Cells and Their Functions

Name:

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

The smallest unit that can carry out all activities we associate with life is:

a.	atom.
b.	organelle.
c.	cell.
d.	tissue.
e.	organ.

What characteristic of cells could be used to determine the presence or absence of life?

a.	presence of organic molecules
b.	presence of inorganic molecules
c.	alteration of concentrations of organic and/or inorganic molecules
d.	relatively constant concentrations of organic and/or inorganic molecules
e.	None of the above would be useful in determining the presence or absence of life.

Which of the following is not found in single celled organisms?

a.	atoms
b.	cells
c.	tissues
d.	Neither A nor B is found in single celled organisms.
e.	Neither A, nor B, nor C is found in single celled organisms.

Evidence that all living cells have a common origin is provided by:

a.	the cell theory, which states that the cell is the basic unit of life.
b.	the fact that all new cells come from previously existing cells.
c.	the fact that cells are the building blocks of the most complex plants.
d.	basic similarities in cell structure and chemistry.
e.	the fact that cells are the smallest units that can carry out all life activities.

As biologists continue to unlock the secrets of ________, many new doors are opening to development of medical treatments.

a.	proteins
b.	mitochondria
c.	cell membranes
d.	DNA
e.	ribosomes

The function of the plasma membrane is to:

a.	serve as a highly selective barrier.
b.	completely isolate the cell from the external environment.
c.	equalize the chemical composition inside and outside the cell.
d.	allow cells to accumulate materials and energy.
e.	Both A and D.

It is advantageous for cells to be small because:

a.	a small cell size prevents a cell from weighing too much.
b.	a small cell size occupies less space in nature where space is limited.
c.	a small cell has a small volume relative to surface area, thereby increasing efficient transport.
d.	a small cell has a small surface area relative to volume, thereby facilitating ion balance.
e.	a small cell is better able to conserve energy than a larger cell.

Figure 04-01
Use the figure below to answer the corresponding questions.

Which of the following statements about Figure 04-01 is true?

a.	Figure B has a greater surface area than Figure A.
b.	Figure B has a greater volume than Figure A.
c.	Figure B has a smaller volume than Figure A.
d.	Figure B has a greater surface area to volume ratio than Figure A.
e.	Figure B has a smaller surface area to volume ratio than Figure A.

Based on your knowledge of basic geometric relationships, the actual surface area to volume ratio for Figure B in Figure 04-01 is:

a.	0.01.
b.	0.06.
c.	100.
d.	1,000.
e.	This cannot be determined from the information provided.

10.

One strategy that allows larger cells to have an effective surface area to volume ratio is:

a.	having a completely spherical shape.
b.	being short and fat.
c.	having thin, finger-like projections.
d.	having a thinner plasma membrane.
e.	locomotion.

11.

Which of the following is not an example of homeostasis?

a.	A cell maintains a constant pH.
b.	A cell maintains a constant glucose concentration.
c.	A cell maintains a constant salt concentration.
d.	A cell maintains a constant water concentration.
e.	All of the above are examples of homeostasis.

12.

Which of the following descriptions or structures does not match the cell type?

a.	Sperm cells have flagella.
b.	Nerve cells have long, thin extensions.
c.	Epithelial cells are rectangular.
d.	White blood cells can change shape.
e.	All of the above are correct.

13.

Which scientist first viewed living cells?

a.	Robert Hooke
b.	Matthias Schleiden
c.	Theodor Schwann
d.	Anton van Leeuwenhoek
e.	August Weismann

14.

The ratio of the size of the image seen with the microscope to the actual size of the object is:

a.	magnification.
b.	resolution.
c.	resolving power.
d.	centrifugation.
e.	None of the above.

15.

Electron microscopes have a much higher resolution than either the human eye or any light microscope because:

a.	of their higher magnification.
b.	the lenses used are of much higher quality.
c.	of the very short (nanometer) wavelengths of electrons.
d.	the images are viewed on screens, rather than directly using an eyepiece or ocular lens.
e.	All of the above.

16.

The advantage of studying cells using a phase contrast microscope is that:

a.	the magnification is greater.
b.	the resolving power is greater.
c.	it is faster.
d.	it permits us to view internal structures of live cells.
e.	it uses a beam of electrons to allow us to see the organelles enclosed by the plasma membrane.

17.

The accompanying figure is the product of a:

a.	phase-contrast light microscope.
b.	Nomarski differential interference microscope.
c.	transmission electron microscope.
d.	scanning electron microscope.
e.	confocal fluorescence microscope.

18.

The scanning electron microscope differs from the transmission electron microscope in that the scanning electron microscope:

a.	can view a live specimen.
b.	relies on the detection of electrons from the beam after contact with the specimens.
c.	can view the internal structure of a cell.
d.	utilizes a beam of light that passes through the specimen.
e.	gives a three dimensional image of the object being studied.

19.

Differential centrifugation is a process that:

a.	separates different components of the cell that function differently.
b.	separates components of the cell that have a different chemical makeup.
c.	analyzes the chemical components of the cell.
d.	separates components of the cell that have different densities.
e.	allows researchers to view the contents of the cells.

20.

Which cell structure would not be in a eukaryotic cell, but would be found in a prokaryotic cell?

a.	cell wall
b.	flagellum
c.	ribosomes
d.	Gogli complex
e.	DNA

21.

Membrane-bounded organelles facilitate faster chemical reactions because:

a.	reactants are within close proximity to each other.
b.	membranes lower the activation energy of biochemical reactions.
c.	membrane-bounded organelles act as catalysts for biochemical reactions.
d.	reactants move faster within membrane-bounded organelles.
e.	reactants are less likely to encounter each other within membrane-bounded organelles.

22.

A eukaryotic cell:

a.	is usually smaller than a prokaryotic cell.
b.	has its DNA concentrated in one area of the cell without a nuclear membrane.
c.	typically has a cell wall, in addition to a plasma membrane.
d.	is a bacteria-like organism.
e.	has a variety of membranous organelles.

23.

Membranes facilitate all of the following except:

a.	facilitating the formation of energy-yielding gradients.
b.	acting as barriers to ions.
c.	acting as important "work benches" within cells.
d.	directing the synthesis of proteins.
e.	maintaining the identity of different cellular compartments.

24.

Which of the following structures would not be found in cells of a plant's roots?

a.	mitochondria
b.	chloroplasts
c.	endoplasmic reticulum
d.	nucleus
e.	All of the above would be found in cells of a plant's root.

25.

Select the cell type that is not correctly matched with the type of predominate organelle it would need to perform its unique function:

a.	Sperm cells have many mitochondria to provide energy for the flagellum.
b.	Pancreas cells have many ribosomes to produce the protein insulin.
c.	Liver cells have many ribosomes to produce detoxifying protein enzymes.
d.	Plant leaf cells have many chloroplasts to produce sugar by using energy from sunlight.
e.	All of the cells above are correctly matched with the predominate type of organelle they would need to perform their unique function.

26.

Which of the following structures or activities is not directly part of the endomembrane system?

a.	budding
b.	lysosomes
c.	ribosomes
d.	peroxisomes
e.	Golgi complex

27.

DNA is associated with proteins, forming a complex known as:

a.	chromosomes.
b.	nucleoli.
c.	nucleus.
d.	genes.
e.	chromatin.

28.

In the classic experiments by Bracht and Hammerling, the nucleus of Acetabularia was removed, the cap was cut off, a nucleus of a different species was inserted, and the cap was allowed to regenerate. The new cap was then removed. After the second regeneration, the cap was observed, and the following conclusion was made:

a.	The shape of the cap was controlled by the nucleus, thus, the nucleus was the control center of the cell.
b.	The shape of the cap was under the control of the stalk, which produced a control substance.
c.	The shape of the cap was independent of both the stalk and the holdfast.
d.	The "cren" caps were defective due to some mutation in the cap. Thus, "cren" caps are independent of control from both the base and the holdfast.
e.	At the time no conclusion could be made because in the early 20^th century, biologists did not know about the composition of DNA.

29.

Nucleoli contain chromosomal regions that specialize in making:

a.	proteins.
b.	RNA.
c.	ribosomes.
d.	lipids.
e.	hormones.

30.

If a toxin, such as a bacterial toxin, destroys ribosomes, what cellular activity will be affected first?

a.	protein synthesis
b.	DNA synthesis
c.	movement
d.	energy storage
e.	active transport

31.

Proteins made on ribosomes may be further modified within the:

a.	lysosomes.
b.	nucleus.
c.	mitochondria.
d.	Golgi complex.
e.	peroxisomes.

32.

The smooth endoplasmic reticulum:

a.	is absent in most plant cells.
b.	synthesizes proteins.
c.	provides structural support.
d.	synthesizes lipids.
e.	is required for ribosome synthesis.

Figure 04-02
Use the figure below to answer the corresponding questions.

33.

The cellular structure indicated by the arrow in Figure 04-02 is responsible for:

a.	lipid and fatty acid metabolism.
b.	protein synthesis.
c.	digestion of unused organelles.
d.	replication.
e.	None of the above.

34.

Which of the following statements about the structure surrounded by the box in Figure 04-02 is true?

a.	This structure is only found in plant cells.
b.	This structure is characteristic of both prokaryotic and eukaryotic cells.
c.	This structure plays a central role in the process of transcription.
d.	This structure typically represents a significant portion of the overall cell volume.
e.	This structure represents the main storage area for the cell.

35.

Which of the following pairs is correctly matched?

a.	chloroplast - storage of enzymes
b.	lysosome - powerhouse of the cell
c.	nucleolus - site of ribosomal subunit synthesis
d.	plastids - structural support of the cell
e.	Golgi complex - production of energy

36.

Which of the following organelles plays an important role in apoptosis, or programmed cell death?

a.	ribosomes
b.	mitochondria
c.	chloroplasts
d.	vacuoles
e.	peroxisomes

37.

One function of peroxisomes involves the process of:

a.	cell death.
b.	water storage.
c.	protein synthesis.
d.	DNA replication.
e.	detoxification.

38.

During an infection, white blood cells travel to the infected site and phagocytize the pathogens. After phagocytosis, primary lysosomes fuse with the phagocytic vesicle to form a larger vesicle called a secondary lysosome. The reason for this is:

a.	to introduce antibodies to the phagocytic vesicles.
b.	to wrap the pathogen in additional membrane, rendering them harmless.
c.	to coat the bacteria in lipids derived from the Golgi complex, which cover and smother them.
d.	to mix the pathogens with strong hydrolytic enzymes and destroy them.
e.	to prepare the bacteria for export from the body.

39.

All of the following functions are performed by plant vacuoles except:

a.	maintaining hydrostatic (turgor) pressure.
b.	waste storage and recycling.
c.	storage of proteins.
d.	breakdown of unneeded cellular materials.
e.	storage of nucleic acids.

40.

The theory that chloroplasts and mitochondria had their evolutionary beginnings in eukaryotic cells as endosymbionts is supported by all of the following except:

a.	chloroplasts and mitochondria are completely autonomous within eukaryotic cells.
b.	chloroplasts and mitochondria have DNA.
c.	chloroplasts and mitochondria have small ribosomes for protein synthesis.
d.	chloroplasts and mitochondria are approximately the same size as prokaryotic cells.
e.	chloroplasts and mitochondria have the same shape as prokaryotic cells.

41.

A cellular structure found in plant but not animal cells is the:

a.	chloroplast.
b.	ribosome.
c.	endoplasmic reticulum.
d.	microtubule.
e.	microfilament.

Figure 04-03
Use the figure below to answer the corresponding questions.

42.

Refer to Figure 04-03. The formation of ATP occurs in the portion of the chloroplast labeled:

a.	structure A.
b.	structure B.
c.	structure C.
d.	structure D.
e.	structure E.

43.

The formation of carbohydrates from carbon dioxide and water occurs in the portion of the chloroplast in Figure 04-03 labeled:

a.	structure A.
b.	structure B.
c.	structure C.
d.	structure D.
e.	structure E.

44.

Which of the following is a key component of the cytoskeleton?

a.	membranes
b.	cytoskeleton
c.	DNA
d.	ribosomes
e.	None of the above.

45.

The force necessary to cause microtubules of cilia and flagella to slide alongside one another is provided through the action of _________ proteins, which derive the energy to perform their work directly from ______ molecules.

a.	kinesin; ADP
b.	kinesin; glucose
c.	tubulin; ATP
d.	dynein; ATP
e.	dynein; ADP

46.

The structures in the micrograph could be:

a.	chloroplasts.
b.	cilia.
c.	RER.
d.	flagella.
e.	B and D

Figure 04-04
Use the figure below to answer the corresponding questions.

47.

The organelle featured in Figure 04-04:

a.	is present in a few prokaryotes.
b.	is the major site of protein synthesis in the cell.
c.	plays a vital role in packaging materials to be secreted.
d.	plays a central role in energy metabolism.
e.	is located in the nucleus.

48.

The structures indicated by the arrows in Figure 04-04 are:

a.	thylakoid lamellae.
b.	grana.
c.	cristae.
d.	matrices.
e.	plastids.

49.

The main process that occurs at the site of the structures marked by arrows in Figure 04-04 is:

a.	protein synthesis.
b.	photosynthesis.
c.	conversion of food molecules to ATP.
d.	processing and packaging of proteins.
e.	transcription.

50.

A single cell in a smoker's lung has become cancerous. It doubles its DNA and divides much faster than a normal lung cell. The most likely change that would have caused this condition took place in the:

a.	nucleus.
b.	nucleolus.
c.	microtubule.
d.	mitochondria.
e.	lysosome.

51.

Cells have internal structures called organelles. Which is not a function of organelles?

a.	Store genetic information.
b.	Convert energy to more usable forms.
c.	Synthesize polymers.
d.	Manufacture membranes.
e.	All of the above are organelle functions.

52.

Which of the following is not a cell covering or part of a cell covering?

a.	glycocalyx
b.	extracellular matrix
c.	cristae
d.	cell wall
e.	integrins

53.

The principle cell adhesion molecules in vertebrates and in many invertebrates are cadherins. These are important in:

a.	preventing the invasiveness of some malignant tumors.
b.	calcium-dependent adhesion between cells that form multicellular sheets.
c.	embryonic development.
d.	cell adhesion in vertebrates and in many invertebrates.
e.	All of the above.

54.

All of the following are functions of the cell membrane except:

a.	transmitting signals.
b.	participating in energy transfer.
c.	being freely permeable.
d.	regulating the passage of materials.
e.	participating in chemical reactions.

55.

Which of the following structures is composed of two layers of phospholipids associated with proteins integrated within or attached to these layers?

a.	cell wall
b.	plasma membrane
c.	microfilaments
d.	flagellum
e.	ribosomes

56.

Phospholipids can form bilayer structures because of their:

a.	rectangular shapes.
b.	amphipathic nature.
c.	ability to dissolve well in water.
d.	inability to associate with other phospholipids.
e.	lack of fatty acids.

57.

Phospholipids can form bilayers because the molecules:

a.	have two distinct regions, one strongly hydrophobic and the other strongly hydrophilic.
b.	are amphipathic molecules.
c.	have cylindrical shapes that allow them to associate with water most easily as a bilayer structure.
d.	Both A and B.
e.	A, B, and C.

58.

A key discovery that weakened the Davson-Danielli "sandwich" model of cell membranes was that:

a.	membrane proteins form a solid sheet on either side of the phospholipid bilayer.
b.	membrane proteins form a solid sheet separating the phospholipid layer.
c.	the phospholipids do not associate with each other in the hydrophobic region of membranes.
d.	membrane proteins were not uniform and did not form flattened sheets.
e.	membrane proteins occurred in regular organized patterns on the surface of membranes.

59.

Proposed the fluid mosaic model of cell membrane structure in 1972:

a.	S. Jonathan Singer.
b.	Garth Nicolson.
c.	Hugh Davson.
d.	Both A and B.
e.	A, B, and C.

60.

Which of the following is a typical component of eukaryotic cell membranes?

a.	DNA
b.	glucose
c.	cholesterol
d.	water
e.	All of the above.

61.

Cholesterol within membranes functions as a(an) ____________ through its interactions with both hydrophobic and hydrophilic parts of phospholipids.

a.	water blocker
b.	pH buffer
c.	energy source
d.	temperature controller
e.	fluidity buffer

62.

In a lipid bilayer, ___________ fatty acid tails face each other within the bilayer and form a region that excludes water.

a.	hypertonic
b.	hyperosmotic
c.	hypotonic
d.	hydrophilic
e.	hydrophobic

63.

Which of the following functions best explains the reason for the asymmetrically oriented structure of the proteins in the cell membrane?

a.	These proteins are manufactured by free ribosomes.
b.	Each type of protein has its own function.
c.	These proteins pass through the ER membrane into the ER lumen.
d.	Enzymes are needed to modify the carbohydrate chains on these proteins.
e.	These proteins are initially formed by ribosomes on the rough ER.

64.

Which of the following is not a function associated with membrane proteins?

a.	Recognition of surface antigens of bacterial cells.
b.	Forming junctions between adjacent cells.
c.	Identify the cell as belonging to a particular individual.
d.	Serve as anchoring points for networks of cytoskeletal elements.
e.	All of the above are functions associated with membrane proteins.

65.

Which of the following is not a function of the transmembrane proteins called aquaporins?

a.	Transmembrane proteins
b.	Facilitate the rapid transport of water through the plasma membrane
c.	Located in mammalian kidney tubules
d.	Respond to specific hormones
e.	All of the above are functions associated with aquaporins.

66.

Catalysts are reusable. Enzymes are protein catalysts, and are reusable. Select the protein(s) below that is (are) not used up by the process carried out:

a.	Sodium-potassium pump carrier proteins
b.	Aquaporins
c.	Proteins involved in facilitated diffusion
d.	Both A and B.
e.	A, B, and C.

67.

Integral proteins:

a.	are weakly bound to the surface of the membrane.
b.	are strongly bound to the cytosolic surface of the membrane.
c.	have no hydrophobic portions.
d.	are completely embedded within the lipid bilayer.
e.	are amphipathic.

68.

What is meant by the term "fluid mosaic model"?

a.	It is the diffusion of lipid-soluble substances through the lipid bilayer.
b.	It is the movement of lipids and integral proteins within the lipid bilayer.
c.	It is the solubility of water in the membrane.
d.	It is the method of substance transport across the membrane.
e.	It is the movement of surface proteins through the membrane.

69.

A transmembrane protein differs from other membrane proteins because it:

a.	is covalently linked to the outer surface of the plasma membrane.
b.	is a glycoprotein with carbohydrates attached.
c.	is attached to the inside of the membrane by an ionic bond.
d.	completely extends through the membrane.
e.	is completely embedded within the membrane.

70.

Peripheral proteins are linked to either surface of the plasma membrane by:

a.	covalent disulfide bonds.
b.	associating with fatty acids through hydrophobic interactions.
c.	embedding in one side of the membrane and, thus, not extending through to the other side.
d.	associating with glycoproteins on the inner membrane surface.
e.	bonding to integral proteins through weak linkages.

71.

Which of the following statements explaining the differences in number and types of peripheral proteins found on the inner and outer surfaces of cell membranes is correct?

a.	The functions of the membrane differ on the inside and outside of the cell.
b.	Not all proteins can pass through the membrane and, thus, more accumulate on the inside.
c.	Proteins on the outside of the membrane are synthesized at a slower rate than proteins on the inside of the membrane.
d.	Proteins on the outside of membrane are made extracellularly and are unable to penetrate the phospholipid bilayer and enter the cell.
e.	The external peripheral proteins are weakly attached to the membrane and are readily washed away.

72.

Proteins that are destined to become associated with the inner surface of the plasma membrane are:

a.	manufactured in the same way as protein hormones.
b.	manufactured in the same way as proteins destined to become external peripheral proteins.
c.	made on free ribosomes in the cytoplasm.
d.	made on ribosomes located on the rough endoplasmic reticulum.
e.	transported to the plasma membrane within a secretory vesicle.

73.

Biological membranes are normally permeable to:

a.	large, hydrophilic molecules.
b.	small, hydrophilic molecules.
c.	large, hydrophobic molecules.
d.	small, hydrophobic molecules.
e.	None of the above.

74.

A bottle of perfume is opened on the opposite side of the room and within minutes you begin to smell the perfume. This phenomenon is a classic example of:

a.	dialysis.
b.	osmosis.
c.	active transport.
d.	facilitated diffusion.
e.	diffusion.

75.

Which of the following molecules is least likely to cross a cellular membrane by simple diffusion?

a.	carbon dioxide
b.	nitrogen
c.	oxygen
d.	potassium ion
e.	water

76.

The passive movement of a substance along its concentration gradient is termed:

a.	active transport.
b.	dialysis.
c.	diffusion.
d.	exocytosis.
e.	osmosis.

77.

Simple diffusion may involve the movement of ______________________ through the plasma membrane down a concentration gradient.

a.	small polar molecules
b.	small nonpolar molecules
c.	large polar molecules
d.	large nonpolar molecules
e.	water

78.

The difference between dialysis and osmosis is that:

a.	in osmosis, the solute moves through a selectively permeable membrane.
b.	in dialysis, the solvent moves through a selectively permeable membrane.
c.	in osmosis, the solute moves from a region of high concentration to a region of low concentration.
d.	in dialysis, the solute moves from a region of high concentration to a region of low concentration.
e.	in dialysis, the solvent moves from a region of high concentration to a region of low concentration through a selectively permeable membrane.

79.

If the concentration of solutes in a cell is less than the concentration of solutes in the surrounding fluid, then the extracellular fluid is said to be:

a.	hypertonic.
b.	hypotonic.
c.	isotonic.
d.	stable.
e.	amphipathic.

80.

The higher the concentration of solute in a solution, the _________ the effective water concentration and the ________ the osmotic pressure.

a.	lower; lower
b.	lower; higher
c.	higher; higher
d.	higher; lower
e.	Answer cannot be determined from the information provided.

Figure 05-01
Use the figure below to answer the corresponding questions.

81.

Which of the following statements about the red blood cells in Figure 05-01 Sample B is true?

a.	These red blood cells have been placed in an isotonic solution.
b.	These red blood cells have swollen in response to a hypertonic external solution.
c.	These red blood cells have swollen in response to a hypotonic external solution.
d.	These red blood cells have shrunken in response to a hypertonic external solution.
e.	These red blood cells have shrunken in response to a hypotonic external solution.

82.

Which of the following statements about the red blood cells in Figure 05-01 Sample A is true?

a.	There has been no net water movement.
b.	There has been a net flow of water out of the cell.
c.	There has been a net flow of water into the cell.
d.	Pinocytosis has occurred.
e.	Plasmolysis has occurred.

83.

A patient who has had a severe hemorrhage accidentally receives a large transfusion of distilled water directly into a major blood vessel. You would expect this mistake to:

a.	have no unfavorable effect as long as the water is free of bacteria.
b.	have serious, perhaps fatal consequences because there would be too much fluid to pump.
c.	have serious, perhaps fatal consequences because the red blood cells could shrink.
d.	have serious, perhaps fatal consequences because the red blood cells could swell and burst.
e.	have no serious effect because the kidney could quickly eliminate excess water.

84.

A plant cell placed in a hypertonic solution will:

a.	remain unchanged.
b.	undergo lysis.
c.	undergo plasmolysis.
d.	swell slightly.
e.	become crenated.

85.

Penicillin is toxic to certain dividing bacterial cells because it prevents cell wall formation, causing the cells to burst. This indicates that the bacteria live in:

a.	a hypotonic medium.
b.	a hypertonic medium.
c.	an isotonic medium.
d.	a medium with higher osmotic pressure than the cell.
e.	Both B and D.

86.

A wilted flower placed in a vase of water for several hours became stiff and stood erect. When it was placed in a salt solution, it wilted. From this information we can say that the cells of the flower are:

a.	hypotonic to both fresh water and the salt solution.
b.	hypertonic to both the fresh water and the salt solution.
c.	hypertonic to fresh water but hypotonic to the salt solution.
d.	hypotonic to fresh water but hypertonic to the salt solution.
e.	isotonic to fresh water but hypotonic to the salt solution.

87.

Which of the following membrane activities does not require the expenditure of energy by the cell?

a.	active transport
b.	osmosis
c.	endocytosis
d.	exocytosis
e.	synthesis of more membrane

88.

Facilitated diffusion:

a.	requires a transmembrane protein.
b.	requires ATP.
c.	can move molecules against a concentration gradient.
d.	is typically used to transport small nonpolar molecules.
e.	All of the above.

89.

A bacterium containing sodium ions at a concentration of 0.1 mM lives in a pond that contains sodium ions at 0.005 mM. Evidently, sodium ions are entering the cell by:

a.	active transport.
b.	endocytosis.
c.	diffusion.
d.	facilitated diffusion.
e.	osmosis.

90.

The energy-requiring movement of materials against a concentration gradient is termed:

a.	active transport.
b.	dialysis.
c.	facilitated diffusion.
d.	osmosis.
e.	plasmolysis.

91.

Although glucose molecules constantly diffuse into a cell along their concentration gradient, equilibrium is never reached and glucose continues to enter the cell. This is a direct result of:

a.	the very fast turnover rate of glucose metabolism.
b.	the continuous excretion of glucose from other parts of the cell.
c.	the rapid and continuous intracellular formation of glucose-6-P.
d.	the active transport of glucose.
e.	the ability of the cell to engulf glucose by pinocytosis.

92.

Which of the following statements about the sodium-potassium pump is true?

a.	It transports hydrogen ions out of the cell.
b.	It transports 3 sodium ions out of the cell in exchange for 2 potassium ions.
c.	It transports 2 sodium ions out of the cell in exchange for 2 potassium ions.
d.	It transports 2 sodium ions out of the cell in exchange for 3 potassium ions.
e.	It transports water directly out of the cell.

93.

A person has a genetic disease that prevents the phospholipids in the plasma membrane of the white blood cells from freely fusing with the other membranes within the cell. How would this disease affect phagocytosis?

a.	Lysosomes would not be formed.
b.	Facilitated diffusion would not occur.
c.	Lysosomes would be formed lacking hydrolytic enzymes.
d.	The phagocytic vacuole would not fuse with the lysosome.
e.	Endocytosis would not occur.

94.

Which of the following are forms of carrier-mediated transport?

a.	Facilitated diffusion.
b.	Carrier-mediated active transport.
c.	Osmosis.
d.	Both A and B.
e.	A, B, and C.

95.

Which of the following describes how facilitated diffusion is powered?

a.	Facillitated diffusion is "free of cost."
b.	Energy is required to do the work of establishing and maintaining a concentration gradient.
c.	ATP is required directly.
d.	Both A and B.
e.	A, B, and C.

96.

Pinocytosis:

a.	is engulfment of large particles by the cell.
b.	occurs in protozoans and algae but not in more complex organisms.
c.	involves the specific binding of molecules to receptors on the cell surface.
d.	is the nonspecific uptake of fluids by an invagination of the cell membrane.
e.	is movement of molecules against the concentration gradient through a permeable membrane.

97.

Receptor-mediated endocytosis:

a.	is a passive process.
b.	involves only membrane transport proteins.
c.	brings about the selective uptake of materials by enclosing them in membranous vesicles.
d.	does not require energy.
e.	is most likely to be found in cells that release large amounts of hormones.

98.

A human white blood cell engulfs a bacterial cell by:

a.	carrier-mediated facilitated diffusion.
b.	exocytosis.
c.	phagocytosis.
d.	pinocytosis.
e.	the sodium-potassium pump.

99.

Select the receptor mediated endocytosis events that are in the correct (before, after) order:

a.	Endosome fuses with lysosome; receptors are transported to plasma membrane and recycled.
b.	Ligand binds to receptors; coated vesicle forms by endocytosis.
c.	Contents are digested and released in the cytosol; ligand separates from its receptor.
d.	Endosome fuses with lysosome; receptors are transported to plasma membrane and recycled.
e.	None of the events are listed in the correct order.

100.

In cells that are constantly involved in secretion, an equivalent amount of membrane must be returned to the interior of the cell for each vesicle that fuses with the plasma membrane; if this does not occur, then what would happen?

a.	The ratio of cell surface would decrease, compared to cell volume.
b.	The cell surface would shrivel.
c.	The surface area would remain constant.
d.	The number of membrane receptor proteins would decrease.
e.	The cell surface will keep expanding.

Figure 05-02
Use the figure below to answer the corresponding questions.

101.

The process illustrated in Figure 05-02 is called:

a.	facilitated diffusion.
b.	pinocytosis.
c.	cotransport.
d.	lysis.
e.	exocytosis.

102.

The process illustrated in Figure 05-02 would most likely be used to transport:

a.	glucose.
b.	hormones.
c.	potassium ions.
d.	carbon dioxide.
e.	bacteria.

103.

One difference between tight junctions and desmosomes is that tight junctions:

a.	are regions where the plasma membrane from two neighboring cells are in actual contact.
b.	occur only in plants.
c.	involve connective microfilaments that traverse the space between adjacent cells.
d.	are anchored by microfilaments on the insides of the cell membranes of adjacent cells.
e.	contain a 24 nm space between two adjacent membranes.

104.

Plasmodesmata of plant cells are functionally equivalent to ____________ of animal cells.

a.	gap junctions
b.	desmosomes
c.	tight junctions
d.	cell surface receptors
e.	microvilli

105.

The structures in this figure:

a.	provide anchorage points between adjacent cells.
b.	allow the transport of small molecules and ions between adjacent cells.
c.	allow passage of materials through intercellular spaces.
d.	prevent the passage of materials through intercellular spaces.
e.	can only be found in plants.

106.

Which of the following is not part of the process of cell signaling?

a.	Synthesis and release of signaling molecules.
b.	Facilitated transport.
c.	Transport to target cells.
d.	Response by the cell.
e.	Termination of signaling.

107.

The process in which cells convert and amplify an extracellular signal into an intracellular signal:

a.	Synthesis and release of signaling molecules.
b.	Transport to target cells.
c.	Signal transduction.
d.	Response by the cell.
e.	Termination of signaling.

108.

In a signaling pathway, the second messenger is often:

a.	GTP.
b.	GDP.
c.	cyclic AMP.
d.	cyclic ADP.
e.	ATP.