Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: The heart is a muscular organ in the chest that consists mainly of cardiac muscle. It pumps blood through blood vessels by repeated, rhythmic contractions. Blood flows through four chambers of the heart when it beats. Heartbeat is controlled by electrical signals from special cells within the heart called the pacemaker. Answer: cardiac muscle

Answer: What type of muscle makes up most of the heart?

Question: Passage: The Gaia hypothesis states that the biosphere is its own living organism. Answer: the gaia hypothesis

Answer: What hypothesis states that the biosphere is its own living organism

Question: Passage: For a long time, scientists classified fungi as members of the Plant Kingdom. Fungi share several obvious traits with plants. For example, both fungi and plants lack the ability to move. Both grow in soil, and both have cell walls. Some fungi even look like plants. Answer: fungi

Answer:
What group of organisms was initially misclassified as plants because they also lack the ability to move, grow in soil, and have cell walls?