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

[EX Q]: What did darwin call the evolutionary concept of change in populations over generations?
[EX A]: descent with modifications

[EX Q]: The cytoplasm is all the contents of the cell inside the cell membrane, with the exception of what?
[EX A]: nucleus

[EX Q]: What is the name for the organs behind the head of a fish that absorb oxygen from water?
[EX A]:
gills