Which type of respiration probably arose first?

Options

A. aerobic as it releases more energy
B. anaerobic as it releases more energy
C. aerobic as it is more complex
D. anaerobic as early atmosphere contained little or no oxygen

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question asks which type of respiration likely arose first on primitive Earth. We need to consider the environmental conditions of early Earth to answer this.

2. **Analyzing Early Earth Conditions:**
Primitive Earth had high temperatures, high pressure, and an inorganic mixture of gases. Importantly, it is noted that there was little to no oxygen present in the atmosphere.

3. **Types of Respiration:**
- **Aerobic Respiration:** This type of respiration requires oxygen and is more complex. It releases more energy compared to anaerobic respiration.
- **Anaerobic Respiration:** This type does not require oxygen and is simpler. It occurs in environments where oxygen is absent.

4. **Determining the First Type of Respiration:**
Given that the early atmosphere contained little or no oxygen, aerobic respiration could not have occurred. Therefore, the first type of respiration that likely arose would be anaerobic respiration.

5. **Evaluating the Options:**
- Option A: Aerobic as it releases more energy - Incorrect, as aerobic respiration requires oxygen.
- Option B: Anaerobic as it releases more energy - Incorrect, as anaerobic respiration releases less energy than aerobic.
- Option C: Aerobic as it is more complex - Incorrect, for the same reason as option A.
- Option D: Anaerobic as early atmosphere contained little or no oxygen - Correct, as this aligns with the conditions of primitive Earth.

6. **Conclusion:**
The correct answer is that anaerobic respiration probably arose first due to the lack of oxygen in the early atmosphere.

**Final Answer:**
Anaerobic respiration arose first as the early atmosphere contained little or no oxygen.

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