Free Enzymes MCQs with Answers

• A. Speed up
• B. Do not affect
• C. Slow down
• D. None of these

Explanation: Enzymes are biological catalysts i.e they speed up (catalyze) the rate of a reaction.

• A. Maintaining a constant
• B. Increasing
• C. Decreasing
• D. None of these

Explanation: One of the primary functions of enzymes is to lower the activation energy required for a chemical reaction to occur.

• A. Cyanide
• B. Anti-cholinesterase
• C. Methanol
• D. Malonic acid

Explanation: Poisons like cyanide are irreversible inhibitors as they destroy the structure of the active sites of the enzymes by forming covalent…

• A. Vitamins
• B. Cellulose
• C. Phospholipids
• D. Nucleic acids

Explanation: Most coenzymes are derived from vitamins. Coenzymes are organic molecules that work with enzymes to facilitate and enhance their catalytic…

• A. Both active and binding site
• B. Binding site
• C. Active site
• D. Apoenzyme

Explanation: The correct answer is Option B: Binding site. The enzyme-substrate complex is formed at the binding site, which is a specific region…

• A. Chemical properties
• B. Chemical formula
• C. Physical properties
• D. Structure

Explanation: In competitive inhibition, the inhibitor has a similar structure or shape to the substrate.

• A. Protein
• B. Lipid
• C. Cholestrol
• D. All of these

Explanation: Enzymes that are integral parts of ribosomes are not directly involved in the synthesis of molecules.

• A. Protein
• B. Vitamin
• C. Carbohydrates
• D. None of these

Explanation: Catalysts that increase the rate of biological chemical reactions are called enzymes.

• A. 1.0
• B. 1.5
• C. 2
• D. 5.5

Explanation: The enzyme enterokinase (converts trypsinogen to trypsin) has an optimum pH of 5.5.

• A. Substrate
• B. Inhibitors
• C. Catalyst
• D. Both A and B

Explanation: The competitive inhibitor is a molecule that closely resembles the substrate and competes with the substrate for binding to the active…

• A. Holoenzymes
• B. Coenzymes
• C. Apoenzymes
• D. Allosteric enzymes

Explanation: Allosteric enzymes are enzymes that change their conformational ensemble upon binding of an effector which results in an apparent change…

• A. Uncompetitive inhibition
• B. Noncompetitive inhibition
• C. Competitive inhibition
• D. All of these

Explanation: If a new inhibitor binds at the active site of an enzyme, it is displaying competitive inhibition.

• A. Coenzyme
• B. Cofactor
• C. Prosthetic group
• D. Activator

Explanation: If the non-protein part of an enzyme is covalently bonded to the enzyme, it is known as a prosthetic group.

• A. Active site
• B. Binding site
• C. Catalytic site
• D. Allosteric site

Explanation: The active site is the three-dimensional region of an enzyme where substrate molecules bind and undergo a chemical reaction.

• A. Chemical properties
• B. Physical properties
• C. Bonding on amino acids
• D. pH of amino acids

Explanation: Covalent modifications are enzyme-catalyzed alterations of synthesized proteins and include the addition or removal of chemical groups.

• A. Km
• B. Ko
• C. Vo
• D. Both A and B

Explanation: Uncompetitive inhibition occurs when the inhibitor binds to the enzyme-substrate complex (ES) to form an ESI complex, which can no longer…

• A. Active site
• B. Allosteric site
• C. Catalytic site
• D. None of the above

Explanation: The correct answer is the active site, which is the specific region of the enzyme where the substrate binds, forming the enzyme-substrate…

• A. Oxidases
• B. Dehydrogenases
• C. Hydrolyses
• D. Both a and b

Explanation: Oxidases are enzymes that catalyze the transfer of electrons from a substrate to oxygen, while dehydrogenases are enzymes that catalyze…

• A. Protein nature
• B. Active site
• C. Globular shape
• D. Co-factor

Explanation: The specificity of an enzyme is primarily due to the unique structure of its active site.

• A. Sucrase
• B. Salivary enzymes
• C. Pepsin
• D. Enterokinase

Explanation: Pepsin is a digestive enzyme secreted by the stomach to help break down proteins.