Which part of a neuron transmits an electrical signal to a target cell?

Correct Answer: D

Rationale: The axon is the part of a neuron that transmits an electrical signal (action potential) to a target cell, such as another neuron or muscle cell, via the synapse. Dendrites receive signals, and the soma (cell body) processes them, but the axon is responsible for transmission.

Correct Answer: B

Rationale: Ligand-gated channels open when a neurotransmitter (ligand) binds to them, allowing ions to flow. Voltage-gated channels respond to depolarization, not ligand-gated ones.

Correct Answer: D

Rationale: Metabotropic receptors require effector proteins (e.g., G-proteins) to initiate intracellular signaling cascades. Ionotropic receptors are ligand-gated channels that don’t use effector proteins.

Correct Answer: B

Rationale: The superior colliculus in the midbrain coordinates visual reflexes, including light reflexes (e.g., pupillary response via pretectal nuclei). The red nucleus and substantia nigra are motor-related, and the inferior colliculus processes sound.

Correct Answer: D

Rationale: The lumbar plexus (L1-L4) forms the femoral nerve from L2-L3-L4, innervating thigh muscles. It’s lateral to the inferior vena cava, formed from anterior rami, and includes more than the last three lumbar nerves.