Final answer:
The endomembrane system includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and plasma membrane, but not peroxisomes. The organelle not part of this system among the choices given is (A) the peroxisome.
Step-by-step explanation:
The endomembrane system in eukaryotic cells is responsible for the modification, packaging, and transport of proteins and lipids. This system includes components such as the nuclear envelope, the endoplasmic reticulum (both smooth and rough ER), Golgi apparatus, lysosomes, vesicles, as well as the plasma membrane. However, certain organelles such as mitochondria, chloroplasts, and peroxisomes are not considered part of this system.
When considering the components listed in the student's question, the one that is not part of the endomembrane system is (A) the peroxisome. Other components like the Golgi complex, smooth ER, endosome, and rough ER are all integral parts of the endomembrane system.