The high osmolarity of the renal medulla is maintained by which of the following? (A) active transport of salt from the upper region of the descending limb. (B) the loose packing of juxtamedullary nephrons. (C) diffusion of urea into the collecting duct. (D) diffusion of salt from the descending limb of the loop of Henle

In this schematic of urine production in a nephron, label the four processes involved and list some of the substances that are moved in each process.

Which of the following organisms would lose the most water by osmosis across its gills?a. marine bony fishb. sharkc. freshwater fishd. freshwater invertebrate

Which of the following animals generally has the lowest volume of urine production?a. vampire batb. salmon in fresh waterc. marine bony fishd. freshwater flatworm

What effect does antidiuretic hormone (ADH) have on the nephron?a. It increases water permeability of the descending limb of the loop of Henle.b. It decreases water permeability of the descending limb of the loop of Henle.c. It increases water permeability of the collecting duct.d. It decreases water permeability of the collecting duct.

The high osmolarity of the renal medulla is maintained by all of the following excepta. active transport of salt from the upper region of the ascending limb.b. the spatial arrangement of juxtamedullary nephrons.c. diffusion of urea from the collecting duct.d. diffusion of salt from the descending limb of the loop of Henle.

In each nephron of the kidney, the glomerulus and Bowman's capsulea. filter the blood and capture the filtrate.b. reabsorb water into the blood.c. break down harmful toxins and poisons.d. refine and concentrate the urine for excretion.

Fill in the blank: In Gila monsters, the organ in which water from urine is reabsorbed into the bloodstream is the .

In which of the following species should natural selection favor the highest proportion of juxtamedullary nephrons?a. a river otterb. a mouse species living in a temperate broadleaf forestc. a mouse species living in a desertd. a beaver