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

[EX Q]: The structure of the boeing 787 has been described as essentially one giant macromolecule, where everything is fastened through cross-linked chemical bonds reinforced with this?
[EX A]: carbon fiber

[EX Q]: A mutation is a random change in an organism's what?
[EX A]: genes

[EX Q]: What fibres are seen in some vertebrates that twitch at rates far faster than any human muscle?
[EX A]:
skeletal muscle fibers