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 22 of 32
- 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.
Correct answer: Prosthetic group- A. Decreasing kinetic energy.
- B. Decreasing chemical energy.
- C. Decreasing potential energy.
- D. Decreasing activation energy.
Explanation: Enzymes increase the rate of a chemical reaction by lowering the activation energy required for the reaction to proceed.
Correct answer: Decreasing activation energy.- A. Sucrase
- B. Salivary enzymes
- C. Pepsin
- D. Enterokinase
Explanation: Pepsin is the enzyme that works best at a pH of 2.00. Pepsin is a digestive enzyme that is secreted by the stomach to help break down…
Correct answer: Pepsin424. A chemical substance which can react with an enzyme but not transform into a product is called a/an:
- A. Substrate
- B. Product
- C. Inhibitor
- D. Allosteric regulator
Explanation: An inhibitor is a chemical substance that can bind to an enzyme and disrupt its activity, thereby preventing or reducing the rate of a…
Correct answer: Inhibitor- A. Splitting of two molecules
- B. Oxidation of molecules
- C. Joining of molecules
- D. Both Options A and B are correct
Explanation: This option is correct. Ligase enzymes are specifically involved in catalyzing the joining or ligation of two molecules.
Correct answer: Joining of molecules426. Which of the following strategies of enzymatic inhibition is used by non-competitive inhibitors?
- A. Bind to substrate so that it cannot bind to the active site
- B. Target the enzyme for destruction using a protease
- C. Bind to the active site and prevent the substrate from binding
- D. Bind to an allosteric site to cause a conformational shift in the enzymes
Explanation: Noncompetitive inhibition, a type of allosteric regulation, is a specific type of enzyme inhibition characterized by an inhibitor binding…
Correct answer: Bind to an allosteric site to cause a conformational shift in the enzymes- A. Stomach
- B. Pancreas
- C. Small intenstine
- D. Large intestine
Explanation: The small intestine secretes enzymes responsible for the activation for pancreatic zymogens.
Correct answer: Small intenstine- A. 5
- B. 7.5
- C. 9
- D. 3
Explanation: Option B is correct because the optimum PH for working enzyme is neutral which is around 7 which is closest to (7.5).
Correct answer: 7.5- A. 1960
- B. 1961
- C. 1959
- D. 1966
Explanation: Option C is correct because, in "1959", Koshland introduced the induced fit model.
Correct answer: 1959- A. Fat soluble vitamins
- B. Minerals
- C. Fats
- D. Water soluble vitamins
Explanation: Option D is correct since water-soluble vitamins are readily absorbed by water and are immediately available to tissues for consumption.
Correct answer: Water soluble vitamins- A. Irreversible inhibition
- B. Competitive inhibition
- C. Non-competitive and reversible inhibition
- D. Reversible inhibition
Explanation: Non-competitive inhibition is when the inhibitor binds to another part of the enzyme, thus denaturing the active site, and inhibiting the…
Correct answer: Non-competitive and reversible inhibition- A. Reversible inhibitors
- B. Irreversible inhibitors
- C. Competitive inhibitors
- D. Non-competitive inhibitors
Explanation: Inhibitors which cause permenant damage to the enzyme, thus rendering it useless, are known as irreversible inhibitors.
Correct answer: Irreversible inhibitors- A. Proteins
- B. Metal ions
- C. Carbohydrates
- D. Vitamins
Explanation: Coenzymes are small organic molecules that assist enzymes in catalyzing biochemical reactions.
Correct answer: Vitamins- A. Activator
- B. Coenzymes
- C. Non-Competitive Inhibitor
- D. End-Product Inhibitor
Explanation: In non-competitive inhibition, the inhibitor binds at an allosteric site separate from the active site of substrate binding.
Correct answer: Non-Competitive Inhibitor- A. Binding site
- B. Reaction center
- C. Allosteric site
- D. Lock and Key Model
- E. Active site
Explanation: Option A: Binding site typically also refers to the active site, but active site is the better answer for the question.
Correct answer: Active site- A. Activators
- B. Prosthetic groups
- C. Coenzymes
- D. Apo-enzymes
Explanation: Coenzymes are inorganic cofactors that are loosely bound to the protein part of the enzyme. For Example ATP, NAD+, FAD+, etc.
Correct answer: Coenzymes- A. Lysozyme
- B. Ribozyme
- C. Ligase
- D. Deoxyribonuclease
Explanation: A ribozyme is a ribonucleic acid (RNA) enzyme that catalyzes a chemical reaction similarly to that of a protein enzyme.
Correct answer: Ribozyme- A. decrease activation energy
- B. increase activation energy
- C. inorganic catalyst
- D. none of the above.
Explanation: (a) : All molecules require certain amount of energy for activation (to overcome the energy barrier) before they can react.
Correct answer: decrease activation energy- A. Lipase
- B. DNAase
- C. Phospholipase
- D. Pepsin
Explanation: Since cell's internal ernvironment is mainly made of proteins. So for its digestion, a protein digesting enzyme is required which is pepsin.
Correct answer: Pepsin- A. There is probably more substrate present than there is enzyme
- B. There is probably more product present than either substrate or enzyme
- C. The enzyme substrate complex is probably failing to from during the reaction
- D. There is probably more enzyme available than there is substrate available
Explanation: Initially, an increase in substrate concentration leads to an increase in the rate of an enzyme-catalyzed reaction.
Correct answer: There is probably more enzyme available than there is substrate available