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

[EX Q]: Constructive interference is when two waves combine to create a larger wave.
[EX A]: What is it called when two waves combine to create a larger wave?

[EX Q]: A skeleton that consists of hard, mineralized structures located within the soft tissue of organisms is called endoskeleton.
[EX A]: A skeleton that consists of hard, mineralized structures located within the soft tissue of organisms is called what?

[EX Q]: On a global scale, plants and other photosynthetic organisms have generated all of the oxygen in the air.
[EX A]:
On a global scale, plants and other photosynthetic organisms have generated all of what element in the air?