Final answer:
The rate of facilitated diffusion of an uncharged solute is determined by the concentration gradient and the availability of transport proteins within the cell membrane. Facilitated diffusion mimics enzyme kinetics and becomes saturated at peak solute concentrations. External factors like temperature can also influence the rate.
Step-by-step explanation:
In facilitated diffusion of an uncharged solute, the rate of transport is determined by the concentration gradient and the number of transport proteins in the membrane. These transport proteins include channel proteins and carrier proteins, which aid in the passive movement of solutes across the cell membrane without expenditure of energy. The facilitated diffusion process is akin to the kinetics of enzyme catalysis where the rate approaches a maximum (Vmax) when all proteins are occupied with solutes. The process becomes saturated when the concentration of the substrate, in this case, the uncharged solute, is so high that all the transport proteins are in use. However, various conditions, such as temperature and cohesive and adhesive forces, can also affect the diffusion constant (D), thereby impacting the rate of facilitated diffusion.