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 16 of 32
- A. Concentration of products
- B. Concentration of reactants
- C. Keq
- D. Options A, B and C are correct
Explanation: Keq is called the equilibrium constant which is the ratio of the concentration of products to the concentration of reactants.
Correct answer: Options A, B and C are correct- A. Glycoproteins
- B. Enzymes
- C. Activators
- D. Inhibitors
Explanation: Biologically active refers to the substance having an effect on a living organism, tissue, or cell.
Correct answer: Enzymes- A. Co-factor
- B. Prosthetic group
- C. Isoenzyme
- D. Substrate
Explanation: Substrate binds to the active site on the enzyme surface and is converted into products.Co-factors are non-protein molecules or ions that…
Correct answer: Substrate- A. Reversible inhibitors
- B. Irreversible inhibitors
- C. Competitive inhibitors
- D. Non-competitive inhibitors
Explanation: Irreversible inhibitors are characterized by their ability to bind permanently to enzymes, often through covalent bonds, leading to an…
Correct answer: Irreversible inhibitors- A. Only competitive Inhibitors
- B. Reversible inhibitors
- C. Irreversible inhibitors
- D. Both reversible and irreversible inhibitors
Explanation: The explanation is as follows: (PTB, Chapter 3)
Correct answer: Reversible inhibitors- A. 4.50
- B. 7.60
- C. 2.00
- D. 9.00
Explanation: The optimum pH for pancreatic lipase is 9.00, which is suitable for its activity in the alkaline environment of the small intestine.
Correct answer: 9.00- A. Lock & key model
- B. Induced fit model
- C. Sliding filament model
- D. Specificity model
Explanation: The induced fit model is the correct answer. It proposes that the active site of an enzyme is not a rigid structure.
Correct answer: Induced fit model- A. Proteins
- B. Metal ions
- C. Carbohydrates
- D. Vitamins
Explanation: Coenzymes play a vital role in the function of enzymes, acting as carriers for chemical groups or electrons during biochemical reactions.
Correct answer: Vitamins- A. They alter the product
- B. The nature of the product is completely changed
- C. No effect
- D. The end product is not obtained
Explanation: Enzymes are biocatalysts that speed up chemical reactions by lowering activation energy.
Correct answer: No effect- A. Koshland
- B. Emil Fischer
- C. De Duve
- D. Golgi
Explanation: The lock and Key model was given by Emil Fischer in 1890.According to this model, the active site is a rigid structure.
Correct answer: Emil Fischer- A. Competitive Inhibitors
- B. Permanent inhibitors
- C. Non-competitive inhibitors
- D. Irreversible inhibitors
Explanation: A competitive inhibitor is a substance similar in structure to an enzyme's substrate that binds to the active site and inhibits a…
Correct answer: Competitive Inhibitors- A. 7.8-8.7
- B. 7.0
- C. 4.5
- D. 8.0
Explanation: The optimum pH of enzyme urease is 7.0 i.e neutral
Correct answer: 7.0- 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 Inhibitor314. An enzyme can:
- A. Maintain the biochemical reaction
- B. Decrease the biochemical reaction
- C. Lower the need of activation energy
- D. Be the substitute of activation energy
Explanation: The activation energy is the energy required to start a reaction. Enzymes are proteins that bind to a molecule, or substrate, to modify…
Correct answer: Lower the need of activation energy- A. Substrate
- B. Co-factor
- C. DNA
- D. RNA
Explanation: A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst.
Correct answer: Co-factor- A. 0oC
- B. 15oC
- C. 25°C
- D. 370C
Explanation: This optimal temperature is usually around human body temperature (37.5oC) for the enzymes in human cells.
Correct answer: 370C- A. Looks like a lump projection from the surface of an enzyme
- B. Forms no chemical bond with substrate
- C. Never changes
- D. The specificity of an enzyme is determined by its structure
Explanation: The active site of enzymes are specific to their substrates, and their structure determines the specificity.
Correct answer: The specificity of an enzyme is determined by its structure- A. Cause chemical reactions that would not otherwise take place
- B. Change the rate of a chemical reaction
- C. Change the direction of a chemical reaction
- D. Raise the activation energy of a chemical reaction
- E. None of the given reactions
Explanation: Option A: Enzymes can not initiate a chemical reaction.They can only accelerate a chemical reaction.So,option A is incorrect.Option B…
Correct answer: Change the rate of a chemical reaction- A. Structure
- B. Chemical properties
- C. Physical properties
- D. None of these
Explanation: Competitive Inhibitors and substrates have similar structures. Due to the similarity in structure, competitive inhibitors can compete with…
Correct answer: Structure- A. Holoenzyme
- B. Apoenzyme
- C. Coenzyme
- D. Zymoenzyme
Explanation: Enzyme with a non-proteinous part is called Holoenzyme; without that non-proteinous part, it is called Apoenzyme.
Correct answer: Apoenzyme