IB Biology HL C2.2.11 Hl Saltatory Conduction Questions
Practise IB Biology HL 2.2.11 by applying saltatory conduction concepts to exam questions.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- Identify the myelin sheath and nodes of Ranvier as structures required for saltatory conduction.
- Explain how myelin insulates the axon and concentrates ion exchange at nodes of Ranvier.
- Explain how node-to-node jumping in a myelinated axon increases action-potential propagation speed.
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IB Biology HL C2.2.11 Hl Saltatory Conduction Questions question 1
Earthworms (Lumbricus terrestris) have a nerve cord on the ventral (underside) side of their body. It contains three nerve fibres (axons), each with a very large diameter, which extend along the whole length of the nerve cord. There is one medial giant fibre (MGF) and two lateral giant fibres (LGFs). The diameter of the MGF is 1.4 times larger than the LGF.
Scientists developed a non-invasive method to record giant nerve fibre activity. The response from the MGF was measured by the electrical activity produced when touching the front segments of the earthworm while the LGF was measured when touching the back segments.
The table shows the mean conduction rates, standard deviation (SD) and number of individual measurements of MGF and LGF action potentials in each earthworm. At the end of the table, the mean and standard error (SE) for 9 of the earthworms are shown.
Explain saltatory conduction.
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