Chemistry chapter 19 Entry Test MCQs
51. An enzyme that joins the ends of two strands of nucleic acid is:
a. Synthetise
b. Polymerase
c. Helicase
d. Ligase
52. The coenzyme is:
a. often a vitamin
b. Often a metal
c. always an inorganic
d. always a protein
53. The general mechanism is that an enzyme acts by:
a. Increasing activation energy
b. Reducing the activation energy
c. Increasing the pH value
d. Decreasing pH value
54. Diastase takes part in digestion of which one:
a. Amino acids
b. Protein
c. Fat
d. Starch
55. Enzyme catalysing rearrangement of atomic grouping without altering molecular weight or number of atom is:
a. Oxidoreductase
b. Ligase
c. Hydrolase
d. Isomerase
56. In the human body optimum temperature for enzymatic activities is:
a. 20°C
b. 37°C
c. 15°C
d. 25°C
57. Of the following statements about enzymes which one is not true
a. Enzymes catalyse chemical reactions by lowering the activation energy
b. Enzymes lack in nucleophilic groups
c. Pepsin is a proteolytic enzyme
d. Enzymes are highly specific both in binding chiral substrates and in catalyzing their reactions
58. Enzymes in the living systems
a. Provide immunity
b. Provide energy
c. Transport oxygen
d. Catalyse biological processes
59. Enzymes
a. Have optimum activity at body temperature
b. Accelerate biochemical reactions
c. Have all these properties
d. Consist of amino acids
60. Enzymes belong to which class of compounds
a. Heterocyclic compounds
b. Polysaccharides
c. Hydrocarbons
d. Polypeptides
61. A biological catalyst is essentially
a. A nitrogen molecule
b. A carbohydrates
c. Fats
d. An amino acid
Nucleic Acid
61. A nucleotide consists of
a. Sugar and phosphate
b. Base and sugar
c. Base, sugar and phosphate
d. Base and phosphate
63. The base adenine occurs in
a. DNA and RNA both
b. DNA only
c. Protein
d. RNA only
64. In DNA, the complementary bases are
a. Adenine and thymine; guanine and cytosine
b. Uracil and adenine; cytosine and guanine
c. Adenine and guanine; thymine and cytosine
d. Adenine and thymine; guanine and uracil
65. Nucleic acid is a polymer of
a. Nucleotides
b. Nucleosides
c. Glucose
d. Αn α-amino acid
66. The number of nitrogen atoms in purines are:
a. 4
b. 2
c. 5
d. 3