Solved Important MCQs of Biomolecules

1. Biomolecules are
(a) Aldehydes and Ketones
(b) Acids and Esters
(c) Carbohydrates, Proteins, and Fats
(d) Alcohols and Phenols
Ans 1. (c) Carbohydrates, proteins, and fats are biomolecules.

2. Which of the following is a disaccharide?
(a) Lactose                              (b) Starch
(c) Cellulose                           (d) Fructose
Ans 2. (a) Lactose is a disaccharide.

3. The sugar that is characteristic of milk is
(a) Maltose                             (b) Ribose
(c) Lactose                              (d) Galactose
Ans 3. (c) It is found in the milk of all animals and imparts sweetness to milk (hence named milk sugar).

4. Which one is a disaccharide?
(a) Glucose                             (b) Fructose
(c) Xylose                               (d) Sucrose
Ans 4. (d) The disaccharides are sugars which on hydrolysis give two moles of the same or different monosaccharides. Sucrose, maltose, and lactose (C12H22O11) are common examples.

5. Which of the following monosaccharide is pentose?
(a) Glucose                             (b) Fructose
(c) Arabinose                          (d) Galactose
Ans 5. (c) Aldo-(keto) pentoses having 5 carbon
Aldo-(keto) hexoses having 6 carbon is an example of Pentose Sugar, arabinose (aldopentose) glucose, galactose, and fructose are important examples of hexose sugar.

6. The commonest disaccharide has the molecular formula
(a) C10H18O9                           (b) C10H20O10
(c) C18H22O11                          (d) C12H22O11
Ans 6. (d) The most common disaccharide, Lactose has the molecular formula C12H22O11.

7. Monosaccharides usually contains … carbon atoms.
(a) C3 to C10                            (b) C1 to C6
(c) C4 to C10                            (d) C5 to C8
Ans 7. (a)

8. Which one of the following compounds is found abundantly in nature?
(a) Fructose                            (b) Starch
(c) Glucose                             (d) Cellulose
Ans 8. (d)

9. A carbohydrate that cannot be hydrolysed into simpler units is called
(a) Polysaccharides                (b) Trisaccharides
(c) Disaccharides                    (d) Monosaccharides
Ans 9. (d) Monosaccharides cannot be hydrolysed to simpler molecules.

10. Which of the following statements is incorrect?
(a) Maltose gives two molecules of glucose only.
(b) Cellulose and sucrose are polysaccharides.
(c) Polysaccharides are not sweet in taste.
(d) Polysaccharides are also known as non-sugars.
Ans 10. (b) Sucrose is an oligosaccharide and cellulose is a polysaccharide.

Solved Important MCQs of Biomolecules

11. Reducing sugars reduce.
(a) Only Fehling’s solution
(b) Only Tollen’s solution.
(c) Both (a) & (b)
(d) Neither (a) nor (b)
Ans 11. (c) All those carbohydrates which reduce Fehling’s solution and Tollens’ reagent are referred to as reducing sugars.

12. Which among the following is the simplest sugar?
(a) Glucose                             (b) Starch
(c) Cellulose                           (d) None of these
Ans 12. (a) Glucose (C6H12O6) is the simplest molecule which is monosaccharide while others are polysaccharides which on hydrolysis give monosaccharides. Option (a) is correct.

13. Glucose can’t be classified as
(a) Hexose                              (b) Carbohydrate
(c) Aldose                               (d) Oligosaccharide
Ans 13. (d) Glucose is aldohexose. Glucose is a monosaccharide, i.e. it cannot be hydrolysed further to simple sugars. Oligosaccharides on hydrolysis give 2-10 molecules of monosaccharides.

14. Which of the following properties of glucose cannot be explained by its open-chain structure?
(i) Glucose does not form hydrogen sulphite with NaHSO3
(ii) On oxidation with HNO3 glucose gives saccharic acid.
(iii) Glucose is found to exist in two different crystalline forms which are named as α and E.
(a) (ii) only                             (b) (i) and (iii)
(c) (ii) and (iii)                       (d) (i) and (ii)
Ans 14. (b) To explain the properties which cannot be explained by open chain structure of glucose it was proposed that one of the –OH groups may add to the –CHO group and form a cyclic hemiacetal structure.

15. Which of the following gives a positive Fehling solution test?
(a) Protein                               (b) Sucrose
(c) Glucose                             (d) Fats
Ans 15. (c) Glucose contains an aldehyde group. Hence it gives a positive Fehling solution test.

16. Which of the following statements is incorrect regarding glucose?
(a) It is an aldohexose.
(b) It is also known as dextrose
(c) It is a monomer of cellulose.
(d) It is the least abundant organic compound on earth.
Ans 16. (d) It is the most abundant organic compound on earth.

17. Glucose gives silver mirror test with Tollen’s reagent. It shows the presence of
(a) Acidic group                     (b) Alcoholic group
(c) Ketonic group                   (d) Aldehyde group
Ans 17. (d) Tollen’s reagent is reduced by glucose due to aldehydic group and gives grey colour as silver metal.

18. The symbols D and L represent
(a) The optical activity of compounds.
(b) The relative configuration of a particular stereoisomer.
(c) The dextrorotatory nature of molecule.
(d) The levorotatory nature of molecule
Ans 18. (b) The letter ‘D’ or ‘L’ before the name of any compound indicate the relative configuration of a particular stereoisomer.

19. Antibodies are
(a) Carbohydrates                   (b) Proteins
(c) Lipids                                (d) Enzymes
Ans 19. (b) An antibody, also called immunoglobulin, a protective protein produced by the immune system in response to the presence of a foreign substance, called an antigen.

20. The function of enzymes in the living system is to
(a) Transport oxygen
(b) Provide immunity
(c) Catalyze biochemical reactions
(d) Provide energy
Ans 20. (c) Catalyze biochemical reactions

Solved Important MCQs of Biomolecules

21. Vitamin A is called
(a) Ascorbic acid                    (b) Retinol
(c) Calciferol                          (d) Tocopherol
Ans 21. (b) Retinol

22. Which carbohydrate is an essential constituent of plant cells?
(a) Starch                                (b) Cellulose
(c) Sucrose                              (d) Vitamins
Ans 22. (b) Cellulose

23. Vitamin B1 is
(a) Riboflavin                                     (b) Cobalamin
(c) Thiamine                           (d) Pyridoxine
Ans 23. (c) Thiamine

24. Which statement is incorrect about peptide bond?
(a) N bond length in proteins is longer than usual bond length of C – N bond
(b) Spectroscopic analysis shows a planar structure of –CO–NH– group
(c) C – N bond length in proteins is smaller than usual bond length of C – N bond
(d) None of the above
Ans 24. (a) N bond length in proteins is longer than the usual bond length of C – N bond

25. The vitamins absorbed from the intestine along with fats are
(a) A, D                                               (b) A, B
(c) A, C                                               (d) D, B
Ans 25. (a) A, D

26. The functional group which is found in an amino acid is
(a) –COOH                                         (b) –NH2
(c) –CH3                               (d) both (a) and (b)
Ans 26. (d). An amino acid is an organic molecule that is made up of a basic amino group (−NH2), an acidic carboxyl group (−COOH), and an organic R group (or side chain) that is unique to each amino acid.

27. Complete hydrolysis of cellulose gives
(a) L – glucose                                    (b) D-Fructose
(c) D-ribose                                        (d) D-glucose
Ans 27. (d) D-glucose.

28. In both DNA and RNA, heterocyclic base and phosphate ester linkages are at
(a) C5‘ and C2‘ respectively of the sugar molecule
(b) C2‘ and C5‘ respectively of the sugar molecule
(c) C1‘ and C5‘ respectively of the sugar molecule
(d) C5‘ and C1‘ respectively of the sugar molecule
Ans 28.  (c) C1‘ and C5‘ respectively of the sugar molecule

29. The human body does not produce
(a) Enzymes                                        (b) DNA
(c) Vitamins                                       (d) Hormones
Ans 29. (c) Vitamins

30. Cellulose is a straight-chain polysaccharide composed of only
(a) D-glucose units joined by a – glycosidic linkage
(b) D – glucose units joined by b – glycosidic linkage
(c) D – galactose units joined by a – glycosidic linkage
d) D – galactose units joined by b – glycosidic linkage
Ans 30. (a) D-glucose units joined by a – glycosidic linkage

Solved Important MCQs of Biomolecules

31. Which of the following vitamins is water-soluble?
(a) Vitamin E                                      (b) Vitamin K
(c) Vitamin A                                      (d) Vitamin B
Ans 31. (d) Vitamin B

32. Cellulose is insoluble in
(a) Ammoniacal cupric hydroxide solution
(b) Organic solvents
(c) Water
(d) None
Ans 32. (c) Water

33. Which one of the following is the reagent used to identify glucose?
(a) Neutral ferric chloride
(b) Chloroform and alcoholic KOH
(c) Ammoniacal silver nitrate
(d) Sodium ethoxide
Ans 33. (c) Glucose contains an aldehyde group due to which gives a positive test with ammonical silver nitrate.

34. Which of the following structures represents thymine?

Ans 34. (d) is the correct structure

Solved Important MCQs of Biomolecules

35. DNA multiplication is called as
(a) Translation                                   (b) Transduction
(c) Transcription                                (d) Replication
Ans 35. (d) DNA has the property of self – replication. It is therefore a reproducing molecule. This unique property of DNA is at the root of all reproduction. Through its replication, DNA acts as the key to heredity. In the replication of DNA, the two strands of a double helix unwind and separate as a template for the formation of a new complementary strand.

36. Vitamin B2, a water-soluble vitamin is also known as
(a) Ascorbic acid                                 (b) Riboflavin
(c) Thiamine                                       (d) Pyridoxine
Ans 36. (b) Riboflavin

37. Coagulation of protein is known as
(a) Dehydration                                  (b) Decay
(c) Deamination                                  (d) Denaturing
Ans 37. (d) When a protein, in its native form, is subjected to a physical change like change in temperature, or a chemical change like change in pH, the native conformation of the molecule is disrupted and proteins so formed are called denatured proteins. The denaturation may be reversible or irreversible. The coagulation of egg on boiling is an example of irreversible protein denaturation. However, it has been shown now that in some cases, the process is actually reversible. The reverse process is called renaturation.

38. Which of the following is not a characteristic of fibrous proteins?
(a) In the fibrous proteins polypeptide chains are held together by hydrogen and disulphide bonds.
(b) These have fiber-like structures.
(c) These are generally soluble in water.
(d) These have an elongated shape.
Ans 38. (c) These are generally insoluble in water.

39. Which of the following is not a fibrous protein?
(a) Keratin                                          (b) Myosin
(c) Insulin                                           (d) Both (a) and (b)
Ans 39. (c) Insulin is an example of a globular protein.

40. Globular proteins are present in
(a) Blood                                             (b) Eggs
(c) Milk                                              (d) All of these
Ans 40. (d) All these are examples of globular proteins. These are soluble in water.

Solved Important MCQs of Biomolecules

41. The protein that transport oxygen in the bloodstream is
(a) Haemoglobin                                 (b) Insulin
(c) Collagen                                        (d) Albumin
Ans 41. (a) Hemoglobin

42. Two functional groups that are present in all amino acids are the
(a) Hydroxy, amine                            (b) Hydroxy, amide
(c) Carboxyl, amino                           (d) Carboxyl, amide
Ans 42. (c) Amino acids are the compounds having one or more amino groups and one or more carboxyl groups in the same molecule.

43. An acidic amino acid among the following is
(a) Glycine                                          (b) Valine
(c) Proline                                           (d) Leucine
Ans 43. All the given options are an example of neutral amino acids.

44. Amino acids are the building blocks of
(a) Fats                                                (b) Proteins
(c) Vitamins                                       (d) Carbohydrates
Ans 44. (b) D- Amino acid is the building block unit of protein which is formed by polymerization of amino acid through peptide linkage.

45. Which one of the amino acids can be synthesized in the body?
(a) Alanine                                          (b) Lysine
(c) Valine                                           (d) Histidine
Ans 45. (a) Except for alanine, all amino acids are essential amino acids that cannot be synthesized in the body and must be obtained through diet.

46. Amino acids generally exist in the form of Zwitter ions. This means they contain
(a) Basic—NH2 group and acidic —COOH group
(b) Basic—NH3+ group and acidic —COO group
(c) Basic—NH2 and acidic —H+ group
(d) Basic – COO group and acidic –NH3+ group
Ans 46. (d) Zwitter ion contains both +ve and –ve charge. Proton of –COOH group is transferred to the –NH2 group.—NH3+ group is acidic since it can donate a proton and —COO group is basic since it can accept a proton.

47. Which of the following molecules is capable of forming Zwitter ion?
(a) NH2CH2COOH                              (b) CH3CH2NH2
(c) CH3CH2COOH                              (d) All of these
Ans 47. (a) Amino Acids are amphoteric in nature. So for it, a special term is coined called Zwitter ion. They have the following structure in solution

Solved Important MCQs of Biomolecules

48. Invert sugar is
(a) Chemically inactive form of sugar
(b) Equimolecular mixture of glucose and fructose
(c) Mixture of glucose and sucrose
(d) A variety of cane sugar
Ans 48. (b) An equimolecular mixture of glucose and fructose

49. Which one of the following does not exhibit the phenomenon of mutarotation?
(a) (+) – Sucrose                                 (b) (+) – Lactose
(c) (+) – Maltose                                (d) (–) – Fructose
Ans 49. (a) Sucrose does not have free —CHO or CO group, hence it does not undergo mutarotation.

50. The sugar present in fruits is
(a) Fructose                                        (b) Glucose
(c) Sucrose                                          (d) Galactose
Ans 50. (a) Sweet taste of fruits is due to fructose.

51. During the process of digestion, the proteins present in food are hydrolyzed to amino acids. The two enzymes involved in the process are:
a. Invertase and zymase
b. Amylase & maltase
c. Diastase and lipase
d. Pepsin & trypsin
Ans 51. d

52. Deficiency of which vitamin causes beriberi and pain in joints
a. A
b. B
c. C
d. K.
Ans 52. (b)  

53. Vitamin B12 contains
a. Fe
b. Co
c. Zn
d. Ca
Ans 53. (b)

Solved Important MCQs of Biomolecules

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