Given a scientific question, generate a correct answer to it.

[EX Q]: What is the outer layer of an axon that acts like a layer of insulation, similar to the plastic that encases an electrical cord?
[EX A]: myelin sheath

[EX Q]: A problem with using food chains to describe ecosystems is that some organisms can feed on or be consumed by species from more than one of what level?
[EX A]: trophic level

[EX Q]: Because their cells are arranged in bundles, the appearance of skeletal and cardiac muscles is described as what?
[EX A]:
striated