Bio I Quiz 6: Cell Membranes

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO2

In what way do the membranes of a eukaryotic cell vary?

Certain proteins are unique to each membrane.

Which of the following is true of osmosis?

In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

Which of the following most accurately describes selective permeability?

Only certain molecules can cross a cell membrane.

When a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur?

The cell will become turgid.

A patient was involved 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 the most probable result of this transfusion?

The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.

Cell membranes are asymmetrical. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature?

The two sides of a cell membrane face different environments and carry out different functions.

The solutions in the two arms of this U- tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half- filled with a solution of 2 M sucrose and 1 M glucose. Side B is half- filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. Refer to the figure. After the system reaches equilibrium, what changes are observed?

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

For a protein to be an integral membrane protein, it would have to be _____.

amphipathic, with at least one hydrophobic region

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

aquaporins

The presence of cholesterol in the plasma membranes of some animals

enables the membrane to stay fluid more easily when cell temperature drops.

Membrane proteins are not very soluble in water, because they possess long stretches of non-polar amino acids that are

hydrophobic.

The membranes of winter wheat are able to remain fluid when it is extremely cold by _____.

increasing the percentage of unsaturated phospholipids in the membrane

Diffusion _____.

is a passive process in which molecules move from a region of higher concentration to a region of lower concentration

The solutions in the two arms of this U- tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half- filled with a solution of 2 M sucrose and 1 M glucose. Side B is half- filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. Refer t o the figure. Initially, in terms of tonicity, the solution in side A with respect to the solution in side B is _____.

isotonic.

A sodium-potassium pump _____.

move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle

Which of the following processes includes all others?

passive transport

Which of these are NOT embedded in the hydrophobic portion of the lipid bilayer at all?

peripheral proteins

Which of the following types of molecules are the major structural components of the cell membrane?

phospholipids and proteins

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

small and hydrophobic