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Biomolecules — Chemistry STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceChemistryBiomolecules1 Mark
MCQ
Which of the following statement is true for enzymes?
  • A
    They lower the activation energy of a reaction by increasing the energy level of the substrate.
  • B
    They lower the activation energy of a reaction by raising the energy level of the product.
  • C
    They do not affect the free energy change between substrate and product.
  • D
    They can be steroids instead of proteins at times.
✓

Answer

  1. They lower the activation energy of a reaction by increasing the energy level of the substrate.

Explanation:

Enzymes are biological catalysts which speed up biochemical reactions.

According to the most widely accepted theory, enzymes bind to the substrate molecule and form a transition state.

During the progress of a reaction the substrates are separated from products by an energy barrier which the substrates need to cross.

This energy barrier is called as the activation energy. The activation energy barrier in case of transition state is far less as compared to the activation energy barrier in absence of enzymes.

Hence, the rate of reaction is more in case of enzyme catalyzed reactions due to the formation of transition state and lower activation energy requirement.

This change is brought about by an apparent increase in energy level of substrate molecules.

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