plumiBiochemical tests and chromatography: OCR A‑Level Biology A questions
OCR A-Level Biology A past-paper questions on 2.1.2.7 Biochemical tests and chromatography, 2016–2025, with mark schemes and examiner’s reports where available.
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All 40 questions on Biochemical tests and chromatography, as a list
- June 2025, AS Paper 1, Q4 (1 mark): A student carries out a non-reducing sugar test on a sample of fruit juice. What is the correct reason for heating the sample with hydrochloric acid? A It break
- June 2025, AS Paper 1, Q5 (1 mark): A student is finding out the concentration of a sample of protein. • They set up five solutions that have a range of different protein concentrations. • They ca
- June 2025, AS Paper 2, Q1(b) (2 marks): Students complete paper chromatography on carbohydrates. The table shows the Rf values for known carbohydrates. © researchgate.net, ResearchGate. Item removed d
- June 2025, AS Paper 2, Q1(c) (2 marks): Outline the role of the solvent in paper chromatography. [2]
- June 2023, Paper 3, Q2(a)(i) (1 mark): Most vitamins are colourless. Suggest one method for visualising the vitamins in TLC. [1]
- June 2023, Paper 3, Q2(a)(ii) (2 marks): The results of the TLC are shown in the chromatogram in Fig. 2.1. Fig. 2.1 Solvent front Vitamin B6 Vitamin B1 Vitamin B2 Vitamin C Origin Use Fig. 2.1 to calcu
- June 2023, AS Paper 1, Q23(b)(i) (2 marks): Use the chromatogram to calculate the Rf value of valine. Rf = [2]
- June 2023, AS Paper 1, Q23(b)(ii) (1 mark): Serine and leucine have different R groups. With reference to the chromatogram, suggest what can be concluded about the chemical properties of the R groups in s
- June 2023, AS Paper 2, Q3(a)(i) (1 mark): The above test would not detect the presence of protein in the sample. State the change that needs to be made to this test to enable protein to be detected. [1]
- June 2023, AS Paper 2, Q3(b) (6 marks): (b)* The students were provided with another sample of an unknown liquid. They carried out chemical tests on this sample to determine what biological molecules
- June 2023, AS Paper 2, Q3(c)(i) (3 marks): The students were then asked to carry out an experiment to determine the glucose concentration of another test solution using a colorimeter. Describe how the st
- June 2023, AS Paper 2, Q3(c)(ii) (2 marks): The students plotted their results, shown in the graph. 80 70 60 50 40 Absorption (%) 30 20 10 0 0 0.001 0.002 0.003 0.004 0.005 0.006 Glucose concentration (mm
- June 2022, Paper 2, Q21(d)(i) (4 marks): A colorimeter can be used, along with biuret reagent, to determine the concentration of protein in a solution. Outline how to use a colorimeter to determine the
- June 2022, Paper 2, Q21(d)(ii) (1 mark): State one alternative method for determining the concentration of protein in a solution. [1]
- November 2021, Paper 3, Q4(a) (2 marks): Some organisms use a disaccharide called trehalose as a respiratory substrate. Trehalose has a similar structure and very similar chemical properties to sucrose
- November 2021, AS Paper 1, Q20 (1 mark): A student carried out four tests on samples from a beaker of starch and amylase. Which row, A to D, would show the correct results if the reaction was still hap
- November 2020, AS Paper 1, Q22(b) (3 marks): Outline the method of chromatography that will separate the main amino acids in collagen. [3]
- November 2020, AS Paper 1, Q22(c)(i) (2 marks): Calculate Rf values for the two highest concentration amino acids. Rf value 1 = Rf value 2 = [2]
- November 2020, AS Paper 1, Q22(c)(ii) (2 marks): The table shows the Rf values of a range of amino acids. amino acid Rf value glutamine 0.13 glycine 0.27 isoleucine 0.72 leucine 0.73 methionine 0.55 phenylalan
- June 2019, Paper 1, Q17(c)(i) (1 mark): Name a type of food molecule that the student will not be able to detect using these chemical tests. [1]
- June 2019, Paper 1, Q17(c)(ii) (2 marks): The table below is a summary of some of the student’s findings. Complete the table by writing in the missing observations and conclusions. Tube Observation Conc
- June 2019, Paper 1, Q17(c)(iii) (1 mark): The student then used a colorimeter to measure the absorbance of the contents of Tube 2. Explain how the use of a colorimeter could improve the student’s conclu
- June 2019, AS Paper 1, Q22(a) (3 marks): Table 22 is a list of practical apparatus used in biological investigations. Each piece of apparatus has been assigned a letter. Letter Apparatus A calorimeter
- June 2019, AS Paper 1, Q22(b)(i) (1 mark): Describe how a colorimeter is calibrated. [1]
- June 2019, AS Paper 1, Q22(b)(ii) (1 mark): Why is it important to calibrate a colorimeter? [1]
- June 2019, AS Paper 2, Q1(a)(ii) (4 marks): Separate samples of the sap were tested for the presence of glucose, starch and sucrose. Using Table 1, complete the following passage, using the most appropria
- June 2018, Paper 3, Q2(b) (3 marks): Glucose and other carbohydrates are present in respiring cells. The concentrations of carbohydrate molecules vary between tissues. A student conducted tests on
- June 2018, AS Paper 2, Q1(c)(i) (4 marks): Describe four ways you would refine the method used by the students. For each change you suggest, give a reason why this would improve the results of the experi
- June 2018, AS Paper 2, Q1(c)(ii) (2 marks): Table 1 shows the Rf values of some amino acids. Name of amino acid Rf value Alanine 0.31 Cysteine 0.40 Glutamine 0.13 Phenylalanine 0.59 Table 1 Using the info
- June 2017, Paper 2, Q20(c) (4 marks): Lactose is a reducing sugar. Benedict’s reagent can be used to detect the presence of lactose in a solution. A colorimeter can be used to measure the concentrat
- June 2017, Paper 3, Q1(a)(ii) (1 mark): Students used thin layer chromatography to separate leucine from other amino acids. The chromatogram they produced is shown in Fig. 1.2. Y X leucine origin solv
- June 2017, Paper 3, Q1(a)(iii) (3 marks): Amino acid Z was in the mixture analysed by the students. It is not shown on the chromatogram in Fig. 1.2. Amino acid Z has an Rf value that is 0.20 lower than
- June 2017, Paper 3, Q1(b)(i) (1 mark): State a material that can be used as the stationary phase in thin layer chromatography. [1]
- June 2017, Paper 3, Q1(c) (3 marks): When sequencing DNA, fragments of DNA are separated by electrophoresis. Describe three differences between the process of thin layer chromatography and the form
- June 2017, AS Paper 1, Q10 (1 mark): A group of students was given a 1% solution of an unknown digestive enzyme. They were also given three tubes containing an identical mixture of foods. The stude
- June 2017, AS Paper 2, Q6(a)(i) (3 marks): Plot a graph of the mean % absorbance at each glucose concentration. [3]
- June 2017, AS Paper 2, Q6(a)(ii) (2 marks): The students were provided with three different fruit juices labelled A, B and C. The Benedict’s test was carried out on each fruit juice and samples were prepa
- June 2017, AS Paper 2, Q6(b)(i) (4 marks): Describe how you would carry out a controlled experiment to test this hypothesis without using a colorimeter. [4]
- June 2017, AS Paper 2, Q6(b)(ii) (1 mark): Suggest one reason why the results for this experiment might not support the students’ hypothesis. [1]
- June 2016, AS Paper 1, Q11 (1 mark): A student investigates some solutions, X, Y and Z, using paper chromatography. The results are shown below. solvent front X Y Z Which of the following options,
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