AP Biology : Understanding Neurotransmitters

Study concepts, example questions & explanations for AP Biology

varsity tutors app store varsity tutors android store

Example Questions

Example Question #1 : Understanding Neurotransmitters

What kind of molecule can be used to inhibit the effects of a neurotransmitter?

Possible Answers:

Protagonistic molecules

Antagonistic molecules

Agonistic molecules

None of these

Synergistic molecules

Correct answer:

Antagonistic molecules

Explanation:

Neurotransmitters in the human body are under tight control. Many drugs, such as anti-depressants or drugs for ADHD, limit neurotransmitter responses. Antagonistic molecules will inhibit neurotransmitters and are used in many drugs. These molecules structurally interact with receptor proteins, either blocking the active site or binding allosterically to alter the binding site shape. Antagonists can be competitive or uncompetitive.

In contrast, agonists are molecules that structurally resemble the ligand for a certain receptor and can bind to the active site to trigger a response. Nicotine, for example, is an agonist to certain acetylcholine receptors and can trigger these receptors.

Example Question #2 : Understanding Neurotransmitters

Which of the following is true regarding a synapse?

I. The neurotransmitter attaches to receptors on the presynaptic neuron

II. Propagation of the nerve signal is slowest at the synapse

III. Calcium ion channels located on the membrane of postsynaptic neuron facilitate the release of neurotransmitters

Possible Answers:

II and III

II only

I only

I and III

Correct answer:

II only

Explanation:

Neurotransmitters, such as acetylcholine, are chemical signals that transmit action potentials from one neuron to another. This process occurs at the synapse, where a neurotransmitter is released from the presynaptic neuron. This neurotransmitter travels across the synaptic cleft and binds to a receptor on the postsynaptic neuron. Statement I is thus false.

The rate of propagation of a nerve signal is limited by the synapse because neurotransmitters must diffuse across the gap; statement II is true.

Calcium ions are very important in the release of neurotransmitters. Voltage-gated calcium channels are located on the axon of the presynaptic neuron. When an action potential reaches the synapse, calcium ions are allowed to enter into the presynaptic neuron. This influx of calcium ions interacts with vesicles containing neurotransmitters and causes them to release their contents into the synaptic cleft. Statement III is false because calcium ion channels are located on the membrane of presynaptic neuron, not postsynaptic neuron.

Example Question #1 : Understanding Neurotransmitters

A postsynaptic neuron has undergone a mutation that renders its SNARE proteins nonfunctional. What is the result of this mutation?

Possible Answers:

Neurons are unable to deliver neurotransmitter into the synaptic cleft

Action potentials are unable to propagate down the postsynaptic axon

Neurons are unable to maintain resting membrane potential

Neurons are unable to synthesize neurotransmitter

None of the other answers

Correct answer:

Neurons are unable to deliver neurotransmitter into the synaptic cleft

Explanation:

The SNARE proteins are responsible for allowing vesicles filled with neurotransmitter to fuse with the cell membrane at the synaptic cleft, resulting in exocytosis. Without these proteins, the neurotransmitter cannot propagate the signal to any other cells.

Neurotransmitter synthesis occurs via translation or synthesis in the smooth endoplasmic reticulum, depending on the identity of teh molecule. Resting potential is determined by the sodium-potassium pump, and action potential propagation relies heavily on voltage-gated sodium channels and myelin.

Example Question #4 : Understanding Neurotransmitters

Which of the following types of molecules could potentially be a neurotransmitter?

I. Peptides

II. Gases

III. Monoamines

Possible Answers:

I and III

I, II, and III

I and II

III only

Correct answer:

I, II, and III

Explanation:

All of the choices could potentially be neurotransmitters.

Peptide neurotransmitters are proteins. An example of a peptide neurotransmitter is somatostatin. Nitric oxide is the most well-known gaseous neurotransmitter. Monoamines are molecules that contain an amine group connected to an aromatic ring. These molecules are derived from aromatic amino acids. Dopamine, norepinephrine, and epinephrine are very well-known monoamine neurotransmitters.  

Example Question #2 : Understanding Neurotransmitters

Which answer gives the two possible effects of a neurotransmitter on a postsynaptic neuron?

Possible Answers:

Inhibitory or excitatory

Inhibitory or no effect

Excitatory or no effect

Apoptotic or no effect

Correct answer:

Inhibitory or excitatory

Explanation:

Receptors on postsynaptic neurons are connected to ion channels. When the neurotransmitter binds to the receptor, the channel opens, making that neuron more or less likely to have an action potential depending upon which type of ion the channel allows to enter or exit the neuron. The result is either an excitatory postsynaptic potential (EPSP) or an inhibitory postsynaptic potential (IPSP).

Example Question #6 : Understanding Neurotransmitters

Which of the following is true regarding the parasympathetic nervous system?

Possible Answers:

It works to decrease heart rate and blood pressure

It works to funnel blood to the muscles in preparation for a fight-or-flight response

It works to elevate heart rate and blood pressure

It is a part of the somatic nervous system

It is a part of the central nervous system

Correct answer:

It works to decrease heart rate and blood pressure

Explanation:

The parasympathetic division of the autonomic nervous system promotes the "rest and digest mode." The somatic nervous system controls voluntary skeletal muscles, but the parasympathetic nervous system controls involuntary smooth & cardiac muscles. The neurons of the parasympathetic nervous system release acetylcholine, which is a neurotransmitter that leads to a decrease in heart rate and blood pressure. Results of increased parasympathetic activity include: decreasing blood flow to skeletal muscles, increasing blood flow to the gut, constricting pupils, and glycogenesis. 

Example Question #3 : Understanding Neurotransmitters

Which neurotransmitter is involved in muscle movement?

Possible Answers:

Serotonin

GABA

Acetylcholine

Dopamine

Glutamate

Correct answer:

Acetylcholine

Explanation:

The correct answer is ACh (acetylcholine) because it is involved with muscle contraction. It is released at the neuromuscular junction, the site where the neuron and muscle meet.

Learning Tools by Varsity Tutors

Incompatible Browser

Please upgrade or download one of the following browsers to use Instant Tutoring: