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

Q: Passage: The lungs of mammals are unique in having alveoli. These are tiny, sac-like structures. Each alveolus is surrounded by a network of very small blood vessels (see Figure below ). Because there are millions of alveoli in each lung, they greatly increase the surface area for gas exchange between the lungs and bloodstream. Human lungs, for example, contain about 300 million alveoli. They give the lungs a total surface area for gas exchange of up to 90 square meters (968 square feet). That's about as much surface area as one side of a volleyball court!. Answer: alveoli

A: What in mammalian lungs, increases the surface area for gas exchange?
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Q: Passage: Cloning is the process of creating an exact genetic replica of an organism. The clone's DNA is exactly the same as the parent's DNA. Bacteria and other single-celled organisms have long been able to clone themselves through asexual reproduction. Plants can also reproduce asexually. In animals, however, cloning does not happen naturally. In 1997, that all changed when a sheep named Dolly was the first large mammal ever to be successfully cloned. Other animals can now also be cloned in a laboratory. Answer: cloning

A: What is the process of creating an exact genetic replica of an organism called?
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Q: Passage: The sun's energy is converted to chemical energy by a plant. An animal gets energy when it eats the plant. The student gets energy when it eats the animal. The boy's energy is used to pedal the bike. Answer: plant

A:
The sun's energy is converted to chemical energy by a what?
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