Given a scientific question, generate a correct answer to it.
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Question: What type of experiment involves two identical experiments carried out side-by-side, with and without an independent variable?

Answer: controlled experiment

Question: What consists of four major components: inorganic mineral matter, organic matter, water and air, and living matter?

Answer: soil

Question: The remainder is transferred by contraction of what before the ventricles begin to contract?

Answer:
the atria