ALL LIVING THINGS DEPEND ON PLANTS!!!!! This is why plants are so important in the food web because without them we wouldn't be getting the energy and nutrients we need. So without them we would probably die.
Most of the plants live in the ocean/water. This is good because they need water and sun to grow so then sunlight will go into the water and help them grow so we can eat them.
Plants breathe in carbon dioxide and breathe out oxygen, and humans breathe in oxygen and breathe out carbon dioxide. So in a way we help each other by breathing. They give us oxygen and we give them carbon dioxide.