Biological molecules: Edexcel International GCSE Biology questions

Every Edexcel International GCSE Biology exam question on Biological molecules (specification points 2.7–2.14), 2019–2025, with its mark scheme and examiner’s report.

All 94 questions on Biological molecules, as a list

June 2025, Paper 1, Q2(a)(i) (1 mark): Give one variable that the teacher controls in the investigation. (1)
June 2025, Paper 1, Q2(a)(ii) (1 mark): Give a method that the teacher could safely use to keep the boiling tube at 70 °C for five minutes in step 3. (1)
June 2025, Paper 2, Q6(a)(i) (2 marks): Calculate the percentage increase in time taken for the apple pulp to turn brown at pH 11 compared with the time taken at pH 7. (2) percentage increase = %
June 2025, Paper 2, Q6(a)(ii) (3 marks): Explain why the change in pH affects the time taken for the apple pulp to turn brown. (3)
June 2025, Paper 2, Q6(a)(iii) (2 marks): Explain how the student could modify this method to give a more accurate measure of the time taken for the apple pulp to turn brown. (2) QUESTION 6 CONTINUES ON
June 2025 (R), Paper 1, Q4(c)(i) (1 mark): The graph shows the effect of concentration of vitamin C on the number of drops needed to change DCPIP solution to colourless. 30 25 20 Number of drops of 15 fr
June 2025 (R), Paper 1, Q4(c)(ii) (1 mark): Give the fruit juices in order of increasing concentration of vitamin C. One has been done for you. (1) highest concentration lime lowest concentration
June 2025 (R), Paper 1, Q4(c)(iii) (2 marks): Explain how the student could modify the experiment to give a more accurate measure of the concentrations of vitamin C in the fruit juices. (2)
June 2025 (R), Paper 2, Q1(c)(i) (1 mark): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Pollination in fruit trees Plants need to
November 2024, Paper 1, Q7(b)(iv) (2 marks): Chlorella contains many starch granules. Describe the function of the starch granules in the organism. (2)
June 2024, Paper 2, Q6(a)(i) (1 mark): Use the table to determine the ratio of lipid to protein to carbohydrate. Give your answer in the form 1: n : 1 (1) ratio = 1: : 1
June 2024, Paper 2, Q6(a)(ii) (2 marks): Describe how to test a sample of tilapia to show the presence of lipid. (2)
June 2024 (R), Paper 1, Q4(b)(i) (1 mark): State why the test tubes are placed in a water bath for 10 minutes before mixing the contents. (1)
June 2024 (R), Paper 1, Q4(b)(ii) (2 marks): Describe how the student could test a sample of the mixture for starch. (2)
June 2024 (R), Paper 1, Q4(c)(i) (2 marks): Calculate the mean time taken for all starch to be digested at 30 ºC. Give your answer to two significant figures. (2) mean time = minutes
June 2024 (R), Paper 1, Q4(c)(ii) (2 marks): Explain the effect of increasing the temperature from 10 ºC to 40 ºC on the time taken for all the starch to be digested. (2)
June 2024 (R), Paper 1, Q4(c)(iii) (2 marks): Explain why the starch was not digested when the temperature was 50 ºC. (2)
June 2024 (R), Paper 1, Q4(c)(iv) (2 marks): Explain how the student could modify the investigation to give a more accurate measure of the temperature at which the amylase activity is fastest. (2)
November 2023, Paper 2, Q2(a) (1 mark): State what is meant by the term enzyme. (1)
November 2023, Paper 2, Q2(b) (1 mark): Suggest why each potato cylinder was cut into six discs rather than left as one cylinder. (1)
November 2023, Paper 2, Q2(c)(i) (1 mark): Give the dependent variable in this experiment. (1)
November 2023, Paper 2, Q2(c)(ii) (2 marks): The teacher controls the time for gas collection and also the volume of hydrogen peroxide used. State two other abiotic variables the teacher should control in
November 2023, Paper 2, Q2(d)(i) (2 marks): Calculate the percentage change in the mean rate of reaction as the pH is changed from pH 4 to pH 7. (2) percentage change = %
November 2023, Paper 2, Q2(d)(ii) (2 marks): The teacher calculated the mean rate of reaction by collecting the oxygen released for the first five minutes of the reaction. Explain why the mean rate of reac
November 2023, Paper 2, Q2(d)(iii) (3 marks): Explain the effect of changing pH on an enzyme-controlled reaction. (3)
November 2023, Paper 2, Q3(b)(ii) (2 marks): Describe how a sample of urine could be tested for glucose. (2)
June 2023, Paper 1, Q7(a) (1 mark): State why the student leaves the test tube and the beaker in the water bath for 5 minutes in steps 6 and 7. (1)
June 2023, Paper 1, Q7(b)(i) (1 mark): Give the dependent variable in this investigation. (1)
June 2023, Paper 1, Q7(b)(ii) (1 mark): State one variable the student controls in their investigation. (1)
June 2023, Paper 1, Q7(c) (1 mark): Suggest the purpose of the phenolphthalein indicator in the investigation. (1)
June 2023, Paper 1, Q7(d) (5 marks): The table shows the student’s results. Temperature Time taken for contents to lose in °C the pink colour in seconds 20 385 25 340 30 300 35 250 40 275 45 360 Pl
June 2023, Paper 1, Q7(e) (4 marks): Explain why increasing temperature affects the time taken for the contents of the test tube to lose the pink colour. (4)
June 2023, Paper 2, Q3(c) (2 marks): Protein is often found in the urine of people who have high blood pressure. Describe how urine could be tested for protein. (2)
June 2023 (R), Paper 2, Q1(d) (2 marks): Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Tissue culture and plants In micropropaga
June 2023 (R), Paper 2, Q3(a) (2 marks): Calculate the percentage of the total carbohydrate in biscuit A that is starch. (2) percentage = %
January 2023, Paper 1, Q3(b) (2 marks): Describe how a student could test a milk sample for glucose. (2)
January 2023 (R), Paper 1, Q4(a)(i) (1 mark): The main sugar in milk is a carbohydrate called lactose. Which chemical elements are present in carbohydrates? (1) A carbon and hydrogen only B carbon, hydrogen
January 2023 (R), Paper 1, Q4(a)(ii) (2 marks): Describe how to test a sample of milk for protein. (2)
January 2023 (R), Paper 1, Q11(b) (6 marks): Design an investigation to find the best temperature for removing protein stains by using washing powder that contains protease enzyme. Include experimental det
January 2023 (R), Paper 2, Q2(b)(ii) (2 marks): Describe how to test for glucose in a sample of urine. (2)
June 2022, Paper 2, Q5(a)(i) (3 marks): Calculate the mean volume of gelatine digested in cm3. Give your answer to two decimal places. (3) mean volume = cm3
June 2022, Paper 2, Q5(a)(ii) (1 mark): State what substances are produced when the gelatine protein is digested. (1)
June 2022, Paper 2, Q5(b)(i) (2 marks): Give two variables the student should control. (2) 1 2
June 2022, Paper 2, Q5(b)(ii) (3 marks): Explain the effect of changing the pH on the mean volume of gelatine digested. (3)
June 2022, Paper 2, Q5(c) (2 marks): Describe how to test for the presence of protein. (2)
June 2022 (R), Paper 1, Q1(a)(iii) (1 mark): Which molecule is the storage carbohydrate in the root cell? (1) A glucose B glycerol C glycogen D starch
June 2022 (R), Paper 1, Q9(b)(i) (2 marks): State which carbohydrates the scientist identified in the ungerminated seeds and the germinating seeds. (2) ungerminated seeds germinating seeds
January 2022, Paper 2, Q2(b)(i) (1 mark): Suggest a problem with using the level of cloudiness of the solution to determine how spoiled the peas have become. (1)
January 2022, Paper 2, Q2(b)(ii) (2 marks): Explain the appearance of the peas in water at 4 °C. (2)
January 2022, Paper 2, Q2(b)(iii) (2 marks): Explain the appearance of the peas in vinegar at 37 °C. (2)
January 2022, Paper 2, Q5(c)(i) (2 marks): Describe how a sample of urine could be tested to see if it contains protein. (2)
January 2022 (R), Paper 1, Q3(b)(iii) (2 marks): Explain why the dough rises to a different height at 25 °C compared with the height at 35 °C. (2)
January 2022 (R), Paper 1, Q3(b)(iv) (2 marks): Explain why the dough rises to a different height at 35 °C compared with the height at 65 °C. (2)
November 2021, Paper 1, Q1(a) (2 marks): Describe how you would test a piece of bread to show it contains starch. (2)
November 2021, Paper 1, Q11(b)(i) (2 marks): Suggest why the liquid contains lysozyme. (2)
November 2021, Paper 1, Q11(b)(ii) (2 marks): Suggest why the liquid is maintained at pH 7 (2)
June 2021, Paper 1, Q8(c) (2 marks): Describe how a sample of cow’s milk could be tested for protein. (2)
June 2021, Paper 2, Q5(b)(i) (1 mark): Which of these is the optimum pH for urease? (1) A 2.5 B 4.5 C 7.5 D 8.5
June 2021, Paper 2, Q5(b)(ii) (2 marks): Explain the activity of urease at pH 8.5 (2)
January 2021, Paper 2, Q6(a) (2 marks): Give the expected relationship between the named independent variable and the named dependent variable in this demonstration. (2)
January 2021, Paper 2, Q6(b) (2 marks): Give two variables that the teacher controls in this demonstration. (2) 1 2
January 2021, Paper 2, Q6(c)(i) (2 marks): Calculate the mean volume of oxygen produced in one minute using 5 potato discs. (2) mean reading = cm3
January 2021, Paper 2, Q6(c)(ii) (2 marks): Calculate the percentage increase in mean volume of oxygen produced in one minute as the concentration of enzyme changes from 15 to 20 discs. (2) percentage inc
January 2021, Paper 2, Q6(c)(iii) (2 marks): Explain the relationship between the concentration of enzyme and mean volume of oxygen produced in one minute. (2)
January 2021, Paper 2, Q6(d) (2 marks): Suggest why the teacher measures the volume of oxygen after the first minute of the reaction rather than after 10 minutes. (2)
January 2021 (R), Paper 1, Q4(c) (2 marks): Plants convert the glucose they produce into starch. Explain why plants store carbohydrate as starch rather than as glucose. (2)
January 2021 (R), Paper 1, Q10(c) (1 mark): Other white blood cells produce proteins called antibodies. State how you could test a sample of plasma for protein. (1)
November 2020, Paper 1, Q1(a)(ii) (1 mark): The bacterium has evolved to release an enzyme called urease. The action of the bacterium neutralises the acid in the stomach. What is the pH changed to? (1) A
November 2020, Paper 1, Q7(a) (2 marks): Describe how you would test a sample of cow’s milk and a sample of human milk to show they contain different masses of protein. (2)
November 2020, Paper 1, Q11 (6 marks): Some cosmetic companies claim that adding argan oil to their shampoo increases the strength of human hair. Design an investigation to find out if argan oil sham
November 2020, Paper 2, Q2(a)(ii) (1 mark): The optimum temperature for the enzymes involved in blood clotting is 37 °C. Sketch a graph to show how temperature affects the time taken for blood to clot. (1
November 2020 (R), Paper 1, Q1(a)(ii) (1 mark): Which of these substances is a carbohydrate stored in plant cells? (1) A chlorophyll B glucose C glycogen D starch
November 2020 (R), Paper 1, Q7(a) (2 marks): Explain the results of Benedict’s test if the amylase digests the starch. (2)
November 2020 (R), Paper 1, Q7(b) (4 marks): The student’s method lacks detail. Rewrite the method so that the student could make a valid conclusion about the effect of temperature on amylase. (4)
November 2020 (R), Paper 1, Q7(c) (4 marks): The student predicted that the rate of digestion of starch would keep increasing as temperature increased. Comment on this prediction. (4)
January 2020, Paper 1, Q3(a) (3 marks): Describe a method you could use to show that the nut contains fat. (3)
January 2020, Paper 1, Q4(a)(i) (1 mark): State what is meant by the term catalyst. (1)
January 2020, Paper 1, Q4(a)(ii) (1 mark): State what is meant by the term metabolic. (1)
January 2020, Paper 1, Q4(b)(i) (5 marks): Plot a line graph to show the effect of enzyme concentration on the mean rate of oxygen production. Use a ruler to join the points with straight lines. (5)
January 2020, Paper 1, Q4(b)(ii) (3 marks): Explain the effect of increasing enzyme concentration on the rate of oxygen production. (3)
January 2020, Paper 1, Q4(b)(iii) (1 mark): Name a piece of apparatus suitable for measuring the volume of oxygen produced. (1)
January 2020, Paper 1, Q4(b)(iv) (2 marks): Explain why it is important for the teacher to keep the volume and concentration of the hydrogen peroxide constant. (2)
January 2020, Paper 1, Q4(b)(v) (1 mark): Name another variable the teacher should keep constant in his investigation. (1)
January 2020, Paper 2, Q5(b)(iii) (2 marks): Describe a simple test to show that a urine sample contains protein. (2)
January 2020 (R), Paper 1, Q5(b)(ii) (2 marks): Explain the result at 55 °C. (2)
January 2020 (R), Paper 1, Q5(c) (2 marks): Describe how the student should modify the investigation to obtain a more accurate measure of the optimum temperature. (2)
June 2019, Paper 1, Q5(a) (1 mark): What is the name of this large insoluble molecule? (1) A glucose B lipid C protein D starch
June 2019, Paper 1, Q7(a)(i) (2 marks): Give two variables that the student controls in his investigation. (2) 1 2
June 2019, Paper 1, Q7(a)(ii) (2 marks): Give the juices A, B, C and D in order of sugar content, from highest to lowest. (2) highest lowest
June 2019, Paper 1, Q7(a)(iii) (3 marks): The student is now given sugar solutions with concentrations of 1%, 5%, 10% and 20%. Explain how the student could use these solutions to estimate the concentra
June 2019, Paper 2, Q2(a) (3 marks): Describe how you would test a leaf to show that it contains starch. (3)
June 2019, Paper 2, Q3(b)(i) (1 mark): Calculate the percentage loss in mass shown by the square in pH 9.0 soil. (1) percentage =
June 2019, Paper 2, Q3(b)(ii) (1 mark): Calculate the difference between the percentage loss in mass for the two squares. (1) difference =
June 2019, Paper 2, Q3(b)(iii) (4 marks): Explain how the student could improve her method so that she can obtain more accurate results. (4)

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