Biomolecules: Class 12 Previous Year Questions

Biomolecules questions asked in CBSE board exams

Repeated questions first. Open the free app to see each question as it appeared in the paper, with its marking scheme.

1. Which of the following reactions is not explained by the open chain structure of glucose ? 1 (A) Glucose on prolonged heating with HI forms n-hexane. (B) Glucose reacts with hydroxylamine to form an oxime. (C) Glucose gets oxidized to gluconic acid on reaction…
   Board 20261 markAssertion-Reason
2. Write the reactions of D-Glucose with the following : 3  1 (a) HI (b) Br2 water (c) Conc. HNO3
   Board 20263 marksshort answer
3. Differentiate between the following : 2  1 (i) Peptide linkage and Glycosidic linkage (ii) Essential amino acids and Non-essential amino acids
   Board 20262 marksshort answer
4. The base which is present in DNA but not in RNA is : 1 (A) Guanine (B) Cytosine (C) Thymine (D) Adenine
   Board 20261 markMCQ
5. Proteins are polymers of -amino acids which are joined to each other by : 1 (A) Covalent Bond (B) Peptide Bond (C) Glycosidic Bond (D) Coordinate Bond { } 8 12.                 ? 1 …
   Board 20261 markMCQ
6. (A) Define the following term : 2 + 1 (a) Reducing sugar (b) Differentiate between the following : (i) Fibrous proteins and globular proteins (ii) Nucleotide and nucleoside OR (B) Write the reaction of glucose with the following : 3  1 = 3 (a) H2N – OH (b) (C…
   Board 20263 marksshort answer
7. The deficiency of which of the following vitamins causes increased fragility of red blood cells and muscular weakness : 1 (A) Vitamin A (B) Vitamin K (C) Vitamin E (D) Vitamin D { } 8   13  16  ,      –     (A)  …
   Board 20261 markMCQ
8. Assertion (A) : Glucose gets oxidized to six carbon gluconic acid on reaction with bromine water. 1 Reason (R) : The carbonyl group is absent in the open chain structure of glucose.
   Board 20261 markAssertion-Reason
9. Scurvy is caused due to deficiency of (A) Vitamin B1 (B) Vitamin B2 (C)Ascorbic acid (D) Glutamic acid (R) (A), (B), (C) (A) (A) (R) (R), (A) (B) (A) (R) , (R), (A) (C) (A) , (R) 1 (D) (A) , (R) 1 13. RUT (R) : 14. ()·C H,1 RUT (R) : C RUT (R) : 16. RUT (R).
   Board 20251 markAssertion-Reason
10. Define the following terms : 28. 3×1=3 (a) Glycosidic linkage (b) Invert sugar (c) Oligosaccharides
    Board 20253 marksshort answer
11. Write the reactions involved when D-glucose is treated with the following reagents : (1 + 1 = 2) (a) HCN (b) Br, water 11 22. =180go1-1) 100.20 1.86 K kg mol-1 3 0.512 K kg mol-1 I 23.(a·: (i) (b) f : E&2+/x = -2.36 V, E2/y = -0.14 V, 24.300 2050%350 [R = 8.31…
    Board 20252 marksshort answer
12. (a) What is the difference between native protein and denatured protein ? (1 +1 +1= 3) (b) Which one of the following is a disaccharide ? Glucose, Lactose, Amylose, Fructose (c) Which vitamin is responsible for the coagulation of blood ? · 15 (a) (i) (1 + 1 = …
    Board 20253 marksshort answer
13. Which of the following statements is not true about glucose ? (A) It is an aldohexose. (B) On heating with HI it forms n-hexane. (C) It exists in furanose form. (D) It does not give Schiff's test.
    Board 20251 markMCQ
14. Assertion (A) : All naturally occurring ·-amino acids except glycine are optically active. Reason(R) : Most naturally occurring acids amino have L-configuration. 17. (A) : s (1 + 1 = 2) (a) (b) 18. fa f gf : (a) 2MnO7(aq) + 10I(aq) + 16H+(aq) ··) (b) Cr,02(aq)…
    Board 20251 markAssertion-Reason
15. Which of the following is/are examples of denaturation of protein ? Coagulation of egg white (A) (B) Curdling of milk Clotting of blood (D) (C) Both (A) and (B)
    Board 20251 markMCQ
16. {ZåZ{b{IV Ho$ {bE H$maU Xr{OE : 3 1=3 (H$) \ à{VñWmnZ A{^{H«$`mAm| _| Am°Wm}/n¡am {ZX}eH$ h¡ & (I) ao{g{_H$ {_lU Y«wdU AKyU©H$ hmoVm h¡ & (J) n- -AnK{Q>V hmo OmVm h¡ &
    Board 20243 marksshort answer
17. Define the following terms : 2 1=2 (a) Denaturation of protein (b) Invert sugar
    Board 20242 marksshort answer
18. Answer the following : (any three) 3 1=3 (a) What is peptide linkage ? (b) What type of bonds hold a DNA double helix together ? (c) Which one of the following is a polysaccharide ? Sucrose, Glucose, Starch, Fructose (d) Give one example each for water-soluble…
    Board 20243 marksshort answer
19. Two among the three components of DNA are -D-2-deoxyribose and a heterocyclic base. The third component is : (A) Adenine (B) Phosphoric acid (C) Sulphuric acid (D) Uracil
    Board 20241 markMCQ
20. Assertion (A) : Uracil base is present in DNA. Reason (R) : DNA undergoes self-replication.
    Board 20241 markAssertion-Reason

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