Body temperature, sensory perception, and the onset of sleep are partially regulated by the neurotransmitter:

Correct Answer: B

Rationale: Serotonin influences body temperature (hypothalamus), sensory perception (modulation), and sleep (via raphe nuclei). Glycine is inhibitory, acetylcholine aids arousal, dopamine affects movement, and enkephalins reduce pain.

Correct Answer: B

Rationale: Dendrites in motor neurons receive signals from other neurons, forming synapses (B) to integrate incoming information. They do not act as sensory organs (A) or receptors (C)—those roles belong to sensory neurons. 'None of the above' (D) is incorrect as dendrites have a clear synaptic role.

Correct Answer: B

Rationale: The frontal lobe, particularly the prefrontal cortex, is critical for intelligence, executive function, and decision-making (B). Gait control involves motor areas and basal ganglia (A is partial), memory is more hippocampal (C), and smell sensation is primarily olfactory bulb and temporal lobe (D). B is the most accurate.

Correct Answer: A

Rationale: Medullary postural reflexes include tonic labyrinthine (B) and neck reflexes (C, D), adjusting posture via vestibular input. The optical righting reflex (A) is a midbrain/cortical reflex using visual cues, not medullary. A is the exception.

Correct Answer: B

Rationale: The spinothalamic tract carries pain and temperature (B, correct), not pressure (A, dorsal columns). It terminates in the thalamus (C, also true), but tuning fork tests vibration (D, dorsal columns). B is most specific.