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

[EX Q]: What equals the mass of the object (in kilograms) times the acceleration due to gravity (9.8 m/s 2 )?
[EX A]: weight

[EX Q]: Hormones, ions, and neurotransmitters are all types of what?
[EX A]: chemical signals

[EX Q]: Loss of energy is the reason that what typically has few levels?
[EX A]:
food chain