Which of the following is not a component of the

endomembrane system?

a. mitochondrion

b. Golgi apparatus

c. endoplasmic reticulum

d. lysosome

Golgi apparatus is an endomembrane that helps in the processing and packaging of protein and lipid molecules. So, option b is wrong.

The endoplasmic reticulum is responsible for the production, processing, and packaging of protein, hence is an endomembrane. So, option c is wrong as well.

Lysosomes are responsible for digestion both in the intracellular and extracellular of the cell, as well as bodily defense and autophagy. Option d is wrong too.

The Endomembrane system is a collection of organelles that work together for transportation and packaging, as mitochondria help in cellular respiration hence is not an endomembrane. Thus, option a is correct.

Mitochondria is not a component of endomembrane system as they do not perform coordinated function of transportation and packaging.