When a person enters a dark room, in the rods of his eyes:

1. cGMP levels are high.
2. cGMP levels are low.
3. G protein is degraded.
4. An influx of Ca²⁺ ions is prevented.

A proprioceptor can detect:

1. taste
2. odor
3. gravity
4. pain

As a sound grows in intensity while remaining at one frequency the basilar membrane:

1. vibrates more toward the base.
2. vibrates more toward the apex.
3. does not vibrate at all.
4. vibrates equally all along its length.

Identify the correct statement regarding the semicircular canals of the human internal ear:
1. There are three of them, all oriented in the same direction but sensitive to all possible head motions.
2. There are six of them, organized in three pairs with each pair sensitive to one kind of motion, such as up or down.
3. There are three stacked in a random fashion; all contributing to fluid flow through the utricle and saccule which interpret the direction of head movement from the resulting
fluid flow.
4. There are three oriented in different planes so that angular acceleration can be detected.

The skeletal muscles in humans are innervated by:

1. somatic neural system
2. sympathetic neural system
3. parasympathetic neural system
4. All of these

Schwann cells:
1. are found in the PNS
2. produce a myelin sheath around axons
3. are neuroglia
4. All of the above.

All the following statements regarding an action potential are true except that they:
1. are all or none events
2. occur when depolarization reaches a threshold potential
3. do not add or interfere with one another
4. are propagated along axons with a decrease in amplitude

A drug acts as an inhibitor of acetylcholinesterase. Administration of this drug would lead to:
1. accumulation of acetylcholine in the synaptic cleft
2. accumulation of acetylcholinesterase in the synaptic cleft
3. muscle relaxation
4. repeated action potentials

The part of the mammalian brain that has shown maximum relative growth is the:
1. the cerebellum
2. the cerebrum
3. the diencephalon
4. corpora quadrigemina

Interneurons:
1. are seen only in the central nervous system
2. are seen only in the peripheral nervous system
3. are always motor in nature
4. occur in the central nervous system and link afferent and efferent neurons