Enzymes are biocatalysts. They catalyze biochemical reactions. In general, they reduce the activation energy of reactions. Many physicochemical processes are enzyme-mediated. Which of the following reactions is not enzyme-mediated in the biological system?

1.  Dissolving CO2 in water

2.  Untwining the two strands of DNA

3.  Hydrolysis of sucrose

4.  Formation of peptide bond

Subtopic:  Enzyme Catalysis |
From NCERT
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The catalytic cyclic of an enzyme action is described as: 
A. Enzyme releases products of the reaction and gets free.
B. Substrate induces the enzyme to alter its shape.
C. The substrate binds with the active site of the enzyme.
D. Enzymes-product complex is formed.
1. \(\mathrm C \rightarrow \mathrm B \rightarrow \mathrm A \rightarrow \mathrm D\)
2. \(\mathrm{C} \rightarrow \mathrm{B} \rightarrow \mathrm{D} \rightarrow \mathrm{A}\)
3. \(\mathrm B \rightarrow \mathrm C \rightarrow \mathrm D \rightarrow \mathrm A\)
4. \(\mathrm D \rightarrow \mathrm C \rightarrow \mathrm A \rightarrow \mathrm B\)
Subtopic:  Enzyme Catalysis |
 79%
From NCERT
NEET - 2024
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Which of the following statements regarding enzyme inhibition is correct:
 

1. Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein
2. Non-competitive inhibitors often bind to the enzyme irreversibly
3. Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme
4. Non-competitive inhibition of an enzyme can be overcome by adding large amounts of substrate
Subtopic:  Enzyme Catalysis |
 86%
From NCERT
AIPMT - 2005
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Role of enzyme in reactions is to:
1. Decrease activation energy
2. Increase activation energy
3. Act as an inorganic catalyst
4. None of the above

Subtopic:  Enzyme Catalysis |
 87%
From NCERT
AIPMT - 2000
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NEET 2025 - Target Batch
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The figure given below shows the conversions of a substrate into product by an enzyme. In which one of the four options (1-4), the components of the reaction labelled as A, B, C and D are identified correctly:

 Options

 A B C D
1. Transition
state
Potential
energy
Activation
energy
without
enzyme
Activation
energy with
enzyme
2. Potential
energy
Transition
state
Activation
energy with
enzyme
Activation
energy
without
enzyme
3. Activation
energy with
enzyme
Transition
state
Activation
energy
without
enzyme
Potential
energy
4. Potential
energy
Transition
state
Activation
energy
without
enzyme
Activation
energy with
enzyme
Subtopic:  Enzyme Catalysis |
 86%
From NCERT
AIPMT - 2010
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NEET 2025 - Target Batch
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