What is it called when a high percentage of the species on Earth dies off?
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A. Founder situation
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B. Mass extinction
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C. Selective pressure
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D. Disruptive selection

good one: produce hormones that plants grow.

bad one: the problem with organic matter is that while plant nutrients are needed for crop growth, they can also stimulate excessive growth of the wrong plants – mainly, algae.

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.