There are many reactions, like Oxidation and Reduction
They would be the primary producers. otherwise known as an autotroph. (makes their own food)
While active transportrequires energy and work, passive transportdoes not. There are several different types of this easy movement of molecules. It could be as simple as molecules moving freely such as osmosis or diffusion. You may also see proteins in the cell membrane that act as channels to help the movement along. And of course there is an in-between transport process where very small molecules are able to cross asemi-permeable membrane.
The correct answer is b: cattle on rangeland. A point source of pollution occurs from a single identifiable and usually spatially narrow source. These sources of pollution are usually relatively easily to quantify and manage. In contrast, a non-point source of pollution, such as cattle on rangeland or irrigated agriculture, is variable on both spatial and temporal scales. These sources of pollution are difficult to quantify and manage.
