In feedback inhibition, the <strongend product</strong of a metabolic pathway

Answer: Inhibits an early enzyme of the pathway End-product inhibition prevents wasteful overproduction once the cell has enough of the product.

What best explains the steep decline in activity above the optimum temperature?

Answer: The enzyme denatures, losing the tertiary structure required for catalysis Above the optimum, increased kinetic energy disrupts the weak interactions (H-bonds, hydrophobic) that maintain the enzyme's 3D shape. Denaturation eliminates the active site.

Based on the graph, which best explains the difference in pH optima of pepsin vs trypsin?

Answer: Each enzyme's tertiary structure is most stable and active in its native cellular environment Pepsin functions in the acidic stomach (pH 2), while trypsin operates in the slightly alkaline small intestine (pH 8). Each protein's shape is optimized for its physiological pH.

AP Biology · Topic 3.3

Environmental Impacts on Enzyme Function Practice

Q: In feedback inhibition, the <strongend product</strong of a metabolic pathway

Answer: Inhibits an early enzyme of the pathway End-product inhibition prevents wasteful overproduction once the cell has enough of the product.

Q: What best explains the steep decline in activity above the optimum temperature?

Answer: The enzyme denatures, losing the tertiary structure required for catalysis Above the optimum, increased kinetic energy disrupts the weak interactions (H-bonds, hydrophobic) that maintain the enzyme's 3D shape. Denaturation eliminates the active site.

Q: Based on the graph, which best explains the difference in pH optima of pepsin vs trypsin?

Answer: Each enzyme's tertiary structure is most stable and active in its native cellular environment Pepsin functions in the acidic stomach (pH 2), while trypsin operates in the slightly alkaline small intestine (pH 8). Each protein's shape is optimized for its physiological pH.

Part of Cellular Energetics.(ENE-1.N)

Practice questions

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Sample questions

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Sample 1difficulty 2/5
$In feedback inhibition, the <strong> end product </strong> of a metabolic pathway$
- A
  $Increases gene transcription of the pathway$
- B
  $Binds the regulatory site of the substrate$
- C
  $Inhibits an early enzyme of the pathway$
  check_circle
- D
  $Activates a downstream enzyme of the pathway$
Why
$End-product inhibition prevents wasteful overproduction once the cell has enough of the product.$
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Sample 2difficulty 2/5
$A human enzyme's activity was assayed at temperatures from 0 to 60 C with substrate in excess.$
$What best explains the steep decline in activity above the optimum temperature?$
- A
  $Hydrogen bonds to substrate become permanent$
- B
  $The enzyme denatures, losing the tertiary structure required for catalysis$
  check_circle
- C
  $Substrate concentration decreases as temperature rises$
- D
  $The enzyme is consumed in the reaction at higher temperatures$
Why
$Above the optimum, increased kinetic energy disrupts the weak interactions (H-bonds, hydrophobic) that maintain the enzyme's 3D shape. Denaturation eliminates the active site.$
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Sample 3difficulty 2/5
$Pepsin and trypsin activity were assayed across pH values. Pepsin operates in the stomach; trypsin operates in the small intestine.$
$Based on the graph, which best explains the difference in pH optima of pepsin vs trypsin?$
- A
  $Pepsin has a smaller active site$
- B
  $Pepsin has more disulfide bridges than trypsin$
- C
  $Each enzyme's tertiary structure is most stable and active in its native cellular environment$
  check_circle
- D
  $Trypsin uses noncompetitive inhibition while pepsin does not$
Why
$Pepsin functions in the acidic stomach (pH ~2), while trypsin operates in the slightly alkaline small intestine (pH ~8). Each protein's shape is optimized for its physiological pH.$
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Sample 4difficulty 2/5
$Pepsin (stomach enzyme) and trypsin (intestinal enzyme) have different pH optima because$
- A
  $The stomach maintains a higher pH than the intestine, so pepsin needs basic conditions$
- B
  $Random variation in amino acid sequence makes their pH preferences unpredictable$
- C
  $Each enzyme's structure and active-site chemistry are tuned to its physiological location's pH$
  check_circle
- D
  $All enzymes work the same way regardless of pH because the active site is universal$
Why
$Stomach pH ~2 selects for pepsin's optimum near 2; intestinal pH ~8 selects for trypsin's optimum near 8.$
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Sample 5difficulty 2/5
$Enzyme rate peaks at an optimum temperature, then drops sharply because$
- A
  $Cold denatures the enzyme, freezing its active site$
- B
  $High temperature destroys the substrate's binding region$
- C
  $Heat increases substrate diffusion, overwhelming sites$
- D
  $Heat denatures the enzyme, disrupting its 3D shape$
  check_circle
Why
$Past the optimum, weak interactions holding the active site unravel; the enzyme loses its specific shape and activity.$
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