A living organism in terms of its energy requirements from the environment, operates as

Options

A. An open system
B. A closed system
C. An inefficient system
D. An incognizable system.

Answer

**Step-by-Step Solution:**

1. **Understanding Thermodynamic Systems**: Begin by recognizing that thermodynamic systems can be classified into three types: open systems, closed systems, and isolated systems.

2. **Defining Open Systems**: An open system is one where both energy and matter can be exchanged with the environment. This means that living organisms can take in energy (e.g., food, sunlight) and matter (e.g., nutrients, gases) from their surroundings.

3. **Defining Closed Systems**: In a closed system, energy can be exchanged, but matter cannot. This means that while energy can enter or leave the system, the matter remains constant within the system.

4. **Defining Isolated Systems**: An isolated system is one where neither energy nor matter is exchanged with the environment. This type of system is theoretical and does not occur in living organisms.

5. **Applying to Living Organisms**: Living organisms engage in various life processes such as eating, digestion, and excretion. They take in food (matter) and convert it into energy, while also releasing waste materials back into the environment.

6. **Conclusion**: Since living organisms exchange both energy and matter with their environment, they operate as open systems.

**Final Answer**: A living organism in terms of its energy requirements from the environment operates as an **open system**.

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