What is a closed curculatory system

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

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above

In general, did the simulated mice align with your predictions from the punnett squares? yes or no?