A : Allosteric enzymes do not show a typical Michaelis Menten constant or behaviour.
R : All enzymes work at same pH.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statements but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To analyze the given statements, let's break down the assertion and reason step by step:

### Step 1: Evaluate the Assertion
- **Assertion (A)**: Allosteric enzymes do not show a typical Michaelis-Menten constant or behavior.
- **Explanation**: Allosteric enzymes are unique in their kinetics. Unlike typical enzymes that follow Michaelis-Menten kinetics, allosteric enzymes exhibit a sigmoidal (S-shaped) curve in their reaction velocity versus substrate concentration graph. This is due to their ability to exist in multiple conformations and their cooperative binding nature, meaning the binding of substrate to one active site affects the binding at other sites. Therefore, the assertion is **true**.

### Step 2: Evaluate the Reason
- **Reason (R)**: All enzymes work at the same pH.
- **Explanation**: This statement is incorrect. Different enzymes have different optimal pH levels at which they function most effectively. For example, pepsin in the stomach works best at a low pH (around 2), while trypsin in the small intestine operates optimally at a neutral to slightly alkaline pH (around 7.5). Thus, this reason is **false**.

### Step 3: Conclusion
- Since the assertion is true and the reason is false, the correct conclusion is that the assertion is correct but the reason is incorrect.

### Final Answer
- The correct option is: **Assertion is true, but Reason is false.**

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