Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

The heterotroph eats only or mainly plants.
The heterotroph eats only or mainly what?

Processing of filtrate in the proximal tubule helps maintain the ph level in body fluid.
Processing of filtrate in the proximal tubule helps maintain what level in body fluid?

The fact that water in a reservoir is elevated above the ground means that it has potential kind of energy.
The fact that water in a reservoir is elevated above the ground means that it has what kind of energy?