Given a scientific passage and an answer, generate a question for the given answer.

Q: Passage: The heating curve shown is for water but other substances have similarly shaped heating curves. Suppose you begin with solid water (ice) at -30C and add heat at a constant rate. The heat you add in the beginning will be absorbed as kinetic energy and the temperature of the solid will increase. When you reach a temperature of 0C (the melting point for water), the heat you add is no longer absorbed as kinetic energy. Instead, the added heat is absorbed as potential energy and the particles separate from each other. During the flat part of the curve labeled "melting", heat is being added constantly but the temperature does not increase. At the left edge of this flat line, the water is solid; by the time enough heat has been added to get to the right edge, the water is liquid, but maintains the same temperature. Once all the water is in the liquid form, the added heat will once again be absorbed as kinetic energy and the temperature will increase again. During the time labeled "water being heated as a liquid", all the added heat is absorbed as kinetic energy. Answer: potential energy

A: In what form is the heat absorbed when you heat ice and it reaches a temperature of 0 c?
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Q: Passage: The Moon has no atmosphere. With no atmosphere, the Moon is not protected from extreme temperatures. The average surface temperature during the day is approximately 107C (225F). Daytime temperatures can reach as high as 123C (253F). At night, the average temperature drops to -153C (-243F). The lowest temperatures measured are as low as -233C (-397F). Answer: atmosphere

A: What does the moon not have to protect it from extreme temperatures?
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Q: Passage: In biological systems, matter is continuously changing states as well. For example, carbon in the form of the gas carbon dioxide is changed into glucose, a solid. This change, of course, occurs during photosynthesis. During cellular respiration, carbons from the glucose molecule are changed back into the carbon dioxide gas. Answer: carbon dioxide

A:
During cellular respiration, carbons from the glucose molecule are changed back into what gas?
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