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JEE Main · 2021 · 20 Jul 2021 · Shift 2 · Biomolecules

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Which one of the following statements is not true about enzymes ?
  1. (A)The action of enzymes is temperature and pH specific.
  2. (B)Enzymes are non-specific for a reaction and substrate.✓ Correct
  3. (C)Enzymes work as catalysts by lowering the activation energy of a biochemical reaction.
  4. (D)Almost all enzymes are proteins.

Answer: (B)

Solution

An enzyme binds its substrate at an active site whose shape and charge distribution accommodate that substrate alone, so each enzyme catalyses essentially one reaction on one substrate. The other descriptions hold: enzymes are globular proteins, they work by opening a path of lower activation energy, and the weak forces that hold the active site in its folded shape are disturbed outside a narrow range of temperature and pH, which is why activity is lost there. The statement that is not true is the one calling enzymes non-specific for a reaction and substrate.

JEE Main · 2021 · 20 Jul 2021 · Shift 2 · Single correct option

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