Biological molecules: past paper questions
Real questions on biological molecules
The newest 20 of 30 written questions, plus 16 multiple-choice. Open one to see it on the real paper.
- 5090/21 · May/June 2025 · Q1a[3]
Large molecules in cells are made from smaller molecules. Complete Table 1.1 to show which small molecules make up each large molecule. Choose the small molecules from this list. fatty acids glucose glycerol nucleotides amino acids Table 1.1 large molecule small molecules protein cellulose lipid
See it on the paper → - 5090/22 · May/June 2025 · Q6a(i)[1]
state the name of the structure labelled P
See it on the paper → - 5090/22 · May/June 2025 · Q6a(ii)[1]
state the name of the unit of DNA labelled Q
See it on the paper → - 5090/21 · October/November 2023 · Q3a(i)[2]
Calculate the percentage of the total human body mass made up from the three most common elements. total = %
See it on the paper → - 5090/21 · October/November 2023 · Q3a(ii)[2]
Name two types of substance found in the human body that contain only carbon, hydrogen and oxygen.
See it on the paper → - 5090/21 · October/November 2023 · Q5a(i)[1]
Identify the type of tooth shown in the diagram.
See it on the paper → - 5090/21 · October/November 2023 · Q5a(ii)[1]
Name the outer layer of the tooth.
See it on the paper → - 5090/22 · October/November 2023 · Q2b(i)[1]
List the chemical elements that make up a molecule of lichenan.
See it on the paper → - 5090/61 · October/November 2022 · Q1a(i)[1]
State what you would use to produce the 1 cm × 1 cm × 1 cm cubes of A and B.
See it on the paper → - 5090/61 · October/November 2022 · Q1a(ii)[1]
Describe what you would do to ensure that the tests with the small pieces of A and B were comparable. The student poured equal volumes of distilled water into two new test-tubes labelled A1W and B1W. He took test-tube A1 and carefully poured the liquid into test-tube A1W. He followed the same procedure with test-tube B...
See it on the paper → - 5090/61 · October/November 2022 · Q1a(iii)[1]
Explain why he cleaned the glass rod after using it in test-tube A2 and before using it in test-tube B2. He then added the same volume of biuret reagent to both test-tubes. The photograph shows a graduated measuring cylinder with the biuret reagent that he added to one of the test-tubes. cm 3
See it on the paper → - 5090/61 · October/November 2022 · Q1a(iv)[1]
State the volume of biuret reagent that he added. cm 3 After adding the biuret reagent he observed the mixtures in test-tubes A2 and B2 and recorded his observations in his notebook. For the third test, he placed the third pieces of A and B on a white tile, added some iodine solution and recorded his observations in hi...
See it on the paper → - 5090/61 · October/November 2022 · Q1b(i)[5]
The student’s notebook is shown. appearance of solutions after tests test-tube A1W - colourless test-tube B1W - cloudy test-tube A2 - pale purple test-tube B2 - darker purple iodine on A - brown iodine on B – brown Complete the table using only the information from his experimental method and his notebook. test number...
See it on the paper → - 5090/61 · October/November 2022 · Q1b(ii)[6]
Use the student’s observations to state what you can conclude about the composition of foods A and B. test test test He found that it was easy to cut A into a cube and divide it into three equal parts. However, he found that B crumbled (easily fell apart) which made it difficult to cut to produce a cube and to ensure t...
See it on the paper → - 5090/61 · October/November 2022 · Q1c(i)[3]
Suggest how this problem could have affected the results in test-tubes A2 and B2 and your conclusions.
See it on the paper → - 5090/61 · October/November 2022 · Q1c(ii)[1]
Suggest a change to the method to help overcome this problem.
See it on the paper → - 5090/61 · October/November 2021 · Q1b(v)[1]
Describe the method you used to determine this concentration of sucrose.
See it on the paper → - 5090/62 · October/November 2021 · Q1a[2]
State which reagents you would use to test for glucose and protein. glucose protein He labelled four glass test-tubes to do these tests.
See it on the paper → - 5090/62 · October/November 2021 · Q1b(i)[1]
State what you would use to label glass test-tubes.
See it on the paper → - 5090/62 · October/November 2021 · Q1b(ii)[1]
Suggest what you would write on each test-tube and record this in the table on page 3. He completed the tests and recorded the resulting colours of the solutions in his notebook. Glucose test A – pale blue Glucose test B – orange Protein test A – pale blue Protein test B – purple
See it on the paper →
What examiners said
The majority of candidates could read the percentages of the three most common elements and then add them together. However, a significant number then went on to add all five percentages together and calculate the percentage of the first three as a percentage of all five. In this case, they were awarded one mark for the first step in their calculation.
— Examiner report, October/November 2023, 5090/21 Q3(a)(i) (Cambridge)
The main error here was to give specific chemicals rather than types of substance. There were also a number of incorrect references to proteins.
— Examiner report, October/November 2023, 5090/21 Q3(a)(ii) (Cambridge)
There were less correct answers to this question compared to part (i), with some candidates confusing crown or gum with enamel.
— Examiner report, October/November 2023, 5090/21 Q5(a)(ii) (Cambridge)
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