The kangaroo rat can survive in the desert without drinking water. Which of the following statement(s) is/are most appropriate explanation for this feature?
(a) Its kidneys have long loops of Henle.
(b) It conserves energy by excreting ammonia.
(c) Air exhaled from its lungs becomes warm as it passes through the nose.
(d) It gains water mainly from oxidation of fat.
In the absence of an external source of water, the kangaroo rat in North American deserts is capable of meeting all its water requirements through its internal fat oxidation (in which water is a by-product). It also has the ability to concentrate its urine so that minimal volume of water is used to remove excretory products. This ability to concentrate urine is due to long loops of Henle. Their long nasal cavities reduce water loss by cooling the air leaving the lungs.
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