Neural Signaling · Paper 1 — Free Biology HL Practice Questions

A motor neuron shows dendrites, a cell body, an axon with a myelin sheath, and terminal boutons at the axon's end. A nerve impulse arrives at the terminal boutons. Which structure receives the signal immediately after neurotransmitter is released from the terminal boutons?

In multiple sclerosis, progressive demyelination of axons leads to slowed or blocked nerve impulse conduction. Which property of intact myelin sheaths is directly responsible for rapid saltatory conduction along a myelinated axon?

A student examines a stained slide of a mammalian spinal cord motor neuron under a light microscope. She identifies a long, thin extension from the cell body that is wrapped by a series of Schwann cells, with small unmyelinated gaps between successive Schwann cells. Which of the following correctly identifies this structure and the primary function of these gaps?