Deck 3: Bacteria

Question 1

The structure that enables bacterial cells to form biofilms on surfaces is the

A)flagellum.
B)pilus.
C)glucan.
D)slime layer.
E)protoplast.

Answer 1

D

Question 2

A major component of the cell wall of Gram-positive bacteria is

A)lipopolysaccharide.
B)phospholipid.
C)peptidoglycan.
D)lipoproteins.
E)protein.

Answer 2

C

Question 3

The cell walls of bacteria

A)enable them to be pleomorphic.
B)protect them against penicillin-derived antibiotics.
C)are single layered,but very thick.
D)protect the cells against changes in osmotic pressure.
E)all of the above.

Answer 3

D

Question 4

The polysaccharide layer surrounding some bacteria is called a

A)waxy layer.
B)capsid.
C)basal body.
D)glycocalyx.
E)any of the above.

Question 5

Which of the following statements is TRUE?

A)Bacterial cells contain a small number of chromosomes.
B)A plasmid is an extra piece of DNA attached to the cell wall.
C)Bacterial DNA is double stranded.
D)Genes for antibiotic resistance are found in cytoplasmic inclusions.
E)All of the above.

Question 6

Peptidoglycan is a substance that

A)is found in Gram-positive,but not Gram-negative,bacterial cells.
B)forms a layer in bacterial cell membranes.
C)plays a role in antibiotic resistance.
D)consists of a polymer of lipopolysaccharides.
E)consists of a carbohydrate chain with peptide cross bridges.

Question 7

The Ziehl-Neelson stain is used to

A)observe bacteria which have a waxy outer layer.
B)detect the presence of mycobacteria in sputum.
C)aid in the diagnosis of tuberculosis.
D)stain certain bacteria which do not react with the Gram stain.
E)all of the above.

Question 8

Plasmids are

A)small pieces of DNA which may carry genes for antibiotic resistance.
B)structures which are only found in pathogenic bacteria.
C)essential for the correct replication of a bacterial cell.
D)small pieces of DNA attached to the plasma membrane.
E)only found in Gram-positive bacteria.

Question 9

Rod-shaped bacteria are called

A)eubacteria.
B)bacilli.
C)cocci.
D)vibrios.
E)endospores.

Question 10

Bacteria which are classified as Gram-positive

A)always form endospores.
B)do not have peptidoglycan in the cell wall.
C)appear blue/purple when stained with the Gram stain.
D)have a capsule to help absorb the stain.
E)all of the above.

Question 11

A swab from an infected wound is stained with the Gram stain and examined under the microscope.The purpose of Gram staining the specimen is to

A)kill the bacteria on the slide.
B)assist in identifying the organism.
C)dissolve away contaminating material.
D)determine whether the organism has a capsule.
E)examine the cell structure.

Question 12

A bacterium with spherical cells that exist in pairs would be termed a

A)staphylococcus.
B)bacillus.
C)diplococcus.
D)vibrio.
E)streptococcus.

Question 13

The DNA that codes for the basic structure and function of a bacterium is

A)contained in a single circular chromosome.
B)single stranded in a double helix.
C)contained in the nucleus.
D)usually in the form of a plasmid.
E)contained within a membrane-bound vesicle.

Question 14

One of the functions of a bacterial capsule is to

A)assist the organism to avoid phagocytosis.
B)prevent the bacteria from getting stuck to surfaces.
C)protect the organism from osmosis.
D)protect the cell from drying out.
E)all of the above.

Question 15

Which of the following statements about flagella is TRUE?

A)They enable bacteria to move.
B)They assist in chemotaxis.
C)They are attached to the cell wall by a series of concentric protein rings.
D)They propel the cell by a propeller-like motion.
E)All of the above.

Question 16

Pili

A)are hair-like appendages on some bacterial cells.
B)are structures that assist the bacterial cell to swim.
C)are required for asexual reproduction in bacterial cells.
D)are involved in the process of agglutination.
E)only occur in some Gram-positive bacteria.

Question 17

Gram-positive bacteria differ from Gram-negative bacteria because Gram-positives

A)have a different cell wall structure.
B)contain a thicker layer of peptidoglycan.
C)stain blue with the Gram stain.
D)are generally more susceptible to penicillin.
E)all of the above.

Question 18

Bacteria which can have more than one cell shape are described as

A)pleomorphic.
B)heterotrophic.
C)actinomycetes.
D)archaebacteria.
E)pathogenic.

Question 19

When viewed under the microscope,the shape of the organism responsible for cholera would be

A)round.
B)rod-shaped.
C)a corkscrew.
D)comma-shaped.
E)a spiral.

Question 20

Flagella are

A)protein filaments which enable bacterial cells to move.
B)found only in Gram-positive bacteria.
C)hair-like appendages on bacterial cells that detect nutrients in the environment.
D)structures that enable bacteria to attach to surfaces.
E)important for cell division in bacterial cells.

Question 21

High concentrations of salt and sugars in food act as preservatives by

A)inactivating nutrients essential for bacterial growth.
B)changing the level of available oxygen.
C)altering the pH of the medium.
D)creating a hypertonic environment.
E)inhibiting enzyme activity.

Question 22

Endospores are

A)an important method of survival for some bacteria.
B)a method of sexual reproduction.
C)only formed by intracellular bacteria.
D)found in all pathogenic bacteria.
E)all of the above.

Question 23

During the logarithmic (log)phase of bacterial growth

A)the cells are in a resting state.
B)the cells are dividing at a minimal rate.
C)there is an exponential increase in cell numbers.
D)the cells are adapting to their new environment.
E)none of the above.

Question 24

Which of the following methods is used to differentiate between different strains of bacteria?

A)Phage typing.
B)DNA typing.
C)Pulse field gel electrophoresis.
D)Biochemical tests.
E)All of the above.

Question 25

Most medically important bacteria have a generation time of around

A)5 minutes.
B)30 minutes.
C)10 hours.
D)24 hours.
E)48 hours.

Question 26

Which of the following bacteria can produce endospores?

A)Staphylococcus aureus.
B)Clostridium perfringens.
C)Streptococcus pneumoniae.
D)Escherichia coli.
E)Streptococcus pyogenes.

Question 27

The cellular structure which is primarily responsible for determining which substances enter and leave the cell is the

A)cell wall.
B)cell membrane.
C)peptidoglycan layer.
D)capsule.
E)teichoic acid layer

Question 28

Which of the following is NOT a function of the bacterial cell membrane?

A)To provide structural support for the bacterial cell.
B)To control the passage of nutrients into the cell.
C)The synthesis of cell wall components.
D)The secretion of proteins out of the cell.
E)To carry out metabolic reactions.

Question 29

The passage of water from an area of high water concentration to an area of low water concentration is called

A)active transport.
B)facilitated diffusion.
C)filtration.
D)osmosis.
E)none of the above.

Question 30

Anaerobic bacteria

A)must have oxygen to grow.
B)do not reproduce in the presence of oxygen.
C)are always pathogenic.
D)can survive in the presence or absence of oxygen.
E)can only grow in the intestine.

Question 31

Which of the following is an essential requirement of all bacteria for reproduction?

A)Water.
B)Oxygen.
C)Light.
D)Warmth.
E)Nitrogen.

Question 32

During the stationary phase of bacterial growth

A)the rate of cell division equals the rate of cell death.
B)the lack of nutrients means there is no cell replication.
C)the cells stop growing to produce endospores.
D)the cells are in a resting phase prior to rapid multiplication.
E)all of the above.

Question 33

A bacterium that can grow in the presence or absence of oxygen is called a(n)

A)obligate anaerobe.
B)obligate aerobe.
C)mesophile.
D)facultative anaerobe.
E)heterotroph

Question 34

Endospores can be destroyed

A)by autoclaving at 121OC for 15 minutes.
B)by boiling for one hour.
C)by exposure to most disinfectants for 15 minutes.
D)only by incineration.
E)by treating with chlorine bleach.

Question 35

The structure that protects some bacteria from heat at 100ᵒC is the

A)capsule.
B)capsid.
C)endospore.
D)envelope.
E)cell wall.

Question 36

Which of the following is TRUE of endospores?

A)They can withstand boiling at 100OC.
B)They are formed under adverse conditions.
C)Only one endospore is formed from each bacterial cell.
D)They consist of DNA enclosed in a spore coat.
E)All of the above.

Question 37

Bacteria that infect humans grow best at

A)pH 6.5 and 37OC.
B)pH 7.4 and 37OC.
C)pH 6.8 and 40OC.
D)pH 7.4 and 40OC.
E)ph 7.8 and 37OC.

Question 38

Endospores are formed

A)when Gram-positive bacteria are growing very rapidly.
B)by bacteria when threatened by other organisms.
C)when bacterial growth is inhibited due to unfavourable conditions.
D)as a more efficient method of reproduction for bacteria.
E)as a type of sexual reproduction in bacteria.
C)when bacterial growth is inhibited due to unfavourable conditions.

Question 39

Bacterial cell membranes consist of
A)a single layer of phospholipids.

A)lipopolysaccharide embedded in a phospholipid bilayer.
B)protein molecules embedded in a phospholipid bilayer.
B)proteins,peptidoglycan and sterols.
C)glycoprotein,phospholipid and sterols.

Question 40

The generation time of bacteria refers to

A)the time spent in the logarithmic phase of growth.
B)the time taken for a cell to reproduce itself.
C)the period before the bacteria start to grow.
C)how long it takes for a colony of bacteria to become visible on an agar plate.
D)the evolutionary period when bacteria first appeared.

Question 41

Which of the following organisms is a normal inhabitant of the upper respiratory tract,but can cause otitis media and meningitis?

A)Group B streptococci.
B)Streptococcus pneumoniae.
C)Staphylococci.
D)Escherichia coli.
E)Normal inhabitants don't cause disease.

Question 42

The Gram-negative bacillus that is a normal inhabitant of the human intestine is

A)Clostridium difficile.
B)Pseudomonas aeruginosa.
C)Campylobacter jejuni.
D)Vibrio cholerae.
E)Escherichia coli.

Question 43

Which of the following organisms has been shown to be implicated in the formation of gastric ulcers?

A)Salmonella typhimurium.
B)Campylobacter jejuni.
C)Escherichia coli 0157.
D)Helicobacter pylori.
E)Staphylococcus aureus.

Question 44

Which of the following statements about phage typing is FALSE?

A)All bacteria can be typed by the use of the appropriate bacteriophage.
B)Phage typing relies on the ability of a phage to infect a specific bacterial cell.
C)Bacteriophage destroy the cells they infect.
D)Phage typing is useful in epidemiology studies.
E)Phage typing can be performed on bacteria grown on agar plates.

Question 45

Which obligate intracellular bacterium causes a common sexually transmitted infection in humans?

A)Treponema pallidum.
B)Chlamydia trachomatis.
C)Neisseria gonorrhoeae.
D)Trichomonas vaginalis.
E)Rickettsiae.

Question 46

Which of the following opportunistic pathogens is a frequent cause of infection in burns patients?

A)Clostridium tetani.
B)Pseudomonas aeruginosa.
C)Group B streptococci.
D)Salmonella.
E)Mycobacterium tuberculosis.

Question 47

The anaerobic Gram-positive bacillus that can cause severe diarrhoea in patients given antibiotics is

A)Clostridium difficile.
B)Pseudomonas aeruginosa.
C)Campylobacter jejuni.
D)Vibrio cholerae.
E)Escherichia coli.