Ch 44

The loop of Henle dips into the renal cortex. This is an important feature of osmoregulation in terrestrial vertebrates because _____.

differential permeabilities of ascending and descending limbs of the loop of Henle are important in establishing an osmotic gradient

To maintain homeostasis, freshwater fish must ________.

excrete large quantities of water

Which process in the nephron is LEAST selective?

filtration

Excessive formation of uric acid crystals in humans leads to _____.

gout, a painful inflammatory disease that primarily affects the joints

The body fluids of an osmoconformer would be ________ with its ________ environment

isoosmotic; seawater

Ammonia is likely to be the primary nitrogenous waste in living conditions that include _____.

lots of fresh water flowing across the gills of a fish

Animals have adapted different mechanisms for excreting nitrogenous waste products. Which of the following are selective pressures that likely influence which mechanism an animal uses? I) the amount of water available in the animal's habitat II) the energy needs of the animal III) the temperature of the animal's environment

only I and II

Birds secrete uric acid as their nitrogenous waste because uric acid _____.

requires little water for nitrogenous waste disposal, thus reducing body mass

Urea is _____.

the primary nitrogenous waste product of humans

The advantage of excreting nitrogenous wastes as urea rather than as ammonia is that ________.

urea is less toxic than ammonia