Which structure in the motor neuron is required for saltatory conduction?

State the approximate value of the membrane potential at X.

Describe the movements in ions that occur during time t.

Compare and contrast the cumulative increase in mass of the three groups of colonies once they were placed in the field.

Explain how neonicotinoids affect synaptic transmission in insects.

The diagram shows the synaptic transmission of nerve impulses by the neurotransmitter acetylcholine. 

[Source: Zhang, X. A Mathematical Model of a Neuron with Synapses based on Physiology. Nat Prec (2008).
https://doi.org/10.1038/npre.2008.1703.1 available at https://www.nature.com/articles/npre.2008.1703.1
Source adapted.]

What is the fate of acetylcholine immediately after binding to the receptor?

A. It is pumped into the postsynaptic neuron.

B. It diffuses into the presynaptic neuron.

C. It is broken down in the synaptic cleft.

D. It binds to another receptor in the postsynaptic neuron.

Common pesticides used by gardeners contain neonicotinoids.

[Source: © International Baccalaureate Organization 2018]

What is the effect of a neonicotinoid pesticide on the transmission of a nerve impulse between neurons in an insect?

A. It prevents the release of acetylcholine from the presynaptic membrane.

B. It widens the synaptic cleft so diffusion of acetylcholine across the gap is slower.

C. It irreversibly binds with acetylcholine receptors on the postsynaptic membrane.

D. It interferes with the enzymatic breakdown of acetylcholine by acetylcholinesterase.

The diagram shows a motor neuron.

[Source: © International Baccalaureate Organization 2019]

What are the biochemical nature and function of the myelin sheath?

A. The myelin sheath is mainly protein which allows growth of the axon.

B. The myelin sheath is mainly protein which acts as membrane carriers.

C. The myelin sheath is mainly lipid which allows saltatory conduction.

D. The myelin sheath is mainly lipid which provides an energy source.

The diagram shows a graph of an action potential.

Using the data in the graph, predict how the use of neonicotinoid pesticides will affect bumblebee populations.

Outline how neurons generate a resting potential.

Explain how a nerve impulse is passed on to other neurons.

Y is the threshold potential. State what happens when the threshold potential is reached.

Describe the effect of neonicotinoid pesticides on the nervous system of insects.

The decline in European honeybee (Apis mellifera) populations may be linked to neonicotinoid pesticides. What effect do these pesticides have on the nervous system of insects?

A. They prevent acetylcholinesterase from breaking down acetylcholine.
B. They inhibit depolarization in the presynaptic neuron which increases the levels of acetylcholine.
C. They produce an inhibitor that promotes the binding of acetylcholine.
D. They block synaptic transmission by binding with postsynaptic acetylcholine receptors.

State the action of the enzyme acetylcholinesterase.

Using evidence from the chart, identify, giving a reason, which group of neurons responded most to the chemicals.

Explain the propagation of nerve impulses along the membrane of a neuron.

Compare and contrast hormonal and nervous communication.

Explain how acetylcholine initiates an action potential in a postsynaptic membrane.

Companies that manufacture neonicotinoid pesticides have argued that they do not cause significant harm to honeybees. Construct an argument, based on the data in this question, for serious concern about the manufacture and use of neonicotinoid pesticides.

Outline how depolarization of the membrane of an axon occurs.

Deduce, based on the data presented, whether the levels of neonicotinoids used in agriculture cause direct harm to B. terrestris.

The electron micrograph shows a transverse section through a myelinated neuron.

Describe the overall effects of low and high doses of neonicotinoid on the egg lengths of all four species.