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 regarding which process does not occur in the endomembrane system, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding the Endomembrane System**:
The endomembrane system consists of several organelles that work together to modify, package, and transport lipids and proteins. Key components of the endomembrane system include the nuclear membrane, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and the plasma membrane.

2. **Analyzing Each Option**:
- **Option A: Aerobic Respiration**:
- Aerobic respiration primarily occurs in the mitochondria, which is not part of the endomembrane system. Therefore, this process does not occur within the endomembrane system.

- **Option B: Protein Glycosylation**:
- Protein glycosylation occurs in the Golgi apparatus, which is a part of the endomembrane system. Thus, this process does occur in the endomembrane system.

- **Option C: Excretion**:
- Excretion in cells is often facilitated by lysosomes, which are also part of the endomembrane system. Therefore, this process occurs within the endomembrane system.

- **Option D: Synthesis of Lipid-like Steroidal Hormones**:
- This synthesis occurs in the smooth endoplasmic reticulum, which is a component of the endomembrane system. Hence, this process is included in the endomembrane system.

3. **Conclusion**:
After analyzing all the options, we find that the only process that does not occur in the endomembrane system is **aerobic respiration**.

### Final Answer:
**Aerobic respiration** does not occur in the endomembrane system.

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