Deck 10: Bacterial Growth

Question 1

A recent hurricane has disrupted the local sewage facilities in your community.A water sample is filtered to trap suspected fecal contaminants and the filter is transferred to an eosin methylene blue (EMB)agar plate.On the following day you note growth and a bright green sheen on some of the colonies.The green colonies are most likely to be

A)Gram-negative bacteria
B)Gram-positive bacteria
C)Unable to ferment lactose
D)Viruses

Answer 1

Gram-negative bacteria

Question 2

The enzyme catalase catalyzes conversion of _____ to water and oxygen.

A)Free-radical oxygen
B)Hydrogen ion
C)Hydroxyl ion
D)Hydrogen peroxide

Answer 2

Hydrogen peroxide

Question 3

A consequence of raising the pH above the optimum pH when culturing bacteria is

A)Dissolved oxygen is depleted
B)There is an increase in hydroxyl ions, which disrupts hydrogen bonding
C)Salts crystallize out of solution
D)There is an increase in hydrogen ions, which disrupts hydrogen bonding
E) There is an increase in hydroxyl and hydrogen ions, which disrupts hydrogen bonding

Answer 3

There is an increase in hydroxyl ions, which disrupts hydrogen bonding

Question 4

The _____ growth temperature is the temperature at which the fastest growth rate occurs.

A)Minimum
B)Suboptimal
C)Maximum
D)Optimal

Question 5

Bacteria requiring multiple growth factors to survive are classified as _____ bacteria.

A)Fastidious
B)Selective
C)Differential
D)Beta hemolytic
E)Stationary

Question 6

The reason that bacteria can grow in the presence of oxygen is that they contain

A)Superoxide dismutase
B)Alcohol dehydrogenase
C)Catalase
D)Oxygen free radicals
E)Both superoxide dismutase and catalase

Question 7

Infections manifested on the body's extremities are most likely to be associated with microbes that prefer temperatures _____ the host's normal body temperature.

A)The same as
B)On the low side of
C)Above

Question 8

You have cultured a bacterial specimen obtained from an abscess on mannitol salt agar.On the following day you note growth and a yellow zone around the colonies.Your specimen is most likely to be

A)Gram-negative
B)Gram-positive
C)Salt-sensitive
D)Unable to ferment mannitol

Question 9

You have isolated a bacterium from the hot springs of Rotorua in New Zealand,one of the world's largest geothermal locations.It grows optimally between 45 and 60°C.This is an example of a(n)

A)Extreme thermophile
B)Mesophile
C)Thermophile
D)Psychrophile
E)Psychrotroph

Question 10

Plant and meat extracts are commonly found in _____ media.

A)Complex
B)Selective
C)Differential
D)Chemically defined

Question 11

A throat swab specimen was cultured on a blood agar plate.Colonies are formed,which produce a greenish halo around the colonies.These bacteria are exhibiting

A)Gamma hemolysis
B)Beta hemolysis
C)Alpha hemolysis
D)Lactose fermentation
E)Mannitol fermentation

Question 12

Which of the following is required for biosynthesis of cysteine but not other amino acids?

A)Sulfur
B)Carbon
C)Nitrogen
D)Oxygen
E)Phosphorus

Question 13

Which of the following is a mismatched pair?

A)Hyperthermophile; grows at 80°C or above
B)Acidophile; grows between pH 0 and pH 5
C)Mesophile; grows near human body temperature
D)Microaerophile; grows in 20% oxygen
E)Alkalophile; grows between pH 8.5 and pH 11.5

Question 14

What is the name of microorganisms that cannot survive unless they are in an environment containing a great deal of salt?

A)Extreme halophile
B)Facultative halophile
C)Facultative anaerobe
D)Obligate halophile
E)Obligate aerobe

Question 15

Which of the following is a mismatched pair?

A)Growth at low pH values; acidophiles
B)Obligate halophile; requires high salt conditions for growth
C)Facultative anaerobes; require oxygen for growth
D)Selective medium; prohibits growth of some organisms

Question 16

A growth medium for which the exact chemical makeup is known and can be precisely reproduced is a _____ medium.

A)Complex
B)Selective
C)Differential
D)Chemically defined

Question 17

Chemoheterotrophs obtain carbon by

A)Photosynthesis
B)Carbon fixation
C)Anaerobic processes
D)Recycling the carbon of preexisting biological molecules

Question 18

A consequence of raising the temperature above the maximum growth temperature when culturing bacteria produces a marked

A)Destabilization of hydrogen bonds in proteins
B)Increase in the oxygen concentration
C)Decrease in pH causing acidification
D)Increase in osmotic pressure

Question 19

How would you differentiate Streptococcus pyogenes from nonpathogenic streptococci?

A)Grow colonies on blood agar plates
B)Grow colonies on Mannitol salt agar plates
C)Grow colonies on EMB plates
D)Gram stain the cells
E)Acid fast stain the cells

Question 20

A thioglycolate tube was inoculated with an unknown bacterium.After overnight incubation growth is seen only in the area several millimeters below the surface of the agar.This bacterium exhibits a growth pattern characteristic of a(n)

A)Aerotolerant organism
B)Microaerophile
C)Obligate aerobe
D)Obligate anaerobe
E)Facultative anaerobe

Question 21

Use the figure below to answer the following questions.

What part of the growth curve is the region where number of living cells is increasing exponentially?

Question 22

Which of the following is not a method used to count viable bacteria?

A)Flow cytometry
B)Spectrophotometry
C)Measurement of biomass
D)Plate count

Question 23

Use the figure below to answer the following questions.

In the figure of the bacterial growth curve which letter (A-D)indicates the region of the growth curve where the number of new cells formed equals the number of cells dying?

Question 24

Answer true or false to the following statement: Differential medium contains ingredients that that allow only a few species of bacteria to grow.

Question 25

Use the figure below to answer the following questions.

In the figure of the bacterial growth curve which letter (A-D)indicates the region where the cells are dying at a greater rate than they are reproducing?

Question 26

Answer true or false to the following statement: Trace elements are not required for growth.

Question 27

Which growth characteristic best matches Treponema pallidum?

A)Extreme thermophile
B)Spirochete
C)Obligate anaerobe
D)Short doubling time
E)Grows inside mucous layer

Question 28

Answer true or false to the following statement: Pathogens of humans can be facultative anaerobes.

Question 29

Answer true or false to the following statement: A GasPak™ jar is often used to culture Clostridium perfringens.

Question 30

Which of the following methods would be used to obtain a clinical sample from the stomach?

A)Catheterization
B)Intubation
C)Needle aspiration
D)Sterile swab
E)"Clean catch" method

Question 31

Which growth characteristic best matches Helicobacter pylori?

A)Extreme thermophile
B)Spirochete
C)Obligate anaerobe
D)Short doubling time
E)Grows inside mucous layer

Question 32

Answer true or false to the following statement: Obligate anaerobes can grow in the presence of oxygen under some conditions.

Question 33

Answer true or false to the following statement: Samples of cerebrospinal fluid are obtained by needle aspiration.

Question 34

Answer true or false to the following statement: Eosin methylene blue agar allows Gram-positive,but not the growth of Gram-negative organisms.

Question 35

Answer true or false to the following statement: Successful bacterial growth depends on the right temperature,pH,and osmotic pressure.

Question 36

Use the figure below to answer the following questions.

In the figure of the bacterial growth curve what does the horizontal axis represent?

A)Growth
B)Mass
C)Dry weight
D)Time
E)Temperature

Question 37

Answer true or false to the following statement: Pathogens of humans are chemoautotrophs.

Question 38

Which growth characteristic best matches Escherchia coli?

A)Extreme thermophile
B)Spirochete
C)Obligate anaerobe
D)Short doubling time
E)Grows inside mucous layer

Question 39

Answer true or false to the following statement: Chemically defined media are used to study bacterial end products.

Question 40

Which growth characteristic best matches Clostridium perfringens?

A)Extreme thermophile
B)Spirochete
C)Obligate anaerobe
D)Short doubling time
E)Grows inside mucous layer

Question 41

Answer true or false to the following statement: Superoxide dismutase is produced by obligate aerobes.

Question 42

Answer true or false to the following statement: When the number of cells dying is equivalent to the number of cells being produced by cell division,stationary phase has been reached.

Question 43

Which growth medium is needed to culture Haemophilus influenzae in the laboratory? How is this medium made and why is it needed?

Question 44

Answer true or false to the following statement: Blood agar is a defined medium.

Question 45

While ailment is attributed to Helicobacter pylori? Explain how H.pylori is able to withstand conditions found in the stomach.

Question 46

What is a chemostat? Why are chemostats used by biotechnology and pharmaceutical companies?

Question 47

You need to culture Clostridium perfringens and will use a GasPak™ jar.Explain how a GasPak™ jar ensures that oxygen is removed from the environment.How will you know that an anaerobic state has been reached?

Question 48

Explain why growth rate is an important consideration in the context of the disease process and diagnosis.

Question 49

Answer true or false to the following statement: The time interval needed for a bacterial colony to form is called the half-life.

Question 50

Before the widespread use of refrigerators,people often preserved their food for long-term storage by adding large amounts of salt.In the context of osmotic pressure,why is this process effective against food spoilage? Are all microorganisms inhibited by high salt?

Question 51

Answer true or false to the following statement: Answer true or false to the following statement: The lag phase is when bacteria are most sensitive to antibiotics.

Question 52

Explain the difference between selective and differential growth media,providing an example of each.Identify two media (other than those already used as examples)which act as both selective and differential media,and explain how to interpret the results.