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

What effect does antidiuretic hormone (ADH) have on the nephron?

a. It increases the water permeability of the descending limb of the loop of Henle.

b. It decreases the water permeability of the descending limb of the loop of Henle.

c. It increases the water permeability of the collecting duct.

d. It decreases the water permeability of the collecting duct.

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.

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.

In each nephron of the kidney, the glomerulus and Bowman's capsule

a. 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.

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

As filtrate passes through the loop of Henle, salt is reabsorbed and concentrated in the interstitial fluid of the medulla. This high solute concentration in the medulla enables nephrons to

a. Excrete the maximum amount of salt.

b. Neutralize toxins that might be found in the kidney.

c. Excrete a large amount of water.

d. Reabsorb water from the filtrate very efficiently.

Compare and contrast the types of nitrogenous wastes excreted by animals. Identify which type can be excreted with the least water, which is most toxic, and which waste is excreted by bony fishes, by mammals, and by insects. Which type would you expect to be produced by embryos inside eggs laid on land?

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.