Tuesday, November 13, 2012

Enzymes



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


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


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



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


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 ++



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


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



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
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
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
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
54. Enzymes are usually specific in action
55. In Absolute specificity the enzyme acts at different rates on one type of bond in
Compounds chemically related
56. Enzymes may be considered to lower energy barriers for chemical reactions
57. Increase in the substrate concentration will lead to decrease in enzyme activity
58. Increase in enzyme concentration increase the rate of reaction
59. Some enzymes containing SH groups requires Minerals to be activated
60. In Competitive inhibition Vmax of the enzyme is not decreased
61. Inducers are substances which inhibit gene expression
62. Isoenzyme is oligomeric enzyme

Answers
1. A
2. C
3. A
4. C
5. C
6. D
7. A
8. D
9. C
10. A
11. B
12. B
13. C
14. A
15. C
16. A
17. D
18. D
19. C
20. B
21. D
22. A
23. B
24. C
25. B
26. D
27. C
28. D
29. D
30. A
31. B
32. A
33. B
34. D
35. A
36. A
37. A
38. B
39. C
40. D
41. D
42. A
43. D
44. B
45. A
46. A
47. B
48. C
49. D
50. B
51. C
52. D
53. A
54. A
55. B
56. A
57. B
58. A
59. B
60. A
61. B
62. A







------------------------------------------ Best Wishes: Dr.Ehab Aboueladab, Tel:01007834123 Email:ehab10f@gmail.com,ehababoueladab@yahoo.com ------------------------------------------
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