Biological Molecules

9.Which of the following is NOT a polysaccharide?

10.A food sample is tested with Benedict's solution and heated. The solution remains blue. Which conclusion is correct?

11.Which statement about lipids is correct?

12.A student performs the emulsion test for lipids. What is the correct procedure and positive result?

13.Which of the following correctly describes the structure of a triglyceride?

14.Which part of an amino acid varies between different amino acids?

15.Which food test would you use to distinguish between a solution of glucose and a solution of starch?

16.A student carries out the iodine test on a piece of bread and observes a blue-black colour. What does this indicate?

17.A student tested a food sample with iodine solution. The colour changed from orange-brown to blue-black. Which nutrient is present?

18.A student tested a food sample with the emulsion test and observed a cloudy white layer. Which nutrient is present?

19.A student carries out the DCPIP test on three fruit juices: A, B, and C. The student adds 1 cm³ of DCPIP to each test tube, then adds 1 cm³ of fruit juice. The time taken for the blue colour to disappear is recorded. Fruit juice A: 30 seconds, B: 60 seconds, C: 120 seconds. Which fruit juice contains the highest concentration of vitamin C?

20.In a food test experiment, a student is asked to test a sample for the presence of reducing sugars. The student heats the sample with Benedict's solution for 5 minutes but observes no colour change from blue. Which of the following could explain this result?

21.Which food test involves mixing the sample with ethanol, then adding cold water, and observing a cloudy white emulsion?

22.A student tests a food sample with Biuret solution. The colour remains blue. What does this indicate?

23.Which of the following is a correct description of a triglyceride molecule?

24.A student is testing a colourless solution for the presence of reducing sugars. After adding Benedict's solution and heating, the solution turns orange. Which of the following statements is correct?

25.In an experiment, a student uses the DCPIP test to compare the vitamin C content of two fruit juices. 1 cm³ of DCPIP is added to each test tube. Juice X is added dropwise until the blue colour disappears. Juice Y requires 15 drops, while Juice X requires 10 drops. Which juice has the higher concentration of vitamin C?

26.Which of the following contains only carbon, hydrogen and oxygen?

27.What is the basic unit (monomer) of proteins?

28.In a food test, a student is asked to distinguish between two solutions: one contains glucose and the other contains sucrose. Which test would allow the student to distinguish between them?

29.Which of the following is a polysaccharide?

30.A student performs the emulsion test for lipids. The correct procedure is:

31.What colour change indicates a positive result for the Biuret test?

32.A student is given three food samples: X, Y, and Z. The student tests each sample with iodine solution. X turns blue-black, Y remains orange-brown, Z turns blue-black. Which of the following is a correct conclusion?

33.Which elements are always present in carbohydrates?

34.What is the monomer of proteins?

35.In a triglyceride molecule, one glycerol molecule is bonded to three fatty acid chains by ester bonds. Which part forms the central backbone of the molecule?

36.All organic molecules in living organisms contain carbon.

37.Which of the following is a monosaccharide?

38.Match each food test to the nutrient it detects.

39.A triglyceride molecule is composed of:

40.Proteins are made up of long chains of amino acids.

41.Which of the following elements are found in all carbohydrates, proteins, and lipids? (Select all that apply)

42.Arrange the following in order of increasing complexity: amino acid, protein, dipeptide, polypeptide.

43.Match each biomolecule to its correct description.

44.A student tests an unknown food sample with iodine solution and observes a blue-black colour. Which of the following is most likely present in the sample?

45.Complete the sentence.

46.State one safety precaution that should be taken when carrying out the Benedict's test and explain why.

47.Complete the sentence:

48.A student tests a food sample with Biuret solution and observes a colour change from blue to violet. The student then heats the same sample with Benedict's solution and observes a colour change from blue to orange. Describe the food tests and state which nutrients are present in the sample.