Which statement best describes passive transport across a cell membrane?

• It moves molecules from lower to higher concentrations using ATP.

• It moves molecules from higher to lower concentrations and does not require energy.

• It always moves water only through protein pumps.

• It requires vesicles to move very large particles.

Diffusion is defined as the movement of particles from areas of _______ concentration to areas of _______ concentration until equilibrium is reached.

• higher; lower

• lower; higher

• equal; higher

• equal; lower

Which form of passive transport specifically involves water molecules moving through a channel protein?

• Endocytosis

• Osmosis

• Exocytosis

• Protein pump

Facilitated diffusion differs from simple diffusion because facilitated diffusion

• requires ATP to move molecules.

• moves molecules against the concentration gradient.

• uses a channel protein to help larger molecules cross.

• only moves water molecules.

The term concentration gradient refers to

• the equal distribution of particles on both sides of a membrane.

• a difference in concentration across a space or membrane.

• the process of using ATP to move molecules.

• the formation of vesicles during transport.

Which gas is shown diffusing into the cell during passive transport in the diagram?

• Carbon dioxide

• Oxygen

• Nitrogen

• Hydrogen

Which process is illustrated by particles moving out of the cell through a channel without the use of energy?

• Active transport via pumps

• Facilitated diffusion

• Endocytosis

• Exocytosis

What is required for active transport but not for passive transport?

• A concentration gradient

• ATP (energy)

• Water channels

• Equilibrium

Active transport generally moves substances

• with the concentration gradient, from higher to lower concentration.

• against the concentration gradient, from lower to higher concentration.

• only through open pores in the membrane.

• only when equilibrium is reached.

Protein/membrane pumps are used to

• move large particles into the cell using vesicles.

• allow water to diffuse freely.

• pump molecules against the concentration gradient using energy.

• move oxygen out of the cell without energy.