Solution. 1  This species has a 2â charge on it, so it is an anion. Anions are named using the stem of the element name with the suffix -ide added. 2  Because this species has no charge, it is an atom in its elemental form. This is cobalt. 3  In this case, there is a 2+ charge on the atom, so it is a cation.
1. 2. 3. The walls of the alveoli are composed of a single layer of flattened epithelial cells, as are the walls of the capillaries, so gases need to diffuse through just two thin cells. The alveoli walls are kept moist by water diffusing from the surrounding cells.he walls of the alveoli are composed of a single layer of flattened epithelial cells, as are the walls of the capillaries, so gases need to diffuse through just two thin cells. The alveoli walls are kept moist by water diffusing from the surrounding cells.
An example of diffusion in biological system is diffusion of oxygen and carbon dioxide across the alveolar-capillary membrane in mammalian lungs. Diffusion may be a simple diffusion or facilitated diffusion. A simple diffusion is one in which that occurs unassisted. Facilitated diffusion in contrast is an assisted diffusion in a way that it requires a carrier molecule. For instance, polar molecules diffuse across a cell membrane through carrier molecules embedded in the cell membrane.