plumiOsmosis and water potential: Edexcel International A Level Biology questions
Edexcel International A Level Biology past-paper questions on 2.2.1 Osmosis and water potential, 2019–2025, with mark schemes and examiner’s reports where available.
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Q8(e)
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All 31 questions on Osmosis and water potential, as a list
- January 2025, Unit 5, Q8(e) (2 marks): Explain why ‘cells shrink a bit’ when blood electrolyte concentration increases (paragraph 21). (2)
- June 2024, Unit 5, Q8(e) (3 marks): Suggest how the skin cells ‘doubled in size to cover the area of the damage’ (paragraph 19). (3)
- January 2024, AS Unit 1, Q3(f) (4 marks): A student investigated the effect of four different coloured solutions on the mass of pieces of sweet potato. Dyes were dissolved in water to produce the colour
- June 2023, AS Unit 1, Q9(a)(i) (1 mark): Which row in the table identifies the marine animals P, Q and R? (1) P Q R A partial osmoconformer osmoregulator strict osmoconformer B partial osmoconformer st
- June 2023, AS Unit 1, Q9(a)(ii) (3 marks): Explain the advantages for osmoconformers of having cells with solute concentrations similar to that of the sea water they live in. (3)
- June 2023, AS Unit 1, Q9(b)(i) (1 mark): Estimate the chloride concentration of the cells of a jellyfish. (1) Answer a.u.
- June 2023, AS Unit 1, Q9(b)(ii) (2 marks): Calculate the percentage difference in the concentration of magnesium ions in the lobster compared with the sea urchin. Give your answer to two decimal places.
- June 2023, AS Unit 1, Q9(b)(iii) (2 marks): These three animals are osmoconformers even though they have different concentrations of each ion in their cells. Explain why these three animals can be describ
- June 2023, AS Unit 1, Q9(b)(iv) (1 mark): Suggest why osmoconformers do not have the same concentration of each ion in their cells. (1)
- January 2023, AS Unit 3, Q3(a) (2 marks): State what is meant by the term water potential. (2)
- January 2023, AS Unit 3, Q3(b)(i) (2 marks): Describe how the mass could be measured in a valid and accurate way. (2) Valid Accurate
- January 2023, AS Unit 3, Q3(b)(iii) (3 marks): In this investigation, the tubes containing the cylinders and the solutions were kept at the same temperature. Explain the effect on this investigation if the y
- January 2023, AS Unit 3, Q3(c)(iii) (2 marks): Different concentrations of sucrose solutions have different water potentials. The graph shows the water potentials for sucrose solutions of different concentra
- January 2023, AS Unit 3, Q3(c)(iv) (1 mark): The water potential for the yam was –1890 kPa. Suggest why there is a difference between the water potential of the yam and the water potential of the potato. (
- January 2022, AS Unit 1, Q6(b) (3 marks): Osmosis can be defined as the movement of free water molecules through a partially permeable membrane, down a water potential gradient. Explain this definition.
- January 2022, AS Unit 1, Q6(c) (6 marks): The photograph shows a Chinese mitten crab. (Source: © WILDLIFE GmbH / Alamy Stock Photo) Mitten crabs spend most of their lives in fresh water and only return
- January 2022, AS Unit 3, Q3(a)(i) (1 mark): Suggest how the method can be modified to increase validity. (1)
- January 2022, AS Unit 3, Q3(c)(ii) (2 marks): Calculate the rate of change in length of the carrot cylinder in a 1.0 mol dm−3 solution at 15 minutes. (2) Answer mm min−1
- January 2022, AS Unit 3, Q3(c)(iii) (2 marks): Explain the results between 40 and 50 minutes for the 1.0 mol dm−3 solution. (2)
- January 2022, AS Unit 3, Q3(c)(iv) (2 marks): Explain the results between 40 and 50 minutes for the 0.0 mol dm−3 solution. (2)
- June 2021, AS Unit 1, Q8(c) (6 marks): The diagram and table give information about some molecules found inside and outside a cell. Molecule Key Description small dipolar molecule consisting of two E
- October 2020, AS Unit 3, Q1(a) (3 marks): Explain the changes that occur when the mass increases. (3)
- October 2020, AS Unit 3, Q1(b)(i) (5 marks): Describe a method that could have been used to obtain these results. (5)
- October 2020, AS Unit 3, Q1(b)(iii) (2 marks): The graph shows the water potential of different concentrations of salt solution. 0.0 0.2 0.4 0.6 0.8 1.0 0.0 –1.0 –2.0 Water potential –3.0 / MPa –4.0 –5.0 –6.
- October 2020, AS Unit 3, Q1(c) (3 marks): A scientist investigated the effect of storage time on the water potential of potato tubers. The results of this investigation are shown in the graph. 0 5 10 15
- October 2020, Unit 6, Q1(b) (5 marks): Describe an experiment to compare the water potential of the tissue from these two types of tuber. (5)
- October 2020, Unit 6, Q1(d) (3 marks): Explain the factors that may affect the water potential of potato cells. (3)
- January 2020, AS Unit 1, Q5(a)(i) (2 marks): Explain why water enters the paramecium. (2)
- January 2020, AS Unit 1, Q5(a)(ii) (3 marks): Explain the importance of the contractile vacuole in the paramecium. (3)
- January 2020, AS Unit 1, Q5(b) (6 marks): In an investigation, paramecia were placed in three separate solutions: pond water, solution A and solution B. The paramecia were observed using a light microsc
- June 2019, AS Unit 1, Q5(b)(ii) (6 marks): Pineapples can be preserved by a process called osmotic dehydration in which pieces of pineapple are submerged in a solution of sugars. The diagram shows how th
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