instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
The heterotroph eats only or mainly plants.
answer:
The heterotroph eats only or mainly what?


question:
Line graphs are especially useful for showing changes over time.
answer:
Line graphs are especially useful for showing changes over what?


question:
A penguin must do increase muscle mass before molting.
answer:

A penguin must do what before molting?