________ testing enables an increasing number of people to know that they have a risk for illness even before they develop that illness.

Electroconvulsive therapy has proven successful in treating

a. schizophrenia. b. general anxiety disorder. c. obsessive-compulsive disorder. d. severe depression. e. ADHD.

The primary purpose of the myelin sheath is to ______

a. provide a place for neural respiration and cell metabolism to occur b. provide a soft covering to hold axons in place c. insulate the neuron so it can transmit information more efficiently d. receive messages from outside the neuron and carry them to the cell nucleus