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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- A. Analytic function
- B. Metabolism
- C. Meiosis
- D. Mitosis
- E. Catalytic function
Explanation: When substrate combines the active site of an enzyme it induces a conformational changes that enable enzyme to perform catalytic function.
Correct answer: Catalytic function- A. Analytic function
- B. Metabolism
- C. Meiosis
- D. Mitosis
- E. Catalytic function
Explanation: When substrate combines the active site of an enzyme it induces a conformational changes that enable enzyme to perform catalytic function.
Correct answer: Catalytic function- A. Co-factor
- B. Active site
- C. Non active site
- D. Substrate
- E. Prosthetic group
Explanation: Each enzyme has a dimple or groove at a specific side called active site. This is where all the catalytic activity occurs.
Correct answer: Active site- A. Enzyme
- B. Substrate
- C. Product
- D. Coenzyme
Explanation: Competitive inhibitors compete with the substrate for binding to the active site of an enzyme.
Correct answer: Substrate- A. A similar structure to the normal substrate molecule
- B. A quite different structure from the substrate molecule
- C. A different conformation but fit into the active site
- D. A similar conformation but does not fit into the active site
Explanation: Non-competitive inhibitor molecules have a quite different structure from the substrate molecules.
Correct answer: A quite different structure from the substrate molecule386. Zinc ion is attached at the active site of the enzyme carboxypeptidase. The zinc ion functions as:
- A. A coenzyme molecule
- B. An activator
- C. An inhibitor molecule
- D. Controller of Allosteric site
Explanation: The zinc ion serves as an activator in the case of carboxypeptidase. Carboxypeptidase is a metalloenzyme, which means it requires a metal…
Correct answer: An activator387. What is the best physiological pH for optimum functioning for most of the cellular enzymes of human?
- A. 2-3 pH
- B. 3-5 pH
- C. 6-8 pH
- D. 8-10 pH
Explanation: The best physiological pH for optimum functioning for most of the cellular enzymes in humans is in the range of 6-8.
Correct answer: 6-8 pH- A. Lipid
- B. Vitamins
- C. Steroids
- D. Waxes
Explanation: Most of the coenzymes are derivatives of vitamins. Coenzymes are organic molecules that work alongside enzymes to facilitate various…
Correct answer: Vitamins- A. Active site
- B. Passive site
- C. Allosteric site
- D. Regulatory site
Explanation: Enzymes have two sites, active and allosteric. The active site is the one where a substrate is attached and converted into a product.
Correct answer: Active site- A. pH 2
- B. pH 4
- C. pH 6
- D. pH8
Explanation: Pepsin shows maximum activity in a strongly acidic medium. Hence, pH 2 is the optimum pH for pepsin. Option A is the correct option.
Correct answer: pH 2- A. Enzyme starts to denature
- B. Enzyme starts to renature
- C. Enzyme works best
- D. Enzyme is reactivated
Explanation: At higher temperatures, enzymes denature and lose their function. The maximum temperature is the most temperature enzymes can bear before…
Correct answer: Enzyme starts to denature- A. Competitive inhibitor
- B. Non-competitive inhibitor
- C. Coenzyme
- D. Activator
Explanation: Competitive inhibitors are those that cause competition between substrate and inhibitor.
Correct answer: Competitive inhibitor- A. Optimum temperature
- B. Maximum temperature
- C. Minimum temperature
- D. Favourable temperature
Explanation: Option C is correct as Minimum temperature is the temperature at which enzyme becomes activated again after it was previously deactivated.
Correct answer: Minimum temperature- A. Highly acidic
- B. Highly alkaline
- C. Slightly acidic
- D. Slightly alkaline
Explanation: The stomach is known for its highly acidic environment, which is necessary for the activity of digestive enzymes like pepsin.
Correct answer: Highly acidic- A. 3-12
- B. 30-50
- C. 50-100
- D. 100-1000
Explanation: The catalytic site of an enzyme is typically made up of a relatively small number of amino acids.
Correct answer: 3-12- A. 1959
- B. 1952
- C. 1954
- D. 1956
- E. 1949
Explanation: Koshlan proposed the "Induced Fit Model" of enzyme action in the year 1959.
Correct answer: 1959- A. 8°C
- B. 15°C
- C. 37°C
- D. 45°C
- E. 55°C
Explanation: The optimum temperature for enzyme action in humans is typically around 37°C (98.6°F), which is the normal body temperature.
Correct answer: 37°C- A. Darwin
- B. Lamarck
- C. Friedrich Wilhelm Kuhn
- D. Mendel
- E. Thomas Cech
Explanation: The term enzyme was coined by the German physiologist Wilhelm Kühne in 1878.
Correct answer: Friedrich Wilhelm Kuhn- A. Activation energy without enzyme
- B. Energy of reactants
- C. Activation energy with enzyme
- D. Energy of product
- E. Allosteric activators
Explanation: The correct answer is allosteric activators. These molecules bind to an enzyme at a location other than the active site, known as the…
Correct answer: Allosteric activators- A. Binds with the product of catalytic reaction
- B. Is involved in catalytic reactions
- C. Is inhibited by coenzymes and cofactors
- D. Binds allosteric regulators of the enzyme
- E. Is inhibited by coenzymes only
Explanation: The active site of an enzyme is crucial because it is the region where substrates bind and undergo chemical transformation during a…
Correct answer: Is involved in catalytic reactions