How many of the following are not included under endomembrane system? 
Lysosomes; Mitochondria; Endoplasmic reticulum; Chloroplast; Peroxisomes; Vacuoles; Golgi complex; Centrosome; Ribosomes. 

Mitochondria, chloroplasts, peroxisomes, vacuoles, centrosomes, and ribosomes are not included in the endomembrane system.

The endomembrane system includes organelles that are surrounded by a single lipid bilayer membrane and are interconnected by the transfer of membrane vesicles. These organelles include the endoplasmic reticulum, Golgi complex, lysosomes, and vesicles that transport molecules between these organelles and to the plasma membrane.