All of the following processes occur in the endomembrane system , except

Options

A. aerobic respiration
B. protein glycosylation
C. excretion
D. synthesis of lipid - like steroidal hormones

Answer

To solve the question "All of the following processes occur in the endomembrane system, except," we need to identify which of the listed processes does not take place within the endomembrane system. The endomembrane system includes organelles such as the endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles.

### Step-by-Step Solution:

1. **Understand the Endomembrane System**:
- The endomembrane system comprises various organelles that work together to modify, package, and transport lipids and proteins. Key components include the endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and vesicles.

2. **Evaluate Each Option**:
- **Option 1: Aerobic Respiration**: This process occurs in the mitochondria, not in the endomembrane system. Therefore, it is a strong candidate for the answer.
- **Option 2: Protein Glycosylation**: This process occurs in the Golgi apparatus, which is part of the endomembrane system. Hence, this option is not correct.
- **Option 3: Excretion**: This can involve lysosomes and vesicles in the endomembrane system, so it is also not correct.
- **Option 4: Synthesis of Lipid-like Steroidal Hormones**: This process occurs in the smooth endoplasmic reticulum, which is part of the endomembrane system. Thus, this option is also not correct.

3. **Conclusion**:
- Since aerobic respiration is the only process that does not occur in the endomembrane system, the correct answer is **Option 1: Aerobic Respiration**.

### Final Answer:
**Option 1: Aerobic Respiration**