Biology MCQs with Answer (part 3) by General knowledge Solutions

Biology MCQs with Answer (part 3)   by General knowledge Solutions

                                                                                 

1. Cobamides contain a vitamin which is

(A) Folic acid

(B) Ascorbic acid

(C) Pantothenic acid

(D) Vitamin B12

2. A coenzyme required in carboxylation reactions is

(A) Lipoic acid

(B) Coenzyme A

(C) Biotin

(D) All of these

 3. Which of the following coenzyme takes part in tissue respiration?

 (A) Coenzyme Q

 (B) Coenzyme A

 (C) NADP

(D) Cobamide

4. The enzyme hexokinase is a

(A) Hydrolase

(B) Oxidoreductase

(C) Transferase

(D) Ligase

5. Which of the following is a proteolytic enzyme?

(A) Pepsin

(B) Trypsin

(C) Chymotrypsin

(D) All of these

6. Enzymes which catalyse binding of two substrates by covalent bonds are known as

(A) Lyases

(B) Hydrolases

(C) Ligases

 (D) Oxidoreductases

7. The induced fit model of enzyme action was proposed by

(A) Fischer

(B) Koshland

(C) Mitchell

(D) Markert

8. Allosteric inhibition is also known as

(A) Competitive inhibition

(B) Non-competitive inhibition

(C) Feedback inhibition

(D) None of these

9. An allosteric enzyme is generally inhibited by

 (A) Initial substrate of the pathway

(B) Substrate analogues

 (C) Product of the reaction catalysed by allosteric enzyme

(D) Product of the pathway

 10. When the velocity of an enzymatic reaction equals Vmax, substrate concentration is

 (A) Half of Km

 (B) Equal to Km

 (C) Twice the Km

 (D) Far above the Km

11. In Lineweaver-Burk plot, the y-intercept represents

(A) Vmax

(B) Km

(C) Km

(D) 1/Km

12. In competitive inhibition, the inhibitor

(A) Competes with the enzyme

(B) Irreversibly binds with the enzyme

(C) Binds with the substrate

(D) Competes with the substrate

13. Competitive inhibitors

(A) Decrease the Km

(B) Decrease the Vmax

(C) Increase the Km

(D) Increase the Vmax

14. Competitive inhibition can be relieved by raising the

(A) Enzyme concentration

(B) Substrate concentration

(C) Inhibitor concentration

(D) None of these

15. Physostigmine is a competitive inhibitor of

(A) Xanthine oxidase

(B) Cholinesterase

(C) Carbonic anhydrase

(D) Monoamine oxidase

 16. Carbonic anhydrase is competitively inhibited by

(A) Allopurinol

 (B) Acetazolamide

(C) Aminopterin

(D) Neostigmine

 17. Serum lactate dehydrogenase rises in

(A) Viral hepatitis

(B) Myocardial infarction

(C) Carcinomatosis

(D) All of these

 18. Which of the following serum enzyme rises in myocardial infarction:

 (A) Creatine kinase

(B) GOT

(C) LDH

(D) All of these

19. From the following myocardial infarction, the earliest serum enzyme to rise is

(A) Creatine Kinase

(B) GOT

(C) GPT

(D) LDH

20. Proenzymes:

(A) Chymotrysinogen

(B) Pepsinogen

(C) Both (A) and (B)

(D) None of these

21. Alkaline phosphatase is present in

(A) Liver

(B) Bones

(C) Placenta

(D) All of these

22. Which of the following isoenzyme of lactate dehydrogenase is raised in serum in myocardial infarction:

 (A) LD1

(B) LD2

(C) LD1 and LD2

(D) LD5

23. Enzymes which are always present in an organism are known as

(A) Inducible enzymes

(B) Constitutive enzymes

(C) Functional enzymes

(D) Apoenzymes

24. Inactive precursors of enzymes are known as

(A) Apoenzymes

(B) Coenzymes

(C) Proenzymes

(D) Holoenzymes

25. Whcih of the following is a proenzyme?

(A) Carboxypeptidase

(B) Aminopeptidase

(C) Chymotrypsin

(D) Pepsinogen

26. Allosteric enzymes regulate the formation of products by

(A) Feedback inhibition

(B) Non-competitive inhibition

(C) Competitive inhibition

(D) Repression-derepression

27. Regulation of some enzymes by covalent modification involves addition or removal of

(A) Acetate

(B) Sulphate

(C) Phosphate

(D) Coenzyme

 28. Covalent modification of an enzyme generally requires a

 (A) Hormone

(B) cAMP

(C) Protein kinase

(D) All of these

29. An inorganic ion required for the activity of an enzyme is known as

(A) Activator

(B) Cofactor

(C) Coenzyme

(D) None of these

30. The first enzyme found to have isoenzymes was

(A) Alkaline Phosphatase

(B) Lactate dehydrogenase

(C) Acid Phosphatase

(D) Creatine kinase

 31. Lactate dehydrogenase is located in

(A) Lysosomes

(B) Mitochondria

(C) Cytosol

(D) Microsomes

 32. Lactate dehydrogenase is a

(A) Monomer

(B) Dimer

(C) Tetramer

 (D) Hexamer

 33. Ceruloplasmin is absent in

(A) Cirrhosis of liver

(B) Wilson’s disease

 (C) Menke’s disease

 (D) Copper deficiency

 34 Ceruloplasmin oxidizes

 (A) Copper

(B) Iron

(C) Both (A) and (B)

(D) None of these

 35. Creatine kinase is present in all of the following except

(A) Liver

(B) Myocardium

(C) Muscles

(D) Brain

36. Alkaline phosphatase is present in

(A) Liver

(B) Bones

(C) Intestinal mucosa

(D) All of these

 37. All of the following are zinc-containing enzymes except

(A) Acid Phosphatase

(B) Alkaline Phosphatase

(C) Carbonic anhydrase

(D) RNA polymerase

38. All of the following are iron-containing enzymes except

(A) Carbonic anhydrase

(B) Catalase

(C) Peroxidase

(D) Cytochrome oxidase

39. Biotin is a coenzyme for

(A) Pyruvate dehydrogenase

(B) Pyruvate carboxylase

(C) PEP carboxykinase

(D) Glutamate pyruvate transminase

40. Enzymes accelerate the rate of reactions by

(A) Increasing the equilibrium constant of reactions

(B) Increasing the energy of activation

(C) Decreasing the energy of activation

(D) Decreasing the free energy change of the reaction

41. Kinetics of an allosteric enzyme are explained by

(A) Michaelis-Menten equation

 (B) Lineweaver-Burk plot

 (C) Hill plot

 (D) All of these

42. Covalent modification of an enzyme usually involves phosphorylation / dephosphorylation of

 (A) Serine residue

 (B) Proline residue

 (C) Hydroxylysine residue

 (D) Hydroxyproline residue

43. Vmax of an enzyme may be affected by

 (A) pH

 (B) Temperature

 (C) Non-competitive inhibitors

 (D) All of these

 44. In enzyme assays, all the following are kept constant except

 (A) Substrate concentration

(B) Enzyme concentration

(C) pH

(D) Temperature

45. If the substrate concentration is much below the km of the enzyme, the velocity of the reaction is

(A) Directly proportional to substrate concentration

(B) Not affected by enzyme concentration

(C) Nearly equal to Vmax

(D) Inversely proportional to substrate concentration

Answer

1. D 2. C 3. A 4. C 5. D 6. C 7. B 8. C 9. D 10. D 11. B 12. D 13. C 14. B 15. B 16. B 17. D 18. D 19. A 20. B 21. D 22. C 23. B 24. C 25. D 26. A 27. C 28. D 29. B 30. B 31. C 32. C 33. B 34. B 35. A 36. D 37. A 38. A 39. B 40. C 41. C 42. A 43. D 44. B 45. A