Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Density is defined as the mass of an object divided by its volume. Propose a unit of density in terms of the fundamental SI units. Answer: volume

Answer: Density is defined as the mass of an object divided by its what?

Question: Passage: Athletics are very competitive these days at all levels, from school sports to the pros. Everybody is looking for that edge that will make them faster, stronger, more physically fit. One approach taken by many athletes is the use of amino acid supplements. The theory is that the increase in amino acids in the diet will lead to increased protein for muscles. However, the only real benefit comes to the people who make and sell the pills. Studies have not showed any advantage obtained by the athletes themselves. You're much better off just maintaining a healthy diet. Answer: a healthy diet

Answer: Which is the best way to maintain a strong, fit body?

Question: Passage: The cell wall is located outside the cell membrane. It consists mainly of cellulose and may also contain lignin, which makes it more rigid. The cell wall shapes, supports, and protects the cell. It prevents the cell from absorbing too much water and bursting. It also keeps large, damaging molecules out of the cell. Answer: outside cell membrane

Answer:
Where is the cell wall located?