Alright. So, which of the following substances primarily utilizes secondary active transport at the apical membrane and facilitated diffusion at the basolateral membrane? Based on what we just discussed, both sodium ions and glucose are entering the tubule cells using secondary active transport. These typically utilize cotransporters, like the sodium-glucose cotransporters. Just as a quick aside, both water molecules and urea tend to move through more passive transport means.
Both sodium and glucose will enter our tubule cell using secondary active transport. However, only one of them uses facilitated diffusion at that basolateral membrane. Remember, the basolateral membrane is going to have quite a few sodium-potassium pumps. This is a form of primary active transport and that will be the main form of transport that sodium will take during the process of reabsorption. On the other hand, glucose will be traveling through more passive means through the glucose channel. So, our answer here is going to be glucose; it primarily utilizes secondary active transport at the apical membrane and then facilitated diffusion at the basolateral membrane. And there you have it.