A Neurophysiologist Is Investigating Nerve Reflexes in Two Different Animals

question 62

Multiple Choice

A neurophysiologist is investigating nerve reflexes in two different animals: a crab and a fish. Action potentials are found to pass more rapidly along the fish's neurons. What is the most likely explanation?

• A) The fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do.
• B) Unlike the crab, the fish's axons are wrapped in myelin.
• C) There are more ion channels in the axons of the crab compared with fish axons.
• D) Unlike the crab, the fish's axons are wrapped in myelin, and the fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do.

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