June 2025, AS Paper 2, Q2(a)(iii) (2 marks): Suggest a conclusion that can be drawn from the data in the table. You should give evidence to support your conclusion. [2]
June 2025, AS Paper 2, Q2(b) (2 marks): State one similarity and one difference between simple diffusion and facilitated diffusion. Similarity Difference [2]
June 2025, AS Paper 2, Q2(c) (3 marks): Using your knowledge of the phospholipid bilayer in plasma membranes, explain how an increase in temperature affects the permeability of the membrane. [3]
June 2025, AS Paper 2, Q2(d) (2 marks): Exocytosis is an active process. Explain why ATP is needed for exocytosis. [2]
June 2024, Paper 1, Q3 (1 mark): The diagram shows part of a plasma membrane. X How can molecule X be described? A It has a hydrophilic head and a hydrophobic tail. B It is formed when the glyc
June 2024, Paper 1, Q4 (1 mark): Which statement describes a feature of plasma membranes? A Channel proteins are a type of intrinsic protein. B Glycolipids are intrinsic proteins that have lipi
June 2024, Paper 1, Q21(c)(iii) (2 marks): Suggest how hydrogen peroxide could affect the plasma membrane. [2]
June 2024, Paper 1, Q22(a) (2 marks): The student controls the mass of beetroot in this investigation. Identify two other variables that the student should control in this investigation. 1 2 [2]
June 2024, Paper 1, Q22(b)(i) (2 marks): Explain the shape of the graph. [2]
June 2024, Paper 1, Q22(b)(ii) (2 marks): The student repeats the experiment at a temperature of 30 °C. Sketch the graph you expect the student to obtain. [2] Answer on the graph.
June 2024, AS Paper 1, Q21(a) (2 marks): Explain the difference between the mean results obtained at the 0.0 mol dm–3 and 0.8 mol dm–3 sucrose concentrations. [2]
June 2024, AS Paper 1, Q21(b) (3 marks): The students suggested that there was an anomaly in their results. Identify the anomalous result and explain how the anomalous result affects the precision of t
June 2024, AS Paper 1, Q21(c) (2 marks): The students prepared the sucrose concentrations using a serial dilution technique. The students were provided with 10 cm3 of a 0.8 mol dm–3 sucrose concentrati
June 2024, AS Paper 1, Q21(d) (2 marks): The students carried out a similar experiment with carrot tissue. Explain how the students could use their data to estimate whether sweet potato tissue or carro
June 2024, AS Paper 2, Q3(a) (3 marks): The graph shows the rate of uptake of particles across a membrane by two different methods of diffusion. © biology.arizona.edu, The Biology Project Department o
June 2024, AS Paper 2, Q3(b) (1 mark): Temperature and concentration are two factors that affect the rate of diffusion. State one other factor that affects the rate of diffusion. [1]
June 2024, AS Paper 2, Q3(c)(i) (2 marks): Name two more pieces of apparatus they would need to make sure this is a controlled investigation. 1 2 [2]
June 2024, AS Paper 2, Q3(c)(ii) (4 marks): Outline the method that the students would use to carry out an investigation into the effect of temperature on the diffusion rate in their model cells. [4]
June 2024, AS Paper 2, Q3(d) (3 marks): The table below shows some results from a model cell investigation. Concentration of glucose found outside the Temperature (°C) dialysis tubing after two minute
June 2024, AS Paper 2, Q5(c)(iii) (1 mark): The secretory vesicles remove proteins from the cell by a process called exocytosis. Explain why exocytosis is described as an active process. [1]
June 2023, Paper 1, Q14 (1 mark): One student made the following observations: 1 Ethanol disrupts the cell membranes leading to increased permeability. 2 The permeability of the cell membranes i
June 2023, Paper 1, Q15 (1 mark): The students were asked to decide whether the permeability of the membrane is significantly greater with 50% ethanol compared to 40% ethanol. Which statistical
June 2023, Paper 1, Q20(c)(ii) (2 marks): PGE2 receptors are located on the cell surface membrane. State two functions of the cell surface membrane that are illustrated by the action of PGE2. 1 2 [2]
June 2023, AS Paper 1, Q25(a) (2 marks): Describe two roles of a cell surface membrane. 1 2 [2]
June 2023, AS Paper 1, Q25(b) (3 marks): The presence of cholesterol is one of several factors that affect membrane fluidity. A student examined two different cell surface membranes. One membrane had a
June 2022, Paper 1, Q18(a)(i) (3 marks): Complete Table 18.1 to show how the student should prepare the solutions. Final concentration Volume of Volume of Final volume 1 mol dm–3 sucrose of solution di
June 2022, Paper 1, Q18(a)(ii) (2 marks): The solution given to the student was prepared using 34.23 g of sucrose in 100 cm3 water. The sucrose was measured on an electronic balance using the following
June 2022, Paper 1, Q18(b)(i) (1 mark): Identify the anomalous result. [1]
June 2022, Paper 1, Q18(b)(ii) (2 marks): State one variable that should be controlled in this experiment and give a reason for your choice. Control variable Reason [2]
June 2022, AS Paper 1, Q1 (1 mark): The graph below shows the results of an osmosis experiment investigating the effect of changing the concentration of sodium chloride (NaCl) on mass of potatoes.
June 2022, AS Paper 2, Q1(a) (4 marks): A second group of students made improvements to this method. One of the improvements they made was to carry out two further trials at each temperature. Suggest
June 2022, AS Paper 2, Q1(b) (1 mark): Name the independent variable in this investigation. [1]
June 2022, AS Paper 2, Q1(c)(i) (3 marks): The table shows the results obtained by the second group of students. Absorbance (%) Temperature (°C) Trial 1 Trial 2 Trial 3 Mean 10 0 0 0 0.0 20 0 0 0 0.0 30
June 2022, AS Paper 2, Q1(c)(ii) (6 marks): The cells in beetroot contain a red pigment called betalain. The plasma membrane of the beetroot cell is impermeable to betalain. A group of students set out to
June 2022, AS Paper 2, Q1(d) (2 marks): In a second experiment, students followed the same method but used pieces of beetroot that had been frozen for several days and then defrosted. They were surpri
June 2022, AS Paper 2, Q3(a)(ii) (2 marks): A common symptom of lactose intolerance in adults is the creation of extra fluid in the large intestine. Suggest why this occurs. [2]
November 2021, Paper 2, Q18(a) (3 marks): Explain how the structure of phospholipid molecules allows for the formation of plasma membranes. [3]
November 2021, Paper 2, Q18(b)(i) (4 marks): Present the students’ results in an appropriate table in the space below. [4]
November 2021, Paper 2, Q18(b)(ii) (2 marks): The students concluded that the red pigment began to leak out of the beetroot cells at any pH below pH6. Suggest and explain why a low pH might cause the red pi
November 2021, Paper 2, Q18(b)(iii) (2 marks): Outline how the students could modify their investigation to get a more accurate value for the pH at which the red pigment begins to leak out of the beetroot ce
November 2021, AS Paper 1, Q19 (1 mark): The graph below shows readings from a colorimeter as pigment leaks out of beetroot membranes at different temperatures. P Absorbance (arbitrary units) Temperatu
November 2020, Paper 1, Q16(b)(i) (4 marks): The student concluded that one substance entered the cells by simple diffusion and the other by active transport. Evaluate the student’s conclusion. [4]
November 2020, Paper 1, Q16(b)(ii) (4 marks): The student then added 2,4-dinitrophenol (DNP) to the cells. DNP inhibits respiration. Predict the effect of DNP on the uptake of each substance and explain you
November 2020, Paper 1, Q16(c) (4 marks): The student used a colorimeter to measure the concentration of each substance in the liquid surrounding the cells. The colorimeter had an analogue display. The
November 2020, Paper 1, Q18(a) (2 marks): The structure of FURA-2 is shown below. COO– COO– CH3 N O O N O COO– COO– N O COO– Use the information in the figure to explain why FURA-2 is unable to cross ce
November 2020, AS Paper 1, Q3 (1 mark): Which of the lines, A to D, in the graph below, represents the effect of increasing ethanol concentration on the permeability of the plasma membrane to sodium i
November 2020, AS Paper 1, Q23(b) (2 marks): Explain the role of the membrane in the rough endoplasmic reticulum. [2]
November 2020, AS Paper 2, Q5(a)(i) (1 mark): Suggest an improvement to the method that would allow the students to obtain more precise results. [1]
November 2020, AS Paper 2, Q5(a)(ii) (1 mark): State one variable that should have been controlled during this experiment. [1]
November 2020, AS Paper 2, Q5(b)(i) (2 marks): Before the students began their investigation they made a hypothesis. State the hypothesis the students would have made and state the scientific process that su
November 2020, AS Paper 2, Q5(b)(ii) (2 marks): Justify whether the results from the investigation support your hypothesis given in part (b)(i). [2]
November 2020, AS Paper 2, Q5(c) (2 marks): Describe how you would use the same equipment to test if the thickness of the exchange surface affects the diffusion rate. [2]
June 2019, Paper 1, Q19(b) (2 marks): Some bodybuilders use anabolic steroids to increase their muscle mass. Suggest why anabolic steroids are effective when applied to the surface of the skin. [2]
June 2019, Paper 2, Q16(a)(i) (2 marks): Define osmosis. [2]
June 2019, Paper 2, Q16(a)(ii) (3 marks): Plants rely on osmosis for support. Explain the importance of osmosis in plant support. [3]
June 2019, Paper 2, Q16(b)(i) (2 marks): The ruler used to measure the distance along the capillary tube was accurate to the nearest 0.5 mm. Calculate the percentage uncertainty of the measurement. unc
June 2019, Paper 2, Q16(b)(ii) (2 marks): What conclusions can be drawn about the composition of solutions X and Y? [2]
June 2019, Paper 2, Q16(c)(i) (2 marks): Explain why it was necessary to calculate percentage change in
June 2019, Paper 2, Q16(c)(ii) (2 marks): The students identified replicate 3 of the potato in 0.7 mol dm–3 sucrose as anomalous. Suggest a practical error by the students that might have caused this re
June 2019, Paper 2, Q16(c)(iii) (3 marks): Use Table 16 to identify which plant cells contained the highest concentration of sucrose. Justify your conclusion. [3]
June 2019, AS Paper 1, Q1 (1 mark): The diagram below shows one method of transport across a cell membrane. outside cell inside cell Which of the following options, A to D, is the name of this met
June 2019, AS Paper 1, Q2 (1 mark): The diagram below shows the structure of a plasma membrane. A C B D Which label, A to D, indicates the component of the membrane that can affect its fluidity? Y
June 2019, AS Paper 1, Q3 (1 mark): This diagram shows the transport of two molecules across a plasma membrane. tissue fluid Z cytoplasm Y Which row, A to D, correctly identifies the molecule bein
June 2019, AS Paper 1, Q21(a) (3 marks): In the space below, present the student’s results in an appropriate format. [3]
June 2019, AS Paper 1, Q21(b)(i) (2 marks): Explain how the treatment results in the difference in the final lengths of rod A and rod E. [2]
June 2019, AS Paper 1, Q21(b)(ii) (2 marks): Explain how the treatment results in the difference in the final lengths of rod D and rod F. [2]
June 2019, AS Paper 1, Q21(c) (1 mark): State how the student could reduce the uncertainty of their data. [1]
June 2019, AS Paper 2, Q5(a) (2 marks): Explain why Paramecium needs to expel water when in fresh water. [2]
June 2019, AS Paper 2, Q5(b)(i) (2 marks): Calculate the percentage decrease in the mean number of contractions as the concentration of sodium chloride solution increases from 0.00 mol dm−3 to 0.15 mol d
June 2019, AS Paper 2, Q5(b)(ii) (2 marks): Explain why there is a decrease in the activity of the contractile vacuole as the concentration of sodium chloride increases. [2]
June 2019, AS Paper 2, Q5(b)(iii) (3 marks): The cytoplasm of Paramecium contains salt crystals. These salt crystals can be used to alter the water potential of the cytoplasm. Suggest and explain how the w
June 2019, AS Paper 2, Q5(b)(iv) (2 marks): The experiment described in Table 5 was extended to find out the effect of reducing the dissolved oxygen concentration on the mean number of contractions at eac
June 2018, Paper 1, Q17(c)(i) (2 marks): State and explain how one property of region A in Fig. 17.2 contributes to the stability of the plasma membrane. [2]
June 2018, Paper 1, Q17(c)(ii) (2 marks): There are differences between the plasma membrane and membranes within cells. Outline the role of membranes within cells. [2]
June 2018, Paper 1, Q20(a)(i) (3 marks): Each step in the student’s method relies on certain assumptions. For each assumption listed below, select the numbered step from the student’s method that relie
June 2018, Paper 1, Q20(a)(ii) (2 marks): The student kept the ethanol solutions at a constant temperature. State two other variables which need to be controlled in this investigation to ensure the data
June 2018, Paper 1, Q20(b)(i) (3 marks): Make three criticisms of the way the student has displayed these results. 1 2 3 [3]
June 2018, Paper 1, Q20(b)(ii) (2 marks): Explain how carrying out replicates would improve this investigation. [2]
June 2018, AS Paper 1, Q5 (1 mark): The graph shows the rate of movement of four different substances across a membrane. A B C rate of movement across membrane D concentration difference across me
June 2018, AS Paper 1, Q17 (1 mark): Swiss chard is a leafy green vegetable related to spinach. Some varieties have yellow stalks that have vacuoles containing yellow betaxanthin pigments. The grap
June 2018, AS Paper 1, Q18 (1 mark): An investigation into how a change in sodium chloride concentration effects osmosis in potato cells concluded that the isotonic point of the potato was 0.25 M.
June 2018, AS Paper 1, Q22(d) (2 marks): Phospholipid molecules also contain fatty acids. Explain how the fatty acids in phospholipids allow the formation of membranes. [2]
June 2017, Paper 2, Q1 (1 mark): Membranes are found within and surrounding cells. Which of the statements, A to D, is not a role of membranes in cells? A acts as a barrier between areas B cell
June 2017, Paper 2, Q11 (1 mark): The diagram below shows part of a plasma membrane. 1 2 3 Which of the label lines points to a structure that could contain a sulfur atom? A 1, 2 and 3 B Only 1
June 2017, Paper 2, Q20(b)(ii) (2 marks): E. coli usually grows in conditions where the extracellular concentration of lactose is low. In such conditions lactose does not easily cross the bacterial cell
June 2017, AS Paper 1, Q18 (1 mark): Which option, A to D, describes the role of cholesterol in cell surface membranes in the human body? A Cholesterol binds to phospholipid phosphate heads, increa
June 2017, AS Paper 1, Q23(a) (2 marks): How does the fluid mosaic model describe the structure of plasma membranes? [2]
June 2017, AS Paper 1, Q23(b)(i) (2 marks): Explain why progesterone can move across membranes. [2]
June 2017, AS Paper 1, Q23(b)(ii) (1 mark): Name one other molecule that can cross plasma membranes. [1]
June 2017, AS Paper 1, Q23(c)(i) (1 mark): State how the structure of the cell surface membrane allows potassium ions to enter or leave a cell. [1]
June 2017, AS Paper 1, Q23(d)(i) (3 marks): Using the Student’s t-test formula below, calculate the value of t between the data for 50 °C and 60 °C. x x - A B where: x is the mean t = 2 2 S is the standar
June 2017, AS Paper 1, Q23(d)(ii) (2 marks): The critical value for t at the significance level of 5%, with 18 degrees of freedom, is 2.10. Use the value of t that you calculated in part (i) to explain whe
June 2017, AS Paper 1, Q23(e) (3 marks): The students plotted the data onto a graph, shown in Fig. 23. The effect of temperature on beetroot membrane permeability 0.50 0.45 0.40 0.35 0.30 absorbance 0.
June 2016, AS Paper 1, Q16 (1 mark): A group of students were investigating the diffusion of molecules across membranes using a ‘model cell’, as shown below. ‘model cell’ ‘extracellular fluid’ ‘cyt
June 2016, AS Paper 1, Q21(a)(i) (2 marks): State two details of the procedure that must be followed to obtain valid results. 1 2 [2]
June 2016, AS Paper 1, Q21(a)(ii) (3 marks): Explain how a student could use the data in Table 21.2 to determine the water potential of the potato tuber tissue. [3]
June 2016, AS Paper 1, Q21(b)(ii) (1 mark): What will be found at W in the immersed cell? [1]

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