Final answer:
Smaller diameter axons require increased myelination to compensate for increased resistance and ensure efficient signal propagation. Myelination allows for saltatory conduction, which is faster than continuous conduction that occurs in unmyelinated axons.
Step-by-step explanation:
To conduct a signal at relatively comparable speeds, a smaller diameter axon needs more myelination, to compensate for the increased resistance as axon size decreases. Myelination increases conduction speed by preventing current leak and allowing the action potential to jump from one node of Ranvier to the next in a process known as saltatory conduction. In contrast, a lack of myelination results in continuous conduction which is slower due to continuous opening of voltage-gated Na+ channels along the axon. Larger axons have less resistance to ion flow, which allows faster signal propagation, similar to the way water flows faster in a wider river. Therefore, for smaller diameter axons to conduct signals efficiently, increased myelination is required to mitigate the effects of higher resistance.