Question 1

Which of the following best describes the primary mechanism by which an action potential in a presynaptic neuron leads to neurotransmitter release at a chemical synapse?

Accepted Answer

Opening of voltage-gated Ca$$^{2+}$$ channels in the presynaptic terminal

Question 2

A researcher bathes a neuron in a solution with very low Ca$$^{2+}$$ concentration and stimulates it to fire action potentials. What is the most likely outcome regarding neurotransmitter release?

Accepted Answer

Neurotransmitter release will be greatly reduced or absent due to insufficient Ca$$^{2+}$$ influx

Question 3

Which type of synaptic connection is formed when a presynaptic axon synapses directly onto the soma of a postsynaptic neuron?

Accepted Answer

Axo-somatic

Question 4

What is the main functional advantage of axo-axonic synapses in neural circuits?

Accepted Answer

They enhance the specificity of synaptic input by modulating neurotransmitter release from a single terminal

Question 5

During presynaptic facilitation at an axo-axonic synapse, what happens to the postsynaptic potential (PSP) in the recipient neuron?

Accepted Answer

The amplitude and/or duration of the PSP increases

Question 6

Which of the following best explains the 'kiss and run' mechanism of neurotransmitter release?

Accepted Answer

A vesicle briefly contacts the presynaptic membrane, releases some neurotransmitter, and then detaches without full fusion

Question 7

A postsynaptic neuron receives both excitatory and inhibitory inputs. If an axo-axonic synapse causes presynaptic inhibition of an excitatory input, what is the expected effect on the postsynaptic potential?

Accepted Answer

The excitatory postsynaptic potential (EPSP) will be smaller in amplitude

Question 8

Which of the following statements about peptide neurotransmitter release is correct?

Accepted Answer

Peptide neurotransmitters are released from secretory granules and require a high frequency of action potentials to trigger release

Question 9

Which of the following best describes the role of voltage-gated Ca$$^{2+}$$ channels in neurotransmitter release?

Accepted Answer

They open in response to depolarization, allowing Ca$$^{2+}$$ influx that triggers vesicle fusion

Question 10

A scientist directly injects Ca$$^{2+}$$ into a presynaptic terminal in the absence of an action potential. What is the most likely result?

Accepted Answer

Neurotransmitter release will occur even without an action potential

Question 11

Which of the following synaptic arrangements allows for bidirectional communication between neurons?

Accepted Answer

Bi-directional synapse

Question 12

What is the typical synaptic delay (the time from arrival of an action potential at the terminal to the beginning of the postsynaptic response) at a chemical synapse?

Accepted Answer

$$0.2 ms$$

Question 13

Which of the following is a key difference between the release of classical neurotransmitters and peptide neurotransmitters?

Accepted Answer

Peptide neurotransmitter release requires a higher and more prolonged Ca$$^{2+}$$ influx than classical neurotransmitter release

Question 14

In the context of synaptic transmission, what is meant by 'active zones'?

Accepted Answer

Specialized areas of the presynaptic terminal where synaptic vesicles dock and release neurotransmitter

Question 15

Which of the following best describes the effect of presynaptic inhibition at an axo-axonic synapse?

Accepted Answer

It decreases the amplitude and/or duration of the action potential in the recipient terminal

Question 16

A mutation causes voltage-gated Ca$$^{2+}$$ channels in the presynaptic terminal to remain closed even during depolarization. What is the most likely effect on synaptic transmission?

Accepted Answer

Neurotransmitter release will be severely impaired or absent

Question 17

Which of the following best explains why presynaptic facilitation at an axo-axonic synapse can increase the specificity of neural signaling?

Accepted Answer

It selectively enhances neurotransmitter release from a specific terminal without affecting others

Question 18

In a classic experiment, a gill-withdrawal reflex in Aplysia is sensitized by delivering an electric shock to the animal's head. Which molecular mechanism underlies the increased neurotransmitter release from the sensory neuron?

Accepted Answer

Activation of a G-protein coupled receptor (GPCR) leading to increased cAMP and protein kinase A activity

Question 19

Which of the following is NOT a type of anatomical synaptic connection?

Accepted Answer

Axo-glial

Synaptic Connections and Neurotransmitter Release Mechanisms

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