Facilitated diffusion and active transport both require a carrier protein in the cell membrane. Active transport, however 

A carrier molecule that moves two substances in the same direction is 

One way to understand the human body is to look at how its cells work. The concept of understanding large, complex things by looking at their simpler components is called

Which of the following muscle types are involuntary? (Select all that apply.)

A new sports drink advertises that it has MEGA AMOUNTS OF ELECTROLYTES! Electrolytes are substances that

Calcium salts are found in which connective tissue?

Tissue matching! Match the feature with the appropriate tissue type.

The lower portion of epithelial tissue is called

The substance that an enzyme acts on is the 

Body membranes are usually composed of which two tissues?