Quiz 3

Question 1

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?
a) extra cellular matrix
b) desmosomes
c) gap junctions
d) peroxisomes

Answer 1

c) gap junctions

Question 2

All of the following are part of a prokaryotic cell except:
a) DNA
b) cell wall
c) plasma membrane
d) endoplasmic reticulum

Answer 2

d) endoplasmic reticulum

Question 3

Prokaryotes are classified as belonging to two different domains. What are the domains?
a) Archaea and Protista
b) Bacteria and Archaea
c) Bacteria and Protista
d) Bacteria and Fungi
e) Bacteria and Eukarya

Answer 3

b) Bacteria and Archaea

Question 4

One of the key innovations in the evolution of eukaryotes from a prokaryotic ancestor is the endomembrane system. What eukaryotic organelles or features might have evolved as a part of, or as an elaboration of, the endomembrane system?
a) nuclear envelope
b) chloroplasts
c) plasma membrane
d) mitochondria

Answer 4

a) nuclear envelope

Question 5

Which of the following statements about the cytoskeleton is true?
a) Microfilaments are gly rigid and resist compression, whereas microtubules resist tension (stretching).
b) The dynamic aspect of cytoskeletal function is made possible by the assembly and disassembly of a large variety of proteins into complex aggregates.
c) Transport vesicles among the membranes of the endomembrane system produce the cytoskeleton.
d) Chemicals that block the assembly of the cytoskeleton would cause little effect on the cell’s response to external signals and stimuli.
e) Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.

Answer 5

e) Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.

Question 6

Movement of vesicles within the cell depends on what cellular structures?
a) actin filaments and ribosomes
b) microtubules and motor proteins
c) actin filaments and microtubules
d) centrioles and motor proteins
e) actin filaments and motor proteins

Answer 6

b) microtubules and motor proteins

Question 7

Which of the following statements concerning bacteria and archaea cells is correct?
a) Archaea cells contain small membrane-enclosed organelles; bacteria do not.
b) DNA is present in both archaea cells and bacteria cells.
c) Archaea cells contain a membrane-bound nucleus; bacteria do not.
d) DNA is present in the mitochondria of both bacteria and archaea cells.

Answer 7

b) DNA is present in both archaea cells and bacteria cells.

Question 8

The smallest cell structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope is
a) a nuclear pore.
b) a mitochondrion.
c) a ribosome.
d) a microtubule.
e) a microfilament.

Answer 8

b) a mitochondrion.

Question 9

The fluid mosaic model of the membrane proposes that membranes..?
a) are a phospholipid bilayer between 2 layers of hydrophilic proteins
b) consist of protein molecules embedded in a fluid bilayer of phospholipids
c) are a single layer of phospholipids and proteins
d) consist of a mosaic of polysaccharides and proteins

Answer 9

b) consist of protein molecules embedded in a fluid bilayer of phospholipids

Question 10

Which of the following is most likely true of a protein that co-transports glucose and sodium ions into the intestinal cells of an animal?
a) Sodium ions can move down their electrochemical gradient through the co-transporter whether or not glucose is present outside the cell.
b) A substance that blocks sodium ions from binding to the co-transport protein will also block the transport of glucose.
c) The cotransporter can also transport potassium ions.
d) Glucose entering the cell along its concentration gradient provides energy for uptake of sodium ions against the electrochemical gradient.
e) The sodium ions are moving down their electrochemical gradient while glucose is moving up.

Answer 10

b) A substance that blocks sodium ions from binding to the co-transport protein will also block the transport of glucose.

Question 11

Ions diffuse across membranes through specific ion channels..
a) down the electrical gradients
b) down their chemical gradients
c) down their osmotic potential gradients
d) down their electrochemical gradients

Answer 11

d) down their electrochemical gradients

Question 12

What is the voltage across a membrane called?
a) osmotic potential
b) membrane potential
c) chemical gradient
d) water potential

Answer 12

b) membrane potential

Question 13

The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane-more acidic outside the cell than inside the cell. Phosphate transport is an example of..?
a) active transport
b) osmosis
c) passive diffusion
d) facilitated diffusion
e) co-transport

Answer 13

e) co-transport

Question 14

Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this
most probably mean?
a) Cells of each domain evolved proton pumps independently when oceans became more acidic.
b) Proton pumps must have evolved before any living organisms were present on Earth.
c) Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.
d) Proton pumps are necessary to all cell membranes.
e) The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism.

Answer 14

c) Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.

Question 15

A portion that spans the phospholipid bilayer one or more times is..?
a) a peripheral protein
b) an intergral protein
c) a transmembrane protein
d) an integral
e) a glycoprotein

Answer 15

c) a transmembrane protein

Question 16

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
a) amino acid
b) K+
c) glucose
d) starch
e) CO2

Answer 16

e) CO2

Question 17

An organism with a cell wall would most likely be unable to take in materials through..?
a) diffusion.
b) active transport.
c) osmosis.
d) facilitated diffusion.
e) phagocytosis

Answer 17

e) phagocytosis

Question 18

Celery stalks that are immersed in fresh water for several hours become stiff and hard. Similar stalks left in a 0.15 M salt solution become limp and soft. From this we can deduce that the cells of the celery stalks are…?
a) hypertonic to fresh water but hypotonic to the salt solution.
b) hypertonic to both fresh water and the salt solution.
c) hypotonic to both fresh water and the salt solution.
d) hypotonic to fresh water but hypertonic to the salt solution.

Answer 18

a) hypertonic to fresh water but hypotonic to the salt solution.

Question 19

lons can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through..?
a) desmosomes.
b) gap junctions.
c) tight junctions.
d) intermediate filaments.
e) plasmodesmata.

Answer 19

b) gap junctions

Question 20

Which of the following statements correctly describes some aspect of protein secretion from prokaryotic cells?
a) Proteins that are secreted by prokaryotes are synthesized on ribosomes that are bound to the cytoplasmic surface of the plasma membrane.
b) In prokaryotes, the ribosomes that are used for the synthesis of secreted proteins are located outside of the cell.
c) Prokaryotes contain large pores in their plasma membrane that permit the movement of proteins out of the cell.
d) The mechanism of protein secretion in prokaryotes is probably the same as that in eukaryotes.
e) Prokaryotes are unlikely to be able to secrete proteins because they lack an endomembrane system.

Answer 20

a) Proteins that are secreted by prokaryotes are synthesized on ribosomes that are bound to the cytoplasmic surface of the plasma membrane.

Question 21

In a plant cell, DNA may be found in what organelles?

Answer 21

The nucleus, mitochondria and chloroplasts

Question 22

According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
a) They can move laterally along the plane of the membrane.
b) They frequently flip-flop from one side of the membrane to the other.
c) They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane.
d) They are free to depart from the membrane and dissolve in the surrounding solution.

Answer 22

a) They can move laterally along the plane of the membrane.

Question 23

You are working on a team that is designing a new drug. In order for this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells?
a) lipid composition of the target cells’ plasma membrane
b) hydrophobicity of the drug molecule
c) electrical charge (positive, negative, or none) of the drug molecule
d) similarity of the drug molecule to other molecules transported by
the target cells

Answer 23

d) similarity of the drug molecule to other molecules transported by
the target cells

Question 24

White blood cells engulf bacteria through what process?
a) exocytosis
b) phagocytosis
c) pinocytosis
d) receptor-mediated exocytosis

Answer 24

b) phagocytosis

Question 25

Which of the following makes it necessary for animal cells, although they have no cell walls, to have intercellular junctions?

a) Cell membranes do not distinguish the types of ions and molecules passing through them.
b) Maintenance of tissue integrity and barriers to fluid leakage requires cells to adhere tightly to one another.
c) Large molecules, such as proteins and RNA molecules, do not readily get through one, much less two, adjacent cell membranes.
d) Cell-to-cell communication requires physical attachment of one cell to another.
e) The relative shapelessness of animal cells requires a mechanism for keeping the cells aligned.

Answer 25

b) Maintenance of tissue integrity and barriers to fluid leakage requires cells to adhere tightly to one another

Question 26

In which situation is it preferable to use a light microscope instead of an electron microscope?

a) to view specimens at greater than 400X magnification
b) to view specimens smaller than 2 micrometers in diameter
c) to view living specimens
d) to view specimens requiring high contrast

Answer 26

c) to view living specimens

Question 27

The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined by..?

a) the synthesis of different lipids and proteins in each of the organelles of the endomembrane system.
b) the function of the Golgi apparatus in sorting and directing membrane components.
c) the modification of the membrane components once they reach their final destination.
d) the transportation of membrane lipids among the endomembrane system by small membrane vesicles.

Answer 27

b) the function of the Golgi apparatus in sorting and directing membrane components.

Question 28

In the life cycle of a typical cell, the period between cell divisions is called interphase. During this period chromosomes are distributed diffusely throughout the nucleus. During cell division, chromosomes condense into distinct pairs, and decondense again once cell division is complete. Recent evidence shows that when chromosomes decondense during interphase, their DNA molecules do not intermingle. Instead, they occupy distinct territories within the nucleus. Considering the structure and location of the following structures, which is most likely to be involved in chromosome location?

a) nuclear pores
b) the nucleolus
c) the nuclear lamina
d) the nuclear matrix

Answer 28

d) the nuclear matrix

Question 29

The minimum distance two points can be separated and still discerned as separate is the..?

a) magnification.
b) objective magnification.
c) visibility.
d) resolution.
e) contrast.

Answer 29

d) resolution.

Question 30

The nuclear lamina is an array of filaments on the inner side of the nuclear membrane. If a method were found that could cause the lamina to fall into disarray, what would you expect to be the most likely consequence?

a) the inability of the nucleus to divide during cell division
b) failure of chromosomes to carry genetic information
c) inability of the nucleus to keep out destructive chemicals
d) a change in the shape of the nucleus
e) the loss of all nuclear function

Answer 30

d) a change in the shape of the nucleus

Question 31

If an individual has abnormal microtubules due to a hereditary condition, in which organs or tissues would you expect dysfunction?

a) limbs, hearts, areas with a good deal of contraction
b) sperm, larynx, and trachea: cells and tissues that contain flagella or cilia
c) microvilli, alveoli, and glomeruli: cellular projections that increase surface area
d) all ducts, such as those from salivary or sebaceous glands, that transport fluids
e) phagocytic cells and white blood cells that exhibit amoeboid movement

Answer 31

b) sperm, larynx, and trachea: cells and tissues that contain flagella or cilia

Question 32

Which organelle often takes up much of the volume of a plant cell?

a) lysosome
b) vacuole
c) mitochondrion
d) Golgi apparatus
e) peroxisome

Answer 32

b) vacuole

Question 33

Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids?

a) lysosome
b) contractile vacuole
c) ribosome
d) mitochondrion
e) smooth endoplasmic reticulum

Answer 33

e) smooth endoplasmic reticulum

Question 34

Hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components. Which of the following organelles contains these hydrolytic enzymes in animal cells?

a) lysosome
b) chloroplast
c) glyoxysome
d) central vacuole
e) peroxisome

Answer 34

a) lysosome

Question 35

Which organelle or structure is absent in plant cells?

a) centrosomes
b) peroxisomes
c) Golgi vesicles
d) microtubules
e) mitochondria

Answer 35

a) centrosomes

Question 36

Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells?

a) The animal cell is in a hypotonic solution, and the plant cell is in an isotonic solution.
b) The animal cell is in an isotonic solution, and the plant cell is in a hypertonic solution.
c) The animal cell is in a hypertonic solution, and the plant cell is in a hypotonic solution.
d) The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.
e) The animal cell is in a hypertonic solution, and the plant cell is in an isotonic solution

Answer 36

d) The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.

Question 37

Cell membranes are asymmetrical. Which of the following is the most likely explanation?

a) Cell membranes communicate signals from one organism to another.
b) The two sides of a cell membrane face different environments and carry out different functions.
c) The cell membrane forms a border between one cell and another in tightly packed tissues such as epithelium.
d) The “innerness” and “outerness” of membrane surfaces are predetermined by genes.
e) Proteins can only be associated with the cell membranes on the cytoplasmic side.

Answer 37

b) The two sides of a cell membrane face different environments and carry out different functions.

Question 38

Nitrous oxide gas molecules diffusing across a cell’s plasma membrane is an example of

a) active transport.
b) diffusion across the lipid bilayer.
c) osmosis.
d) facilitated diffusion.
e) cotransport.

Answer 38

b) diffusion across the lipid bilayer.

Question 39

Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?

a) The blood cells will expend ATP for active transport of NaCl into the cytoplasm.
b) Water will leave the cells, causing them to shrivel and collapse.
c) The blood cells will take up water, swell, and eventually burst.
d) NaCl will be exported from the red blood cells by facilitated diffusion.
e) NaCl will passively diffuse into the red blood cells.

Answer 39

b) Water will leave the cells, causing them to shrivel and collapse.

Question 40

Which of the following types of molecules are the major structural components of the cell membrane?

a) phospholipids and proteins
b) nucleic acids and proteins
c) glycoproteins and cholesterol
d) phospholipids and cellulose
e) proteins and cellulose

Answer 40

a) phospholipids and proteins

Question 41

Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all?

a) peripheral proteins
b) integrins
c) glycoproteins
d) transmembrane proteins
e) integral proteins

Answer 41

a) peripheral proteins

Question 42

Which of the following is true of integral membrane proteins?

a) They serve only a structural role in membranes.
b)They are loosely bound to the surface of the bilayer.
c) They are usually transmembrane proteins.
d) They are not mobile within the bilayer.

Answer 42

c) They are usually transmembrane proteins.

Question 43

What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?

a) light microscopy
b) confocal fluorescence microscopy
c) super-resolution fluorescence microscopy
d) scanning electron microscopy
e) transmission electron microscopy

Answer 43

a) light microscopy

Question 44

Which plant cell organelle contains its own DNA and ribosomes?

a) glyoxysome
b) peroxisome
c) Golgi apparatus
d) mitochondrion
e) vacuole

Answer 44

d) mitochondrion

Question 45

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

a) proteins
b) cellulose
c) lipids
d) glycogen
e) nucleic acids

Answer 45

a) proteins

Question 46

Signals between the ECM and the cytoskeleton may be transmitted by

a) fibronectin.
b) middle lamella.
c) integrins.
d) collagen.
e) proteoglycans.

Answer 46

c) integrins.

Question 47

Why isn’t the mitochondrion classified as part of the endomembrane system?

a) It is a static structure.
b) Its structure is not derived from the ER or Golgi.
c) It is not involved in protein synthesis.
d) It is not attached to the outer nuclear envelope.
e) It has too many vesicles.

Answer 47

b) Its structure is not derived from the ER or Golgi.

Question 48

A biologist wants specifically to examine the surfaces of different types of cells in kidney tubules of small mammals. The cells in question can be distinguished by external shape, size, and 3-D characteristics. Which of the following would be the optimum method for her study?

a) scanning electron microscopy
b) cell fractionation
c) transmission electron microscopy
d) light microscopy using stains specific to kidney function
e) light microscopy of living unstained material

Answer 48

a) scanning electron microscopy

Question 49

Why are lipids and proteins free to move laterally in membranes?

a) The interior of the membrane is filled with liquid water.
b) There are only weak hydrophobic interactions in the interior of the membrane.
c) Molecules such as cellulose can pull them in various directions.
d) Lipids and proteins repulse each other in the membrane.
e) Hydrophilic portions of the lipids are in the interior of the membrane.

Answer 49

b) There are only weak hydrophobic interactions in the interior of the membrane.

Question 50

Which of the following membrane activities require energy from ATP hydrolysis?

a) movement of carbon dioxide out of a paramecium
b) movement of water into a cell
c) Na+ ions moving out of a mammalian cell bathed in physiological saline
d) facilitated diffusion of chloride ions across the membrane through a chloride channel
e) movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell

Answer 50

c) Na+ ions moving out of a mammalian cell bathed in physiological saline

Question 51

The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is

a) to mediate cell-to-cell recognition.
b) to maintain membrane fluidity at low temperatures.
c) to facilitate diffusion of molecules down their concentration gradients.
d) to maintain the integrity of a fluid mosaic membrane.
e) to actively transport molecules against their concentration gradients.

Answer 51

a) to mediate cell-to-cell recognition.

Question 52

In order for a protein to be an integral membrane protein, it would have to be

a) hydrophobic.
b) completely covered with phospholipids.
c) amphipathic, with at least one hydrophobic region.
d) exposed on only one surface of the membrane.
e) hydrophilic.

Answer 52

c) amphipathic, with at least one hydrophobic region.

Question 53

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in

a) secretory vesicles.
b) peroxisomes.
c) lysosomes.
d) Golgi vesicles.
e) vacuoles.

Answer 53

c) lysosomes.

Question 54

The formulation of a model for a structure or for a process serves which of the following purposes?

a) It serves as a data point among results.
b) It records observations.
c) It can only be arrived at after years of experimentation.
d) It functions as a testable hypothesis.
e) It asks a scientific question.

Answer 54

d) It functions as a testable hypothesis.

Question 55

When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that..?

a) the integral membrane proteins are not strong enough to hold the bilayer together.
b) the hydrophobic interactions that hold the membrane together are weakest at this point.
c) the carbon-carbon bonds of the phospholipid tails are easily broken.
d) water that is present in the middle of the bilayer freezes and is easily fractured
e) hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing.

Answer 55

b) the hydrophobic interactions that hold the membrane together are weakest at this point.

Question 56

When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that..?

a) the integral membrane proteins are not strong enough to hold the bilayer together.
b) the hydrophobic interactions that hold the membrane together are weakest at this point.
c) the carbon-carbon bonds of the phospholipid tails are easily broken.
d) water that is present in the middle of the bilayer freezes and is easily fractured
e) hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing.

Answer 56

b) the hydrophobic interactions that hold the membrane together are weakest at this point.

Question 56

Which structure is the site of the synthesis of proteins that may be exported from the cell?

a) plasmodesmata
b) rough ER
c) free cytoplasmic ribosomes
d) Golgi vesicles
e) lysosomes

Answer 56

b) rough ER

Question 57

Which of the following contains hydrolytic enzymes?

a) lysosome
b) vacuole
c) peroxisome

Answer 57

a) lysosome

Question 58

When biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using

a) a confocal fluorescence microscope.
b) a phase-contrast light microscope.
c) a transmission electronic microscope.
d) a super-resolution fluorescence microscope.
e) a scanning electron microscope.

Answer 58

c) a transmission electronic microscope.

Question 59

Centrioles, cilia, flagella, and basal bodies have remarkably similar structural elements and arrangements. Which of the following hypotheses is most plausible in light of such structural similarities?

a) Cilia and flagella coevolved in the same ancestral eukaryotic organism.
b) Natural selection for cell motility repeatedly selected for microtubular arrays in circular patterns in the evolution of each of these structures.
c) Loss of basal bodies should lead to loss of all cilia, flagella, and centrioles.
d) Cilia and flagella arise from the centrioles.

Answer 59

d) Cilia and flagella arise from the centrioles.

Question 60

Because most receptors are membrane proteins, which of the following is usually true?

a) They are only attached to one membrane surface: exterior or interior.
b) They change their conformation after binding with signal polypeptides.
c) They lead to changes in intracellular ion concentration.
d) They preferentially bind with lipid or glycolipid signal molecules.
e) They open and close in response to protein signals.

Answer 60

b) They change their conformation after binding with signal polypeptides.