Answer:
The portion of the membrane system in eukaryotic cells that is responsible for the making of lipids and breaking down toxic substances is the smooth ER (endoplasmic reticulum). Other functions of smooth ER include storage of calcium ions (in muscle cells).
Step-by-step explanation:
This should be distinguished from the role of rough ER (endoplasmic reticulum), which is the synthesis of membranes and secretory proteins.