If a doctor wanted to be sure that a patient's urinary system is working properly, what would be the best indicators to investigate?

The best indicators would be if the doctor checked urine and stool samples, as well as the bladder and kidneys, and a blood test. Urine and stool first though.

Interphaseinterphase

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.