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Quiz Chapter 5: Metabolism and Enzymes

10 questions · Form 4 Biology Bab 5: Metabolism and Enzymes

10 questions · plays in fullscreen

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. Non-protein chemical compounds or inorganic ions that bind to enzymes to help them function properly are known as:

  1. A. Inhibitors
  2. B. Substrates
  3. C. Cofactors
  4. D. Polypeptides
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Answer: C

Cofactors (inorganic ions like Mg2+, Zn2+ or organic coenzymes like vitamins) assist enzymes in achieving catalytic activity.

2. Why are enzymes described as 'specific' in their action?

  1. A. They only operate at one exact temperature value.
  2. B. Their active site shape complements only one specific type of substrate.
  3. C. They can only be synthesized by specialized stomach cells.
  4. D. They are destroyed after catalyzing a single chemical reaction.
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Answer: B

The precise 3D spatial geometry of an enzyme's active site only fits a specific substrate molecule with a complementary configuration.

3. What happens to an enzyme after it successfully catalyzes a biochemical transformation of a substrate into products?

  1. A. It degrades immediately into free amino acids.
  2. B. It remains chemically unchanged and is free to bind another substrate molecule.
  3. C. It permanently binds to the product molecule.
  4. D. It is converted into energy (ATP).
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Answer: B

Enzymes are catalysts; they emerge from reactions chemically unchanged and can be reused repeatedly in small quantities.

4. Which enzyme is used during the stonewashing process to give denim jeans a faded, soft texture?

  1. A. Cellulase
  2. B. Amylase
  3. C. Lipase
  4. D. Protease
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Answer: A

Cellulase partially digests cellulose fibers on cotton denim surfaces, softening fabric and giving it a stonewashed appearance.

5. Which of the following is an example of a catabolic reaction in living organisms?

  1. A. Synthesis of cellulose in plant cell walls
  2. B. Cellular respiration breaking down glucose into CO2 and water
  3. C. Formation of triglycerides from glycerol and fatty acids
  4. D. Polymerization of amino acids into proteins
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Answer: B

Cellular respiration breaks down complex glucose molecules to yield simpler carbon dioxide and water molecules while releasing ATP energy.

6. During cheese production, which enzyme causes milk proteins (casein) to coagulate into solid curds?

  1. A. Lipase
  2. B. Rennet (Chymosin)
  3. C. Maltase
  4. D. Zymase
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Answer: B

Rennet contains chymosin, an enzyme that cleaves milk casein proteins to curdle milk into solid curds for cheese making.

7. Which hypothesis is commonly used to illustrate the mechanism of substrate binding to an enzyme's active site?

  1. A. Fluid Mosaic Model
  2. B. Lock and Key Hypothesis
  3. C. Sliding Filament Theory
  4. D. Cohesion-Tension Theory
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Answer: B

The Lock and Key Hypothesis compares the complementary shape of an enzyme's active site (lock) with its specific substrate (key).

8. Which statement correctly describes an anabolic pathway in living cells?

  1. A. Breakdown of complex molecules into simple units, releasing energy.
  2. B. Synthesis of complex molecules from simpler precursors, requiring energy.
  3. C. Chemical reactions that occur exclusively outside living cells.
  4. D. Transport of water across cell membranes down a concentration gradient.
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Answer: B

Anabolism is the metabolic process of building complex molecules from simpler ones, which requires an input of energy (endergonic).

9. When substrate concentration is increased continuously while keeping enzyme concentration constant, the reaction rate eventually levels off. What is the limiting factor at this plateau (Vmax)?

  1. A. Substrate concentration
  2. B. Enzyme concentration
  3. C. Accumulation of ATP
  4. D. Temperature of the medium
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Answer: B

At Vmax, all enzyme active sites are fully saturated with substrate; thus, enzyme concentration becomes the limiting factor.

10. What happens to the structure and function of a human enzyme when heated above 60°C?

  1. A. Its kinetic energy drops to zero, temporarily halting activity.
  2. B. It becomes denatured as high temperatures disrupt its 3D active site shape.
  3. C. It speeds up the reaction exponentially without stopping.
  4. D. It converts into a cofactor to assist other enzymes.
Show answer

Answer: B

High thermal energy breaks hydrogen and ionic bonds stabilizing the enzyme's 3D tertiary structure, causing permanent denaturation.

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