The following metal ion activates many enzymes, participates in the oxidation of glucose to produce ATP and with Na, is responsible for the transmission of nerve signals.

Options

A. `Iron`
B. `Copper`
C. `Calcium`
D. `Potassium`

Answer

To solve the question, we need to identify the metal ion that fulfills the following criteria:

1. Activates many enzymes.
2. Participates in the oxidation of glucose to produce ATP.
3. Works with sodium (Na) in the transmission of nerve signals.

Let's analyze the options provided: iron, copper, calcium, and potassium.

### Step-by-Step Solution:

**Step 1: Identify the metal ions and their functions.**
- **Iron (Fe):** Primarily involved in oxygen transport and electron transfer but not directly in enzyme activation related to glucose oxidation or nerve signal transmission.
- **Copper (Cu):** Involved in various enzymatic reactions and electron transport but not specifically tied to glucose oxidation or nerve signaling.
- **Calcium (Ca):** Important for muscle contraction and neurotransmitter release but does not directly participate in glucose oxidation.
- **Potassium (K):** Known to activate many enzymes, particularly around 60, and is crucial in the glucose oxidation process. It also plays a significant role in the sodium-potassium pump, which is essential for nerve signal transmission.

**Step 2: Evaluate the role of potassium.**
- Potassium is a vital electrolyte that activates numerous enzymes, aiding in various biochemical reactions.
- It is involved in the process of glucose oxidation, which is essential for ATP production.
- The sodium-potassium pump (Na+/K+ ATPase) is critical for maintaining the membrane potential of neurons, facilitating the transmission of nerve signals.

**Step 3: Conclusion.**
Based on the analysis, the metal ion that meets all the criteria mentioned in the question is **Potassium (K)**.

### Final Answer:
The correct answer is **Potassium (K)**.

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