A 'red-hot' bacterial infection of the intestinal tract irritates the intestinal cells and interferes with digestion. Such a condition is often accompanied by diarrhea, which causes loss of body water. On the basis of what you have learned about osmotic water flows, explain why diarrhea may occur.

Diffusion is important in body fluids, because it tends to

(a) Increase local concentration gradients

(b) Eliminate local concentration gradients

(c) Move substances against concentration gradients

(d) Create concentration gradients

Osmosis always involves:

a. A selectively permeable membrane

b. A difference in solute concentration

c. Diffusion

d. Active transport

e. a, b, and c

A physiologist observes that the concentration of sodium inside a cell is decidedly lower than that outside the cell. She also observes that there is a small leakage of sodium into the cell. What cellular process prevents the sodium concentration gradient from disappearing?

a. Osmosis

b. Diffusion

c. Primary active transport

d. Secondary active transport

Differentiate between primary and secondary active transport processes.

Fresh water is a precious natural resource in Florida and it is said that supplies are dwindling. Desalinizing (removing salt from) ocean water has been recommended as a solution to the problem. Why shouldn't we drink salt water?

For diffusion to occur, there must be:

a. A selectively permeable membrane

b. Equal amounts of solute

c. A concentration difference

d. Some sort of carrier system

e. All of the above

List five important factors that influence diffusion rates.

When a cell is placed in a(n)___solution, the cell will lose water through osmosis. This process results in the___ of red blood cells

(a) hypotonic; crenation

(b) hypertonic; crenation

(c) isotonic; hemolysis

(d) hypotonic; hemolysis