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Enzymes MCQ Questions & Answers

Enzymes MCQs : This section focuses on the "Enzymes". These Multiple Choice Questions (MCQs) should be practiced to improve the Enzymes skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

What is the name of the substance present in leech that acts as anti blood coagulant

A. Lysozyme
B. Peptin
C. Hirudin
D. Renin

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Question 2

The proteolysis rate enhancement by chymotrypsin (~1010 folds) corresponds to a reduction in activation energy of about

A. 40 kJ/mol
B. 49 kJ/mol
C. 58 kJ/mol
D. 88 kJ/mol

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Question 3

In the enzyme-catalyzed reaction shown below, what will be the effect on substances A, B, C, and D of inactivating the enzyme labeled E2? A ---(E1)---> B ---(E2)---> C ---(E3)--->

A. A, B, C, and D will all still be produced
B. A, B, and C will still be produced, but not D
C. A and B will still be produced, but not C or D
D. A will still be produced, but not B, C, or D

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Question 4

Tryprotophan synthetase of E.coli, a typical bifunctional oligomeric enzyme consist of

A. a protein designated A
B. two proteins designated A and B
C. a protein A and one-subunit a
D. a protein designated B

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Question 5

The nucleophile in serine proteases is

A. Serine
B. water
C. both (a) and (b)
D. Asparagine

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Question 6

Which of the following is false statement with regard to comparison between Serine and HIV proteases?

A. Both use nucleophilic attack to hydrolyze the peptide bond
B. Both require water to complete the catalytic cycle
C. Both forms an acyl-enzyme intermediate
D. Both show specificity for certain amino acid sequences

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Question 7

Which of the common features are shared between serine and aspartate proteases?

A. Both require water to complete the catalytic cycle
B. Both use a base to activate the nucleophile
C. Both show specificity for certain amino acid sequences
D. All of the above

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Question 8

Before they can react, many molecules need to be destabilized. This state is typically achieved through

A. changing the three-dimensional shape of the molecule
B. oxidizing the molecules by removing electrons
C. changing the reaction from a biosynthetic to a catabolic pathway
D. the input of a small amount of activation energy

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Question 9

Common feature in all serine proteases is a

A. hydrophobic specificity pocket
B. hydrophilic specificity pocket
C. cluster of reactive serine residues
D. single reactive serine residue

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Question 10

Which of the following (s) is/are serine proteases?

A. Chymotrypsin
B. Trypsin
C. Elastase
D. all of these

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Question 11

Which of the following statements about enzymes or their function is true?

A. Enzymes do not alter the overall change in free energy for a reaction
B. Enzymes are proteins whose three-dimensional form is key to their function
C. Enzymes speed up reactions by lowering activation energy
D. All of the above

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Question 12

Enzyme-driven metabolic pathways can be made more efficient by

A. concentrating enzymes within specific cellular compartments
B. grouping enzymes into free-floating, multienzyme complexes
C. fixing enzymes into membranes so that they are adjacent to each other
D. All of the above

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Question 13

The role of Asp 102 and His 57 during trypsin catalysis is to

A. neutralize the charge on the other's side chain
B. keep the specificity pocket open
C. function as a proton shuttle
D. clamp the substrate into the active site

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Question 14

What is the specificity of the Clostripain protease?

A. It cleave after Arg residues
B. It cleave after His residues
C. It cleave after Lys residues
D. None of the above

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Question 15

How is the enzyme COX-1 important in human health?

A. It helps to transport carbon dioxide in the blood
B. It is critical for the biosynthesis of DNA
C. It is a chemical derivative of aspirin
D. It catalyzes the production of hormones that maintain the stomach lining

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Question 16

The cleavage specificity of trypsin and chymotrypsin depend in part on the

A. proximity of Ser 195 to the active site or specificity pocket
B. size, shape, and charge of the active site or specificity pocket
C. presence of a low-barrier hydrogen bond in the active site or specificity pocket
D. absence of water in the active site

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Question 17

The E.coli pyruvic acid dehydrogenase complex is reported to

A. decatalyze the oxidation of pyruvic acid to acetyl Co A and CO2
B. Catalyze the oxidation of pyruvic acid to acetyl Co A and CO2
C. retard the reduction of pyruvic acid to acetyl Co A and CO2
D. Catalyze the reduction of pyruvic acid to acetyl Co A and CO2

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Question 18

Albinism is caused by the deficiency of which enzyme?

A. Phenylalanine hydroxylase
B. Streptokinase
C. Prolidase
D. Tyrosinase

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Question 19

Cellulose is not digestible by humans due to the absence of which of the following enzymes?

A. Amylase
B. Urease
C. Cellulase
D. Invertase

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Question 20

Enzymes are basically ______

A. polysaccharides
B. sugars
C. polypeptides
D. pyrimidine bases

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Question 21

Enzymes are generally named after the ________

A. compound on which they work
B. compound which they form as product
C. medium in which they act
D. place from where they are derived

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Question 22

Enzymes are regarded as ______

A. biocatalysts
B. messengers
C. inhibitors
D. antibodies

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Question 23

Enzymes reduce the magnitude of activation energy for a reaction.

A. True
B. False

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Question 24

Identify the correct statement about enzymes.

A. Enzymes increase the activation energy of a reaction
B. Enzymes need to be used in excess compared to the reagent to catalyse the reaction
C. Enzymes work only at their optimum temperature and pH
D. The activity of enzymes cannot be affected by other compounds

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Question 25

The enzyme which catalyses the conversion of proteins to amino acids is ______

A. invertase
B. urease
C. nuclease
D. protease

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Question 26

The hydrolysis of lactose can be catalysed only by the enzyme lactase. Also, lactase is only able to work on lactose and no other compound.

A. True
B. False

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Question 27

The prosthetic groups which get attached to the enzyme at the time of reaction are called _____

A. cofactors
B. coenzymes
C. messengers
D. inhibitors

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Question 28

Which of the following best describes a particular enzyme?

A. Chemical catalyst
B. Fibrous protein
C. Highly selective
D. Can be used for various reactions

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Question 29

Which of the following is a substrate specific enzyme?

A. Maltase
B. Carboxylase
C. Hexokinase
D. Carbonic anhydrase

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Question 30

A __________is a biocatalyst that increases the rate of the reaction without being changed.

A. Aluminum oxide
B. Silicon dioxide
C. Enzyme
D. Hydrogen peroxide

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Question 31

Enzyme increases the rate of reaction by lowering the activation energy.

A. True
B. False

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Question 32

Lineweaver-Burk plot is also known as______

A. Double reciprocal plot
B. Hanes-Woolf plot
C. Eadie-Hofstee plot
D. Steady-state equation

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Question 33

Mark the CORRECT function of enzyme, Peptidase?

A. Cleave phosphodiester bond
B. Cleave amino bonds
C. Remove phosphate from a substrate
D. Removal of H2O

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Question 34

Name the coenzyme of riboflavin (B2)?

B. FAD and FMN
C. Coenzyme A
D. Thiamine pyrophosphate

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Question 35

Name the enzyme secreted by pancreas?

A. Pepsin
B. Chymotrypsin
C. Trypsin
D. Alcohol dehydrogenase

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Question 36

Name the enzyme which catalyzes the oxidation-reduction reaction?

A. Transaminase
B. Glutamine synthetase
C. Phosphofructokinase
D. Oxidoreductase

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Question 37

Name the enzyme which is found in tears, sweat, and an egg white?

A. Ribozyme
B. Lysozyme
C. Zymogen
D. Isozymes

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Question 38

The zymogen is an inactive precursor of an active enzyme.

A. True
B. False

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Question 39

What is an apoenzyme?

A. It is a protein portion of an enzyme
B. It is a non-protein group
C. It is a complete, biologically active conjugated enzyme
D. It is a prosthetic group

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Question 40

What is an Isozyme?

A. Same structure, different function
B. Different structure, the same function
C. Same structure, the same function
D. Different structure, different function

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Question 41

What is the function of phosphorylase?

A. Transfer inorganic phosphate
B. Transfer a carboxylate group
C. Use H2O2 as the electron acceptor
D. Transfer amino group

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Question 42

What is the nature of an enzyme?

A. Vitamin
B. Lipid
C. Carbohydrate
D. Protein

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Question 43

What is the SI unit of enzyme activity?

A. Km
B. Kat
C. Kcat
D. Vmax

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Question 44

Which of the following function is catalyzed by Racemases?

A. Removal of water
B. Intramolecular transfer of a functional group
C. Interconversion of L and D stereoisomers
D. Inversion of asymmetric carbon atom

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Question 45

Which of the following is an example of ligases enzyme?

A. Mutases
B. Epimerases
C. Racemases
D. Carboxylases

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Question 46

Which of the following is not a catalytic strategy for an enzyme to perform specific reaction?

A. Covalent catalysis
B. Metal ion catalysis
C. Michaelis constant
D. Acid-base catalysis

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Question 47

Which of the following is INCORRECT for the lock-and-key model?

A. It is used to describe the binding process
B. The active site of the enzyme is complementary to the substrate
C. It demonstrates enzyme-substrate complex
D. The binding of the substrate produces a conformational change in enzyme

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Question 48

Which of the following is not an example of irreversible enzyme inhibitor?

A. Cyanide
B. Sarin
C. Diisopropyl phosphoflouridate (DIPF)
D. Statin drugs

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Question 49

Which of the following reaction is catalyzed by Lyase?

A. Breaking of bonds
B. Formation of bonds
C. Intramolecular rearrangement of bonds
D. Transfer of group from one molecule to another

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Question 50

Which of this vitamin is associated with the coenzyme Biocytin?

A. Nicotinic acid
B. Thiamine
C. Biotin
D. Pyridoxine

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