Biosphere is

Options

A. a component in the ecosystem
B. composed of the plants present in the soil
C. life in the outer space
D. composed of all living organisms present on earth which interact with the physical environment.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Term "Biosphere":**
- The biosphere is defined as the global sum of all ecosystems. It is the zone of life on Earth, a closed system, and largely self-regulating.

2. **Components of the Biosphere:**
- The biosphere includes all living organisms (flora, fauna, and microorganisms) and their interactions with the physical environment (abiotic components like air, water, and soil).

3. **Biosphere vs. Ecosystem:**
- An ecosystem is a smaller unit that includes a community of living organisms interacting with their environment. The biosphere encompasses many ecosystems, making it a much larger concept.

4. **Misconceptions about the Biosphere:**
- It is important to clarify that the biosphere is not limited to just plants or any single group of organisms. It includes all forms of life.
- The biosphere does not refer to life in outer space; it pertains specifically to life on Earth.

5. **Conclusion:**
- The correct definition of the biosphere is that it is composed of all living organisms present on Earth, interacting with the physical environment. Therefore, the biosphere is the largest unit of the living world.

**Final Answer:**
The biosphere is the global sum of all ecosystems, including all living organisms and their interactions with the physical environment.

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