Passing the signal at a synapse — practice questions

Question 1 · difficulty L1 · recall

A typical chemical synapse conducts in one direction mainly because:

• A. myelin covers the cleft
• B. both sides release identical transmitters simultaneously
• C. neurotransmitter is released presynaptically and receptors are postsynaptic
• D. ions cannot cross any membrane

Question 2 · difficulty L1 · recall

What is released from a presynaptic terminal at a chemical synapse?

• A. Neurotransmitter
• B. Myelin protein
• C. Cerebrospinal fluid
• D. Nissl granules

Question 3 · difficulty L1 · recall

What is the narrow gap between two cells at a chemical synapse called?

• A. Node of Ranvier
• B. Synaptic cleft
• C. Central canal
• D. Axon hillock

Question 4 · difficulty L2 · understanding

Why is transmission at a typical chemical synapse mainly one-way?

• A. The cleft allows current only forward
• B. Both cells release identical transmitters
• C. Release machinery is presynaptic and receptors are postsynaptic
• D. Postsynaptic membranes lack ion channels

Question 5 · difficulty L2 · understanding

What normally triggers synaptic vesicles to fuse with the presynaptic membrane?

• A. Closure of voltage-gated channels
• B. Potassium entry into the postsynaptic cell
• C. Breakdown of the myelin sheath
• D. Calcium entry into the presynaptic terminal

Question 6 · difficulty L3 · application

A toxin prevents synaptic vesicles from fusing with the presynaptic membrane. Which event fails first?

• A. Neurotransmitter release
• B. Axonal action-potential propagation
• C. Myelin formation
• D. DNA replication in the neuron

Question 7 · difficulty L3 · application

A neurotransmitter opens sodium-permeable channels on the postsynaptic membrane. What is the immediate effect?

• A. Postsynaptic hyperpolarisation
• B. Postsynaptic depolarisation
• C. Permanent loss of resting potential
• D. Formation of new myelin

Question 8 · difficulty L3 · application

Why is rapid removal of neurotransmitter from the synaptic cleft important?

• A. It converts the synapse into an electrical junction
• B. It keeps receptors permanently active
• C. It terminates the signal and allows the synapse to reset
• D. It prevents future vesicle production

Question 9 · difficulty L4 · analysis

Neuron Q receives excitatory input from one synapse and inhibitory input from another at the same time. What determines whether Q reaches threshold?

• A. The width of the synaptic clefts
• B. Only the first input to arrive
• C. Only the excitatory input
• D. The net summed effect of the inputs

Question 10 · difficulty L5 · analysis

Two synapses receive identical presynaptic action potentials. Synapse X has normal calcium entry, while synapse Y has none. Receptors are normal at both. What is expected?

• A. X transmits effectively while Y releases little or no transmitter
• B. Both transmit equally
• C. Y transmits more strongly
• D. Neither action potential reaches the terminals