The Feed back mechanism means the inhibition by the:

Options

A. end product
B. substrate
C. inhibitor
D. intermediate product

Answer

**Step-by-Step Solution:**

1. **Understanding Feedback Mechanism**: The feedback mechanism refers to a process in which the output of a system regulates its own production. In biological systems, this often involves enzymes and their products.

2. **Identifying Feedback Inhibition**: Feedback inhibition is a specific type of feedback mechanism where the end product of a metabolic pathway inhibits an enzyme that acts earlier in the pathway. This is a form of regulation that helps maintain homeostasis within the cell.

3. **Role of End Product**: In feedback inhibition, the end product of a reaction binds to an enzyme, preventing it from catalyzing the reaction. This means that when enough end product is produced, it signals the cell to stop producing more, thus conserving resources and energy.

4. **Evaluating Options**:
- **End Product**: This is the correct answer, as it is the substance that inhibits the enzyme's activity.
- **Substrate**: This is incorrect because the substrate is the reactant that the enzyme acts upon, not an inhibitor.
- **Inhibitor**: This is a general term and does not specifically refer to the feedback mechanism in this context.
- **Intermediate Product**: This is also incorrect as intermediate products are typically not involved in feedback inhibition.

5. **Conclusion**: Therefore, the feedback mechanism means the inhibition by the end product of the enzyme's activity.

**Final Answer**: The feedback mechanism means the inhibition by the **end product**.

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