Prompt: rebecca is going for a run to get some exercise. explain how the cardiovascular (aka circulatory), excretory, digestive, respiratory, muscular, nervous, and immune systems work together to support rebecca and carry out the processes of life.

Which of the following will not cause mass extinction? a. drastic change is weather b. geological change c. both a and b d. none of the above

How much time has elapsed from the very beginning of "the memior of the conquistador bernal diaz del castillo" to the end? a. castillo's whole life b. a quarter of an hour c. a few weeks d. a decade

Which of these is an example of land degradation? a. containers designed to store pollutants leak. b. fertilizers provide too many nutrients to crops. c. garbage is buried so the land can be reclaimed later. d. a drought kills all the plants in an area, leaving bare land