Cell Structure and Function & Membrane Dynamics

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Multiple Choice
Identify the choice that best completes the statement or answers the question.

Which statement is false?

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

The relative impermeability of membranes to polar molecules is a result of the

a.	nonpolar nature of water molecules.
b.	presence of large channel proteins that extend through both sides of membranes.
c.	presence of salt molecules and ions scattered through some membranes.
d.	fluid nature of the lipid bilayer preventing molecules from moving through.
e.	presence of largely hydrophobic phospholipids in the lipid bilayer.

The phospholipid molecules of most membranes have

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

Plasma membranes (e.g. cell membranes and all other membranes in the cell) are selectively permeable. This means that

a.	glucose cannot enter the cell.
b.	plasma membranes must be very thick.
c.	anything can pass into or out of a cell as long as the membrane is intact and the cell is healthy.
d.	the plasma membrane allows some substances to enter or leave a cell more easily than others.
e.	cholesterol cannot enter the cell.

Which one of the following is not a function of the plasma membrane? The plasma membrane

a.	has receptors for chemical messages.
b.	has proteins that play a role in regulating what goes in and out of the cell.
c.	forms a selective barrier around the cell.
d.	is involved in the body’s ability for self-recognition.
e.	produces proteins for secretion out of the cell.

Which of the following is a false statement about diffusion? Diffusion

a.	requires no input of energy into the system.
b.	is the result of the random movement of molecules.
c.	proceeds until equilibrium is reached.
d.	may occur more rapidly when temperature is increased.
e.	occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated.

Diffusion does not require the cell to expend energy. Therefore, diffusion is considered a type of

a.	exocytosis.
b.	endocytosis.
c.	active transport.
d.	phagocytosis.
e.	passive transport.

Facilitated diffusion across a biological membrane requires __________ and moves a substance __________ its concentration gradient.

a.	transport proteins . . . against
b.	energy . . . down
c.	transport proteins . . . down
d.	energy and transport proteins . . . against
e.	energy and transport proteins . . . down

Which one of the following processes could result in the net movement of a substance into a cell if the substance is more concentrated in the cell than in the surroundings?

a.	facilitaed diffusion.
b.	osmosis.
c.	diffusion.
d.	active transport.
e.	none of the above can accomplish this.

10.

Active transport

a.	can create a concentration gradient in an environment that is initially at equilibrium.
b.	occurs without a transport protein.
c.	only moves molecules down a concentration gradient.
d.	may or may not require energy.
e.	All of the choices are correct.

11.

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane, and osmosis is allowed to take place, the water will

a.	exhibit a net movement to the side with higher solute concentration.
b.	exhibit an equal movement in both directions across the membrane.
c.	exhibit a net movement to the side with lower solute concentration.
d.	not cross the membrane.
e.	move randomly across the membrane.

12.

A cell that neither gains nor loses water when it is immersed in a solution is

a.	dead.
b.	metabolically inactive.
c.	isotonic to its environment.
d.	hypotonic to its environment.
e.	hypertonic to its environment.

13.

A plant cell in a hypotonic solution

a.	shrivels.
b.	wilts.
c.	is flaccid.
d.	is turgid.
e.	lyses.

14.

Which statement is true?

a.	A cell placed in an isotonic solution will swell.
b.	A cell placed in a hypertonic solution will remain the same size.
c.	A cell placed in a hypotonic solution will remain the same size.
d.	A cell placed in a hypotonic solution will shrink.
e.	A cell placed in a hypertonic solution will shrink.

15.

If placed in pure water, an animal cell may swell and busrt (undergo lysis), whereas a plant cell will not. What accounts for this difference?

a.	Releasing of excess water by the plant cell's vacuole.
b.	The fact that plant cells are isotonic to pure water.
c.	The relative impermeability of the plant cell wall to water.
d.	The relative impermeability of the plant cell membrane to water.
e.	The relative inelasticity and strength of the plant cell wall.

16.

The membranous compartmentalization of a cell

a.	is common in prokaryotes and eukaryotes.
b.	divides the cell into two equal-sized halves.
c.	allows different metabolic processes to occur in different parts of the cell.
d.	requires the presence of a cell wall.
e.	requires the presence of a large central vacuole.

17.

You are told that the cells on a microscope slide are plant, animal, or bacterial. You look at them through a microscope and see cell walls and membrane-bound organelles. You conclude that the cells

a.	could be either plant or bacterial.
b.	could be plant, animal, or bacterial.
c.	are animal cells.
d.	are plant cells.
e.	are bacteria.

18.

What cell structure is found in plant cells but not in animal cells?

a.	ribosome
b.	cell wall
c.	plasma membrane
d.	Golgi body
e.	nucleus

19.

Which are examples of prokaryotes?

a.	Bacteria
b.	Protists
c.	Algae
d.	Fungi
e.	Plants

20.

Prokaryotic cells do not have

a.	ribosomes that manufacture proteins.
b.	membrane bound nuclei.
c.	cytoplasm.
d.	cell membrane.
e.	enzymes.

21.

The two main functions of the rough endoplasmic reticulum are the production of

a.	mitochondria and proteins that are to be secreted by the cell.
b.	ribosomes and steroid hormones.
c.	chromatin and mitochondria.
d.	hydrogen peroxide and steroid hormones secreted by the cell.
e.	membrane and proteins to be secreted by the cell.

22.

The Golgi apparatus

a.	plays a role in generating energy for the cell.
b.	is the site of carbohydrate breakdown.
c.	modifies, and packages proteins.
d.	forms fats from glycerols and fatty acids.
e.	strings together amino acids to produce proteins.

23.

Certain cells that line the stomach synthesize a digestive enzyme and secrete it into the stomach. This enzyme is a protein. Which of the following processes could be responsible for its secretion?

a.	exocytosis
b.	endocytosis
c.	osmosis.
d.	diffusion
e.	passive transport

Other

24.

The next three questions are based on the following diagram.

The dialysis bag is filled with a 20% sucrose solution. Which beaker contains a solution that is hypotonic to the solution inside the dialysis bag?
a. Beaker 1.
b. Beaker 2.
c. Beaker 3.
d. Both beaker 2 and 3.
e. What's hypotonic?

25.

Again, the bag is filled with a 20% sucrose solution. Which statement is false about the dialysis bag used in the above experiment?
a. The dialysis bag is selectively permeable.
b. The dialysis bag is permeable to water.
c. The dialysis bag is permeable to sucrose.
d. Both (b) and (C) are false.
e. All statements are false.

26.

The dialysis bag is filled with a 20% glucose solution. Glucose is able to pass through the dialysis membrane. Which of the three beakers would resemble the appearance of the bag after being placed in pure water for 30 minutes?
a. Beaker 1
b. Beaker 2
c. Beaker 3
d. None of the above
e. Not enough information to determine.

27.

The next four questions are based on the following diagram:

Which part of the diagram represents facilitated diffusion?
a. 1.
b. 2.
c. 3.
d. Both (1) and (2).
e. All (1), (2), and (3)

28.

Which part(s) of the above diagram represents a type of passive transport?
a. 1.
b. 2.
c. 3.
d. Both (1) and (2).
e. All (1), (2), and (3).

29.

Which part of the diagram represents a type of transport that is able to establish an area of higher solute concentration by moving molecules against a concentration gradient?
a. 1.
b. 2.
c. 3.
d. All (1), (2), and (3)
e. None of the above.

30.

The structures labeled (4) and (5):
a. are types of proteins.
b. are channel proteins.
c. contain hydrophobic amino acids that help the protein stabilize in the lipid bilayer.
d. are made up of amino acids.
e. All of the choices are correct.

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