What region of the spinal cord contains motor neurons that direct the movement of skeletal muscles?

Correct Answer: A

Rationale: The anterior horn (A) contains somatic motor neurons controlling skeletal muscles. The posterior horn (B) processes sensory input, lateral horn (C) houses autonomic neurons, and alar plate (D) is an embryonic term region, not adult structure. A is correct.

Correct Answer: D

Rationale: In the peripheral nervous system (PNS), a bundle of axons is called a nerve. A nucleus refers to a cluster of cell bodies in the CNS, a ganglion is a cluster of cell bodies in the PNS, and a tract is a bundle of axons in the CNS.

Correct Answer: C

Rationale: Chemoreceptors detect chemical stimuli, such as molecules (e.g., odors or tastes), in the environment or body. Thermoreceptors detect temperature, not light, sound, or vibration.

Correct Answer: A

Rationale: Mechanically gated channels open in response to physical stimuli, such as pressure or stretch (e.g., in touch receptors). Chemical stimuli affect ligand-gated channels.

Correct Answer: A

Rationale: GABA (gamma-aminobutyric acid) is the primary inhibitory neurotransmitter in the CNS, causing hyperpolarization. Acetylcholine, glutamate (excitatory), and norepinephrine have varied effects.