Based on Figure 7.19 in your textbook, which of these experimental treatments would increase the rate of sucrose transport into the cell?

Based on Figure 7.19 in your textbook, which of these experimental treatments would increase the rate of sucrose transport into the cell?

A)
decreasing extracellular sucrose concentration
B)
decreasing extracellular pH
C)
decreasing cytoplasmic pH
D)
adding an inhibitor that blocks the regeneration of ATP
E)
adding a substance that makes the membrane more permeable to hydrogen ions


Answer: B

Which of the following processes includes all others?

Which of the following processes includes all others?

A)
osmosis
B)
diffusion of a solute across a membrane
C)
facilitated diffusion
D)
passive transport
E)
transport of an ion down its electrochemical gradient


Answer: D

Which of the following factors would tend to increase membrane fluidity?

Which of the following factors would tend to increase membrane fluidity?

A)
a greater proportion of unsaturated phospholipids
B)
a greater proportion of saturated phospholipids
C)
a lower temperature
D)
a relatively high protein content in the membrane
E)
a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses


Answer: A

According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly

According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly

A)
spread in a continuous layer over the inner and outer surfaces of the membrane.
B)
confined to the hydrophobic core of the membrane.
C)
embedded in a lipid bilayer.
D)
randomly oriented in the membrane, with no fixed inside-outside polarity.
E)
free to depart from the fluid membrane and dissolve in the surrounding solution.


Answer: C

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

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

A)
Phospholipids are found only in certain membranes.
B)
Certain proteins are unique to each membrane.
C)
Only certain membranes of the cell are selectively permeable.
D)
Only certain membranes are constructed from amphipathic molecules.
E)
Some membranes have hydrophobic surfaces exposed to the cytoplasm, while
others have hydrophilic surfaces facing the cytoplasm.


Answer: B

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?

A)
on the outside of vesicles
B)
on the inside surface of the cell membrane
C)
on the inside surface of the vesicle
D)
on the outer surface of the nucleus
E)
on the ER


Answer: C

The difference between pinocytosis and receptor-mediated endocytosis is that

The difference between pinocytosis and receptor-mediated endocytosis is that

A)
pinocytosis brings only water into the cell, but receptor-mediated endocytosis brings in other molecules as well.
B)
pinocytosis increases the surface area of the plasma membrane whereas receptor-mediated endocytosis decreases the plasma membrane surface area.
C)
pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.
D)
pinocytosis requires cellular energy, but receptor-mediated endocytosis does not.
E)
pinocytosis can concentrate substances from the extracellular fluid, but receptor-mediated endocytosis cannot.


Answer: A

Familial hypercholesterolemia is characterized by which of the following?

Familial hypercholesterolemia is characterized by which of the following?

A)
defective LDL receptors on the cell membranes
B)
poor attachment of the cholesterol to the extracellular matrix of cells
C)
a poorly formed lipid bilayer that cannot incorporate cholesterol into cell membranes
D)
inhibition of the cholesterol active transport system in red blood cells
E)
a general lack of glycolipids in the blood cell membranes


Answer: A

White blood cells engulf bacteria through what process?

White blood cells engulf bacteria through what process?

A)
exocytosis
B)
phagocytosis
C)
pinocytosis
D)
osmosis
E)
receptor-mediated exocytosis


Answer: B

An organism with a cell wall would have the most difficulty doing which process?

An organism with a cell wall would have the most difficulty doing which process?

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


Answer: D

Several seriously epidemic viral diseases of earlier centuries were then incurable because they resulted in severe dehydration due to vomiting and diarrhea. Today they are usually not fatal because we have developed which of the following?

Several seriously epidemic viral diseases of earlier centuries were then incurable because they resulted in severe dehydration due to vomiting and diarrhea. Today they are usually not fatal because we have developed which of the following?

A)
antiviral medications that are efficient and work well with all viruses
B)
antibiotics against the viruses in question
C)
intravenous feeding techniques
D)
medication to prevent blood loss
E)
hydrating drinks that include high concentrations of salts and glucose


Answer: E

Proton pumps are used in various ways by members of every kingdom of organisms. What does this most probably mean?

Proton pumps are used in various ways by members of every kingdom of organisms. What does this most probably mean?

A)
Proton pumps must have evolved before any living organisms were present on the earth.
B)
Proton pumps are fundamental to all cell types.
C)
The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism.
D)
Cells with proton pumps were maintained in each Kingdom by natural selection.
E)
Proton pumps are necessary to all cell membranes.


Answer: D

The sodium-potassium pump in animal cells requires cytoplasmic ATP to pump ions across the plasma membrane. When the proteins of the pump are first synthesized in the rough ER, what side of the ER membrane will the ATP binding site be on?

The sodium-potassium pump in animal cells requires cytoplasmic ATP to pump ions across the plasma membrane. When the proteins of the pump are first synthesized in the rough ER, what side of the ER membrane will the ATP binding site be on?

A)
It will be on the cytoplasmic side of the ER.
B)
It will be on the side facing the interior of the ER.
C)
It could be facing in either direction because the orientation of proteins is scrambled in the Golgi apparatus.
D)
It doesn't matter, because the pump is not active in the ER.


Answer: A

What mechanisms do plants use to load sucrose produced by photosynthesis into specialized cells in the veins of leaves?

What mechanisms do plants use to load sucrose produced by photosynthesis into specialized cells in the veins of leaves?

A)
an electrogenic pump
B)
a proton pump
C)
a contransport protein
D)
A and C only
E)
A, B, and C


Answer: E

Ions diffuse across membranes down their

Ions diffuse across membranes down their

A)
chemical gradients.
B)
concentration gradients.
C)
electrical gradients.
D)
electrochemical gradients.
E)
A and B are correct.


Answer: D

The movement of potassium into an animal cell requires

The movement of potassium into an animal cell requires

A)
low cellular concentrations of sodium.
B)
high cellular concentrations of potassium.
C)
an energy source such as ATP or a proton gradient.
D)
a cotransport protein.
E)
a gradient of protons across the plasma membrane.


Answer: C

If a membrane protein in an animal cell is involved in the cotransport of glucose and sodium ions into the cell, which of the following is most likely true?

If a membrane protein in an animal cell is involved in the cotransport of glucose and sodium ions into the cell, which of the following is most likely true?

A)
The sodium ions are moving down their electrochemical gradient while glucose is moving up.
B)
Glucose is entering the cell along its concentration gradient.
C)
Sodium ions can move down their electrochemical gradient through the cotransporter whether or not glucose is present outside the cell.
D)
Potassium ions move across the same gradient as sodium ions.
E)
A substance that blocked sodium ions from binding to the cotransport protein would also block the transport of glucose.


Answer: E

The sodium-potassium pump is called an electrogenic pump because it

The sodium-potassium pump is called an electrogenic pump because it

A)
pumps equal quantities of Na+ and K+ across the membrane.
B)
pumps hydrogen ions out of the cell.
C)
contributes to the membrane potential.
D)
ionizes sodium and potassium atoms.
E)
is used to drive the transport of other molecules against a concentration gradient.


Answer: C

In most cells, there are electrochemical gradients of many ions across the plasma membrane even though there are usually only one or two electrogenic pumps present in the membrane. The gradients of the other ions are most likely accounted for by

In most cells, there are electrochemical gradients of many ions across the plasma membrane even though there are usually only one or two electrogenic pumps present in the membrane. The gradients of the other ions are most likely accounted for by

A)
cotransport proteins.
B)
ion channels.
C)
carrier proteins.
D)
B and C only
E)
A, B, and C


Answer: A

What is the voltage across a membrane called?

What is the voltage across a membrane called?

A)
water potential
B)
chemical gradient
C)
membrane potential
D)
osmotic potential
E)
electrochemical gradient


Answer: C