Ch 6: Microbial Growth

Which of the following is NOT a step in bacterial cell division? A. Splitting apart of two new daughter cells B. Cell elongation C. Disappearance of nuclear envelope D. Replication of the genetic material

Disappearance of nuclear envelope

True/False Adding salts to a solution increases osmotic pressure and is used to preserve food.

True

True/False Cells growing in a rich medium will have a steeper log phase slope than will those growing in a nutrient-poor medium.

True

True/False During the stationary phase, bacteria continue to undergo binary fission.

True

True/False Psychrotrophic organisms are often responsible for food spoilage in refrigerated foods.

True

Starting with three cells, how many cells would result from three rounds of replication? A. Six B. Nine C. Twelve D. Twenty-four E. Forty-eight F. Cannot be determined

Twenty-four

What results when a single bacterium reproduces? A. Two genetically unique daughter cells B. One parent cell and a genetically different cell C. One parent cell and a genetically identical daughter cell D. Two genetically identical daughter cells

Two genetically identical daughter cells

An unknown organism grows at the top of a tube of thioglycolate broth. This organism is best described as a/an ___ for its oxygen requirements.

aerobe

An organism that has peroxidase and superoxide dismutase but lacks catalase is most likely an A. aerobe B. aerotolerant anaerobe C. obligate anaerobe

aerotolerant anaerobe

Bacterial reproduction occurs by what process? A. lysogeny B. meiosis C. binary fission D. mitosis

binary fission

Bacteria naturally prefer company instead of solitude for growth. Examples of this kind of communal growth pattern can be found everywhere, from surfaces of the teeth and the intestines, to the surface of a slimy rock in the lake, to the thick floc that clogs water pipes. These examples of communal bacterial growth are known by what name? A. colony B. infectious unit C. biofilm D. planktonic unit

biofilm

Members of the genus Clostridium display the following properties: Gram-positive bacilli Endospore formation Anaerobic growth Which of the following would be appropriate for the culture of members of this genus? A. blood agar plate in a candle jar B. blood agar plate in an anaerobe jar C. nutrient broth D. sodium thioglycolate broth E. both a blood agar plate in an anaerobe jar and sodium thioglycolate broth

both a blood agar plate in an anaerobe jar and sodium thioglycolate broth

A bacterial medium contains chemicals that inhibit gram-positive bacteria and indicators so that bacteria that ferment lactose produce red colonies, and bacteria that do not ferment lactose produce colorless colonies. Such a medium is called __________. A. differential B. both selective and differential C. enriched D. selective

both selective and differential

The enzyme ____ catalyzes the conversion of peroxide to water and oxygen.

catalase

During the lag phase, ________. A. cells are growing in number B. cells are engaged in intense enzymatic activity C. cells are decreasing in number D. changes in pH occur E. nutrients are depleted

cells are engaged in intense enzymatic activity

To look for bacteria that degrade petroleum, a culture medium containing crude oil, sodium nitrate, phosphate buffer, and magnesium sulfate is inoculated with soil. This medium is __________. A. chemically defined B. complex C. differential D. reduced

complex

A culture medium consisting of agar, peptone, and beef heart extract is a/an ________. A. selective medium B. complex medium C. differential medium D. chemically defined medium E. enrichment medium

complex medium

Blood agar used to observe hemolysis or clearing around Streptococcus pyogenes colonies is an example of a/an ________. A. selective media B. differential media C. enrichment media D. isolation media E. reducing

differential media

In microbiology lab, you make three different culture plates: one general purpose plate, one selective media plate, and one differential media plate. Unfortunately, you forget to label the different plates, so you do not know which is which. To determine the identity of each plate, you inoculate it with two different strains of laboratory bacteria. After inoculation, you see that a particular plate has allowed both organisms to grow, but one has changed color. Which plate do you think this is? A. It is impossible to distinguish between selective and differential media in this case. B. selective media C. differential media D. general purpose media

differential media

During log phase, bacteria are __________. A. dividing at the fastest possible rate B. preparing to divide C. dying exponentially D. dying and dividing in equal numbers

dividing at the fastest possible rate

Sampling lake water for microscopic organisms is not as easy as it sounds when you want to both count and identify species. In a given water sample, your bacteria of choice can be rare or difficult to culture, particularly given the mixture of bacteria in a biofilm. Which of the following culture media would be best for growing fecal coliforms when they are relatively less abundant than other bacteria in the lake? A. basic culture medium B. anaerobic culture medium C. enrichment culture medium D. complex culture medium

enrichment culture medium

Which of the following types of culture media would best be used by a veterinarian to grow any bacteria in a blood sample? A. selective and differential media B. general purpose media C. enrichment media D. selective media

enrichment media

An organism that grows both in the presence and the absence of oxygen and uses oxygen when it is available is called a/an ________. A. anaerobe B. facultative anaerobe C. microaerophile D. aerotolerant anaerobe E. aerobe

facultative anaerobe

All of the following are true of the plate count method except ________. A. most commonly used method for assay of bacterial cell number B. involves cell plating and growth C. dependable D. fast-completed in minutes E. measures number of viable cells

fast-completed in minutes

You are testing the number of coliforms in a drinking water source. Which of the following test methods would be best to use? A. dry weight B. turbidity C. direct microscopic count D. filtration

filtration

If a single bacterium replicated every 30 minutes, how many bacteria would be present in 2 hours? A. 32 B. 16 C. 8 D. 4 E. 1

16

Put the following steps of bacterial replication in the correct order, starting from a parent cell. 1.Cell elongation 2.Septum formation 3.Chromosome replication 4.Separation of daughter cells A. 3, 1, 2, 4 B. 1, 4, 3, 2 C. 2, 4, 3, 1 D. 4, 3, 1, 2 E. 3, 2, 1, 4

3, 1, 2, 4

In a pour plate technique, 32 bacterial colonies are counted on the 10-2 dilution of milk. How many bacteria were in the original milk? __________. (Do not use scientific notation in your answer.)

3200

If 52 bacterial colonies grow on a nutrient agar plate inoculated with 1 ml of a 1:1000 dilution of hamburger, how many bacteria are in the original hamburger sample? A. 52 bacteria per g B. 520 bacteria per g C. 5200 bacteria per g D. 52,000 bacteria per g

52,000 bacteria per g

Assume that you inoculated potato salad with 10 bacterial cells and stored it at room temperature. After 3 hours, there are 640 cells. How many generations did the cells go through? A. 1 generation B. 3 generations C. 6 generations D. 12 generations

6 generations

Which one of the following temperatures would most likely kill a mesophile? A. -50 degrees celsius B. zero degrees celsius C. 9 degrees celsius D. 37 degrees celsius E. 60 degrees celsius

60 degrees celsius

Which of the following terms are mismatched? A. hyperthermophiles; no water B. extreme halophiles; 30% salt C. extreme thermophiles; 100°C D. acidophiles; low pH E. psychrophiles; 0°C

hyperthermophiles; no water

Which of the following is not a characteristic of biofilms? A. antibiotic resistance B. hydrogel C. iron deficiency D. quorum sensing

iron deficiency

In which phase of the growth curve is the population doubling time fastest? A. logarithmic decline phase B. lag phase. C. stationary phase D. death phase E. log phase

log phase

What phase of the cell cycle is extended in a chemostat? A. death phase B. stationary phase C. logarithmic decline phase D. log phase E. lag phase

log phase

Which of the following is not a step in binary fission? A. cell elongation B. cross-wall formation C. invagination of the plasma membrane D. lysis of the existing cell wall E. replication of chromosomal DNA

lysis of the existing cell wall

Bacteria growing in and on the human body, including normal microbiota as well as pathogens, are classified as ________. A. mesophilic and acidophilic B. thermophilic and acidophilic C. thermophilic and halophilic D. mesophilic and halophilic E. mesophilic and heterotrophic

mesophilic and heterotrophic

Campylobacter bacteria are grown with a CampyPak that produces 5% carbon dioxide and 15% oxygen. This bacterium is __________. A. capnophile B. microaerophile C. aerotolerant anaerobe D. anaerobe

microaerophile

Which of the following is not a chemical requirement of all bacteria? A. nitrogen B. molecular oxygen C. carbon D. mineral elements E. sulfur

molecular oxygen

The ability of microbes to utilize N2 as a nitrogen source is called _____.

nitrogen fixation

Bacterial growth refers to an increase in the ____ of bacterial cells.

number

Bacteria that CANNOT grow in the presence of oxygen (O2) are called __________. A. obligate aerobes B. aerotolerant anaerobes C. facultative anaerobes D. obligate anaerobes

obligate anaerobes

Niacin, when added to a medium, would be considered a/an ________. A. electron carrier B. reducing agent C. organic growth factor D. enzyme cofactor E. carbon source

organic growth factor

Shrinking of the cell's cytoplasm in response to osmotic loss of water is called _____ .

plasmolysis

In a/an _______, cells are added to melted agar and poured into a petri dish. (2 words)

pour plate

Bacteria require nitrogen for the synthesis of ________. A. carbohydrates B. proteins C. sugars D. lipids E. fatty acids

proteins

An organism that you are studying grows at 4°C and at 25°C. However, it grows best at 20°C. This organism would be classified as a ________. A. halophile B. mesophile C. psychrophile D. thermophile E. psychrotroph

psychrotroph

Bacteria that spoil food in the refrigerator are most likely __________. A. hyperthermophiles B. mesophiles C. thermophiles D. psychrotrophs

psychrotrophs

A type of cell-to-cell communication that allows bacteria growing in biofilms to communicate and coordinate their activity is known as ____ . (two words)

quorum sensing

Clostridium can be cultured in an anaerobic incubator or in the presence of atmospheric oxygen if thioglycolate is added to the nutrient broth. The addition of thioglycolate makes the medium __________. A. reduced B. differential C. selective D. enriched

reduced

Which of the following types of media would not be used to culture aerobes? A. selective media B. reducing media C. enrichment media D. differential media E. complex media

reducing media

A medium containing chemicals to inhibit the growth of gram-positive bacteria would be called __________. A. selective B. differential C. enriched D. reduced

selective

Salt agar tends to inhibit the growth of most organisms, except Staphylococcus. This is an example of a/an ____ media.

selective

Martin Lewis agar is an enriched media (containing heated blood) designed for the growth of Neisseria gonorrhea. Antibiotics are added to suppress the growth of normal microbiota that may be found in patient specimens, yet permit the growth of Neisseria gonorrhea. This medium would best be described as ________. A. nutrient agar B. selective media C. reduced media D. defined media E. differential media

selective media

The term trace elements refers to: A. the elements CHONPS B. vitamins C. nitrogens, phosphorus, and sulfur D. small mineral requirements E. toxic substances

small mineral requirements

All of the following can be used to preserve bacterial cultures EXCEPT __________. A. lyophilization (freeze-drying) B. refrigeration C. freezing quickly and storing at -70 degrees Celsius D. storing cultures at room temperature (25 degrees Celsius)

storing cultures at room temperature (25 degrees Celsius)

Before bacteria can be identified, mixed cultures must be separated. What technique is used to separate bacteria and get individual colonies? A. streak plate B. differential media C. enriched media D. selective agar

streak plate

The ____ is the most common technique used to obtain pure cultures of microbes. (3 words)

streak plate method

What is quorum sensing? A. the ability of bacteria in a biofilm to grow on selective media B. the ability of bacteria in a biofilm to use inorganic nitrogen sources C. the ability of bacteria in a biofilm to communicate with each other and coordinate their activities D. the ability of bacteria in a biofilm to sense O2

the ability of bacteria in a biofilm to communicate with each other and coordinate their activities

You inoculate two tubes of liquid culture media with 100 bacterial cells and incubate one tube at 37 degrees Celsius and the other at 55 degrees Celsius. After 48 hours, there are 20,000 bacteria per ml in the 37-degree tube and 1,568,000 bacteria per ml in the 55-degree tube. You conclude that this species is a __________. A. mesophile B. hyperthermophile C. thermophile D. psychrophile

thermophile

Which biosafety level features open laboratory bench tops, gloves, lab coat, and face/eye protection? A. BSL-2 B. BSL-1 C. BSL-3 D. BSL-4

BSL-2

Which level of biosafety (BSL) is appropriate for handling organisms that present the highest risk level for infection and the lowest success rate for prevention and treatment? A. BSL-1 B. BSL-4 C. BSL-3 D. BSL-2

BSL-4

In microbiology lab, you make three different culture plates: one general purpose plate, one selective media plate, and one differential media plate. Unfortunately, you forget to label the different plates, so you do not know which is which. To determine the identity of each plate, you inoculate it with two different strains of laboratory bacteria. Which of the following results would indicate the plate you used was the general purpose media? A. Both organisms would grow equally well. B. Only one organism would grow. C. Both organisms would grow, but they would be dyed different colors. D. Only one organism would grow, and it would grow a different color.

Both organisms would grow equally well.

Through metabolism, pathogens often produce acids that interfere with their own growth. ________ are/is added to media to control pH changes. A. Growth inhibitors B. Buffers C. Oxygen D. Salts E. pH indicators

Buffers

True/False Aerotolerant organisms can grow in the presence of oxygen because their cell wall protects them from toxic products of oxygen.

False

True/False Candle jars work well for cultivating anaerobic bacteria.

False

True/False In a direct microscopic count, dead cells are easily differentiated from live cells.

False

True/False Microaerophiles do not require oxygen for growth.

False

True/False Turbidity, or cloudiness, of cell cultures measured by spectrophotometry is useful in detecting small amounts of microbial contamination in liquids.

False

True/False When the spread plate technique is used to inoculate culture media, some colonies form within the agar.

False

Which of the following situations will lead to food being in the "danger zone," with the potential for food poisoning? A. Five pounds of homemade potato salad, refrigerated overnight in one huge bowl, and served without any cooling on a warm summer day. B. Beef stew cooked in a pressure cooker and eaten right away. C. A rotisserie chicken bought hot at the store and eaten within a half hour of getting home. D. Canned soup brought to a boil, the leftovers refrigerated right away, and microwaved to steaming before eating it again.

Five pounds of homemade potato salad, refrigerated overnight in one huge bowl, and served without any cooling on a warm summer day.

If you begin with six cells, how many cells would you have after three rounds of division? A. Twelve cells B. Nine cells C. Eighteen cells D. Twenty-four cells E. Forty-eight cells F. It is impossible to determine.

Forty-eight cells

How long does it take for the daughter cells from one round of replication to replicate themselves? A. No time is required -- they are fully mature and ready to divide immediately after separation if conditions are right. B. After the cells have matured fully. C. 20 minutes D. No time is needed -- the daughter cells cannot replicate further.

No time is required -- they are fully mature and ready to divide immediately after separation if conditions are right.

All of the following statements about culture media are accurate EXCEPT which one? A. Reducing media are complex media containing chemicals, such as thioglycolate, that combine with oxygen, creating an anaerobic environment. B. A chemically defined medium is specifically formulated, and each ingredient is known. C. Nutrient agar contains ingredients that combine with oxygen and remove it. D. Complex media are formulated from nutrient-rich whole food sources whose exact ingredients may not be known.

Nutrient agar contains ingredients that combine with oxygen and remove it.

Which step of binary fission is the reason for genetically identical daughter cells? A. There are four new daughter cells that result from one parental cell B. Replication of the bacterial chromosome C. Splitting of the two daughter cells D. Elongation of the cell

Replication of the bacterial chromosome

What do all of these bacteria have in common? Bacteria in the rumen of cattle and sheep Bacteria in a sewage treatment plant Bacteria growing in the middle ear in chronic otitis media Bacteria growing on the teeth in dental plaque A. The bacteria are all fermenters. B. The bacteria are most likely growing in biofilms. C. The bacteria are all gram-positive. D. The bacteria are all obligate aerobes. E. The bacteria are all thermophilic.

The bacteria are most likely growing in biofilms.

An unknown culture is assayed via the plate count method. After dilution of cells and incubation, no colonies are observed. Which of the following is not a possible explanation? A. The wrong dilution was plated. B. There were no cells in the culture. C. The incubation conditions were incorrect. D. The bacterial cells formed invisible colonies. E. The media did not support the growth of the microbes.

The bacterial cells formed invisible colonies.

What enables the copied chromosomes to separate during binary fission? A. The chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes. B. The septum splits the replicated chromosomes. C. The nuclear membrane dissolves. D. The mitotic spindle drives the separation.

The chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes.

Which of the following statements regarding biofilms is true? A. The close proximity of microbes within a biofilm probably inhibits conjugation. B. The microbes in biofilms can work cooperatively to carry out complex tasks. C. Fortunately, biofilms are not an issue that impacts human health. D. Biofilms occur in nature but rarely occur in human infections.

The microbes in biofilms can work cooperatively to carry out complex tasks.

What would happen if the septum did not form during binary fission? A. The daughter cells would not be genetically identical. B. The chromosome could not replicate. C. The parent cell would now have two copies of the chromosome. D. Nothing; the septum is not required for binary fission.

The parent cell would now have two copies of the chromosome.