The simplest of all nutrient cycles operating in an ecosystem is _______ cycle.

Options

A. Carbon
B. Phosphorous
C. Nitrogen
D. Oxygen

Answer

To determine the simplest nutrient cycle operating in an ecosystem, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Nutrient Cycles**: Nutrient cycles are pathways through which essential elements and compounds circulate through the ecosystem, involving biological, geological, and chemical processes.

2. **Identify Common Nutrient Cycles**: The most commonly discussed nutrient cycles include the carbon cycle, nitrogen cycle, oxygen cycle, and phosphorus cycle.

3. **Evaluate the Phosphorus Cycle**: The phosphorus cycle is characterized by the movement of phosphorus through the lithosphere (rocks), hydrosphere (water), and biosphere (organisms). Unlike other cycles, phosphorus does not have a gaseous phase and is not found in the atmosphere.

4. **Consider the Complexity of Other Cycles**:
- **Carbon Cycle**: Involves multiple forms (CO2, organic compounds) and processes (photosynthesis, respiration).
- **Nitrogen Cycle**: Involves nitrogen fixation, nitrification, denitrification, and is more complex due to the involvement of various bacteria.
- **Oxygen Cycle**: Involves photosynthesis and respiration, which also adds complexity.

5. **Conclusion**: Since the phosphorus cycle operates primarily through geological processes and biological uptake without a gaseous phase, it is considered the simplest nutrient cycle.

### Final Answer:
The simplest of all nutrient cycles operating in an ecosystem is the **phosphorus cycle**.

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