The document is about enzymes and contains 50 multiple choice questions testing knowledge about enzymes. Some key points covered are: 1. Enzymes are organic catalysts that are protein in nature and present inside living cells. 2. Enzymes act specifically on substrates at active sites and with absolute or relative specificity. 3. Enzyme activity can be affected by factors like temperature, pH, inhibitors, and activators like coenzymes or metal ions. 4. There are different classes of enzymes based on their reaction type including oxidases, hydrolases, ligases, etc. The questions cover topics like enzyme kinetics, specificity, classes, cofactors, effects of conditions,

1. Enzyme
1. Group of organic catalysts, protein in nature, present inside the living cells
a- Enzymes
b- Catalysts
c- Hormones
d- None of the above
2. All of the following is true regarding enzymes except …..
a- Heat labile
b- Colloidal
c- Dialyzable
d- High molecular weight
3. Organic substance on which the enzyme acts …….
a- Substrate
b- Co-Enzyme
c- Product
d- None of the above
4. All of the following can be considered as a co Enzyme for transfer of H except
a- Biotin
b- ATP
c- FAD
d- Folic acid
5. One of the following can be considered as a co Enzyme for transfer of groups other than H except
a- Biotin
b- ATP
c- FAD
d- Folic acid
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

2. Enzyme
6. One of the following is considered a feature of Enzymes except ……
a- Globular Proteins
b- Undergo Denaturation
c- Simple Proteins
d- Non-Specific
7. Enzyme acts on a special type of bond at specific site and attached to specific groups ……
a- Group Specificity
b- Absolute Specificity
c- Relative Specificity
d- Optical Specificity
8. D-amino acid Oxidase represents ……
a- Group Specificity
b- Absolute Specificity
c- Relative Specificity
d- Optical Specificity
9. Pancreatic Lipase represents …….
a- Group Specificity
b- Absolute Specificity
c- Relative Specificity
d- Optical Specificity
10. Special sequence of amino acids in the protein molecule of the enzyme to which the substrate is
attached…….
a- Catalytic Site
b- Active site
c- Allosteric Site
d- None of the above
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

3. Enzyme
11. All sequences of amino acids which affect the activity of the enzyme ……
a- Catalytic Site
b- Active site
c- Allosteric Site
d- All of the above
12. Substrate induces a conformational change in the catalytic site …….
a- Lock and key model
b- Flexible model of catalytic site
c- Rigid model of catalytic site
d- None of the above
13. Concentration of the product increases directly by time …….
a- Maximum Velocity
b- End velocity
c- Initial Velocity
d- None of the above
14. Increase in substrate concentration leads to ……..
a- Increase of velocity
b- Increase in enzyme activity
c- Increase of V max
d- All of the above
15. Substrate concentration which produces half maximal velocity (½Vmax.) ……….
a- Full Concentration
b- Null Concentration
c- Michael’s Concentration
d- All of the above
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

4. Enzyme
16. Increase in enzyme concentration ……. the rate of reaction
a- Increase
b- Decrease
c- No effect
d- Permissive effect
17. Complete irreversible loss of enzyme activity occurs at ……
a- 37 degree C
b- 45 degree C
c- 0 degree C
d- 60-65 degree C
18. Temperature at which the enzymatic reaction velocity is maximal ……
a- Optimum Temperature
b- 37 degree C
c- 65 degree C
d- A and b together
e- None of the above
19. Optimum PH for Trypsin is ……
a- 6.8
b- 8.4
c- 8
d- 2
20. Optimum PH for Alkaline Phosphatase
a- 6.8
b- 8.4
c- 8
d- 2
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

5. Enzyme
21. All of the following inhibits enzymatic activity except
a- Physical Agents
b- Heating
c- Shaking
d- Red and Blue lights
22. Pepsin is activated through ……..
a- Removal of inhibitory peptide
b- Reducing agent
c- Minerals
d- Allosteric activators
23. Glyceraldehyde 3-P dehydrogenase is activated through …..
a- Removal of inhibitory peptide
b- Reducing agent
c- Minerals
d- Allosteric activators
24. Metaloenzymes is activated through …..
a- Removal of inhibitory peptide
b- Reducing agent
c- Minerals
d- Allosteric activators
25. Tyrosinase requires ……
a- ZN ++
b- CU ++
c- CL –
d- MG ++
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

6. Enzyme
26. Phosphofructokinase enzyme is activated through …..
a- Removal of inhibitory peptide
b- Reducing agent
c- Minerals
d- Allosteric activators
27. Activation by Phosphorylation excludes one of the following …….
a- Hormone sensitive lipase
b- Glycogen Phosphyrlase
c- Glycogen Synthetase
d- None of the above
28. Competitive inhibition includes all of the following except
a- Chemical structure of the inhibitor closely resembles that of the substrate.
b- Combines Reversibly with the enzyme
c- When both the substrate and the inhibitor are present they compete for the same binding site.
d- V max is decreased
e- Is removed by increases the concentration of inhibitor
29. Reversible noncompetitive Inhibition includes all of the following except
a- I combine with the enzyme away from the catalytic site.
b- The I is not similar to the substrate in structure.
c- The I can combine with the free enzyme or with the enzyme substrate
d- increase the Km
30. Phosphoglyceraldehyde dehydrogenase Resembles …….
a- Reversible Non Competitive Inhibition
b- Irreversible noncompetitive Inhibition
c- Allosteric inhibition
d- Competitive inhibition
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

7. Enzyme
31. Increased product concentration …… the enzyme activity
a- Increases
b- Decreases
c- No effect
d- Permissive effect
32. Substances which stimulate gene expression into protein …….
a- Inducer
b- Suppressor
c- Repressors
d- Co-Enzymes
33. Concerning Isoenzymes …….
a- Have quaternary structure and the individual subunits in each isoenzyme are different from the others
b- They act on the different substrate and will give the same product
c- They have different affinity to the substrate.
d- They are present in different tissues.
34. HMMM is present in ……..
a- Heart
b- Kidney
c- Liver
d- Muscles
35. HHMM is present in
a- Kidney
b- Muscles
c- Heart
d- None of the above
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

8. Enzyme
36. Non Functional plasma enzymes include all of the following except …..
a- Transaminases ( AST & ALT )
b- Alkaline Phosphatase
c- Lipoprotein lipase
d- None of the above
37. Increased in bone metastasis ………
a- Alkaline phosphatase
b- Creatine kinase
c- LDH
d- None of the above
38. Increased in Prostatic Carcinoma ………
a- Alkaline phosphatase
b- Creatine kinase
c- LDH
d- None of the above
39. Decreased in Galactosemia ………
a- Streptokinase
b- Digestive enzymes
c- Galactosyl transferase
d- α-chymotrypsin
40. Treatment of intraocular hemorrhage is done by
a- Streptokinase
b- Digestive enzymes
c- LDH
d- α-chymotrypsin
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

9. Enzyme
41. The oxidation process occurs by ………
a- Addition of oxygen.
b- Removal of hydrogen.
c- Loss of electron
d- All of the above
42. Redoxes that use oxygen as a hydrogen receptor are called ……..
a- Oxidases
b- Hyper peroxidases
c- Dehydrogenases
d- Oxygenases
43. Catalase is specifically abundant in all of the following except ……..
a- Liver
b- Kidney
c- Erythrocytes
d- Milk and leucocytes
44. Enzymes utilizing H2O2 as substrate ……….
a- Oxidases
b- Hyper peroxidases
c- Dehydrogenases
d- Oxygenases
45. LDH depends on ………. In dehydrogenation
a- Nicotinamide
b- FAD
c- C.AMP
d- None of the above
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

10. Enzyme
46. Enzymes which catalyze transfer of functional groups (G) other than hydrogen between a pair of
substrates …….
a- Transferase
b- Oxygenases
c- Dehydrogenases
d- Hydrolases
47. All of the following are included in Transferase class of enzymes except …….
a- Transaminase
b- Hydrolase
c- Transglycosayl
d- None of the above
48. Split terminal peptide linkage splitting one amino acid at a time is ……..
a- Estrases
b- Endoeptidases
c- Exopeptidases
d- Glycosidases
49. Fumerase is an example of …….
a- Transferase
b- Hydrolase
c- Oxidase
d- Lyases
50. Lipase is an example of …….
a- Transferase
b- Estrases
c- Oxidases
d- Lyases
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

11. Enzyme
51. Enzymes link two molecules using energy from ATP ……
a- Lyases
b- Hydrolase
c- Ligase
d- Redox
52. Carboxylase is an example of …….
a- Transferase
b- Estrases
c- Oxidases
d- Ligases
Choose (A) for true and (B) For false of the following
53. Pepsin acts on peptide bonds between amino groups of aromatic amino acid and carboxylic group of
another amino acid (A)
54. Enzymes are usually specific in action (A)
55. In Absolute specificity the enzyme acts at different rates on one type of bond in
Compounds chemically related (B)
56. Enzymes may be considered to lower energy barriers for chemical reactions (A)
57. Increase in the substrate concentration will lead to decrease in enzyme activity
58. Increase in enzyme concentration increase the rate of reaction (A)
59. Some enzymes containing SH groups requires Minerals to be activated (B)
60. In Competitive inhibition Vmax of the enzyme is not decreased (A)
61. Inducers are substances which inhibit gene expression (B)
62. Isoenzyme is oligomeric enzyme (A)
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

12. Enzyme
1: What is a cofactor?
(A) Inorganic ions
(B) Organic molecules
(C) Both a and b
(D) None of the above
2: Mg+2 is an inorganic activator for the enzyme
(A) Phosophatase
(B) Carbonic anhydrase
(C) Enterokinase
(D) Amylase
3: Zn+2 is an inorganic activator for enzyme.
(A) Carbonic anhydrase
(B) Phosophatase
(C) Chymotrypsin
(D) Maltase
4: Which antibiotic blocks the active site of an enzyme that many bacteria used to make cell-
walls?
(A) Amphotericin
(B) Gentamicin
(C) Penicillin
(D) Cephalosporin
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

13. Enzyme
5: DDT and Parathion are inhibitors of key enzymes in
(A) Nervous system
(B) Respiratory system
(C) Digestive system
(D) Circulatory system
6: At high temperature the rate of enzyme action decreases because the increased heat
(A) Changes the pH of the system
(B) Alters the active site of the enzyme
(C) Neutralize acids and bases in the system
(D) Increases the concentration of enzymes
7: Which of the following enzymes would digest a fat?
(A) sucrase
(B) protease
(C) Ligase
(D) lipase
8: In the Lock and Key model of enzyme action, the part of the enzyme that recognizes the
substrate is known as the
(A) Enzyme-substrate complex
(B) Product
(C) Enzyme-product complex
(D) Active site
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com

14. Enzyme
9: Which model of enzyme action is represented in this diagram.
(A) Fluid mosaic model
(B) Induce fit model
(C) Lock and key model
(D) Reflective index model
10: A certain enzyme will hydrolyze egg white but not starch. Which statement best explains
this observation?
(A) Starch molecules are too large to be hydrolyzed
(B) Enzyme molecules are specific in their actions
(C) Egg white acts as a coenzyme for hydrolysis
(D) Starch is composed of amino acids.
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Dr. Ehab Aboueladab, Associate Prof.Dr. Of Biochemistry and Nutrition, email:ehab10f@gmail.com