Answer:
Most of the mammals excrete urine in the form of water along with nitrogenous wastes dissolved in it. This removes water from the body and if there is a constant loss of water from the body then there will be dehydration in the body.
In case of birds and reptiles they excrete the waste out of their body in the form of semi solid matter which does not includes water.
This prevents the loss of water from the body and in this way it helps in maintaining the internal homeostasis of the body.
