Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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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: The cardiovascular system in the human body consists of the heart, a network of blood vessels, and blood.

Answer: Which system in the human body consists of the heart, a network of blood vessels, and blood?

Question: Juvenile hormone modulates the activity of ecdysteroid.

Answer:
Juvenile hormone modulates the activity of what?