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.
Diffusion and Transport Across Cell Membranes II. LIPID DIFFUSION: THE MAJOR MEANS OF DRUG ABSORPTION AND PERMEATION The rate at which a molecule diffuses across a membrane depends on its size and its degree of hydrophobicity (Fig. 2). Hydrophobic substances such as gases and steroid hormones diffuse across membranes easily. Due to the fact that they are repelled by the hydrophobic interior of the bilayer, polar molecules do not diffuse