Planning: apparatus, variables and fair tests: Edexcel International A Level Biology questions

Edexcel International A Level Biology past-paper questions on P.1.1 Planning: apparatus, variables and fair tests, 2019–2025, with mark schemes and examiner’s reports where available.

All 157 questions on Planning: apparatus, variables and fair tests, as a list

June 2025, AS Unit 3, Q1(b)(i) (2 marks): Explain why a temperature of 25 °C was used. (2)
June 2025, AS Unit 3, Q1(b)(ii) (1 mark): State the independent variable in this investigation. (1)
June 2025, AS Unit 3, Q1(b)(iii) (2 marks): Give two reasons why the grains were germinated before being transferred to the Petri dishes. (2) 1 2
June 2025, AS Unit 3, Q1(b)(iv) (2 marks): Explain why some seedlings were placed in the solvent without trifluralin. (2)
June 2025, AS Unit 3, Q2(a)(i) (5 marks): Justify each step of a method that could be used to obtain the results shown in the graph. (5)
June 2025, Unit 6, Q2(c)(i) (2 marks): State two abiotic variables, other than temperature, that could affect this investigation. (2) first variable second variable
June 2025, Unit 6, Q2(c)(ii) (1 mark): Choose one of the variables you have identified in part (c)(i). Describe how this variable can be controlled. (1) Variable Method of control
June 2025, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
June 2025, Unit 6, Q4(b) (9 marks): Devise a detailed method, including how you would control and monitor important variables to provide quantitative results. (9)
January 2025, AS Unit 3, Q2(b)(ii) (6 marks): Describe how the data in the table could be obtained. (6)
January 2025, AS Unit 3, Q3(c)(i) (1 mark): State the independent variable in this study. (1)
January 2025, Unit 6, Q1(a) (6 marks): Describe an experiment to investigate the effect of the concentration of copper ions on the time taken for the brine shrimps to hatch from eggs. (6)
January 2025, Unit 6, Q2(b)(iv) (2 marks): State two abiotic variables, other than mineral ions, that could affect the results of this investigation. (2) first variable second variable
January 2025, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
January 2025, Unit 6, Q4(a) (2 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (2)
January 2025, Unit 6, Q4(b) (9 marks): Devise a detailed method, including how you would control and monitor important variables. (9)
October 2024, AS Unit 3, Q2(a)(i) (4 marks): Describe a method that could be used to obtain the results for the complete Hoagland treatment, so that it can be compared with the other treatments. (4)
October 2024, AS Unit 3, Q3(b)(ii) (1 mark): State one independent variable in this investigation. (1)
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 5, Q3(c)(ii) (1 mark): State one reason why the lactate concentration was measured 15 minutes before starting the exercise. (1)
October 2024, Unit 5, Q3(c)(iii) (1 mark): State one variable that would need to be controlled in this investigation and how this would be achieved. (1)
October 2024, Unit 6, Q1(b) (6 marks): The drawing shows a wheat grain and the locations of the endosperm and the embryo. endosperm embryo Describe an experiment to determine if gibberellin stimulate
October 2024, Unit 6, Q2(c)(i) (2 marks): State one abiotic and one biotic variable, other than temperature, that could affect this investigation. (2) Abiotic variable Biotic variable
October 2024, Unit 6, Q2(c)(ii) (1 mark): Choose one of the variables you have identified in part (i). State how this variable can be controlled. (1) Variable Method of control
October 2024, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
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)
June 2024, AS Unit 3, Q1(a) (2 marks): Explain why, in step 1, it is important to cut the squid meat into equal sized pieces. (2)
June 2024, AS Unit 3, Q1(b)(i) (1 mark): Name a suitable control solution that could be used in step 2. (1)
June 2024, AS Unit 3, Q1(b)(ii) (1 mark): State the importance of using a control in this study. (1)
June 2024, AS Unit 3, Q1(c) (1 mark): Give two variables that need to be controlled in step 3. (1) 1 2
June 2024, AS Unit 3, Q2(d) (6 marks): A student suggested that: The larger a fish is, the larger its heart will be. Devise a method that could be used to collect and analyse data to test this sugges
June 2024, AS Unit 3, Q3(a)(iv) (3 marks): A coating made from a combination of chitosan and cinnamon oil was also tested. Describe an investigation to determine if this coating is more effective than th
June 2024, Unit 6, Q1(b) (5 marks): Describe an experiment to investigate the effect of temperature on the rate of respiration in yeast, using an artificial hydrogen carrier (redox indicator). (5)
June 2024, Unit 6, Q2(a) (4 marks): Woodlice are small animals that live in damp places, for example under stones and in areas with decomposing leaves. The photograph shows one species of woodlous
June 2024, Unit 6, Q2(b)(iv) (2 marks): State one abiotic and one biotic variable that could affect this investigation of habituation in zebrafish. (2) Abiotic variable Biotic variable
June 2024, Unit 6, Q2(b)(v) (2 marks): Choose one of the variables you have identified in (iv). Describe how this variable could be controlled and the effect it would have on the results if it is not
June 2024, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
June 2024, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
January 2024, AS Unit 3, Q1(b) (5 marks): The vitamin C content of the leaves from spinach plants was investigated. Describe how comparative measurements of the vitamin C content of the leaves from two
January 2024, AS Unit 3, Q2(c)(ii) (5 marks): Describe a procedure that could have been used to obtain the results shown in this graph. (5)
January 2024, AS Unit 3, Q3(b)(iv) (6 marks): This process preserves the animal feed because it kills bacteria. The process involves heating for a period of time, the heating temperature and the addition of
January 2024, Unit 4, Q8(c)(i) (2 marks): Explain two ways in which this investigation would have to be controlled to provide valid data. (2)
January 2024, Unit 6, Q1(a) (6 marks): Describe how the antibacterial activity of different parts of this plant could be compared. (6)
January 2024, Unit 6, Q2(c)(i) (2 marks): State two abiotic variables other than temperature that could affect this investigation. (2) First variable Second variable
January 2024, Unit 6, Q2(c)(ii) (1 mark): Choose one of the variables you have identified in (i). Describe how this variable can be controlled. (1) Variable Method of control
January 2024, Unit 6, Q2(c)(iii) (1 mark): Suggest what effect not controlling this variable would have on the results. (1)
January 2024, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
January 2024, Unit 6, Q4(a) (2 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. . (2)
January 2024, Unit 6, Q4(b) (9 marks): Devise a detailed method, including how you would control and monitor important variables. (9)
October 2023, AS Unit 3, Q3(b)(i) (1 mark): State the independent variable in this investigation. (1)
October 2023, Unit 6, Q1(b) (6 marks): The student read that ‘the vitamin C content of these fruits decreases the most during the first 14 days of storage.’ Describe an experiment to investigate the
October 2023, Unit 6, Q2(c)(i) (2 marks): State two biotic variables that could affect this investigation. (2) First variable Second variable
October 2023, Unit 6, Q2(c)(ii) (1 mark): Choose one of the variables you have identified in (i). Describe how this variable can be controlled. (1) Variable Method of control
October 2023, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
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)
June 2023, AS Unit 3, Q1(b)(i) (1 mark): Name the independent variable in this investigation. (1)
June 2023, AS Unit 3, Q2(b) (5 marks): The percentage germination of the pollen grains was used to determine the viability of the pollen. Describe a procedure to compare the percentage germination of
June 2023, Unit 6, Q2(d)(i) (2 marks): State two abiotic variables in the soil that could affect this investigation. (2) First variable Second variable
June 2023, Unit 6, Q2(d)(ii) (1 mark): Choose one of the variables you have identified in (i). State the effect it could have on the results if the measured values were not similar. (1) Variable The
June 2023, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
June 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)
June 2023, Unit 6, Q4(b) (9 marks): Devise a detailed method, including how you would control and monitor important variables. (9)
January 2023, AS Unit 3, Q3(b)(ii) (1 mark): State the independent variable in this investigation. (1)
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, Q2(c)(i) (2 marks): State two abiotic variables that could affect the growth rate of these bacteria. (2) First variable Second variable
January 2023, Unit 6, Q2(c)(ii) (2 marks): Choose one of the variables you have identified in (c)(i). Describe how this variable could be controlled and the effect it could have on the results if it is n
January 2023, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
January 2023, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to find a suitable method for observing these grasshoppers to provide quantitative results. (3)
January 2023, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
October 2022, AS Unit 3, Q1(b)(i) (5 marks): Describe a method to allow a quantitative comparison of the vitamin C content of two of these foods. (5)
October 2022, AS Unit 3, Q1(b)(ii) (1 mark): State the independent variable in this investigation. (1)
October 2022, AS Unit 3, Q3(a)(i) (4 marks): Devise a procedure to provide a valid comparison of the growth of shoots, bulbs and roots of onion plants grown in these three solutions. (4)
October 2022, Unit 4, Q7(d)(i) (2 marks): Explain why this investigation included treatment with the solvent only. (2)
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, Q2(b)(i) (2 marks): State one abiotic and one biotic variable that could affect this investigation. (2) Abiotic variable Biotic variable
October 2022, Unit 6, Q2(b)(ii) (2 marks): Choose one of the variables you have identified in (b)(i). Describe how this variable could be controlled and the effect it could have on the results if it is n
October 2022, Unit 6, Q3(a)(ii) (1 mark): State a suitable null hypothesis for this investigation. (1)
October 2022, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
October 2022, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
June 2022, AS Unit 3, Q1(b)(i) (2 marks): State two dependent variables in this investigation. (2) 1 2
June 2022, AS Unit 3, Q1(c)(ii) (1 mark): The calcium ion solution is alkaline. State how the pH of the sucrose solutions used in this investigation could be adjusted to a required value. (1)
June 2022, Unit 4, Q3(b)(ii) (2 marks): Describe how this study should have been designed to collect valid data. (2)
June 2022, Unit 6, Q1(c)(i) (1 mark): State one abiotic variable that could affect the results of this investigation. (1) Abiotic variable
June 2022, Unit 6, Q1(c)(ii) (2 marks): Describe how this abiotic variable could be controlled and the effect it could have on the results if it is not controlled. (2) Variable Describe how this varia
June 2022, Unit 6, Q1(d) (1 mark): Suggest why the scientist used each zebrafish only once. (1)
June 2022, Unit 6, Q2(a) (6 marks): Describe an experiment to measure the vitamin C content of each type of fruit. (6)
June 2022, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
June 2022, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
June 2022, Unit 6, Q4(b) (8 marks): Devise a detailed method, including an explanation of how you would control and monitor important variables. (8)
January 2022, AS Unit 3, Q1(a)(i) (2 marks): State a suitable dependent variable with units for this investigation. (2) Dependent variable Units
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(b)(ii) (2 marks): Suggest two properties of sucrose that make it suitable for use in this investigation. (2) 1 2
January 2022, Unit 6, Q2(c)(i) (2 marks): Give two abiotic variables, other than the independent variable, that could affect this experiment. (2) 1 2
January 2022, Unit 6, Q2(c)(ii) (1 mark): Name one of the variables you have identified in (i). Variable State how this variable could be controlled. (1)
January 2022, Unit 6, Q2(c)(iii) (1 mark): Suggest the effect that not controlling this variable could have on the results. (1)
January 2022, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
January 2022, Unit 6, Q4(a) (2 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (2)
January 2022, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
October 2021, AS Unit 3, Q1(a)(ii) (3 marks): Describe how the filtrates should have been prepared to allow a valid comparison of the protein content of these foods. (3)
October 2021, AS Unit 3, Q1(a)(iii) (2 marks): Protein solutions of concentrations from 0.0 to 10.0 mg cm−3 were tested using a semi-quantitative method. The results of the test are shown in the diagram. 0.0
October 2021, AS Unit 3, Q2(a)(i) (3 marks): Explain how using a colorimeter allows valid measurements of light transmitted through the betalain solutions. (3)
October 2021, AS Unit 3, Q2(a)(ii) (2 marks): Temperature and pH affect the rate of leakage of betalain from discs of beetroot. Describe how each of these variables could be kept constant in this investigat
October 2021, AS Unit 3, Q2(c)(ii) (3 marks): Explain how you could modify the method to decide if the difference in colour intensity, at a concentration of 0.002 mmol dm−3, is statistically significant. (3
October 2021, AS Unit 3, Q3(a)(i) (1 mark): State the dependent variable in this investigation. (1)
October 2021, AS Unit 3, Q3(a)(ii) (3 marks): One of the variables that needs to be controlled in this investigation is pH. Describe how a suitable pH could be decided on experimentally. (3)
October 2021, Unit 6, Q2(b)(i) (2 marks): State one abiotic and one biotic variable that could affect this investigation. (2) Abiotic variable Biotic variable
October 2021, Unit 6, Q2(b)(ii) (2 marks): Choose one of the variables you have identified in (b)(i). Describe how this variable could be controlled and the effect it could have on the results if it is n
October 2021, Unit 6, Q3(b)(i) (1 mark): State a suitable null hypothesis for this investigation. (1)
October 2021, Unit 6, Q3(e)(ii) (3 marks): Describe how this factor could be measured to produce valid comparisons in this investigation. (3)
October 2021, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
October 2021, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
June 2021, AS Unit 3, Q3(a) (1 mark): State the dependent variable in this study. (1)
June 2021, AS Unit 3, Q3(b) (2 marks): In this study, the solutions used were maintained at pH 6. Explain why this pH was maintained. (2)
June 2021, AS Unit 3, Q3(d)(ii) (4 marks): Describe how the results shown in the graph could have been obtained. You are provided with a 500 mg dm–3 boric acid solution. (4)
June 2021, Unit 6, Q1(a) (5 marks): Describe an experiment to investigate the effect of calcium ion concentration on the time taken for brine shrimps to hatch. (5)
June 2021, Unit 6, Q1(b)(i) (2 marks): State two abiotic variables, other than the independent variable, that could affect this experiment. (2) First variable Second variable
June 2021, Unit 6, Q1(b)(ii) (2 marks): Choose one of the variables you have identified in (b)(i). Explain how this variable could be controlled. Describe what effect it could have on the results if i
June 2021, Unit 6, Q2(a) (1 mark): Write a suitable null hypothesis for this investigation. (1)
June 2021, Unit 6, Q3(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
June 2021, Unit 6, Q3(b) (10 marks): Devise a detailed method, including an explanation of how you would control and monitor important variables. (10)
January 2021, AS Unit 3, Q2(a)(i) (2 marks): Describe the contents of two more Petri dishes that could be controls for this investigation. (2) Dish 1 Dish 2
January 2021, AS Unit 3, Q2(a)(ii) (2 marks): In this investigation, temperature and pH are variables that need to be controlled. Describe how these variables could be controlled in this investigation. (2)
January 2021, Unit 6, Q1(a) (6 marks): Describe an experiment to investigate the effect of this extract on the rate of pollen tube growth. (6)
January 2021, Unit 6, Q2(b)(i) (2 marks): State two biotic variables that could affect this investigation. (2) First variable Second variable
January 2021, Unit 6, Q2(b)(ii) (2 marks): Choose one of the variables you have identified in (b)(i). Describe how this variable could be controlled and the effect it could have on the results if it is n
January 2021, Unit 6, Q3(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
January 2021, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
January 2021, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
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, Q2(a)(ii) (1 mark): The effect of pH on the initial rate of the reaction catalysed by invertase was investigated at 25 °C. State the independent variable in this investigation. (1)
October 2020, AS Unit 3, Q2(a)(iii) (2 marks): Suggest why the temperature was kept at 25 °C. (2)
October 2020, AS Unit 3, Q2(a)(iv) (1 mark): Name one non‑biological (abiotic) variable, other than temperature, that should be kept constant in this investigation. (1)
October 2020, AS Unit 3, Q2(a)(v) (2 marks): Describe how you would keep the variable you have named in (a)(iv) at a constant value. (2)
October 2020, Unit 4, Q6(b)(i) (3 marks): Design a laboratory investigation to find out which of these three types of nut ground squirrels prefer to eat. (3)
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(c)(i) (2 marks): State one abiotic and one biotic variable, other than the independent variable, that could affect this experiment. (2) Abiotic variable Biotic variable
October 2020, Unit 6, Q1(c)(ii) (2 marks): Choose one of the variables you have identified in (i). Explain how this variable could be controlled. Describe what effect it could have on the results if it i
October 2020, Unit 6, Q2(a) (1 mark): State a suitable null hypothesis for this investigation. (1)
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)
January 2020, AS Unit 3, Q3(a)(i) (1 mark): State the independent variable in this investigation. (1)
January 2020, AS Unit 3, Q3(a)(ii) (2 marks): State two abiotic (environmental) variables that should be controlled in this investigation. (2) 1 2
January 2020, AS Unit 3, Q3(a)(iii) (1 mark): Choose one of the variables you named in (a)(ii) and state how it could be controlled. (1) Variable How it could be controlled
January 2020, AS Unit 3, Q3(a)(v) (2 marks): Explain why five discs were used for each concentration of detergent. (2)
January 2020, AS Unit 3, Q3(b)(i) (1 mark): Suggest why this investigation included a 0.0% detergent solution. Use the information in the table to support your answer. (1)
January 2020, Unit 4, Q6(b)(ii) (4 marks): Describe how this study could be carried out in a laboratory. (4)
June 2019, AS Unit 3, Q1(a)(i) (1 mark): State the independent variable in this investigation. (1)
June 2019, AS Unit 3, Q1(a)(ii) (1 mark): State one abiotic (environmental) variable that should be controlled in this investigation. (1)
June 2019, AS Unit 3, Q1(a)(iii) (3 marks): Explain why the results might have been affected if the variable you named in (a)(ii) had not been controlled. (3)
June 2019, AS Unit 3, Q1(c)(ii) (5 marks): You are provided with a solution containing 500 g dm–3 of sucrose . Devise a procedure to investigate the effect of different concentrations of sucrose on the r
June 2019, AS Unit 3, Q2(a)(ii) (3 marks): Explain how this investigation should be carried out to give a semi‑quantitative estimate of the concentration of the reducing sugars by comparing the colour of
June 2019, AS Unit 3, Q2(a)(iii) (2 marks): It was assumed that the extract contained all the reducing sugars from the food sample. Suggest how this assumption could be tested. (2)
June 2019, AS Unit 3, Q2(c)(ii) (4 marks): Devise a procedure to determine the concentration of reducing sugars in a sweet potato. (4)
June 2019, AS Unit 3, Q3(a)(i) (4 marks): Explain why the urease solution and the urea solution were kept in the water bath at 40 °C before and after being mixed. (4)
June 2019, AS Unit 3, Q3(a)(ii) (2 marks): Explain how you could determine suitable concentrations of urea and urease solutions to use in this investigation. (2)

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