Osmolarity measures the moles of solute per liter of solution.
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Select the correct statement about osmoregulation.
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All osmoconformers are marine animals.
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Examine the figure of a human nephron. Where and when does osmolarity of the filtrate increase?
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As the filtrate moves down the descending limb of the loop of Henle
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What is the difference between a countercurrent multiplier system, such as the one involving the loop of Henle, and the countercurrent systems that maximize oxygen absorption by fish gills or reduce heat loss in endotherms?
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Unlike the other countercurrent systems, a countercurrent multiplier system, such as the one involving the loop of Henle, expends energy in active transport.
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Select the correct statement describing the osmolarity of mammalian urine.
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The osmolarity of mammalian urine may vary over time.
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You just received a freshwater aquarium as a gift and decide to add more fish. When you get to the pet store, you find that the most beautiful fish are saltwater animals, but you decide to buy them anyway. What will happen when you put your expensive saltwater fish in your freshwater aquarium?
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The cells of the fish will take up too much water, and the fish will die.
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Terrestrial animals are _____.
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osmoregulators that must obtain water from the environment
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Birds, insects, and many reptiles excrete nitrogenous waste in the form of uric acid, which _____.
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reduces water loss compared to other nitrogenous wastes, but requires more metabolic energy to produce
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Freshwater fish excrete nitrogenous wastes as _____.
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ammonia
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An appropriate group of animals to examine to observe a Malpighian tubule would be _____.
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the insects
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Osmoregulation and excretion are _____.
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mechanisms that maintain volume and composition of body fluids
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As a result of the non-selectivity of the kidney's filtration of small molecules, _____.
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useful substances must be selectively reabsorbed
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The structural component(s) of the mammalian nephron where increased permeability to water occurs due to the action of anti-diuretic hormone is/are the _____.
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collecting duct
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Aldosterone is _____.
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a steroid hormone that reduces the amount of fluid excreted in the urine
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Which process in the nephron is least selective?
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filtration
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Natural selection should favor the highest proportion of juxtamedullary nephrons in which of the following species?
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a mouse species living in a desert
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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?
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Small stagnant pools do not provide enough water to dilute the toxic ammonia.
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The body fluids of an osmoconformer would be ________ with its ________ environment.
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isoosmotic; saltwater
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A human who has no access to fresh water but is forced to drink seawater instead
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will excrete more water molecules than taken in, because of the high load of ion ingestion.
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Urea is produced in the
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liver from NH3 and CO2.
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Which nitrogenous waste requires hardly any water for its excretion?
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uric acid
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Excretory structures known as protonephridia are present in
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flatworms.
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The osmoregulatory process called secretion refers to the
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selective elimination of excess ions and toxins from body fluids.
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The osmoregulatory/excretory system of an insect is based on the operation of
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Malpighian tubules.
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The transfer of fluid from the glomerulus to Bowman's capsule
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is mainly a consequence of blood pressure in the capillaries of the glomerulus.
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Juxtamedullary nephrons can concentrate salt effectively in the renal medulla because of their long
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loops of Henle.
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A primary reason that the kidneys have one of the highest metabolic rates of all body organs is that
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they operate an extensive set of active-transport ion pumps.
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Processing of filtrate in the proximal and distal tubules
