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

Q: Passage: Light may transfer its energy to matter rather than being reflected or transmitted by matter. This is called absorption . When light is absorbed, the added energy increases the temperature of matter. If you get into a car that has been sitting in the sun all day, the seats and other parts of the car's interior may be almost too hot to touch, especially if they are black or very dark in color. That's because dark colors absorb most of the sunlight that strikes them. Answer: absorption

A: When light transfers its energy to objects, this is known as what?
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Q: Passage: Models may be physical, conceptual, or mathematical. Answer: mathematical

A: Models may be physical, conceptual, or what else?
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Q: Passage: Summary Real crystals contain large numbers of defects. Defects may affect only a single point in the lattice (a point defect), a row of lattice points (a line defect), or a plane of atoms (a plane defect). A point defect can be an atom missing from a site in the crystal (a vacancy) or an impurity atom that occupies. Answer: vacancy

A:
A point defect can be an atom missing from a site in the crystal known as a what?
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