Describe what substances must pass through to diffuse into cells

Passive transport: diffusion. Some substances pass through small holes in the surface cell membrane. This is called diffusion and does not require the cell to expend energy. Oxygen gets into a cell and carbon dioxide (the product of respiration reactions) leaves it this way.

The return of the wolf to yellowstone national park will probably affect the bird population to some degree, not significantly. while wolves will hunt birds when necessary, they prefer to hunt larger prey. the bird population will most likely only be affected when hunting is scarce for the wolves. birds of prey will also probably not be affected as much as other birds who spend more time on the ground hunting for food as the tend to spend more time in the air or in trees since they do not need to stay on the ground for long due to the nature of the way they hunt.