Biomolecules Mock Test – Class 11 Biology

1. Consider the following statements about the ends of a represented polypeptide.
I. The first residue defines the N-terminal end.
II. The last residue defines the C-terminal end.
III. Removing the first residue can expose a new N-terminal residue without changing the last residue.
IV. Adding a residue specifically at the C-terminal end necessarily changes the N-terminal residue.

2. The protein component of a cofactor-dependent enzyme, when considered without its required non-protein component, is called the ______.

3. Three equal samples are prepared from a purified catalyst. Sample P is untreated and remains active. Sample Q is completely hydrolysed and yields amino acids. Sample R is heated strongly without breaking most peptide bonds but loses its compact three-dimensional shape and activity. Which conclusion is strongest?

4. Which statements correctly describe the acid-insoluble fraction of living tissue?
I. It contains proteins, nucleic acids, polysaccharides and lipids.
II. Proteins, nucleic acids and polysaccharides are true polymeric biomacromolecules.
III. Lipid recovery in this fraction does not establish that lipids are polymers.
IV. Every organic substance in this fraction is built by indefinite repetition of one monomer.

5. Four compounds are characterised below.

Which compound belongs to the nitrogenous-base family?

6. Four unknown cellular molecules are summarised below.

Which synthesis is correct?

7. Match each organic class with the relation that applies most directly. A Column II entry is used once.

8. Compare cellulose and chitin using the information below.

Which conclusion follows?

9. Assertion: An enzyme accelerates a reaction by raising the final product to a higher potential-energy level.
Reason: An enzyme provides a reaction route with lower activation energy while leaving the represented substrate and product energy levels unchanged.

10. Four polysaccharide samples are tested under identical conditions.

Which synthesis is best supported?

11. Evaluate the following statements about proteins as amino-acid polymers.
I. A protein contains amino-acid residues joined in a linear chain.
II. Peptide bonds connect adjacent residues.
III. Every side chain in a protein must be chemically identical.
IV. The order of residues can differ among proteins.

12. An enzyme is heated and loses its compact shape. Its peptide bonds remain intact, but the substrate no longer fits into the original pocket and catalytic activity falls. What is the strongest inference?

13. Study the mass records for two fresh tissues.

Which comparison is supported by the complete data?

14. A reaction is initially performed at its optimum pH and temperature with abundant substrate. The mixture is then heated excessively and a chemical that binds the enzyme is added. Activity falls almost to zero. Which interpretation is strongest?

15. Enzyme converts B into C but cannot act on A. In one tube, A is mixed only with , and no C forms. In another tube, A is first treated with , which produces B, and addition of then produces C. What is the strongest conclusion?

16. A low-molecular-mass compound is found only in a limited group of plants. It is not required as a universal monomer of proteins, polysaccharides or nucleic acids, and evidence suggests that it discourages herbivores. Which description is most appropriate?

17. A protein segment forms an extended, folded sheet-like arrangement, while no information is provided about the complete three-dimensional shape of the chain. This segment is best classified as:

18. Four reactions are described below.

Which reactions represent isomerase action?

19. A membrane lipid loses its phosphate-containing component while retaining its fatty-acid-containing portion. Which prediction is most justified?

20. NAD and NADP can participate transiently with different enzymes and contain a vitamin-derived component associated with niacin. NAD and NADP are best described as:

21. Two inactive samples of the same haem-containing enzyme are prepared. In Sample P, haem is removed but the polypeptide remains folded. In Sample Q, the polypeptide is completely hydrolysed into amino acids while haem remains present. What result is most likely after haem is added to both samples?

22. Two forms of the same enzyme are tested at identical temperature, enzyme concentration and substrate concentration. The normal enzyme reaches maximum activity at pH , whereas a variant reaches maximum activity at pH . Both show lower activity on either side of their respective peaks. What is the strongest interpretation?

23. Match each compound with its most appropriate chemical category. Column II entries may be reused.

24. Four soluble compounds recovered from a tissue extract have the molecular masses shown below.

Using the stated approximate range, which compounds fit the usual molecular-mass description of the acid-soluble pool?

25. A tissue sample is examined by two complementary procedures.

Which conclusion best integrates the observations?

26. Assertion: Replacing ribose with -deoxyribose in a base–sugar–phosphate unit changes it from an RNA-type nucleotide to a DNA-type nucleotide.
Reason: Pentose identity distinguishes the stated DNA and RNA nucleotide types, while retained phosphate preserves nucleotide status.

27. Four compounds recovered from a tissue extract have molecular masses of , , and . The acid-soluble pool is described by an approximate range, while micromolecules are also described more broadly as usually below . Which interpretation is most accurate?

28. An RNA-type nucleotide undergoes two changes: ribose is replaced by -deoxyribose, and phosphate is subsequently removed. The nitrogenous base remains unchanged. What is the final product?

29. Consider the following statements about cellular molecules.
I. Amino acids and nucleotides can occur as small acid-soluble building units.
II. Proteins and nucleic acids are true acid-insoluble polymers.
III. A low-molecular-mass membrane lipid may occur in the acid-insoluble fraction without being a polymer.
IV. A restricted-distribution defensive plant compound may be a secondary metabolite even if it is acid-soluble.

30. After a tissue slurry in trichloroacetic acid is filtered, the liquid passes through the cloth while particulate material remains on it. The two products are identified, respectively, as:

31. One amino acid in a functional protein is replaced by a different amino acid. The altered side chain prevents the polypeptide from acquiring its normal compact fold. Which conclusion best integrates the changes?

32. Two purified triglycerides contain the same glycerol backbone and the same number of esterified fatty acids. Lipid P contains no bonds and melts at a higher temperature than Lipid Q, whose fatty acids contain several bonds. Which conclusion is best supported?

33. Study the elemental records from two samples.

No abundance values were measured. Which conclusion is justified by these records?

34. Which statements accurately describe the two fractions obtained from trichloroacetic-acid extraction?
I. The filtrate is called the acid-soluble pool.
II. Material retained on the filter forms the acid-insoluble fraction.
III. The two labels describe behaviour under a particular experimental treatment.
IV. The fractions should not be treated as two universal chemical kingdoms with no exceptions or associations.

35. Chemical P is normally associated with an enzyme and must be present for catalysis. Chemical Q binds to the same enzyme preparation and decreases activity. Removal of P causes inactivity that is reversed by adding P, whereas removal of Q restores activity. Which classification is best supported?

36. A separation method retains amino acids whose side chains contain the structural feature used to define the aromatic group. Tyrosine, phenylalanine and tryptophan enter the retained fraction, while valine does not. The result indicates that the method is separating primarily by:

37. An acid-insoluble cellular molecule is a high-molecular-mass polymer of ribonucleotides. The purified molecule accelerates a specific chemical reaction even though no polypeptide is present. Which identification best fits all the evidence?

38. In the reaction

which interpretation correctly identifies the donor, acceptor and transferred group?

39. A report listing , , phosphate and sulphate is closer to ______ analysis than to elemental analysis, since it identifies chemical forms rather than only element names.

40. Two enzyme vials carry old class labels that conflict with the reactions now observed.

Which conclusion follows from reaction-based classification?

41. Assertion: Cellulose is classified as a homopolymeric polysaccharide.
Reason: Its long chains are formed by repetition of glucose as one monosaccharide type.

42. Protein samples are analysed after different treatments.

Which conclusion is supported?

43. A purified enzyme is added to a compound containing a peptide bond. Cleavage occurs only when water is available, and the products carry the components of water across the broken bond. No redox change or group transfer between separate substrates is detected. What is the strongest inference?

44. Match each compound with its secondary-metabolite category. Column II entries may be reused.

45. Structural resemblance to the substrate allows a competitive inhibitor to compete for the enzyme's ______.

46. An unknown enzyme converts a compound into a product having the same molecular formula but a different three-dimensional arrangement. A second unknown enzyme converts two separate molecules into one covalently connected product. Which ordered classification is supported?

47. Yeast cells producing ethanol under fermentative conditions are shifted to the stated aerobic context while glucose remains available. Which immediate pathway-level prediction is most appropriate?

48. A mutation in a dehydrogenase prevents it from catalysing oxidation of its reduced substrate. All other pathway enzymes remain normal. Which immediate effect is most likely at that reaction step?

49. Four molecular records are shown below.

Which records are correctly classified?

50. Compare the reactions:


Which statement correctly distinguishes the enzymes involved?