Question

Choose the correct response with respect to given equation.
CO$_2$ + H$_2$O $\rightleftharpoons$ H$_2$CO$_3$

• A. Carbonic anhydrase is an enzyme required for accelerating the reaction
• B. Even in the absence of enzyme this reaction is fast enough
• C. 200 molecules of H$_2$CO$_3$ per hour are formed in the presence of enzyme.
• D. 6,00,000 molecules of H$_2$CO$_3$ are formed for every second in the absence of enzyme.

Hint:

Carbonic anhydrase is a prime example of enzyme efficiency, demonstrating how enzymes can increase reaction rates by orders of magnitude to meet physiological demands.

Answer 1

The Correct Option is A

Step 1: Analyze the given equation.
The equation is \text{CO}$_2$ + \text{H}$_2$\text{O} $\rightleftharpoons$ \text{H}$_2$\text{CO}$_3$. This represents the reversible reaction between carbon dioxide and water to form carbonic acid. This reaction is fundamental in biological systems, particularly in the transport of carbon dioxide in the blood. Step 2: Evaluate Option (1).
"Carbonic anhydrase is an enzyme required for accelerating the reaction". In biological systems, the hydration of carbon dioxide to carbonic acid and its reverse reaction are indeed catalyzed by a highly efficient enzyme called carbonic anhydrase. This enzyme is crucial for rapidly interconverting \text{CO}$_2$ and \text{H}$_2$\text{CO}$_3$ to maintain pH balance and facilitate gas exchange. This statement is True. Step 3: Evaluate Option (2).
"Even in the absence of enzyme this reaction is fast enough". While the reaction \text{CO}$_2$ + \text{H}$_2$\text{O} $\rightleftharpoons$ \text{H}$_2$\text{CO}$_3$ can occur without an enzyme, its rate in the absence of carbonic anhydrase is very slow. It is not "fast enough" for the physiological demands of carbon dioxide transport and pH regulation in living organisms. For example, in red blood cells, without the enzyme, \text{CO}$_2$ transport would be severely hampered. This statement is False. Step 4: Evaluate Option (3).
"200 molecules of \text{H}$_2$\text{CO}$_3$ per hour are formed in the presence of enzyme."
Carbonic anhydrase is one of the fastest known enzymes. It can catalyze the formation of millions of molecules of \text{H}$_2$\text{CO}$_3$ per second. 200 molecules per hour is an extremely low rate, which is far from the actual catalytic efficiency of carbonic anhydrase. This statement is False. (For reference, carbonic anhydrase can process about $10^4$ to $10^6$ molecules per second). Step 5: Evaluate Option (4).
"6,00,000 molecules of \text{H}$_2$\text{CO}$_3$ are formed for every second in the absence of enzyme."
As established in Step 3, the uncatalyzed reaction is very slow. Forming 6,00,000 (600,000) molecules per second is a rate characteristic of a highly efficient enzyme, not an uncatalyzed reaction. This statement is False. Step 6: Conclude the correct option.
Based on the analysis, only option (1) is true. The final answer is $\boxed{\text{Carbonic anhydrase is an enzyme required for accelerating the reaction}}$.