Question 1

The rate of net diffusion of a substance into a cell is dependent on all the following factors EXCEPT

Accepted Answer

A)  size of molecule. 
B)  temperature. 
C)  type of cell. 
D)  lipid solubility. 
E)  magnitude of concentration gradient. 
A)  size of molecule. 
B)  temperature. 
C)  type of cell. 
D)  lipid solubility. 
E)  magnitude of concentration gradient.

Question 2

Transmembrane carrier proteins

Accepted Answer

A)  undergo radical conformational change while transporting solutes. 
B)  unlike channels, span the lipid bilayer. 
C)  always transport molecules actively. 
D)  form hydrophilic pores through membranes. 
E)  are open only when they bind the correct signal molecule. 
A)  undergo radical conformational change while transporting solutes. 
B)  unlike channels, span the lipid bilayer. 
C)  always transport molecules actively. 
D)  form hydrophilic pores through membranes. 
E)  are open only when they bind the correct signal molecule.

Question 3

Which of the following statements about ion channels is INCORRECT?

Accepted Answer

A)  Ion channels are present on all membranes. 
B)  Ion channels allow the rapid movement of ions along an electrochemical gradient. 
C)  Ion channels act like a pipe, opening a hole in the membrane allowing the passage of many different ions through the one channel. 
D)  Ion channels may be opened or closed by a change in the voltage across a membrane. 
E)  Ion channels may be opened in response to a physical force change in the membrane. 
A)  Ion channels are present on all membranes. 
B)  Ion channels allow the rapid movement of ions along an electrochemical gradient. 
C)  Ion channels act like a pipe, opening a hole in the membrane allowing the passage of many different ions through the one channel. 
D)  Ion channels may be opened or closed by a change in the voltage across a membrane. 
E)  Ion channels may be opened in response to a physical force change in the membrane.

Question 4

A symport is a

Accepted Answer

A)  carrier with two binding sites that transports two substances in opposite directions. 
B)  channel with two binding sites that transports two substances in opposite directions. 
C)  carrier with two binding sites that transports two substances in the same direction. 
D)  carrier that transports H+ ions to activate a channel. 
E)  channel with two binding sites that transports two substances in the same direction. 
A)  carrier with two binding sites that transports two substances in opposite directions. 
B)  channel with two binding sites that transports two substances in opposite directions. 
C)  carrier with two binding sites that transports two substances in the same direction. 
D)  carrier that transports H+ ions to activate a channel. 
E)  channel with two binding sites that transports two substances in the same direction.

Question 5

Ions are charged and so have very low permeability through a hydrophilic lipid membrane. However, ions are able to enter and exit cells by

Accepted Answer

A)  active transport using the energy of ATP. 
B)  facilitated transport using a carrier protein. 
C)  diffusion through a ligand-gated channel. 
D)  active transport using the energy of ATP and facilitated transport using a carrier protein. 
E)  active transport using the energy of ATP and diffusion through a ligand-gated channel. 
A)  active transport using the energy of ATP. 
B)  facilitated transport using a carrier protein. 
C)  diffusion through a ligand-gated channel. 
D)  active transport using the energy of ATP and facilitated transport using a carrier protein. 
E)  active transport using the energy of ATP and diffusion through a ligand-gated channel.

Question 6

Osmotic potential is

Accepted Answer

A)  the same as osmotic pressure. 
B)  inversely proportional to osmotic pressure. 
C)  the negative of the osmotic pressure. 
D)  proportional to the pressure potential. 
E)  None of the above is correct. 
A)  the same as osmotic pressure. 
B)  inversely proportional to osmotic pressure. 
C)  the negative of the osmotic pressure. 
D)  proportional to the pressure potential. 
E)  None of the above is correct.

Question 7

The direction of the net transport of water by osmosis across a cell membrane is determined by

Accepted Answer

A)  active transport. 
B)  diffusion. 
C)  the di-hydrogen monoxide coefficient potential. 
D)  where water has the highest free energy. 
E)  kinetic force. 
A)  active transport. 
B)  diffusion. 
C)  the di-hydrogen monoxide coefficient potential. 
D)  where water has the highest free energy. 
E)  kinetic force.

Question 8

The mechanism for bringing cholesterol into a cell is

Accepted Answer

A)  mediated by the membrane folding inwards to form a pit. 
B)  all of the options listed here are correct. 
C)  more specifically called receptor-mediated endocytosis. 
D)  initially stimulated by the binding of a receptor molecule on the membrane. 
E)  involves the protein clathrin coating the internal surface of the membrane. 
A)  mediated by the membrane folding inwards to form a pit. 
B)  all of the options listed here are correct. 
C)  more specifically called receptor-mediated endocytosis. 
D)  initially stimulated by the binding of a receptor molecule on the membrane. 
E)  involves the protein clathrin coating the internal surface of the membrane.

Question 9

Which one of the following is an INCORRECT result of adding solutes to water?

Accepted Answer

A)  The volume increases. 
B)  The concentration of the water increases. 
C)  The water molecules cluster together to avoid contacting the solute molecules. 
D)  There is an effect on the ability of water molecules to diffuse. 
E)  The free energy of water is decreased. 
A)  The volume increases. 
B)  The concentration of the water increases. 
C)  The water molecules cluster together to avoid contacting the solute molecules. 
D)  There is an effect on the ability of water molecules to diffuse. 
E)  The free energy of water is decreased.

Question 10

Cells are able to control the composition of their cytoplasm and internal compartments because cellular membranes

Accepted Answer

A)  are selective barriers. 
B)  lack membrane-spanning proteins. 
C)  protect the cell interior. 
D)  are selective barriers and protect the cell interior. 
E)  allow water to diffuse in and out of the cell. 
A)  are selective barriers. 
B)  lack membrane-spanning proteins. 
C)  protect the cell interior. 
D)  are selective barriers and protect the cell interior. 
E)  allow water to diffuse in and out of the cell.

Question 11

When a plant cell is placed in a solution that is hyper-osmotic

Accepted Answer

A)  the cell membrane will shrink away from the cell wall. 
B)  the cell will take up water and eventually burst. 
C)  there will be no net movement of water into or out of the cell. 
D)  there will be no change in the appearance of the cell. 
E)  the cell will swell and the cell wall will enlarge to accommodate the cell. 
A)  the cell membrane will shrink away from the cell wall. 
B)  the cell will take up water and eventually burst. 
C)  there will be no net movement of water into or out of the cell. 
D)  there will be no change in the appearance of the cell. 
E)  the cell will swell and the cell wall will enlarge to accommodate the cell.

Question 12

The principal difference between transmembrane carriers and channels is the

Accepted Answer

A)  size of the solute or molecule that can be transported. 
B)  size of the proteins involved in their structure. 
C)  rate of transport. 
D)  type of cells they are found on. 
E)  the charge on the molecule being transported. 
A)  size of the solute or molecule that can be transported. 
B)  size of the proteins involved in their structure. 
C)  rate of transport. 
D)  type of cells they are found on. 
E)  the charge on the molecule being transported.

Question 13

The features of molecules that affect their permeability coefficient include

Accepted Answer

A)  lipid solubility. 
B)  size. 
C)  electrical charge. 
D)  water solubility. 
E)  All of the answers are correct. 
A)  lipid solubility. 
B)  size. 
C)  electrical charge. 
D)  water solubility. 
E)  All of the answers are correct.

Question 14

Which of the following statements about transmembrane channels that open and close is true?

Accepted Answer

A)  Ligand-gated channels open in response to mechanical force. 
B)  Voltage-gated channels open when the charge difference across a membrane decreases. 
C)  Ligand-gated channels close in response to specific ligands binding. 
D)  Voltage-gated channels open when the charge inside a cell becomes more negative. 
E)  Mechanically gated channels are mechanosensitive and open in response to depolarisations. 
A)  Ligand-gated channels open in response to mechanical force. 
B)  Voltage-gated channels open when the charge difference across a membrane decreases. 
C)  Ligand-gated channels close in response to specific ligands binding. 
D)  Voltage-gated channels open when the charge inside a cell becomes more negative. 
E)  Mechanically gated channels are mechanosensitive and open in response to depolarisations.

Question 15

Facilitated diffusion

Accepted Answer

A)  can be an active or passive process. 
B)  can be via transmembrane protein channels or carriers. 
C)  is usually against electrochemical gradients. 
D)  is always against the concentration gradient. 
E)  is generally faster via carrier than channel. 
A)  can be an active or passive process. 
B)  can be via transmembrane protein channels or carriers. 
C)  is usually against electrochemical gradients. 
D)  is always against the concentration gradient. 
E)  is generally faster via carrier than channel.

Question 16

A plant cell placed in a solution that is hypo-osmotic will

Accepted Answer

A)  shrink away from the cell wall due to the efflux of water. 
B)  take up water and eventually burst. 
C)  have no net movement of water into or out of the cell. 
D)  swell with water inside the cell wall. 
E)  swell and the cell wall will enlarge to accommodate the cell. 
A)  shrink away from the cell wall due to the efflux of water. 
B)  take up water and eventually burst. 
C)  have no net movement of water into or out of the cell. 
D)  swell with water inside the cell wall. 
E)  swell and the cell wall will enlarge to accommodate the cell.

Question 17

The phospholipid bilayer of membranes is highly permeable to small non-polar molecules such as dissolved carbon dioxide. Which of the following is most likely to affect the rate of its diffusion?

Accepted Answer

A)  The amount of ATP produced by the cell 
B)  The carbon dioxide concentration gradient 
C)  The electrochemical gradient across the membrane 
D)  The osmotic potential 
E)  The availability of specific carriers 
A)  The amount of ATP produced by the cell 
B)  The carbon dioxide concentration gradient 
C)  The electrochemical gradient across the membrane 
D)  The osmotic potential 
E)  The availability of specific carriers

Question 18

Animal cells take up cholesterol via

Accepted Answer

A)  specific receptor proteins on the external surface of the cell membrane. 
B)  passive transport through the lipid bilayer. 
C)  clathrin receptors on the external surface of the cell membrane. 
D)  protein carriers to transport the cholesterol-receptor complex across the membrane. 
E)  the fusing of clathrin-coated vesicles to the cell membrane. 
A)  specific receptor proteins on the external surface of the cell membrane. 
B)  passive transport through the lipid bilayer. 
C)  clathrin receptors on the external surface of the cell membrane. 
D)  protein carriers to transport the cholesterol-receptor complex across the membrane. 
E)  the fusing of clathrin-coated vesicles to the cell membrane.

Question 19

Which of the following is NOT a function performed by cell membranes?

Accepted Answer

A)  Rigidity for strength 
B)  Regulation of internal environment against changes to the external environment 
C)  Ejection of waste products 
D)  Facilitates the entry of nutrients 
E)  Export of products synthesised for transport out of the cell 
A)  Rigidity for strength 
B)  Regulation of internal environment against changes to the external environment 
C)  Ejection of waste products 
D)  Facilitates the entry of nutrients 
E)  Export of products synthesised for transport out of the cell

Question 20

If a red blood cell is placed in distilled water it will

Accepted Answer

A)  swell and possibly burst because of the lower concentration of solutes outside the cell. 
B)  swell and possibly burst because of the ions diffusing out of the cell. 
C)  swell and possibly burst because of the greater concentration of solutes outside the cell. 
D)  shrink because of the lower concentration of solutes outside the cell. 
E)  shrink because of the greater concentration of solutes outside the cell. 
A)  swell and possibly burst because of the lower concentration of solutes outside the cell. 
B)  swell and possibly burst because of the ions diffusing out of the cell. 
C)  swell and possibly burst because of the greater concentration of solutes outside the cell. 
D)  shrink because of the lower concentration of solutes outside the cell. 
E)  shrink because of the greater concentration of solutes outside the cell.

Exam 5: Movement Across Membranes

The rate of net diffusion of a substance into a cell is dependent on all the following factors EXCEPT

Transmembrane carrier proteins

Which of the following statements about ion channels is INCORRECT?

A symport is a

Ions are charged and so have very low permeability through a hydrophilic lipid membrane. However, ions are able to enter and exit cells by

Osmotic potential is

The direction of the net transport of water by osmosis across a cell membrane is determined by

The mechanism for bringing cholesterol into a cell is

Which one of the following is an INCORRECT result of adding solutes to water?

Cells are able to control the composition of their cytoplasm and internal compartments because cellular membranes

When a plant cell is placed in a solution that is hyper-osmotic

The principal difference between transmembrane carriers and channels is the

The features of molecules that affect their permeability coefficient include

Which of the following statements about transmembrane channels that open and close is true?

Facilitated diffusion

A plant cell placed in a solution that is hypo-osmotic will

The phospholipid bilayer of membranes is highly permeable to small non-polar molecules such as dissolved carbon dioxide. Which of the following is most likely to affect the rate of its diffusion?

Animal cells take up cholesterol via

Which of the following is NOT a function performed by cell membranes?

If a red blood cell is placed in distilled water it will

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