Chapter 44, Problem 4
The high osmolarity of the renal medulla is maintained by all of the following except a. 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.
Video transcript
Unlike an earthworm's metanephridia, a mammalian nephron a. is intimately associated with a capillary network. b. functions in both osmoregulation and excretion. c. receives filtrate from blood instead of coelomic fluid. d. has a transport epithelium.
Which process in the nephron is least selective? a. filtration b. reabsorption c. active transport d. secretion
Which of the following animals generally has the lowest volume of urine production? a. vampire bat b. salmon in fresh water c. marine bony fish d. freshwater flatworm
In which of the following species should natural selection favor the highest proportion of juxtamedullary nephrons? a. a river otter b. a mouse species living in a temperate broadleaf forest c. a mouse species living in a desert d. a beaver
African lungfish, which are often found in small stagnant pools of fresh water, produce urea as a nitrogenous waste. What is the advantage of this adaptation? a. Urea takes less energy to synthesize than ammonia. b. Small stagnant pools do not provide enough water to dilute ammonia, which is toxic. c. Urea forms an insoluble precipitate. d. Urea makes lungfish tissue hypoosmotic to the pool.