Question

what happens as a result of ion flow at a presynaptic terminal?
multiple choice
synaptic vesicles migrate to the plasma membrane and release acetylcholine.
acetylcholine is passively transported from the presynaptic neuron.
acetylcholine is actively transported to the postsynaptic neuron.
ligand - gated sodium channels open.

Explanation:

When there is ion - flow at a presynaptic terminal, calcium ions enter the presynaptic terminal. This influx of calcium causes synaptic vesicles to migrate to the plasma membrane and release neurotransmitter (such as acetylcholine in some synapses) via exocytosis. Acetylcholine is not passively or actively transported in the ways described in the other options immediately after ion - flow at the presynaptic terminal. Ligand - gated sodium channels open at the postsynaptic membrane in response to the binding of neurotransmitter, not directly as a result of ion - flow at the presynaptic terminal.

Answer:

Synaptic vesicles migrate to the plasma membrane and release acetylcholine.