Chapter 4: Fundamentals of Microbiology

Question 1

Which of the following is NOT a distinguishing characteristic of prokaryotic cells?

a. Their DNA is not enclosed within a membrane.
b. They lack membrane-enclosed organelles.
c. They have cell walls containing peptidoglycan.
d. They lack a plasma membrane.

Answer 1

d. They lack a plasma membrane.

Question 2

Which of the following statements best describes what happens when a bacterial cell is placed in a solution containing 5% NaCl?

a. Sucrose will move into the cell from a higher to a lower concentration.
b. The cell will undergo osmotic lysis.
c. Water will move out of the cell.
d. Water will move into the cell.
e. No change will result; the solution is isotonic.

Answer 2

c. Water will move out of the cell.

Question 3

By which of the following mechanisms can a cell transport a substance from a lower to a higher concentration?

a. Simple diffusion
b. Facilitated diffusion
c. Active transport
d. Extracellular enzymes
e. Aquaporins

Answer 3

c. Active transport

Question 4

Which of the following statements about a gram-positive cell wall is false?

a. It maintains the shape of the cell.
b. It is sensitive to lysozyme.
c. It protects the cell in a hypertonic environment
d. It contains teichoic acids..
e. It is sensitive to penicillin.

Answer 4

c. It protects the cell in a hypertonic environment

Question 5

Which of the following have a cell wall?

a. Protoplasts
b. Fungi
c. L forms
d. Mycoplasmas
e. Animal cells

Answer 5

b. Fungi

Question 6

Which of the following statements about prokaryotic cells is generally false?

a. They have a semirigid cell wall.
b. They are motile by means of flagella.
c. They possess 80S ribosomes.
d. They reproduce by binary fission.
e. They lack membrane-bound nuclei.

Answer 6

c. They possess 80S ribosomes.

Question 7

Which of the following statements is true?

a. Endospores are for reproduction.
b. Endospores allow a cell to survive environmental changes.
c. Endospores are easily stained in a Gram stain.
d. A cell produces one endospore and keeps growing.
e. A cell can produce many endospores.

Answer 7

b. Endospores allow a cell to survive environmental changes.

Question 8

Which of the following is NOT a characteristic of the plasma membrane?

a. It may be composed of polysaccharide.
b. It may be composed of polypeptide.
c. It may be responsible for virulence.
d. It is used to adhere to surfaces.
e. It protects from osmotic lysis.

Answer 8

e. It protects from osmotic lysis.

Question 9

Which of the following structures is NOT found in prokaryotic cells?

a. Flagellum
b. Axial filament
c. Cilium
d. Pilus
e. Peritrichous flagella

Answer 9

c. Cilium

Question 10

he difference between simple diffusion and facilitated diffusion is that facilitated diffusion

a. Can move materials from a higher to a lower concentration.
b. Can move materials from a lower to a higher concentration.
c. Requires ATP.
d. Requires transporter proteins.
e. Doesn’t require ATP.

Answer 10

d. Requires transporter proteins.

Question 11

The antibiotic polymyxin B combines with phospholipids. This will cause ________.

a. leakage of cell contents
b. loss of motility
c. sporulation
d. binary fission
e. stoppage of protein synthesis

Answer 11

a. leakage of cell contents

Question 12

Which of the following is a difference between gram-positive and gram-negative cells?

a. Only gram-negative cells have a lipopolysaccharide (LPS) layer.
b. Gram-negative cell walls contain teichoic acids.
c. Only gram-positive cells have peptidoglycan that is made of a carbohydrate backbone.
d. Gram-positive cells contain less peptidoglycan than do gram-negative cells.

Answer 12

a. Only gram-negative cells have a lipopolysaccharide (LPS) laye

Question 13

Which of the following statements is true regarding the principles of osmosis?

a.
If a cell is in a hypertonic solution, water leaves the cell in an attempt to balance to concentration of solutes and reach equilibrium.
b.
The relative concentrations of solutes inside and outside the cell have no influence on the direction of osmosis.
c.
If a cell is in an isotonic solution, no water moves across the membrane because equilibrium has been reached.
d.
If a cell is in a hypotonic solution, water leaves the cell in an attempt to balance to concentration of solutes and reach equilibrium.

Answer 13

a.
If a cell is in a hypertonic solution, water leaves the cell in an attempt to balance to concentration of solutes and reach equilibrium.

Question 14

Fimbriae and pili differ in that pili

a. Are composed of pilin.
b. Are composed of flagellin.
c. Are used to transfer DNA.
d. Are used for motility.
e. Are used for attachment.

Answer 14

c. Are used to transfer DNA.

Question 15

What statement most accurately describes the structure of the plasma membrane?

a. The plasma membrane is a phospholipid bilayer with the hydrophilic phosphate groups oriented toward the inside and outside of the cell.
b. The lipid portion of the bilayer is hydrophilic.
c. Peripheral proteins span the membrane.
d. The plasma membrane is a phospholipid bilayer with the hydrophilic phosphate groups oriented toward one another.

Answer 15

a. The plasma membrane is a phospholipid bilayer with the hydrophilic phosphate groups oriented toward the inside and outside of the cell.

Question 16

Which of the following statements about gram-negative cell walls is false?

a. They protect the cell in a hypotonic environment.
b. They have an extra outer layer composed of lipoproteins, lipopolysaccharides, and phospholipids.
c. They are toxic to humans.
d. They are sensitive to penicillin.
e. Their Gram reaction is due to the outer membrane.

Answer 16

b. They have an extra outer layer composed of lipoproteins, lipopolysaccharides, and phospholipids.

Question 17

Which of the following is NOT a chemical component of a bacterial cell wall?

a. Cellulose
b. Peptidoglycan
c. Teichoic acids
d. Peptide chains
e. N-acetylmuramic acid

Answer 17

a. Cellulose

Question 18

What will happen if a bacterial cell is placed in distilled water with lysozyme?

a. The cell will plasmolyze.
b. The cell will undergo osmotic lysis.
c. Water will leave the cell.
d. Lysozyme will diffuse into the cell.
e. No change will result; the solution is isotonic.

Answer 18

b. The cell will undergo osmotic lysis.

Answers:

Question 19

All of the following are found in the cell walls of gram-positive bacteria except ________.

a. lipoteichoic acid
b. N-acetylglucosamine
c. lipid A
d. peptidoglycan
e. teichoic acid

Answer 19

c. lipid A

Question 20

Which of the following organelles most closely resembles a prokaryotic cell?

a. Nucleus
b. Mitochondrion
c. Golgi complex
d. Vacuole
e. Cell wall

Answer 20

b. Mitochondrion

Question 21

Where are phospholipids most likely found in a eukaryotic cell?

a. Flagella
b. Around organelles
c. Plasma membrane
d. Ribosomes
e. Around organelles and Plasma membrane

Answer 21

e. Around organelles and Plasma membrane

Question 22

During endospore formation, ________.

a. the cell is experiencing a great deal of metabolic activity
b. the population of bacterial cells doubles
c. the only DNA that is copied contains the genes necessary for germination
d. a thick spore coat forms around the forespore before the endospore is released into the environment

Answer 22

d. a thick spore coat forms around the forespore before the endospore is released into the environment

Question 23

Chemotaxis refers to the ability of microorganisms to ________.

a. escape phagocytosis
b. move toward or away from chemical stimuli
c. survive under adverse conditions
d. attach to solid surfaces
e. move in a wavelike motion

Answer 23

b. move toward or away from chemical stimuli

Question 24

Where are phospholipids most likely found in a prokaryotic cell?

a. Flagella
b. Around organelles
c. Plasma membrane
d. Ribosomes
e. Around organelles and Plasma membrane

Answer 24

c. Plasma membrane

Question 25

Which of the following is NOT found in both mitochondria and prokaryotes?

a. Circular chromosome
b. 70S ribosomes
c. Cell wall
d. Binary fission
e. ATP-generating mechanism

Answer 25

c. Cell wall

Question 26

The plasma membrane is considered a barrier to the environment because ________.

a. it controls the passage of molecules into the cell
b. only water and small molecules may penetrate the membrane
c. no molecules may pass through it
d. it is a rigid structure
e. the membrane is the outermost structure of the cell

Answer 26

a. it controls the passage of molecules into the cell

Question 27

A population of bacterial cells has been placed in a very nutrient-poor environment with extremely low concentrations of sugars and amino acids. Which kind of membrane transport becomes crucial in this environment?

a. simple diffusion
b. facilitated diffusion
c. pinocytosis
d. active transport
e. osmosis

Answer 27

d. active transport

Question 28

What will occur if a bacterial cell with a weakened or damaged cell wall is placed in pure water?

a. The cell will form endospores.
b. The cell will remain the same size.
c. The cell will shrink.
d. The cell will form a new cell wall.
e. The cell will swell and burst.

Answer 28

e. The cell will swell and burst.

Question 29

Which of the following processes occurs in bacterial plasma membranes, but not in eukaryotic plasma membranes?

a. active transport
b. protein synthesis
c. RNA synthesis
d. facilitated diffusion
e. ATP synthesis

Answer 29

e. ATP synthesis

Question 30

Why is penicillin selectively toxic to bacterial cells but harmless to human cells?

a. Penicillin specifically weakens peptidoglycan, which is found only in bacterial cells.
b. Penicillin is rapidly metabolized and destroyed by human cells.
c. Human cells actively transport penicillin out of the cell.
d. The glycocalyx of an animal cell provides a barrier through which penicillin cannot pass.
e. Penicillin is inactivated within lysosomes of human cells.

Answer 30

a. Penicillin specifically weakens peptidoglycan, which is found only in bacterial cells.

Question 31

Bacillus anthracis causes the deadly disease anthrax. Organisms of the genus Bacillus may form endospores. This bacterium would be suitable for biological warfare because endospores ________.

a. are difficult to stain
b. are centrally located within the bacterial cells
c. have a high concentration of calcium ions
d. are resistant to high temperatures, UV light, and desiccation
e. are multilayered structures

Answer 31

d. are resistant to high temperatures, UV light, and desiccation

Question 32

Assume you are growing a bacterial culture in a glucose medium. Your lab partner adds more glucose in hopes of speeding up the experiment. The bacteria suddenly die. The best explanation for this result is that ________.

a. glucose is toxic to bacteria
b. the bacteria could not use glucose
c. osmotic lysis occurred
d. the cells underwent sporulation
e. the cells plasmolyzed

Answer 32

e. the cells plasmolyzed

Question 33

The nuclear area of the bacterial cell ________.

a. has abundant histone proteins
b. is enclosed in a nuclear membrane
c. contains the bacterial chromosome
d. is connected to the endoplasmic reticulum
e. contains many linear chromosomes

Answer 33

c. contains the bacterial chromosome

Question 34

A eukaryotic cell can ingest a prokaryotic cell by ________.

a. phagocytosis
b. pinocytosis
c. digestive vacuolization
d. active transport
e. osmosis

Answer 34

a. phagocytosis

Question 35

Which of the following is not a structure of prokaryotic cells?

a. flagella
b. ribosome
c. chloroplast
d. chromosome
e. capsule

Answer 35

c. chloroplast