Answer:
Endoplasmic reticulum is the defective organelle in most CF.
Explanation:
This is because of mutation(deletion) in the proteins of these organelle. The CFTR protein -a transmembrane regulator get stucked inside the E.R, thus the CFTR chloride protein channel is blocked. Therefore the outflow of Cl and water out of the cell is obstructed.
Consequently, the mucus from blocked fluid flow, clogs the lungs, the fallopian tube, sweat duct, and other places.