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​An enzyme has been found to efficiently catalyse the following reaction:​​Where,kf : Forward rate of the reactionkr : Reverse&nbs
Question

An enzyme has been found to efficiently catalyse the following reaction:

Where,kf : Forward rate of the reactionkr : Reverse rate of the reactionKeq : Equilibrium Constant\text{Where,} \\k_f \, : \, \text{Forward rate of the reaction} \\k_r \, : \, \text{Reverse rate of the reaction} \\K_{\text{eq}} \, : \, \text{Equilibrium Constant}

Which one of the following parameters will be increased over the uncatalyzed reaction by the enzyme?

A.

krk_r​​

B.

​​KeqK_{eq}​​

C.

1/kr1/k_r​​

D.

1/Keq1/K_{eq}​​

Correct option is A

An enzyme catalyzes a reaction by lowering the activation energy, which increases the rate of the reaction. For the given reaction 

<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>A</mi><mo>↔</mo><mi>B</mi></mrow><annotation encoding="application/x-tex"> A \leftrightarrow B </annotation></semantics></math>AB, the forward rate (kf) and reverse rate (kr​) define the equilibrium constant <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>K</mi><mrow><mi>e</mi><mi>q</mi></mrow></msub><mo>=</mo><mfrac><msub><mi>k</mi><mi>f</mi></msub><msub><mi>k</mi><mi>r</mi></msub></mfrac></mrow><annotation encoding="application/x-tex"> K_{eq} = \frac{k_f}{k_r} </annotation></semantics></math> Keq = kfkr\frac{k_f}{k_r}krkf

  • Enzymes increase reaction rates: An enzyme will increase both <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>k</mi><mi>f</mi></msub></mrow><annotation encoding="application/x-tex"> k_f </annotation></semantics></math>k(forward rate) and kr (reverse rate) by the same factor, as it lowers the activation energy for both directions of a reversible reaction.
  • Effect on <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>K</mi><mrow><mi>e</mi><mi>q</mi></mrow></msub></mrow><annotation encoding="application/x-tex"> K_{eq} </annotation></semantics></math>Keq: Since Keq = kfkr\frac{k_f}{k_r}, if both kf and k increase by the same factor, their ratio (Keq) remains unchanged. Enzymes do not affect the equilibrium constant; they only speed up the rate at which equilibrium is reached.
  • Effect on kr​ : The reverse rate Kr will increase due to the enzyme.
  • Effect on 1kr\frac{1}{k_r}​ : If kr increases, then 1kr\frac{1}{k_r}​  will decrease.
  • Effect on 1Keq\frac{1}{K_{eq}}​ : Since keq remains unchanged, 
    1Keq\frac{1}{K_{eq}} also remains unchanged.

Now, let's evaluate the options:

1. kr: This is the reverse rate, which will increase due to the enzyme. This matches our analysis.

2.  keq : The equilibrium constant does not change with an enzyme, so this is incorrect.

3.  1Kr\frac{1}{K_{r}} :  Since kr​ increases, <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>1</mn><mi mathvariant="normal">/</mi><msub><mi>k</mi><mi>r</mi></msub></mrow><annotation encoding="application/x-tex"> 1/k_r </annotation></semantics></math>1/kr decreases, so this is incorrect.

4. 1Keq\frac{1}{K_{eq}}​: Since keq remains unchanged, 1Keq\frac{1}{K_{eq}}​ also remains unchanged, so this is incorrect.

Answer: The parameter that will be increased by the enzyme over the uncatalyzed reaction is:

1. kr

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