Question 1

How can freeze-fracture be used to determine the orientation of a protein in a membrane?

Accepted Answer

A) Freeze-fracture allows a cell to be cleaved in between the lipid bilayer,splitting the plasma membrane into two layers. 
B) Freeze-fracture allows a cell to be cleaved in such a way as to preserve the embedded proteins. 
C) Freeze-fracture cuts the membrane in protein-sized components for viewing under an electron microscope. 
A) Freeze-fracture allows a cell to be cleaved in between the lipid bilayer,splitting the plasma membrane into two layers. 
B) Freeze-fracture allows a cell to be cleaved in such a way as to preserve the embedded proteins. 
C) Freeze-fracture cuts the membrane in protein-sized components for viewing under an electron microscope.

Question 2

If two solutions have unequal concentrations of a solute,the solution with the lower concentration is called

Accepted Answer

A) isotonic. 
B) hypertonic. 
C) hypotoniC. 
D) hypnotic. 
E) osmosis. 
A) isotonic. 
B) hypertonic. 
C) hypotoniC. 
D) hypnotic. 
E) osmosis.

Question 3

The type of transport that is specific,which requires specific carrier molecules and energy is

Accepted Answer

A) exocytosis. 
B) facilitated diffusion. 
C) active transport. 
D) endocytosis. 
E) osmosis. 
A) exocytosis. 
B) facilitated diffusion. 
C) active transport. 
D) endocytosis. 
E) osmosis.

Question 4

Which of the following properties is not true of membrane phospholipids?

Accepted Answer

A) The hydrophobic tails are oriented towards the interior. 
B) The hydrophilic heads are oriented towards the exterior. 
C) Only the saturated fatty acids are always present. 
D) Once they are incorporated they remain in the membrane permanently. 
E) The bilayers made up of them are randomly interspersed with proteins. 
A) The hydrophobic tails are oriented towards the interior. 
B) The hydrophilic heads are oriented towards the exterior. 
C) Only the saturated fatty acids are always present. 
D) Once they are incorporated they remain in the membrane permanently. 
E) The bilayers made up of them are randomly interspersed with proteins.

Question 5

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

Accepted Answer

A) are too long to interact with the water molecules. 
B) are hydrophobic. 
C) are transmembranal. 
D) are hydrophilic. 
E) serve as transport channels. 
A) are too long to interact with the water molecules. 
B) are hydrophobic. 
C) are transmembranal. 
D) are hydrophilic. 
E) serve as transport channels.

Question 6

Which of the following is not a component of an animal cell membrane?

Accepted Answer

A) phospholipids 
B) polynucleotides 
C) aquaporins 
D) glycolipids 
E) cholesterol 
A) phospholipids 
B) polynucleotides 
C) aquaporins 
D) glycolipids 
E) cholesterol

Question 7

The process often thought of as "cell eating" is

Accepted Answer

A) osmosis. 
B) pinocytosis. 
C) phagocytosis. 
D) diffusion. 
E) active transport. 
A) osmosis. 
B) pinocytosis. 
C) phagocytosis. 
D) diffusion. 
E) active transport.

Question 8

Membrane proteins serve many functions.One of the functions is transportation of substances across the membrane.If a cell biologist placed cells into an environment in which a chemical has been added that blocks the function of these transport proteins,which process will be blocked?

Accepted Answer

A) active transport 
B) osmosis 
C) diffusion 
D) phagocytosis 
E) pinocytosis 
A) active transport 
B) osmosis 
C) diffusion 
D) phagocytosis 
E) pinocytosis

Question 9

Which of the following protein classes are not found as membrane proteins?

Accepted Answer

A) transport channels 
B) hormones 
C) receptors 
D) enzymes 
E) identity markers 
A) transport channels 
B) hormones 
C) receptors 
D) enzymes 
E) identity markers

Question 10

For the process of diffusion to occur,molecules must

Accepted Answer

A) move from areas of high concentration to areas of lesser concentration until an equilibrium is reached. 
B) move from areas of low concentration to areas of higher concentration until an equilibrium is reached. 
C) remain stationary until their molecular motion allows for an equilibrium to be reached. 
D) move from areas of high concentration to areas of lesser concentration until facilitated transport can assist the molecular equilibrium. 
E) move from areas of high concentration to areas of lesser concentration until an equilibrium is reached by active transport. 
A) move from areas of high concentration to areas of lesser concentration until an equilibrium is reached. 
B) move from areas of low concentration to areas of higher concentration until an equilibrium is reached. 
C) remain stationary until their molecular motion allows for an equilibrium to be reached. 
D) move from areas of high concentration to areas of lesser concentration until facilitated transport can assist the molecular equilibrium. 
E) move from areas of high concentration to areas of lesser concentration until an equilibrium is reached by active transport.

Question 11

Osmosis is the diffusion of water across a membrane in response to the concentration of one or more of the ________.

Accepted Answer

A) solutes 
B) membranes 
C) compartments 
D) cells 
A) solutes 
B) membranes 
C) compartments 
D) cells

Question 12

The lipid layer that forms the foundation of cell membranes is primarily composed of molecules called ____________.

Accepted Answer

A) phospholipids 
B) fats 
C) carbohydrates 
D) proteins 
A) phospholipids 
B) fats 
C) carbohydrates 
D) proteins

Question 13

Incubation of cells at 20$\circ$C blocks the release of proteins from the trans-Golgi.Under such conditions,you would expect to see

Accepted Answer

A) an increase in exocytosis. 
B) a decrease in exocytosis. 
C) an increase in endocytosis. 
D) a decrease in endocytosis. 
A) an increase in exocytosis. 
B) a decrease in exocytosis. 
C) an increase in endocytosis. 
D) a decrease in endocytosis.

Question 14

While eating lobster for dinner one night you begin thinking about the fact that this type of marine invertebrate is isosmotic with respect to the surrounding seawater.Your friend asks what would happen if the lobster you were eating had not been caught,but instead was moved to a bay with a slightly lower concentration of salt.You reply that in order for the lobster to be isosmotic with respect to new environment,

Accepted Answer

A) it must move water in to match the solute concentration of its new environment. 
B) it regulates its internal concentration of solutes to match that of its new environment. 
C) it must move water out to match the solute concentration of its new environment. 
D) it moves water in or out and regulates its internal concentration of solutes as needeD. 
A) it must move water in to match the solute concentration of its new environment. 
B) it regulates its internal concentration of solutes to match that of its new environment. 
C) it must move water out to match the solute concentration of its new environment. 
D) it moves water in or out and regulates its internal concentration of solutes as needeD.

Question 15

The type of diffusion that is specific and passive,and which becomes saturated if all of the protein carriers are in use is

Accepted Answer

A) exocytosis. 
B) facilitated diffusion. 
C) active transport. 
D) endocytosis. 
E) osmosis. 
A) exocytosis. 
B) facilitated diffusion. 
C) active transport. 
D) endocytosis. 
E) osmosis.

Question 16

The actual transport of protons by the proton pump is mediated by a transmembrane protein which undergoes a change in its

Accepted Answer

A) conformation. 
B) amino acid sequence. 
C) net charge. 
D) solubility. 
E) immunity. 
A) conformation. 
B) amino acid sequence. 
C) net charge. 
D) solubility. 
E) immunity.

Question 17

The plasma membrane is a thin sheet of lipid embedded with

Accepted Answer

A) proteins. 
B) carbohydrates. 
C) polymers. 
D) nucleotides. 
E) sodium and potassium ions. 
A) proteins. 
B) carbohydrates. 
C) polymers. 
D) nucleotides. 
E) sodium and potassium ions.

Question 18

Cell-walled organisms cannot carry out

Accepted Answer

A) exocytosis. 
B) active transport. 
C) osmosis. 
D) diffusion. 
E) endocytosis. 
A) exocytosis. 
B) active transport. 
C) osmosis. 
D) diffusion. 
E) endocytosis.

Question 19

A phospholipid molecule has a polar and a nonpolar end.Because of this,water molecules form

Accepted Answer

A) polar bonds with the nonpolar end of the phospholipid molecule. 
B) polar bonds with the polar end of the phospholipid molecule. 
C) hydrogen bonds with the nonpolar end of the phospholipid molecule. 
D) hydrogen bonds with the polar end of the phospholipid molecule. 
E) covalent bonds with the nonpolar end of the phospholipid moleculE. 
A) polar bonds with the nonpolar end of the phospholipid molecule. 
B) polar bonds with the polar end of the phospholipid molecule. 
C) hydrogen bonds with the nonpolar end of the phospholipid molecule. 
D) hydrogen bonds with the polar end of the phospholipid molecule. 
E) covalent bonds with the nonpolar end of the phospholipid moleculE.

Question 20

The Fluid Mosaic Model proposed by Singer and Nicolson in 1972 included that

Accepted Answer

A) the cell membrane was composed of lipids and proteins. 
B) the cell membrane was composed of a phospholipid bilayer between two layers of globular proteins. 
C) the cell membrane was composed of a phospholipid bilayer with globular proteins actually inserted into the bilayer. 
D) the cell membrane was composed of a phospholipid bilayer but the polar ends of the phospholipid molecules were reverseD. 
A) the cell membrane was composed of lipids and proteins. 
B) the cell membrane was composed of a phospholipid bilayer between two layers of globular proteins. 
C) the cell membrane was composed of a phospholipid bilayer with globular proteins actually inserted into the bilayer. 
D) the cell membrane was composed of a phospholipid bilayer but the polar ends of the phospholipid molecules were reverseD.

Exam 5: Membranes

How can freeze-fracture be used to determine the orientation of a protein in a membrane?

If two solutions have unequal concentrations of a solute,the solution with the lower concentration is called

The type of transport that is specific,which requires specific carrier molecules and energy is

Which of the following properties is not true of membrane phospholipids?

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

Which of the following is not a component of an animal cell membrane?

The process often thought of as "cell eating" is

Membrane proteins serve many functions.One of the functions is transportation of substances across the membrane.If a cell biologist placed cells into an environment in which a chemical has been added that blocks the function of these transport proteins,which process will be blocked?

Which of the following protein classes are not found as membrane proteins?

For the process of diffusion to occur,molecules must

Osmosis is the diffusion of water across a membrane in response to the concentration of one or more of the ________.

The lipid layer that forms the foundation of cell membranes is primarily composed of molecules called ____________.

Incubation of cells at 20 ∘\circ∘ C blocks the release of proteins from the trans-Golgi.Under such conditions,you would expect to see

The type of diffusion that is specific and passive,and which becomes saturated if all of the protein carriers are in use is

The actual transport of protons by the proton pump is mediated by a transmembrane protein which undergoes a change in its

The plasma membrane is a thin sheet of lipid embedded with

Cell-walled organisms cannot carry out

A phospholipid molecule has a polar and a nonpolar end.Because of this,water molecules form

The Fluid Mosaic Model proposed by Singer and Nicolson in 1972 included that

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Incubation of cells at 20^$\circ$C blocks the release of proteins from the trans-Golgi.Under such conditions,you would expect to see