Geologic Time Scale.Scientists decide when an era begins<span> and </span>ends<span>, due </span>to<span> mass extinction. ...</span>Scientists determine<span> when drastic changes </span>are<span> made by the fossil record, which shows earths past organisms that have become extinct.</span>
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It is a controlled experiment as everything is the same apart from one variable
Answer:
It means that from time to time, organisms change in form and function
Explanation:
As organisms live, they change and develop/mutate into better, stronger, and more functional creatures. This is in addition, because of the cells in the body.