Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Question: What equals the mass of the object (in kilograms) times the acceleration due to gravity (9.8 m/s 2 )? Answer: weight
Weight is a measure of the force of gravity pulling on an object of a given mass. It equals the mass of the object (in kilograms) times the acceleration due to gravity (9.8 m/s 2 ).

Question: By what kind of change can a chemical change be reversed? Answer: another chemical change
Because chemical changes result in different substances, they often cannot be undone. Some chemical changes can be reversed, but only by other chemical changes.

Question: What is the star-like structure inside the paramecia? Answer: the contractile vacuole
The contractile vacuole is the star-like structure within the paramecia.