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.
Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.Gas exchange in gills and lungs operates by this process.n the case of active transport, the proteins are having to move against the concentration gradient. For example the sodium-potassium pump in nerve cells. Na+ is maintained at low concentrations inside the cell and K+ is at higher concentrations.