Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
One example: Earth rotates on its axis once times in one day.
Solution is here: How many times does Earth rotate on its axis in one day?
Explanation: The given output correctly poses a question based on the scientific fact given.

Now, solve this: Heart valves prevent the backflow of blood from happening in the heart.
Solution:
Heart valves prevent what kind of blood flow from happening in the heart?
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
One example: Earth rotates on its axis once times in one day.
Solution is here: How many times does Earth rotate on its axis in one day?
Explanation: The given output correctly poses a question based on the scientific fact given.

Now, solve this: Heart valves prevent the backflow of blood from happening in the heart.
Solution:
user
Heart valves prevent what kind of blood flow from happening in the heart?
assistant
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
One example: Earth rotates on its axis once times in one day.
Solution is here: How many times does Earth rotate on its axis in one day?
Explanation: The given output correctly poses a question based on the scientific fact given.

Now, solve this: Heart valves prevent the backflow of blood from happening in the heart.
Solution:
Heart valves prevent what kind of blood flow from happening in the heart?