0653.B4.1.03 — Describe the use of: (a). iodine solution test for starch (b). Benedict’s solution test for reducing sugars (c). biuret test for proteins (d: past paper questions
Real questions on 0653.b4.1.03 — describe the use of: (a). iodine solution test for starch (b). benedict’s solution test for reducing sugars (c). biuret test for proteins (d
The newest 20 of 27 written questions. Open one to see it on the real paper.
- 0653/31 · October/November 2025 · Q1c[2]
A student adds food to a test solution. The test solution changes colour from blue to purple (violet). Identify the biological molecule present in the food and name the test solution used. biological molecule
See it on the paper → - 0653/32 · May/June 2025 · Q2b[2]
A plant is left in a warm dark room for three days. After three days, a leaf from the plant is tested with iodine solution. The yellow-brown colour of the iodine solution indicates that the leaf does not contain . Complete the sentences to explain this result. The iodine solution stays yellow-brown in colour.
See it on the paper → - 0653/61 · May/June 2025 · Q1a[3]
Record in Table 1.1 the colours the student observes in each test‑tube. Table 1.1 drink colour with iodine solution colour with biuret solution A B C
See it on the paper → - 0653/61 · May/June 2025 · Q1b[3]
Use Table 1.1 to state conclusions about the nutrient content for each of the drinks. drink A drink B drink C
See it on the paper → - 0653/61 · May/June 2025 · Q1c[1]
State the reagent used to test for fats and oils.
See it on the paper → - 0653/62 · May/June 2025 · Q1d[3]
A student tests the section of carrot root and a piece of potato for the presence of starch. The student: step 1 places the piece of potato and the section of carrot root onto a white tile step 2 adds a few drops of iodine solution to the surface of the carrot and of the potato step 3 observes the colour of the iodine...
See it on the paper → - 0653/43 · October/November 2024 · Q4a(iii)[2]
Carbohydrates produced in photosynthesis are stored as starch in plants. State the solution used to test for the presence of starch and the observation for a positive result. solution
See it on the paper → - 0653/61 · October/November 2024 · Q1c[1]
A few drops of iodine solution are added to the cut surface of the onion. Complete the observation. observation no starch present
See it on the paper → - 0653/62 · October/November 2024 · Q1c[4]
Describe the tests that confirm the presence of fat and the presence of protein in food. Include the observation for a positive result for each test. test for fat observation for a positive result test for protein
See it on the paper → - 0653/61 · May/June 2024 · Q1aiii[2]
Use Fig. 1.4 and the key to record in Table 1.1, the colour of the solution in each well for test-tubes A and C.
See it on the paper → - 0653/63 · October/November 2023 · Q1b[2]
The student does a test to determine whether the leaf contains reducing sugar. State the test the student uses. Include the observation for a positive result. test observation
See it on the paper → - 0653/61 · May/June 2023 · Q1a(i)[1]
Fig. 1.1 shows the syringe after adding iodine solution to the 0.25% concentration of vitamin C. 1 2 3 4 5 6 7 8 9 10 iodine solution remaining cm 3 Fig. 1.1 Record in Table 1.1, the volume of iodine solution remaining in the syringe. Table 1.1 percentage concentration of vitamin C volume of iodine solution remaining /...
See it on the paper → - 0653/61 · May/June 2023 · Q1a(ii)[1]
Calculate the volume of iodine solution added to the 0.25% vitamin C solution. Use the equation shown. volume of iodine solution added = Record this value in Table 1.1. 10 – volume of iodine solution remaining
See it on the paper → - 0653/61 · May/June 2023 · Q1a(iii)[3]
On the grid, plot a graph of the volume of iodine solution added (vertical axis) against the percentage concentration of vitamin C.
See it on the paper → - 0653/61 · May/June 2023 · Q1a(iv)[1]
Draw the line of best‑fit.
See it on the paper → - 0653/61 · May/June 2023 · Q1a(v)[1]
The student repeats Step 1 to Step 4 of the procedure in (a) using 10 cm 3 of fruit juice instead of the vitamin C solutions. Fig. 1.2 shows the syringe after adding the iodine solution to the fruit juice. 1 2 3 4 5 6 7 8 9 10 cm 3 Fig. 1.2 Record the volume of iodine solution remaining and the volume added when the st...
See it on the paper → - 0653/61 · May/June 2023 · Q1a(vi)[1]
Use your graph to estimate the percentage concentration of vitamin C in the fruit juice. percentage concentration of vitamin C in the fruit juice =
See it on the paper → - 0653/61 · May/June 2023 · Q1a(vii)[1]
The student uses the same syringe for Step 1 and Step 7. Suggest why this is a possible source of error.
See it on the paper → - 0653/61 · May/June 2023 · Q1b(i)[1]
Suggest one other reason why the procedure for each concentration should be repeated.
See it on the paper → - 0653/61 · May/June 2023 · Q1b(ii)[1]
Suggest one other way to improve confidence in your estimate in (a)(vi).
See it on the paper →
What examiners said
Most candidates gained partial credit for the second part of the question. They understood that the plant had not photosynthesised because there was no light present. Fewer responses showed an understanding of the negative test for starch, the yellow-brown colour described in the question.
— Examiner report, May/June 2025, 0653/32 Q2(b) (Cambridge)
It is expected that candidates are able to recall the colours for the negative and positive results of food tests. In this case, the tests for starch and protein were tested. Many candidates knew that the positive result of testing starch with iodine solution is a blue-black colour, but fewer gave brown as a description of the negative result. Although A and C were the same result (negative) it wa...
— Examiner report, May/June 2025, 0653/61 Q1(a) (Cambridge)
Some candidates answered this correctly, interpreting the information to make correct statements about the starch and protein content of the drinks. However, some common errors were seen. Firstly, some candidates did not know that the biuret test was for proteins and instead described the sugar content. Some omitted to state the significance of a negative test. For example, for drink A, the negati...
— Examiner report, May/June 2025, 0653/61 Q1(b) (Cambridge)
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