What is an organelle?

How does human environment effect the biosphere

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

Which of the following statements best distinguishes a hypothesis from a theory? a. theories are hypotheses that have been proved. b.hypotheses are guesses; theories are correct answers c. hypotheses usually are relatively narrow in scope; theories have broad explanatory power. d. theories are proved to be true; hypotheses are often contradicted by experimental results.