Neurones & Synapses (DP IB Biology: SL)

The following graph shows an action potential in a mouse neurone after stimulation with a pulse of current.

What is the threshold potential needed to open voltage gated sodium channels in this neurone?

The opening of axon membrane voltage gated potassium channels are responsible for which part of the action potential?

It is thought that conditions such as schizophrenia are caused by an overabundance of the neurotransmitters serotonin and dopamine in some regions of the brain.

Given this is the case, which drug mode of action could work in treating symptoms of schizophrenia?

Which of the following statements about myelinated nerve fibres are correct?

1. Nodes of Ranvier facilitate saltatory conduction. 
2. Schwann cells are responsible for forming the myelin sheath.
3. The myelin sheath acts as an electrical conductor allowing electrical impulses to conduct at a more rapid rate.

The diagram below shows the change in membrane potential during an action potential.

Which of the following best describes the events indicated by the label X?

The diagram below shows a sensory neurone connected to its associated receptor cells.

 Which best describes the function of the structure labelled A?

The diagram below shows a sodium-potassium pump within the axon membrane of a neurone.

What is the role of active transport in the transmission of nerve impulses by neurones?

Which line of the table represents a neurone at its resting potential?

Membrane channel proteins are essential for the normal functioning of nerves.

Which process in nerves does not require a membrane protein?

The use of pesticides is a cause of controversy due to its impact on pollinators such as bees.

What effect do these pesticides have on the nervous system of insects?

Neonicotinoids are synthetic compounds similar to nicotine that are commonly found in pesticides. Neonicotinoids are considered to be especially suitable as pesticides because they're not toxic to humans and other mammals.

Which statements I - IV are the reasons for this?

I. A larger proportion of synapses in insects are cholinergic compared to mammals.

II. Neonicotinoids are more effective at preventing acetylcholinesterase from breaking down acetylcholine in insects compared to mammals.

III. Acetylcholinesterase in insects cannot break down neonicotinoids.

IV. Neonicotinoids bind more strongly to acetylcholine receptors in insects.

The diagram below shows the left to right transmission of an action potential in a myelinated axon by saltatory conduction.

Which of the following rows correctly identifies I - IV?

The oscilloscope trace shown below was taken using a digital oscilloscope. It shows an action potential in a hippocampal pyramidal neurone of a potoroo (a small marsupial species) that occurred when the neurone was stimulated with a current pulse.

How many action potentials could be stimulated in this neurone every second?

A research group of geneticists found a fruit fly mutant that shakes vigorously when anaesthetized with ether. Their studies showed that the shaker mutant has K⁺ channels that do not function properly. An action potential of a normal fruit fly and a shaker mutant is shown below.

Which of the following statements (I - IV) could be possible explanations for the differences between the action potentials?

I. The faulty K⁺ channels don't open for as long so there is slower diffusion of K⁺ ions.

II. The faulty K⁺ channels may be opening early, preventing maximum depolarisation.

III. The faulty K⁺ channels cause K⁺ ions to diffuse back into the axon more slowly, resulting in slower repolarisation.

IV. In wild-type drosophila, the functioning K⁺ channels allow for a faster rate of depolarisation.

Study the diagram below.

Which of the following table rows correctly identifies I - VI?