The golden poison frog, Phyllobates terribilis, is one of the most poisonous animals on Earth.
Its skin secretions contain batrachotoxin (BTX), a neurotoxin that can cause paralysis and cardiac arrest within minutes.
The following information has been discovered about the effects of BTX on nerve cells:
Using the information provided, explain how BTX affects the electrical activity of neurones.
A common cause of death from BTX poisoning is asphyxiation (not getting enough oxygen) as a result of paralysis of the intercostal muscles.
Explain how paralysis of the intercostal muscles could lead to asphyxiation.
BTX also affects the cardiac muscle cells, preventing them from repolarising and causing ventricular fibrillation (uncoordinated contraction of the ventricles).
Suggest and explain what effect this would have on the ability of the heart to pump blood.
Amphibians such as P. terribilis have unmyelinated post-ganglionic neurones.
Why is transmission of action potentials along the axon slower in the absence of saltatory conduction?
22 exam-style questions on OCR A A Level Biology Neuronal communication. Each one has a worked solution and a mark scheme showing where the marks go.