L7 Bio Homework

What is the primary structural component of the cell membrane?

• A single layer of phospholipids

• A phospholipid bilayer

• A protein channel

• A carbohydrate chain

Which characteristic describes simple diffusion?

• Requires a transport protein and energy

• Moves molecules from low to high concentration

• Does not require a transport protein or energy

• Only transports large, polar molecules

How does facilitated diffusion differ from simple diffusion?

• Facilitated diffusion moves against the concentration gradient

• Facilitated diffusion requires energy

• Facilitated diffusion requires a transport protein

• Facilitated diffusion only transports nonpolar molecules

What is a key characteristic of active transport?

• It moves molecules from a high concentration to a low concentration

• It does not require energy

• It moves molecules against their concentration gradient

• It is only used for very small, nonpolar molecules

What is the difference between endocytosis and exocytosis?

• Endocytosis is a type of exocytosis.
• Endocytosis brings substances into the cell; exocytosis expels substances from the cell.
• Endocytosis and exocytosis are the same process.
• Exocytosis brings substances into the cell; endocytosis expels them.

Why would a cell need to use exocytosis to get rid of something?