Free Enzymes MCQs with Answers

• A. Substrate
• B. Prosthetic Group
• C. Coenzyme
• D. Co-factors

Explanation: Co-factors are non-protein molecules that bind to enzymes. and are essential for their catalytic activity.

• A. Binding site
• B. Active site
• C. Catalyst site
• D. Inhibition side

Explanation: The active site is the specific region on the enzyme where the substrate binds and the reaction takes place.

• A. Fibrous proteins
• B. Lipoproteins
• C. Low molecular weight proteins
• D. Globular proteins

Explanation: Enzymes are typically globular proteins, characterized by their compact, three-dimensional structures that allow them to act as catalysts…

• A. Products
• B. Substrates
• C. Metabolites
• D. Catabolites

Explanation: Substrates are the specific reactants that enzymes bind to and act upon.

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

Explanation: Inorganic ions often serve as activators for enzymes, enhancing their catalytic activity by forming.

• A. Antibiotics
• B. Anti-metabolites
• C. Cyanide
• D. Succinic acid

Explanation: Succinic acid is a substrate which binds to enzyme to get converted into product.

• A. Anti-metabolites
• B. Sucrose
• C. Antibiotics
• D. ATP

Explanation: Sucrose is a disaccharide, commonly known as table sugar, and is not known to inhibit enzyme activity.

• A. Ionic bonds
• B. Disulphide bonds
• C. Hydrogen bonds
• D. Peptide bonds

Explanation: Ionic bonds are most affected by changes in pH. These bonds are formed between oppositely charged ions.

• A. Optimum temperature
• B. Minimum temperature
• C. Maximum temperature
• D. Activation temperature

Explanation: The minimum temperature is the lowest temperature at which an enzyme becomes active from an inactive state.

• A. Peptide bonds
• B. Disulfide bridges
• C. Hydrogen bonds
• D. Ionic bonds

Explanation: Heavy metal ions such as mercury, silver, and copper act as enzyme inhibitors by breaking disulfide bridges.

• A. It has only one binding site
• B. It is regulated by covalent modification
• C. Its activity is altered by binding of an effector molecule at a site other than the active site
• D. It follows Michaelis-Menten kinetics strictly

Explanation: Allosteric enzymes have an allosteric site (different from the active site) where regulators (activators or inhibitors) bind, causing a…

• A. Lipids
• B. Proteins
• C. Carbohydrates
• D. Vitamins

Explanation: Almost all enzymes are proteins, except some RNA enzymes (ribozymes).

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

Explanation: Coenzymes are organic molecules (often vitamins) that bind loosely to enzymes.

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

Explanation: The active site is the specific region where the substrate fits and reaction occurs.

• A. Increasing activation energy
• B. Decreasing activation energy
• C. Increasing product stability
• D. Increasing substrate concentration

Explanation: Enzymes lower activation energy so reactions happen faster.

• A. Plasma membrane
• B. Chloroplast
• C. Mitochondria
• D. Nucleolus

Explanation: Fatty acid oxidation (B-oxidation) occurs in the mitochondrial matrix (in the inner membrane), where the enzymes that break down fatty…

• A. Faster
• B. Moderate
• C. Slower
• D. Both A and B

Explanation: Enzymes function as biological catalysts that significantly enhance the rate of chemical reactions by decreasing the activation energy…

• A. Dissolve
• B. Ionize
• C. Denature
• D. React with substrate

Explanation: Excess heat breaks hydrogen and ionic bonds ---> enzyme loses shape ---> inactive.

• A. Holoenzyme
• B. Coenzyme
• C. Apoenzyme
• D. Cofactor

Explanation: Apoenzyme = protein portion; holoenzyme apoenzyme + cofactor.

• A. Non-competitive inhibition
• B. Competitive inhibition
• C. Irreversible inhibition
• D. Allosteric inhibition

Explanation: Competitive inhibitors mimic the substrate and bind to the active site.