The urine concentrating ability of mammals and birds is correlated with the length of their:

1.	ureters	2.	proximal convoluted tubules
3.	distal convoluted tubules	4.	loops of Henle

The part of the nephron that is least permeable to water is the:
1. ascending limb of the loop of Henle
2. descending limb of the loop of Henle
3. collecting duct
4. proximal convoluted tubule

Glomerular ultrafiltrate would normally not contain:
1. plasma proteins
2. glucose and amino acids
3. water
4. urea

Bony fishes are:

Urea in humans is synthesized in:

The region of human kidney where you expect to find maximum osmolarity is:
1. at the top of the renal cortex
2. at the bottom of the renal cortex
3. at the top of the renal medulla
4. at the bottom of the renal medulla

Sodium is the principal cation in blood. If the blood concentration of sodium ions gets below normal:
1. blood volume increases and blood pressure decreases
2. water drains from the collecting duct
3. blood volume and blood pressure decrease
4. ADH secretion increases

RAAS is opposed by:

Mammals are:
1. osmoconformers.
2. hypotonic to their environment.
3. hypertonic to their environment.
4. osmoregulators.

The most toxic nitrogenous metabolic waste product is: