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

Ex Input:
What is the stored food in a seed called?

Ex Output:
endosperm

Ex Input:
Carboxylic acids have an acidic hydrogen atom, but esters do not. what do esters have in place of an acidic hydrogen atom?

Ex Output:
hydrocarbon group

Ex Input:
Unlike a crystalline solid, an amorphous solid is a solid that lacks a what?

Ex Output:
ordered internal structure