Muscle fiber (cell) in the ventricular tissue.

Correct Answer: A

Rationale: Purkinje cells are specialized muscle fibers in the heart’s ventricles, conducting electrical signals for contraction. GBS is a disorder, dendrites and axon terminals are neuron parts.

Correct Answer: C

Rationale: Glutamate is the primary excitatory neurotransmitter in the CNS, always depolarizing postsynaptic neurons. Glycine and GABA are inhibitory, and norepinephrine has mixed effects.

Correct Answer: A

Rationale: Jerking away from a hot stove is a spinal reflex (e.g., withdrawal reflex), mediated by sensory neurons, interneurons, and motor neurons in the spinal cord, bypassing higher brain centers for speed.

Correct Answer: C

Rationale: The autonomic nervous system mediates fight-or-flight (sympathetic) and rest-and-digest (parasympathetic) responses, regulating involuntary functions like heart rate and digestion.

Correct Answer: A

Rationale: A motor neuron stimulating the hamstring is a peripheral neuron (lower motor neuron in the PNS), directly innervating muscles. Central neurons are CNS, basal nuclei are brain structures, and interneurons connect neurons.