[Campbell Biology P.1039] Based on Figure 44.14 and its key, which statement correctly identi... | Practice Question

Based on Figure 44.14 and its key, which statement correctly identifies a transport mechanism in the renal tubules?

  • A: In the descending limb of the Loop of Henle, H₂O moves out of the tubule via active transport.
  • B: NaCl is only actively transported out of the ascending limb of the Loop of Henle.
  • C: Urea exits the collecting duct into the inner medulla interstitial fluid through passive transport.
  • D: Water reabsorption in the collecting duct primarily occurs against an osmolarity gradient.

Explanation

The key in Figure 44.14 indicates that purple arrows represent passive transport. In the inner medulla, a purple arrow indicates urea moving from the collecting duct into the interstitial fluid, signifying passive diffusion of urea. The text also states, 'Urea diffuses into the interstitial fluid of the medulla from the collecting duct.'