Biomolecules Mock Test – Class 11 Biology

1. 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:

2. Assertion: A competitive inhibitor can reduce productive enzyme-substrate complex formation.
Reason: Competitive inhibition occurs through permanent hydrolysis of every peptide bond in the enzyme.

3. An unknown cellular molecule has a molecular mass of , contains fatty-acid components and phosphate, and is recovered mainly with disrupted membrane fragments in the acid-insoluble fraction. What is the strongest conclusion?

4. An unknown compound is found in many cell types and is consistently linked with an ordinary physiological process. A second compound occurs only in selected plant and fungal tissues. How should their relationship be interpreted?

5. Examine the records for four substances recovered from an acid-insoluble fraction.

Which synthesis is most accurate?

6. An unknown polysaccharide becomes blue after iodine addition. In the same experiment, a starch control becomes blue and a cellulose control remains unchanged. Which conclusion is most justified?

7. Four compounds are characterised below.

Which compound belongs to the nitrogenous-base family?

8. Match each reaction with the appropriate enzyme class. Column II entries may be reused.

9. Arrange the stages that lead from a crude tissue extract to information about an individual compound.
P. Separate components of the extract.
Q. Isolate the compound of interest.
R. Purify the isolated compound.
S. Apply analytical methods to determine its molecular formula and probable structure.

10. An amino acid is identified as aromatic from the structure of its -group. What can be concluded about its acidic, basic or neutral classification from that observation alone?

11. An investigator records only the presence or absence of elements in living tissue and nearby soil. The two lists are almost the same. What change would most directly reveal the major chemical distinction emphasised by such a comparison?

12. An investigator analyses only the acid-soluble filtrate and concludes that the measured amino acids, sugars and ions represent every major chemical class in the original tissue. What is the main limitation of this conclusion?

13. A lipid isolated from seeds contains glycerol esterified with three fatty acids. At least one fatty-acid chain contains a bond, and the material is liquid under the stated room condition. Which description best fits the evidence?

14. Combustion of a purified enzyme preparation leaves a small amount of zinc-containing ash. Removing zinc from an unburned sample abolishes catalytic activity, and adding restores it. The polypeptide sequence remains unchanged throughout the removal-and-restoration experiment. What is the strongest conclusion?

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

16. Match each feature of enzyme classification with its description. A Column II entry is used once.

17. Assertion: Water is an essential constituent of living tissue but is not classified as a biomolecule under the carbon-compound definition.
Reason: The term biomolecule is applied to carbon compounds obtained from living tissue, whereas water is an inorganic compound.

18. A graph plots total product on the vertical axis and time on the horizontal axis. Product rises from to units during the first , then rises from to units during the next . What is the correct interpretation?

19. Equal enzyme and substrate concentrations are placed in two tubes. Tube P receives no additional chemical, while Tube Q receives Chemical X. Product formation in Q falls sharply. After X is removed, the enzyme from Q regains its original activity. Which conclusion is strongest?

20. The following observations were made for four protein samples.

Which sample provides direct evidence of quaternary structure?

21. An ordinary enzyme is heated to , cooled and then tested over a very wide range of substrate concentrations. Reaction velocity remains close to zero at every substrate concentration. Which explanation best distinguishes this result from ordinary substrate saturation?

22. The data below were obtained using a fixed amount of enzyme.

Which conclusion best fits the full data set?

23. Match each reaction pattern with the correct enzyme class. A Column II entry is used once.

24. Assess the following statements about preparing a tissue extract with trichloroacetic acid.
I. Grinding increases contact between tissue contents and the extraction medium.
II. The product before filtration is a slurry.
III. Filtration directly reveals the molecular formula of each separated compound.
IV. The preparation enables separation into operationally soluble and insoluble fractions.

25. Non-hydrolytic removal of a group by a lyase is represented by:

26. Three analytical records are obtained from living tissue.

How should the records be classified?

27. 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?

28. Which statements correctly describe the identification of compounds from living tissue?
I. Components of an extract are separated before a particular compound is isolated.
II. An isolated sample may still require purification.
III. Analytical techniques can provide a molecular formula and evidence for probable structure.
IV. A molecular formula alone always reveals the complete arrangement of atoms in a compound.

29. Two enzyme samples show equally low activity at moderate substrate concentration. Sample P contains a competitive inhibitor. Sample Q lacks an essential cofactor. Substrate concentration is then increased greatly without changing any other condition. Which result is most likely?

30. 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?

31. Assertion: The doubling rule should not be extended indefinitely to predict enzyme activity at progressively higher temperatures.
Reason: Excessive heat can disrupt an enzyme's tertiary structure and reduce its catalytic activity.

32. Consider the following statements about integrated lipid classification.
I. Saturation depends on the presence or absence of bonds in fatty-acid chains.
II. Mono-, di- and triglyceride names depend on the number of fatty acids esterified to glycerol.
III. Phosphate-containing lipids such as lecithin are associated with cell membranes.
IV. Acid-insoluble recovery proves that every lipid is a high-mass polymer.

33. Use the four arrangements described below.
P. An unbranched glucose chain forms a major structural component of a plant cell wall.
Q. A glucose reserve polymer contains numerous branches and occurs in animal tissue.
R. A plant reserve glucose polymer possesses iodine-holding helical regions.
S. A structural chain of modified amino sugars occurs in an arthropod exoskeleton.
Which ordered identification is correct?

34. Living systems are built from atoms and molecules that are not living by themselves. Which statement best explains how these components contribute to life?

35. A graph plots reaction velocity on the vertical axis and substrate concentration on the horizontal axis. The curve obtained with a competitive inhibitor lies below the uninhibited curve at moderate substrate concentrations, but the gap becomes smaller as substrate concentration becomes very high. What does this pattern indicate?

36. Assertion: After selective hydrolysis of starch in a starch–cellulose mixture, the remaining residue may be iodine-negative yet still contain a glucose polymer.
Reason: Cellulose is a glucose polymer but lacks the starch-like iodine-holding helical organisation.

37. An inactive protein preparation is analysed. It contains the complete polypeptide sequence but lacks a non-protein component. The missing component is organic, remains tightly bound in the normal enzyme and forms part of its active site. Which sequence correctly describes restoration of activity?

38. Three graph observations are listed below.

Which synthesis is valid?

39. Two enzymes act on similar substrates. Enzyme P cleaves a bond only when water is supplied. Enzyme Q removes a group without consuming water and forms a double bond in the product. How should they be classified?

40. Four reactions are described below.

Which reactions represent isomerase action?

41. Enzyme P requires tightly bound haem, Enzyme Q requires transient NAD and Enzyme R requires zinc. Each enzyme is stripped of its required component. Adding NAD to P, zinc to Q and haem to R fails to restore activity. What is the strongest inference?

42. Consider the following statements about phosphorus in biological samples.
I. Phosphorus may occur in nucleotide phosphate groups.
II. Phosphorus may occur in membrane phospholipids.
III. Phosphorus may contribute to inorganic residue detected in ash.
IV. Detection of phosphorus alone is sufficient to identify an unknown substance as a nucleic-acid polymer.

43. Consider the symbolic pathway:

Which statement best interprets the relation?

44. A functional enzyme consists of two folded polypeptide subunits. The subunits are separated under conditions that preserve each chain's secondary and tertiary structures. Neither isolated subunit is active, but activity returns when the two are mixed and reassociate. What is the strongest inference?

45. Two polypeptides have the compositions shown below.

Which comparison is accurate?

46. A lipid isolated from neural tissue does not match the component descriptions of a simple fatty acid, a glyceride or lecithin. No further structural evidence is available. What is the strongest justified conclusion?

47. Let represent a nitrogenous base, a sugar, a phosphate group, a nucleoside and a nucleotide. Consider the relation:

Which interpretation is valid?

48. An apoenzyme is supplied with excess substrate at optimum pH and temperature, but no product forms. Addition of one specific metal ion restores rapid catalysis. Which conclusion is best supported?

49. Assertion: A molecule containing cytosine, ribose and phosphate is an RNA-type pyrimidine nucleotide.
Reason: Cytosine is a pyrimidine, ribose gives RNA-type identity and phosphate completes nucleotide composition.

50. Four proposed central-carbon arrangements are shown.

Which structure alone matches the general plan of an -amino acid?