instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
Exotic species are also called invasive species because they threaten other species.
answer:
Why are exotic species also called invasive species?


question:
Filter feeders called rotifers collect digestive and excretory wastes in cloacal bladder primitive organ.
answer:
Filter feeders called rotifers collect digestive and excretory wastes in what primitive organ?


question:
Mechanical to sound energy transformation occurs when a person hits a drum with a drumstick.
answer:

Which energy transformation occurs when a person hits a drum with a drumstick?