AP CH 5

Name:

AP CH 5

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

The phospholipid molecules of most membranes have

a.	a hydrophobic head and a hydrophilic tail.
b.	a hydrophobic head and a hydrophobic tail.
c.	a hydrophobic head and two hydrophobic tails.
d.	a hydrophilic head and two hydrophobic tails.
e.	none of these

Hydrophobic reactions of phospholipids can produce clusters of their fatty acid tails to form

a.	a lipid bilayer.
b.	hydrolysis of the fatty acids.
c.	a protein membrane.
d.	a cytoskeleton.
e.	a nonpolar membrane.

Which of the following statements is true?

a.	When lipids and water are mixed, it is the water molecules that isolate themselves into droplets.
b.	When lipids and water are mixed, the lipids dissolve and enter into a solution.
c.	Lipids are classified as nonpolar substances and will not mix with water.
d.	Polar substances are able to pass through a plasma membrane more readily than nonpolar substances.
e.	All portions of a phospholipid molecule found in a membrane are classified as nonpolar.

Which statement is NOT true?

a.	Membranes are often perforated by proteins that extend through both sides of the membrane.
b.	Some membranes have proteins with channels or pores that allow for the passage of hydrophilic substances.
c.	Hydrophilic substances have an easier time passing through membranes than do hydrophobic substances.
d.	The current concept of a membrane can be best summarized by the fluid mosaic model.
e.	The lipid bilayer serves as a hydrophobic barrier between two fluid regions.

Which of the following statements is NOT true?

a.	A lipid bilayer is characteristic of all membranes.
b.	Cellular organelles are associated with membranes.
c.	In a plasma membrane, the hydrophilic portion is oriented to the outside of the cell.
d.	Lipid molecules make the cell membrane relatively impermeable to water.
e.	Even under extremely high magnification, an electron microscope cannot reveal the substructure of cell membranes.

Cholesterol

a.	is not found in plant membranes.
b.	makes a membrane more fluid (flexible) wherever it is found.
c.	at high concentrations tends to make fatty-acid tails stick together.
d.	renders membranes more fluid in cold temperature.
e.	all of these

Most of the functions of plasma membranes are carried out by

Which of the following proteins is not necessarily associated with the plasma membrane?

The rate of diffusion through a semipermeable membrane will be lowest when which of the following is (are) true?

I. Concentration gradients are steep.

II. Temperatures are low.

III. Solutes are small molecules.

10.

The carrier molecules used in active transport are

a.	calcium ions in the calcium pump.
b.	proteins.
c.	ATP molecules.
d.	carbohydrates.
e.	lipids.

11.

Which statement is true?

a.	The movement of solvent occurs from a hypotonic solution to an isotonic solution.
b.	The net movement from an isotonic to a hypotonic solution involves the movement of solute molecules only.
c.	The concentration of the solute is greater in an isotonic solution than in a hypertonic solution.
d.	The concentration of the solvent is greater in a hypertonic solution than in an isotonic solution.
e.	Osmosis involves only hypertonic solutions.

12.

The net direction that an ion or molecule moves is

a.	dependent upon the size of the molecule.
b.	unpredictable because movement is random.
c.	controlled by the temperature of the medium.
d.	controlled by the membranes in the vicinity.
e.	the result of concentration differences.

13.

A red blood cell will lyse when placed in which of the following kinds of solution?

14.

If a plant cell is placed in a hypotonic solution,

a.	the entire cell will not swell or shrink.
b.	the entire cell will shrink.
c.	the turgor pressure will increase.
d.	the cell wall prevents the cell from exploding.
e.	the turgor pressure will increase but the cell wall prevents the cell from exploding.

15.

White blood cells use __________ to get rid of foreign particles in the blood.