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.

Q: Question: What is a simple machine that consists of a rope wrapped around a grooved wheel? Answer: a pulley

A: A pulley is a simple machine that consists of a rope wrapped around a grooved wheel. Pulleys are generally used to lift a load.
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Q: Question: What is the connecting piece of a sperm packed with? Answer: mitochondria

A: The connecting piece of the sperm is packed with mitochondria. Mitochondria are organelles in cells that produce energy. Sperm use the energy to move.
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Q: Question: Aids is an infectious disease of which system? Answer: immune

A:
AIDS is an infectious disease of the immune system caused by a virus. Some diseases of the immune system are noninfectious. They include autoimmune diseases and allergies.
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