Quiz: Chapter 6

1 The nature of biological catalyst is

Protein Lipid Carbohydrate Nucleic acid

2 The part of enzyme where reaction takes place is called:

Substrate Coenzyme Active Site None of these

3 How many reactions are catalyzed by a specific enzyme?

Only one Two reactions Many reactions No reaction

4 Lock and key hypothesis was proposed by Fischer in:

1790 1890 1990 1999

5 The amount of energy required to start a reaction is called:

Kinetic energy Potential energy Activation energy None of these

6 Co-enzymes are derived from:

Vitamins Minerals Both a and b None of these

7 Cofactor may be:

Organic Inorganic Metallic ions All of these

8 Beriberi is caused due to the lack of:

Vitamin A Vitamin B Vitamin C Vitamin K

9 Which one of the following is a co-enzyme?

NAD FAD NADP All of these

10 Non-protein organic part of enzyme is called:

Co-enzyme Holoenzyme Prosthetic group All of these

11 Apoenzyme is:

Proteins Carbohydrate Vitamin Amino acid

12 A substance that reversibly changes enzyme activity by binding at a site other than active site is called:

Competitive inhibitor Catalytic inhibitor Allosteric inhibitor None of these

13 Lock and key theory was suggested by:

Emil Fischer Koshland Anselme Payen Eduard Buchner

14 The optimum pH for urease is:

15-16 2 4.5 7

15 All enzymes are proteins except:

Ribozyme Lysozyme Both of these None of these

16 Lock and key model was rejected by:

E. Fischer D. Koshland Fedrick R. Mortin

17 The statement "enzyme structure must slightly change" describes:

Key-Lock Model Hand-Gloves Model Induced-Fit Model Both b and c

18 For the reaction 2H₂O₂ → 2H₂O + O₂, activation energy with enzyme is:

86 kJ/mol 8.6 kJ/mol None of these 1 kJ/mol

19 Vitamin B deficiency causes:

No effect Metabolism issues Beri-beri Both b and c

20 Peptidase and esterase belong to:

Hydrolase Isomerase Transferase Both a and b

21 The optimum temperature for snow flea enzymes is:

37°C 0°C 10°C -10°C

22 At 0°C, enzyme activity:

Stops Minimizes Unaffected Denatures

23 Physiological pH for most enzymes is:

7-8 1-3 5-7 1-14

24 Non-competitive inhibitors include:

Cyanides Heavy-metal ions Insecticides All of these

25 Non-competitive inhibitors bind to:

Active site Receptor site Allosteric site Both b and c

26 Optimum pH for pepsin is:

6.8 5.5 4.5 2

27 Arctic snow flea enzymes function at:

60°C 30°C 40°C -10°C

28 Which does NOT affect enzyme action?

Enzyme concentration Light intensity Substrate concentration Temperature

29 Enzyme names typically end with:

-ice -ace -ise -ase

30 Decarboxylase and deaminase are examples of:

Hydrolase Lyases Ligases Isomerases

31 At high temperatures, enzymes lose activity due to:

Active site loss Denaturation Prosthetic group loss Substrate saturation

32 Study of enzymes is called:

Mycology Phycology Enzymology Ornithology

33 Examples of oxidoreductases include:

Oxidase Peroxidase Oxygenase All of these

34 Ligases catalyze:

Isomerization Hydrolysis Bond formation Group removal

35 pH for urease and catalase is:

8 6.1-6.8 7 4-5

36 Example of competitive inhibitor:

Cyanide Heavy metals Insecticides Sulphonamide

37 Co-enzymes attach via:

Covalent bonds Ionic bonds Coordinate bonds Weak bonds

38 Enzyme characteristics include:

Protein nature (except ribozymes) No equilibrium alteration Lower activation energy All of these

39 As enzyme concentration increases, reaction rate:

Decreases Increases Unaffected None

40 Enzyme-substrate complexes may form via:

Ionic bonds Hydrogen bonds Hydrophobic interactions Covalent bonds

41 Functions of enzymes include all of the following except:

Lessening the time required for a reaction to take place Shifting substrates into more favorable positions in the active site Decreasing the activation energy of a reaction Shifting the equilibrium of a reaction

42 Upon increasing the temperature, the shape of enzymes active site:

Remains same Changes Adopts a geometric conformation Denatures

43 The optimum pH for enzyme arginase is which of the following?

9 9.3 9.7 10

44 The optimum pH for the functioning of the enzyme pepsin is?

2 3 4 5

45 If we add more substrate to an already occurring enzymatic reaction and it has no effect on the rate reaction, the process is called?

Denaturing Saturation Composition Inhibition

46 pH of salivary amylase is:

6.8 7.60 2.00 5.50

47 It works in acidic medium:

Arginase Pancreatic lipase Catalase Enterokinase

48 Extreme change in pH results in which of the following?

Change in ionization of amino acids at the active site of the enzyme Change in the ionization of the substrate Increase in the reaction rate Denaturation of the enzyme

49 What is meant by optimum temperature of an enzyme?

The temperature at which the primary structure of an enzyme remains intact The temperature at which an enzyme makes the maximum amount of product The temperature at which an enzyme may be more affected by an inhibitor The temperature at which an enzyme makes the least amount of product

50 Rate of reaction is doubled for rise of every ______.

20 °C 10 °C 30 °C 20 °C

51 Which of the following strategies of enzymatic inhibition is used by noncompetitive inhibitors?

Bind to substrate so that it cannot bind to the active site Target the enzyme for destruction using a protease Bind to the active site and prevent substrate from binding Bind to an allosteric site to cause a conformational shift in the enzyme

52 If more substrate is added to an already occurring enzymatic reaction, more enzyme activity is seen because?

There is probably more substrate present than there is enzyme There is probably more product present than either substrate or enzyme The enzyme substrate complex is probably failing to form during the reaction There is probably more enzyme available than there is substrate

53 The optimum pH for the functioning of pancreatic lipase is?

9 8 7 6

54 A researcher has designed a new type of inhibitor that binds at the active site of an enzyme. What type of inhibition does this molecule display?

Uncompetitive inhibition Competitive inhibition Noncompetitive inhibition All of these

55 Enzymes work by which of the following?

Increasing the activation energy Reducing the activation energy Making exergonic reactions undergone Making endergonic reactions exergonic

56 How many models are present for enzyme-substrate complex or reaction?

3 2 4 5

57 Which statement is incorrect about Lock and Key Model?

Specific enzyme can transform only a specific substrate Active site of an enzyme is a non-flexible structure Active site does not change before during or even after the reaction It explains the mechanism of every chemical reaction

58 Which types of bond are never formed when a substrate fits into the active site of an enzyme?

Hydrogen bonds Ionic interactions Hydrophobic interactions Covalent linkages

59 Koshland in 1959 proposed the modified form of which of the following?

Unit membrane model Fluid mosaic model Reflective index model Induced fit model

60 Induced fit model was introduced by Koshland in which of the following year?

1960 1961 1950 1966

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Chapter 6: Enzymes