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

[Q]: All enzymes have an optimal temperature and ph.
[A]: All enzymes have an optimal temperature and what?


[Q]: Metabolism produces waste energy in the form of heat, which helps warm-blooded (endotherm) animals conserve and maintain heat at a relatively constant body temperature.
[A]: Metabolism produces waste energy in the form of heat, which helps what type of animal conserve and maintain heat at a relatively constant body temperature?


[Q]: A(n) esker is a winding ridge of sand deposited by a stream of meltwater called.
[A]:
What is a winding ridge of sand deposited by a stream of meltwater called?