Mark the incorrectly matched pair w.r.t. conduction of nerve impulse through a nerve fibre.

Options

A. Depolarisation - Opening of `Na^(oplus)` channels and rapid influx of `Na^(oplus)` ions
B. Polarisation - Ionic gradient is maintained by `Na^(oplus)– K^(oplus)` pump which transport `3Na^(oplus)` outwards for `2K^(oplus)` into the cell
C. Depolarisation - High permeability of the axon membrane for `K^(oplus)`
D. Repolarisation - High permeability of the membrane for `K^(oplus)` and rapid outflux of `K^(oplus)` ions

Answer

To solve the question of marking the incorrectly matched pair with respect to the conduction of nerve impulse through a nerve fiber, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Process of Nerve Impulse Conduction**:
- Nerve impulse conduction involves three main phases: polarization, depolarization, and repolarization. Each phase has specific characteristics related to ion movement across the nerve cell membrane.

2. **Define Polarization**:
- In the resting state, the nerve cell is polarized, meaning the inside of the cell is negatively charged compared to the outside. This is maintained by the sodium-potassium pump, which pumps 3 sodium ions (Na⁺) out of the cell and 2 potassium ions (K⁺) into the cell.

3. **Define Depolarization**:
- During depolarization, the membrane becomes more permeable to sodium ions (Na⁺). Sodium channels open, allowing Na⁺ to rush into the cell, causing the inside to become positively charged.

4. **Define Repolarization**:
- After depolarization, repolarization occurs. The permeability of the membrane increases for potassium ions (K⁺), allowing K⁺ to flow out of the cell, restoring the negative charge inside the cell.

5. **Analyze the Options**:
- Now, we will evaluate the provided options to identify which one is incorrectly matched:
- **Option 1**: Depolarization involves the opening of Na⁺ channels and rapid influx of Na⁺ ions. (Correct)
- **Option 2**: Polarization involves the ionic gradient maintained by Na⁺ and K⁺ pump. (Correct)
- **Option 3**: Depolarization involves hypermobility of the adjacent membrane for K⁺. (Incorrect - it should be Na⁺)
- **Option 4**: Repolarization involves high permeability of the membrane for K⁺ and rapid outflux of K⁺ ions. (Correct)

6. **Identify the Incorrectly Matched Pair**:
- Based on the analysis, **Option 3** is the incorrectly matched pair because it incorrectly states that depolarization involves hypermobility of K⁺, when it actually involves Na⁺.

### Final Answer:
The incorrectly matched pair is **Option 3**.

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