Chapter-14

Biomolecules
1. Which sugar molecule is present in DNA molecule?
Ans: 2-Deoxyribose.
2. Which sugar molecule is present in RNA molecule?
Ans: Ribose.
3. Name the enzyme which converts sucrose into glucose and fructose.
Ans: Invertase.
4. What is the chemical name of vitamin D and which disease is caused by its deficiency?
Ans: Ergocalciferol, Disease is Rickets.
5. What is the chemical name of vitamin A and which disease is caused by its deficiency?
Ans: Retinol, disease is Xerophthalmia.
6. What is the chemical name of vitamin C and which disease is caused by its deficiency?
Ans: Ascorbic acid, disease is Scurvy.
7. Name the enzyme which converts glucose into alcohol?
Ans: Zymase.
8. How many naturally occurring amino acids in proteins exist? How many of these are synthesized by the body?
Ans: There are 20 amino acids in proteins. The human body can synthesise10 out of 20 amino acids found in proteins.
9. Write the formula of tripeptide alanylglycyl phenylanine.
Ans:

10. Give the structural formula of Glycine and Alanine.

Ans:

11. What are biomolecules?

Ans: These are complex lifeless complex organic compounds which can combine in specific manner to produce life.
12. What does sucrose give on hydrolysis?
Ans: Sucrose on hydrolysis gives a mixture of glucose and fructose.
13. Define genetic code?
Ans: The relation between nucleotide triplets and the amino acids is called genetic code.
14. Name the enzyme whose deficiency cause albinism and phenylketonurea.
Ans: Albinism- Tyrosinase, Phenylketonurea- phenylanine hydroxylase.
15. What is the action of nitrous acid on glycine?
Ans: Nitrous acid reacts with glycine to form glycolic acid.
16. Describe role of vitamin A in our body?
Ans: It helps in maintaining proper vision and healthy teeth structure.
17. Describe role of vitamin D in our body?
Ans: It helps in utilization of calcium and phosphorus.
18. Write the role of vitamin B2.
Ans: It helps in oxidation and utilization of oxygen.
19. What is denaturation of proteins?
Ans: A process that changes the physical and biological properties of proteins without affecting the chemical composition
of protein is called denaturation of protein.
20. What is muta-rotation?
Ans: The spontaneous change in specific rotation of an optically active compound with time to an equilibrium value is
called mutarotation.
21. Write the chemical name of vitamin C?
Ans: Ascorbic acid.
22. Name the enzyme which converts starch into maltose.
Ans: Diastase
23. Name the enzyme which converts glucose and fructose into ethyl alcohol.
Ans: Zymase.
24. Name the enzyme which converts maltose into glucose.
Ans: Maltase
25. What are nucleotides?
Ans: When the phosphate group is attached to the nucleoside, the compound formed is called nucleotide.
26. What is denaturated protein? Give one example.
Ans: A protein which is formed by change in physical and biological properties of proteins without affecting the chemical
composition of protein is called denaturated protein. For example: curd.
27. What is peptide bond? Give one example.
Ans: The –CO-NH- linkage formed by elimination of water molecule when the carboxyl group of one amino acid and
amino group of another amino acid gets condensed is called peptide bond.
28. What are polysachharides?
Ans: The polysachharides are the polymeric carbohydrates which can be hydrolysed to give a large number of
monosachharide units.
29. What are disachharides?
Ans: Disaccharides are the carbohydrates which give two monosachharide molecules on hydrolysis.
30. What are monosachharides?
Ans; Monosaccharide are the simplest carbohydrates which cannot be hydrolyzed into simpler compounds.
31. Write two sources of vitamin-A.
Ans: Cod liver oil and butter.
32. Write two sources of vitamin-C.
Ans: Orange, lemon, amla, green vegetables.
33. Write two sources of vitamin-D.
Ans: Milk, egg yolk.
34. Which enzyme is used for hydrolysis of sucrose?
Ans: Invertase.
35. Name two important polysachharides of D-glucose.
Ans: Amylose and Amylopectin.
36. Which enzyme is used for hydrolysis of maltose?
Ans: Diastase.
37. Name one fibrous and one globular protein.
Ans: fibrous- keratin, collagen; globular- insulin, albumin.
38. Why are carbohydrates generally optically active?
Ans: Because they have one or more chiral carbon atom.
39. Which enzyme is used for hydrolysis of cellulose?
Ans: Cellulase.
40. Name one reducing and one non-reducing disaccharide.
Ans: maltose is reducing and sucrose is non-reducing sugar.
41. Differentiate between reducing and non-reducing sugars.
Ans: The sugars which reduce tollen’s reagent and Fehling’s solution are called reducing sugars while which do not reduce
are called non-reducing sugars.
42. Draw the pyranose structure of D-fructose.
Ans:

43. Draw the Haworth ring structure of D-glucose.

Ans:
44. How are nucleosides, nucleotides and nucleic acids related?
Ans: Nucleosides joined to phosphate group from nucleotides. The polymers of nucleotides are nucleic acids.
45. What type of bonds hold DNA double helix together?
Ans: Hydrogen bonds.
46. What is prosthetic group?
Ans: A prosthetic group is a non-protein portion obtained by hydrolysis of conjugated proteins.
47. Which enzyme is present in saliva? What is its function?
Ans: Amylase. It hydrolyses starch into maltose.
48. What is the function of enzyme present in liver?
Ans: The enzyme present in liver converts galactose into glucose.
49. Write the sequences of bases on m-RNA molecule synthesized on the following strand of DNA AGCGATTAC.
Ans: sequence of m-RNA will be UCGCUAAUG.
50. Define mutation.
Ans: It is the change in a DNA molecule that could lead to the synthesis of proteins with different amino acid sequence.
51. Which -amino acid can cross link peptide chains?
Ans: Cystine can cross link peptide chains through disulphide bonds.
52. Why is glucose given to patients under exhaustion?
Ans: It is an instant source of energy and given to patients under exhaustion.
53. What is the difference between DNA and RNA on the basis of bases they contain?
Ans: DNA contains thymine and RNA contains uracil.
54. Fresh tomatoes are better source of vitamin C than those present in tomatoes which have been stored for some
time.
Ans: On exposure to air, vitamin C present in stored tomatoes is destroyed due to aerial oxidation.
55. What are the hypervitaminoses and avitaminoses?
Ans: Excess of vitamins A and D causes hypervitminoses. Multiple deficiencies caused by lack of more than one vitamin is
called avitaminoses.
56. What is isoelectric point?
Ans: The pH at which no net migration of amino acid takes place under the influence of an applied electric field is called
isoelctric point.
57. What is meant by reducing sugar?
Ans: The carbohydrates which reduce tollen’s reagent or Fehling solution are called reducing sugars. They have free
aldehydic group.
58. Why is cellulose not distinguishable in human being?
Ans: Because human stomach does not have enzyme capable of breaking cellulose molecules.
59. Why carbohydrates act as biofuel?
Ans: Because their slow oxidations by a series of steps provide energy for living organisms.
60. Name the enzyme which converts lactose into glucose.
Ans: Lactase
61. Name the enzyme which converts proteins into amino acids.
Ans: Pepsin, Trypsin.
62. Name the enzyme which converts DNA, RNA into nucleotides.
Ans: Nucleases.
63. What is meant by inversion of sugar?
Ans: The change of specific rotation of sugar form dextro rotatory to leavo rotatory is called inversion of sugar.
64. What is the name given to the linkage which holds together monosaccharide units in polysaccharides?
Ans: Glycosidic linkage.
65. State the use of interferon and insulin in medicines?
Ans: Interferon is an antiviral agent. Insulin is used in treatment of diabetes.
66. What is coenzyme? Give one example.
Ans: The non-protein component of an enzyme which is loosely held by the enzyme and is essential for its biological
activity is called coenzyme. These are derived from vitamins such as thiamine.
67. Give one example of essential and non essential amino acids?
Ans: Essential amino acid: Valine; non essential amino acid: glycine.
68. Define replication.
Ans : It is the property of a molecule to synthesize another molecule.