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

Ex Input:
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 Output:
carbon fiber

Ex Input:
What are ionic solutes?

Ex Output:
electrolytes

Ex Input:
What type of cell transmits electrical impulses in the nervous system?

Ex Output:
nerve cell