Mastering Biology Chapter 5

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.

transport proteins; down

Which of the following statements regarding membrane protein function is false?

Membrane proteins transfer genetic information to the cytoplasm.

Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?

Na+

Relaying a message from a membrane receptor to a molecule that performs a specific function within a cell occurs when ___________

a signaling molecule binds to a protein that extends to the outside of the cell.

Which of the following processes can move a solute against its concentration gradient?

active transport

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of ___________

active transport.

Aquaporins _______________

allow water to cross the plasma membrane via facilitated diffusion.

A plant cell in a hypotonic solution ______________

becomes turgid because of an inflow of water.

Small, nonpolar, hydrophobic molecules such as fatty acids

easily pass through a membrane's lipid bilayer.5d

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of _____________

endocytosis

An enzyme is a protein. Which of the following processes could be responsible for its secretion?

exocytosis

The cholesterol associated with animal cell membranes ____________

helps to keep phospholipids from being too close to one another.

A cell that has neither a net gain of water nor net loss of water when it is immersed in a solution must be _______________

isotonic to its environment.

In active transport,

molecules move across the plasma membrane against their concentration gradient.

Oxygen crosses a plasma membrane by

passive transport

What really drives osmosis?

the difference in water concentration across a selectively permeable membrane

The molecules responsible for membrane transport are _______________

proteins

What is a false statement regarding active transport?

Active transport is driven by the concentration gradient.

Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of

passive transport

The process of a white blood cell engulfing a bacterium is

phagocytosis

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of :

facilitated diffusion.

Part complete Phagocytosis is to eating as pinocytosis is to ___________

drinking

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will __________

exhibit a net movement to the side with lower free water concentration.

Plasma membranes are selectively permeable. This means that _________

the plasma membrane allows some substances to enter or leave a cell more easily than others.

Water crosses the plasma membrane __________________

through facilitated diffusion or diffusion.