You have examined several body systems that rely and work with each other in order function properly. one very important task that amphibians and all living things need is to efficiently exchange gases in order to survive. explain in a brief essay how the cardiovascular system and respiratory system work with each other based on your experience and observations from this virtual lab.

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.

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

Pl as time goes by and water goes through the water cycle again and again, the amount of water on earth: increases decreases ostays the same goes up and down