Question 1

Which is false regarding passive transport?

Accepted Answer

A) It depends on concentration or electrical gradients. 
B) It involves weak binding between solute and protein. 
C) It requires an energy input. 
D) It depends on protein shape change. 
E) None of these are false.

Question 2

Wilting of a plant occurs

Accepted Answer

A) if the plant is placed in an isotonic solution. 
B) if there is a rise in turgor pressure. 
C) as a result of facilitated diffusion. 
D) when a plant with flexible cell walls is placed in a hypertonic solution. 
E) as a result of all of these conditions.

Question 3

The net direction that an ion or molecule moves is

Accepted Answer

A) dependent upon the size of the molecule. 
B) unpredictable because movement is random. 
C) influenced by the temperature of the medium. 
D) influenced by the membranes in the vicinity. 
E) the result of concentration differences.

Question 4

In an attempt to visualize the fluid mosaic model of a membrane, we could describe the __________ as floating in a sea of __________.

Accepted Answer

A) lipid; protein. 
B) phospholipids; carbohydrate. 
C) proteins; lipid. 
D) fats; water. 
E) glycolipids; sterols.

Question 5

If a plant cell is placed in a hypotonic solution, the

Accepted Answer

A) entire cell will not swell or shrink. 
B) entire cell will shrink. 
C) turgor pressure will increase. 
D) cell wall prevents the cell from exploding. 
E) turgor pressure will increase, but the cell wall prevents the cell from exploding.

Question 6

Cystic fibrosis

Accepted Answer

A) results from a mutation in a specific membrane transport protein. 
B) is characterized by inadequate chloride and water movement across epithelial cells. 
C) causes low grade bacterial infections in the lungs to persist for years. 
D) is a common, fatal genetic disorder. 
E) is all of these.

Question 7

Which of the following does NOT require the participation of a membrane protein?

Accepted Answer

A) active transport 
B) exocytosis 
C) facilitated diffusion 
D) simple diffusion 
E) all of these require a protein

Question 8

Phagocytosis involves all EXCEPT which of these?

Accepted Answer

A) receptors 
B) a meshwork of microfilaments 
C) pseudopod formation 
D) bulk-phase endocytosis 
E) vesicle fusion with lysosomes

Question 9

A water-soluble hormone would most likely bind to which of the following membrane proteins?

Accepted Answer

A) adhesion 
B) recognition 
C) receptor 
D) communication 
E) transport

Question 10

Unsaturated tails tend to __________ at the sites of their double bonds.

Accepted Answer

A) dissolve 
B) kink or bend 
C) separate 
D) react with ions 
E) do none of these

Question 11

The rate of diffusion through a selectively permeable 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.

Accepted Answer

A) I only 
B) II only 
C) I and III 
D) II and III 
E) I, II, and III

Question 12

Which substance passes most readily into a cell?

Accepted Answer

A) ions 
B) large molecules 
C) glucose 
D) carbon dioxide 
E) polar molecules

Question 13

Which of the following statements is false?

Accepted Answer

A) The plasma membrane is more like a fluid than a solid. 
B) The cell membrane is symmetrical, so it is impossible to identify which is the extracellular surface. 
C) Calcium pumps move calcium ions across the membrane. 
D) In a plasma membrane, proteins shift positions and phospholipids flex their tails. 
E) There are functional differences between the two sides of the plasma membranes.

Question 14

A transport protein is most analogous to a

Accepted Answer

A) water pipe. 
B) subway train. 
C) light switch. 
D) voice identification device. 
E) television receiver.

Question 15

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

Accepted Answer

A) a lipid bilayer. 
B) hydrolysis of the fatty acids. 
C) a protein membrane. 
D) a cytoskeleton. 
E) a nonpolar membrane.

Question 16

Exocytotic vesicles develop from the membranes of which of the following structures?

Accepted Answer

A) mitochondria 
B) Golgi bodies 
C) lysosomes 
D) vacuoles 
E) phagocytes

Question 17

Which of the following statements is true?

Accepted Answer

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 nonpolar and will not dissolve in 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.

Question 18

Which of the following is true regarding cell membrane proteins?

Accepted Answer

A) All are free to move laterally through the lipid bilayer. 
B) All are rigidly positioned. 
C) Some are tethered by cytoskeletal elements. 
D) Some form complexes. 
E) Some are tethered by cytoskeletal elements, and some form complexes.

Question 19

Which statement is true of plasma membranes?

Accepted Answer

A) They have molecules on their surfaces that identify them. 
B) They are essentially impermeable. 
C) They are basically static, non-changing structures. 
D) They are hydrophilic barriers between cells. 
E) They function primarily through the activity of their carbohydrates.

Question 20

Which of the following statements is NOT true?

Accepted Answer

A) A lipid bilayer is characteristic of all membranes. 
B) Cellular organelles are associated with membranes. 
C) In a plasma membrane, a hydrophilic portion is oriented to the outside of the cell. 
D) Lipid molecules make the cell membrane relatively impermeable to water-soluble substances. 
E) Even by using extremely high magnification, an electron microscope cannot reveal the substructure of cell membranes.

Exam 5: A Closer Look at Cell Membranes