Chapter 44 Bio 2

Single-celled Paramecium live in pond water (a hypotonic environment). They have a structural feature, a contractile vacuole, which enables them to osmoregulate. If you observed them in the following solutions, at which sucrose concentration (in millimolars, mM) would you expect the contractile vacuole to be most active?

0.0 mM sucrose

Glucose is removed from filtrate by _____.

active transport

Unlike most bony fishes, sharks maintain body fluids that are isoosmotic to seawater, so they are considered by many to be osmoconformers. Nonetheless, these sharks osmoregulate at least partially by _____.

tolerating high urea concentrations that are balanced with internal salt concentrations to seawater osmolarity

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

gout, a painful inflammatory disease that primarily affects the joints

Ammonia _____.

is soluble in water

Compared to the seawater around them, most marine invertebrates are _____.

isoosmotic

Urea is produced in the _____.

liver from NH3 and carbon dioxide

Unlike an earthworm's metanephridia, a mammalian nephron

receives filtrate from blood instead of coelomic fluid.

Which regions of the nephron function independently of hormonal control for the most part?

Renal corpuscle, proximal tubule, and loop of Henle.

Freshwater fish excrete nitrogenous wastes as _____.

ammonia

In which region of the nephron is a steep osmotic gradient created?

loop of Henle

The necropsy (postmortem analysis) of a freshwater fish that died after being placed accidentally in saltwater would likely show that _____.

loss of water by osmosis from cells in vital organs resulted in cell death and organ failure

Terrestrial animals are _____.

osmoregulators that must obtain water from the environment

In animals, nitrogenous wastes are produced mostly from the catabolism of _____.

proteins and nucleic acids

Birds, insects, and many reptiles excrete nitrogenous waste in the form of uric acid, which _____.

reduces water loss compared to other nitrogenous wastes, but requires more metabolic energy to produce