Biomolecules Mock Test – Class 12 Chemistry

1. Hydrolysis of sucrose is called inversion because the optical rotation changes:

2. Equal amounts, each, of a linear polypeptide containing amino-acid residues per molecule and a linear double-stranded DNA fragment containing base pairs per molecule are completely hydrolysed only at their backbone linkages. The total water consumed is . What are and the total amount of amino-acid plus nucleotide monomers formed?

3. Four distinct amino acids—Ala, Gly, Ser and Val—are used exactly once each to form linear tetrapeptides. Ignoring stereochemical variations, the number of possible primary sequences is:

4. For an enzyme that requires a non-protein helper, the relation is completed by:

5. Two separate double-stranded B-DNA fragments have lengths in the ratio . Their combined axial length is . Use per base pair and base pairs per turn. What is the sum of the total phosphodiester bonds in the two fragments and their combined number of helical turns?

6. The claim “all biologically essential substances are macromolecules” is rejected because:

7. In the strong-oxidation equation

the missing coefficient is:

8. Glycogen is stored most prominently in:

9. An aldehyde and a ketone are both carbonyl compounds, but they differ because:

10. Vitamin is especially associated with:

11. D-Fructose is commonly associated with the name:

12. Lactose contains:

13. Assertion: Complementary base pairing enables a nucleic-acid strand to guide formation of another strand with a related sequence.
Reason: Each base shows selective pairing with a suitable complementary base.

14. Assertion: Cyclic fructose can participate in a ring–chain equilibrium.
Reason: Its anomeric carbon is part of a hemiketal that can reversibly regenerate the ketonic open-chain form.

15. Match each deficiency condition in Column I with the responsible vitamin in Column II.

16. The following results were obtained at constant enzyme concentration.

The data most strongly support the conclusion that:

17. The molecular formula and carbohydrate class of glucose are:

18. Match each biomolecular class in Column I with the most appropriate description in Column II.

19. Use the strand arrangement described below.
A DNA template runs as:

An RNA strand is synthesised antiparallel to it.
The RNA sequence is:

20. A patient has normal enzyme proteins but lacks an organic helper derived from a dietary micronutrient. In another experiment, a blood-borne substance binds a receptor on liver cells and alters their metabolism without catalysing the reaction directly. The two missing or acting substances are most appropriately classified as:

21. Nucleic acids are best described as:

22. Glycogen differs from amylopectin mainly because glycogen:

23. A graph shows blood-glucose concentration against time after equal glucose intake by two individuals. Curve P rises and returns close to its initial value relatively quickly. Curve Q rises higher and remains elevated for much longer. Which interpretation is most appropriate?

24. Consider the following statements about the chemical classification of hormones.
Statement I: Some hormones are peptides or proteins.
Statement II: Some hormones are steroids.
Statement III: Some hormones are derived from amino acids.
The acceptable statements are:

25. Assertion: Reduction of fructose gives a mixture containing sorbitol and mannitol.
Reason: Reduction of the planar carbonyl group at can produce two configurations at the newly formed alcohol-bearing carbon.

26. The statement “glucose must be an aldehyde because it forms an oxime” is incomplete because:

27. Use the arrangement described below.
Two extended polypeptide segments run in opposite N-to-C directions. Backbone hydrogen bonds connect the neighbouring segments, and side chains alternate above and below the sheet.
This structure is:

28. A structural comparison states that glucose has an anomeric carbon at , while fructose has one at . This difference arises because the anomeric carbon is:

29. Vitamins are best described as:

30. An enzyme loses activity when a required metal ion is removed, regains activity when that ion is restored, and reaches a substrate-saturation plateau after restoration. The observations together show that:

31. A molecule contains one tetrahedral carbon bonded to four different substituents and has no internal symmetry that removes chirality. Pure mirror-image forms of this molecule are expected to:

32. D-Glucose and D-galactose differ in configuration only at:

33. Formation of the common six-membered cyclic structure of glucose begins when:

34. Which statement best represents the biological roles of RNA?

35. Two hexose molecules form a disaccharide by eliminating one molecule of water. The balanced molecular-formula equation is:

36. In the peptide

the N-terminal and C-terminal residues are, respectively:

37. Maltose shows both mutarotation and reducing behaviour, whereas sucrose shows neither. The common structural reason for this difference is that maltose:

38. A carbohydrate molecule will generally behave as a reducing sugar when it contains:

39. Complete hydrolysis of carbohydrate P produces three monosaccharide molecules from each molecule of P. Carbohydrate P is best classified as:

40. A hydrolysed nucleic-acid mixture gives base molecules. Purines account for of the total and satisfy . The remaining bases satisfy . The value of is:

41. Two unknown hexoses P and Q have the same molecular formula. P is oxidised by bromine water to a monocarboxylic acid and gives only one alditol on reduction. Q is not similarly oxidised by bromine water under neutral conditions and gives two alditols on reduction. P and Q are, respectively:

42. A prolonged reduction in thyroxine activity would be expected to affect the body differently from an insulin deficiency mainly because thyroxine:

43. One mole of glucose is completely acetylated with excess acetic anhydride to form glucose pentaacetate. Assuming one mole of acetic anhydride is consumed per hydroxyl group acetylated, the required amount of acetic anhydride is:

44. Direct conversion of -D-glucopyranose into -D-glucopyranose in water proceeds by:

45. A person takes very large doses of vitamins A and D for several months without medical supervision. The principal concern is that:

46. The carbohydrate definition includes substances that yield polyhydroxy aldehydes or ketones on hydrolysis mainly to accommodate:

47. A linear double-stranded DNA molecule contains base pairs. Four complete double-strand breaks occur at different positions, and no nucleotide is lost. After breakage, what are the total number of phosphodiester bonds remaining and the total number of termini?

48. A mixture contains sucrose and maltose. Both disaccharides undergo complete hydrolysis. The correct pair for the total amount of glucose formed and the mass of water consumed is:

49. A mixture contains nitrogenous bases, of which are pyrimidines. Guanine forms of all purines. Cytosine forms of the pyrimidines, while the remaining pyrimidines satisfy . The value of is:

50. A mixture contains nucleotide units. DNA nucleotides constitute of the mixture and belong to double-stranded DNA in which adenine forms of the DNA nucleotides. The remaining units are single-stranded RNA nucleotides with . What is the sum of the total hydrogen bonds in the DNA portion and the number of -hydroxyl groups in the RNA portion?