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