Acetylcholine is an agonist or an excitatory neurotransmitter also found in a part of the brain responsible for forming new memories and stimulating muscle contraction

It is characteristic of robins to build nests. This provides an example of:

a. intrinsic motivation. b. homeostasis. c. a drive. d. a need. e. an instinct.

What structure is primarily responsible for focusing light onto the back of the eye?

A) Cornea B) Fovea C) Lens D) Retina