It is bad to litter because that is harming the environment. When you throw out a can, it can harm a animal or several animals. Litter can also sink into the ground (I think) and harm the plants growing.
It is because that's a place where no one lives so they're safe.
Two substances in the body that will move based on the principle of diffusion are CARBON DIOXIDE AND OXYGEN.
Diffusion is the process by which molecules of a substance move from the region of higher concentration to the region of lower concentration. Carbon dioxide and oxygen can easily move in an out of the cell via diffusion.<span />
The carbon cycle describes the way the element carbon moves between the Earth's biosphere, hydrosphere, atmosphere, and geosphere. It is important for a few reasons: Carbon is an essential element for all life, so understanding how it moves helps us to understand biological processes and factors that influence them.
Source: Google
Hope this helps you :)