Aldosterone:
1. is a steroid secreted by adrenal medulla.
2. acts on PCT leading to the reabsorption of sodium ions and water.
3. stimulates the secretion of K⁺ from the peritubular blood into the distal convoluted tubule.
4. is not regulated by serum potassium concentration.

Regarding the reabsorption of bicarbonate ions in the proximal convoluted tubule, the correct statement is:
1. The cuboidal brush bordered epithelium directly reabsorb bicarbonate ions.
2. The cells secrete H⁺ ions to reabsorb all of the filtered bicarbonate.
3. Carbonic anhydrase is not found in the PCT.
4. More bicarbonate is reabsorbed and less bicarbonate is excreted in alkalosis.

Acid-base balance in the human body is regulated by:

A substance is neither filtered, reabsorbed, nor secreted in the kidney. This substance would be most likely found in:
1. glomerular filtrate
2. blood in the renal vein
3. Collecting duct
4. Loop of Henle

Loops of Henle is found in the nephron of:
1. insects
2. fish
3. birds
4. amphibians

What will be seen in a fish living in a marine environment?
1. They do not drink the water in their surroundings.
2. They drink the water in their surroundings.
3. They move monovalent ions into their bodies through active transport across their epithelial outer tissue.
4. They move monovalent ions out of their bodies through active transport across their epithelial outer tissue.

A vertebrate osmoconformer is:
1. reptile
2. freshwater fish
3. dlophin
4. hagfish

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

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