Photosynthesis and respiration are central to which cycle?

Options

A. The nitrogen cycle
B. The carbon cycle
C. The phosphorus cycle
D. The sulphur cycle

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis and Respiration**:
- Photosynthesis is the process by which plants convert carbon dioxide (CO2) from the atmosphere into organic compounds, primarily sugars, using sunlight and chlorophyll.
- Respiration is the process by which living organisms, including plants and animals, break down these organic compounds to release energy, which also produces CO2 as a byproduct.

2. **Role of Plants in the Cycle**:
- Plants play a crucial role in fixing carbon dioxide from the atmosphere through photosynthesis. They convert CO2 into organic compounds, contributing to the biomass of the ecosystem.

3. **Transfer of Carbon Through the Food Chain**:
- When herbivores eat plants, they consume the organic compounds, which allows carbon to move from plants to animals. This transfer continues up the food chain as carnivores eat herbivores.

4. **Return of Carbon to the Environment**:
- When organisms die, their bodies decompose, returning carbon to the geosphere (soil). This carbon can eventually be released back into the atmosphere as CO2 through respiration or decomposition.

5. **Cycle Completion**:
- The cycle is completed when the CO2 produced from respiration or decomposition is again available for photosynthesis, thus recycling carbon within the ecosystem.

6. **Identifying the Cycle**:
- Given that both photosynthesis and respiration are integral processes that facilitate the movement and recycling of carbon in the ecosystem, the cycle in question is the **Carbon Cycle**.

**Final Answer**: The cycle that photosynthesis and respiration are central to is the **Carbon Cycle**.

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