While serving in Iraq with the U. S. Army, Sergeant Carlos Rogers had an improvised explosive device detonate under his vehicle and cause a concussion. Years later, he's finding that he's having problems with his short-term memory, mood swings, and changes to his personality. His psychiatrist orders an MRI scan to determine if the problems are based.

Biologically  based

Explanation:

Magnetic Resonance Imaging (MRI) is a medical equipment/device used to diagnose the internal organs of the brain. It is something which is not recommended in a psychiatric therapy. Thus, if MRI is recommended by a psychiatrist, it simply means that the psychiatrist want to get assured that the problems related with the brain are not due to any biological cause.

a scenario where a cell may be needed to perform a form of endocytosis is when transporting large molecules. a scenario where a cell may be needed to perform a form of exocytosis is when releasing the large molecule from the cell.