Which of the following is an example of a closed system? A) An estuary where fresh and ocean water mix. B) A chemical reaction within deep ocean organisms allowing them to glow. C) A living single-celled organism such as phytoplankton. D) A river that flows into the ocean.

Which kind of aquatic ecosystem does the photograph most likely show? a. marsh b. swamp c. lake d. river

Which of the following is an oxidation-reduction reaction? (pictured below)

The blue particles in this image are able to cross the cell membrane through simple diffusion. how will they be transported? outside the cell inside the cell o a. the substances will move directly across the membrane from outside the cell to inside the cell. b. the substances will move through channels in the membrane proteins from outside the cell to inside the cell. o c. the substances will move through channels in the membrane proteins from inside the cell to outside the cell. o d. the substances will move directly across the membrane from inside the cell to outside the cell.