1. The net transfer of water between the interstitial fluid and ICF across the plasma membrane
A. Is mainly due to the difference in the osmotic force between the ICF and the interstitial fluid.
B. Is controlled by the channel proteins in the plasma membrane.
C. Is primarily due to the difference in the hydrostatic pressure between the ICF and the interstitial fluid.
D. None of these

2. When Na+ enters a cell
A. Osmotic pressure of the cell increases
B. Water molecules accompany the Na+ ions
C. The cell becomes swollen
D. All of these

3. Insects prevent water loss and disturbance in the osmotic balance in cells by
A. Having a water proof cell wall around each cell
B. Having a cuticle that makes the body water proof
C. Having an outer epidermis made of keratinized cells
D. Having equal concentrations of molecules in ECF and ICF

4. Osmoregulators:
A. Change the ECF osmotic pressure when osmotic pressure in the surrounding water changes.
B. Have to regulate ICF organic osmolytes to counteract cell volume changes.
C. Maintain a relatively steady ECF osmotic pressure even when the osmotic pressure changes in the external environment.
D. Are hyperosmotic in marine environments.

5. Vasopressin and thirst are inhibited when
A. ECF increases
B. Plasma volume increases
C. Arterial blood pressure is raised
D. All of these

6. The most important factor regulating the mammalian ECF volume and blood pressure is
A. Vasopressin
B. Thirst
C. Renin-angiotensin-aldosterone system
D. Decrease of K+ ions in the ECF

7. Kidneys maintain acid-base balance in the body by
A. Removing hydrogen ions from all the sources in the body.
B. Removing hydrogen ions, secreting ammonia into the urine, and excreting bicarbonate ions when body fluid acidity decreases.
C. Secreting ammonia into the urine.
D. Removing hydrogen ions and secreting ammonia into the urine.

8. Hyperosmotic regulation is found in all freshwater animals. T/F
A. True
B. False