7-1
2. what was anton van leeuwenhoek one of the first to see in the 1600s?

How does oxygen move from the respiratory system to the circulatory system? a. by pumping through the heart b. by circulating in an artery c. by moving across a synapse d. by diffusion across a capillary wall

All organisms contribute some water to the water cycle by conducting

At which point is crust neither created nor destroyed? island chain mid-ocean ridge divergent boundary transform boundary