How does carbon enter the atmosphere? options: Burning fossil fuels Cellular respiration Both A and B Neither A nor B

Which is an example of a population?

For a comparative or experimental investigation, scientists often make a testable about a scientific question, and then they test it in the investigation. a.control b.hypothesis c.procedure d.system

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.