1 – Wrong
The nervous system does not only rely on electrical impulses to work. It also relies on transmitter chemicals and molecules, nerve cells, spinal chord and the brain.
2 – Correct
e.g. the nervous system sends signals to contract or relax an effector muscle.
The pituitary gland releases ADH to reabsorb water from the kidneys.
3 – Correct
The central nervous system produces reflex actions (fastest responses in the body).
4 – Wrong
The nervous system also relies on chemicals such as noradrenaline or acetylcholine to work.
5 – Correct
Parts of the nervous system such as the hypothalamus control the pituitary gland (which is part of the hormonal system).
2, 3 and 5 are correct.