The bat, Pizonyx vivesi, lives on desert islands in the Gulf of California, wher
ID: 299974 • Letter: T
Question
The bat, Pizonyx vivesi, lives on desert islands in the Gulf of California, where it subsists on fish and crustaceans. It gets much of its water as preformed and metabolic water from its food. However, it needs more water than its food provides, and the amount of additional water it needs increases as it flies more, because flight greatly increases its rate of evaporative water loss. The bat can concentrate NaCI to about 620 mM in its urine. The concentration of Na^+ in sea water is 470 mM and the concentration of CI^- in sea water in 548 mM. Which of the following are true? (Mark all that apply). A. For H_2O to be acquired by drinking seawater, all the ions in the seawater (including Mg^2+ and SO_4^2- not just Na^+ and CL^-) must be more concentrated in the urine than in the seawater. B. They could drink seawater, but it would evantually cause them to lose body water. C. They could not drink any seawater, and if they did they would rapidly dehydrate. D. The bats would be able to maintain their water balance by drinking seawater.Explanation / Answer
In the case of P.vivesi they need to consume sea water to maintain the water balance of the body. Their kidneys have been adapted to utilise sea water in response to the arid/ dry environment they live.
B & C is false because P.vivesi needs sea water to compensate the evaporation losses incurred by it without which it cannot balance water needs.
D is absolutely true because these bats would drink sea water to maintain water balance.
However, other mammals may even survive without drinking sea water due to fewer losses of water due to evaporation.
A. These bats were able to concentrate their urine, so that they could utilise sea water. In the experiment conducted by Roger E. Carpenter sodium, potassium and chloride ion ( electrolyte) was only measured because they are the major osmolytes which help in osmoregulation.{Note: Magnesium and sulfate ion not mentioned. So the option given here is not quite true.
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