instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
Pyramid ecosystem is used to show energy flow through the trophic levels.
answer:
What is used to show energy flow through the trophic levels?

question:
On a global scale, plants and other photosynthetic organisms have generated all of the oxygen in the air.
answer:
On a global scale, plants and other photosynthetic organisms have generated all of what element in the air?

question:
The types of white blood cells that arrive at an inflamed site depend on the nature of injury or infection.
answer:
The types of white blood cells that arrive at an inflamed site depend on the nature of what?