Free Enzymes MCQs with Answers
633 Enzymes MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Enzymes are biological catalysts that lower activation energy without being consumed, and their specificity is explained by the lock and key and induced fit models. Work includes the effects of temperature, pH and substrate concentration on reaction rate, plus competitive and non-competitive inhibition and how these differ.
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Read the Enzymes notesFree MDCAT chapter notes with key terms633 questions · page 21 of 32
- A. Cannot modify its active sites
- B. Can bind to a single substrate
- C. Can catalyze related reaction
- D. Usually belongs to non-regulatory enzyme
Explanation: The flexibility in the induced fit model allows some enzymes to catalyze related reactions, particularly when similar substrates can fit…
Correct answer: Can catalyze related reaction- A. Apoenzyme
- B. Coenzyme
- C. Holoenzyme
- D. Prosthetic group
Explanation: A prosthetic group is a non-protein component that is tightly and permanently bound to an enzyme or protein, often by covalent bonds.
Correct answer: Prosthetic group- A. Emil Fischer
- B. Erwin Chargaff
- C. Koshland
- D. Lorenz Oken
Explanation: The lock and key model was modified by the induced fit model, proposed by Daniel Koshland in 1958.
Correct answer: Koshland- A. Competitive
- B. Irreversible
- C. Non-competitive
- D. Reversible
- E. Option B and C.
Explanation: Cyanides are irreversible non competitive inhibitors.
Correct answer: Option B and C.- A. Reduced to inactive form
- B. Becomes inert
- C. Changes into substrate
- D. Used for another reaction
Explanation: After an enzyme-catalyzed reaction, the enzyme remains unchanged and can be reused.
Correct answer: Used for another reaction- A. 1
- B. 3
- C. 5
- D. 7
Explanation: The pH required for catalase enzyme is 7.
Correct answer: 7- A. Heavy metal ions
- B. Light
- C. Acid
- D. Base
Explanation: Heavy metal ions can act as enzyme inhibitors by binding to the enzyme's active site or other critical sites, altering its structure and…
Correct answer: Heavy metal ions- A. Amylase
- B. Lipase
- C. Peptidase
- D. Protease
Explanation: Amylase is typically released in its active form. It is an enzyme responsible for breaking down starches and carbohydrates into simpler…
Correct answer: Amylase- A. Changing equilibrium in the direction of the substrate
- B. Increase the activation energy
- C. Increase the substrate concentration
- D. Lowering the activation energy
Explanation: Enzymes lower the activation energy of biochemical reactions, enabling them to occur more rapidly and efficiently.
Correct answer: Lowering the activation energy- A. 2
- B. 4
- C. 6
- D. 8
Explanation: Pancreatic Lipase works at the optimum pH of 8.
Correct answer: 8- A. All enzymes are globular proteins
- B. They lower the activation energy of reactions
- C. They are sensitive to minor changes in substrate concentration
- D. All of the given options
Explanation: All the above statements collectively describe enzyme characteristics.
Correct answer: All of the given options- A. Substrate
- B. Product
- C. Co-factor
- D. None of these
Explanation: A co-factor is an inorganic ion that helps enzymes function by stabilizing the enzyme-substrate complex.
Correct answer: Co-factor- A. Pepsin
- B. Insulin
- C. Sucrase
- D. Catalase
Explanation: Insulin is a hormone, not an enzyme, and regulates blood sugar levels.
Correct answer: Insulin- A. Enzyme molecules each have a distinct shape
- B. Enzyme molecules are catalysts
- C. Enzyme molecules can be damaged by high temperature
- D. Enzyme molecules can be damaged by high pH value
Explanation: Enzyme molecules each have a distinct shape - Correct. The lock and key hypothesis states that enzymes have specific active sites…
Correct answer: Enzyme molecules each have a distinct shape- A. Resistor
- B. Uncompetitive inhibitor
- C. Non-competitive inhibitor
- D. Competitive inhibitor
Explanation: Penicillin is classified as a competitive inhibitor because it competes with the substrate for binding to the active site of the bacterial…
Correct answer: Competitive inhibitor- A. 1 and 4
- B. 2 and 4
- C. 1 and 2
- D. 1,2,3 and 4
Explanation: Enzymes are a type of protein, and they have a three-dimensional, globular shape.
Correct answer: 1 and 2- A. Enzymes are unbiased for the substrate.
- B. Enzymes can modify their active sites.
- C. Enzymes are restricted to one reaction type.
- D. An enzyme can catalyze variety of reactions.
Explanation: Emil Fischer (1890) proposed a Lock and Key model to visualize substrate and enzyme interaction.
Correct answer: Enzymes are restricted to one reaction type.- A. Explains mechanism of enzyme action
- B. Enzyme is specific in nature
- C. Enzyme is a flexible structure
- D. Enzyme doesn't show change during reaction
Explanation: Option A: The induced fit model is a model that explains how enzymes work.
Correct answer: Enzyme doesn't show change during reaction- A. Key
- B. Lock
- C. Both A and B
- D. None of the above.
Explanation: The substrate is the key whose shape fits the lock of the enzyme. The substrate is held in place by temporary bonds which form between the…
Correct answer: Key- A. Key
- B. Lock
- C. Both Options A and B are correct
- D. None of these options is correct
Explanation: Lock and key model assumes that like a particular key opens a particular lock, a specific enzyme (key) acts upon a particular substrate…
Correct answer: Key