If the endoplasmic reticulum were removed from the cell, which organelle would not be able to function properly, and why? mitochondria, because they rely on the er as an energy source ribosomes, because they receive proteins made by the er golgi apparatus, because it packages proteins received from the er cytoplasm, because it relies on the er for structural support

Answer;
Golgi apparatus.

This is because golgi apparatus receive lipids and proteins from the  endoplasmic reticulum, modifies them, concentrates and packages them into vesicles. 

Explanation;
Golgi apparatus, also called the golgi complex or golgi body are membrane bound organellses in eukaryotic cells that are made up of series of flattened, stacked pouches called cisternae. 
Their role is to transport , modifying and packaging lipids and proteins into vesicles, so as to be taken to the target destinations.
These proteins and lipids are made in the endoplasmic reticulum, in fact the golgi apparatus is located near to them, therefore the removal of endoplasmic reticulum means that the golgi apparatus will not function. 

the answer should be Golgi apparatus, because it packages proteins received from the ER. I am taking this test too... hope this helps! :)