Mastering Biology Chapter 7

Only Channels

1. Allow water molecules and small ions to flow quickly across the membrane 2. Provide a continuous path across the membrane

Both Channel and Carrier

1. Provide a hydrophilic path across the membrane 2. Transport solutes down a concentration or electrochemical gradient 3. Are integral membrane proteins

Which of the following statements correctly describes the driving forces for diffusion of Na+and K+ ions through their respective channels?

1. The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane. 2. The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane 3. The electrochemical gradient is larger for Na+ than for K+

Only Carriers

1. Undergo a change in shape to transport solutes across the membrane 2. Transport primarily small polar organic molecules

Hypotonic

A cell will gain water when placed in a hypotonic solution

Crenation

A red blood cell placed in a hypertonic solution will shrink

Hemolysis

A red blood cell placed in a hypotonic solution will swell and potentially burst

Which of the following allows water to move much faster across cell membranes?

Aquaporins

Which of the following statements is TRUE with regard to this animation?

Both sodium and potassium ions are transported against their concentration gradients.

The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following?

Cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

Transport protein

Facilitates the movement of solute across the plasma membrane

You know that this cell is in a ______ solution because it ______

Hypertonic solution ... lost water (a cell will lose water when placed in a hypertonic solution)

In terms of tonicity, the solution in side A with respect to the solution in side B is

Isotonic

The voltage across a membrane is called the

Membrane potential

What name is given to the process by which water crosses a selectively permeable membrane

Osmosis (passive transport for water)

The glucose-sodium cotransporter

Outside cell: Na+ is high while glucose is low Glucose-sodium Contransporter: glucose and Na+ down Inside cell: Nat+ is low while glucose is high 1. Na+ moves down its electrochemical gradient 2. Glucose moves against its concentration gradient

Which of the following molecules can cross the lipid bilayer of a membrane without a transport protein or other mechanism

Oxygen, water, lipids, and carbon dioxide

Which of the following processes includes all others? 1. transport of an ion down its electrochemical gradient 2. osmosis 3. facilitated diffusion 4. diffusion of a solute across a membrane 5. passive transport

Passive Transport

Facilitated diffusion is a type of

Passive Transport (it is not expending energy to move the particles across the membrane)

You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of a specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells?

Similarity of the drug molecule to other molecules transported by the target cells

What kinds of molecules pass through a cell membrane most easily?

Small and hydrophobic

Which solution will decrease in volume? 1) Solution A: 1.4% (m/v) starch 2) Solution B: 7.62% (m/v) starch

Solution A: 1.4% (m/v) starch (net movement of water molecules causes Solution A to decrease and Solution B to increase)

Which solution will increase in volume? 1) Solution C: 9% (m/v) NaCl 2) Solution D: 12.4% (m/v) NaCl

Solution D: 12.4% (m/v) NaCl (net movement again)

What will happen to a red blood cell (RBC), which has an internal ion concentration of about .9 percent, if it is placed into a beaker of pure water?

The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC

A patient was involved in a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water equal to the volume of blood lost is added to the blood directly via one of his veins. What will be them most probable result of this transfusion?

The patient's red blood cells will swell an possible burst because other blood has become hypotonic compared to the cells

Which factors affect the rate of osmotic movement of water?

The rate of osmosis increase with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane.

The permeability of a biological membrane to a specific polar solute may depend on which of the following?

The types of transport proteins in the membrane

After the system reacher equilibrium, what changes are observed?

The water level is higher in side A than in side B

Hypertonic

There is a greater concentration of solute outside the cell

In facilitated diffusion, what is the role of the transport protein?

Transport proteins provide a hydrophilic route for the solute to cross the membrane

Which of the following best describes the structure of a biological membrane?

Two layers of phospholipids with proteins either crossing the layers or on the surface of the layers

What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium?

Water molecules move between the two solutions, but there is no net movement of water across the membrane.

The sodium-potassium pump is called an electrogenic pump because it

contributes to the membrane potential

A solute is crossing the

plasma membrane through a transport protein

The force driving simple diffusion is _____, while the energy source for active transport is _____

the concentration gradient; ATP