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Which toxin blocks neuromuscular transmission by irreversibly binding to nicotin

ID: 275525 • Letter: W

Question

Which toxin blocks neuromuscular transmission by irreversibly binding to nicotinic acetylcholine receptors, thus preventing acetylcholine from opening postsynaptic ion channels?

A- Nicotine

B- Arecoline

C- Alpha-bungarotoxin

Which neurotransmitter is released at the majority of brain synapses, making it the most abundant neurotransmitter in the nervous system?

A- Acetlycholine

B- Dopamine

C- GABA

D- Glutamate

When a GABAA ionotropic receptor is stimulated by GABA in a developing neuron, which ions flow through its channel, and what effect does this have on the postsynaptic cell?

A- Cl, which hyperpolarizes the postsynaptic cell

B- Na+, which depolarizes the postsynaptic cell

C- K+, which hyperpolarizes the postsynaptic cell

D- Cl, which depolarizes the postsynaptic cell

Cell X fires an action potential and releases GABA onto Cell Y. Assuming only GABAA receptors are present on the postsynaptic membrane, which is at rest at –55mV, which ion is responsible for the changes that would be observed?

Which statement describes a possible outcome for a neurotransmitter after release into the synaptic cleft?

A- Activation of G-protein-coupled receptor on postsynaptic cell

B- Uptake into postsynaptic cell via endocytosis

C- Modulation by an enzyme, increasing its efficiency

D- Reuptake into postsynaptic terminal via transporter proteins

A- Activation of G-protein-coupled receptor on postsynaptic cell

B- Uptake into postsynaptic cell via endocytosis

C- Modulation by an enzyme, increasing its efficiency

D- Reuptake into postsynaptic terminal via transporter proteins

Explanation / Answer

1. C- Alpha-bungarotoxin

2. D. glutamate

3. A. Cl–, which hyperpolarizes the postsynaptic cell

4. A- Chloride

5. B- Uptake into postsynaptic cell via endocytosis