1.  All the bacterial cells that result from the replication of a single organism are said to be a

            a. population.

            b. pure culture.

            c. lag culture.

            d. mutant culture.

The scientist that contributed most to the development of pure culture techniques was

            a. Alexander Fleming.

            b. Louis Pasteur.

            c. Edward Jenner.

            d. Robert Koch.

d. Robert Koch

In order for a colony to be visible to the naked eye, about how many cells must be present?

            a.  1,000,000

            b. 100,000

            c. 10,000

            d. 1,000

The simplest technique for isolating bacteria in growth media is referred to as the

            a. pour plate method.

            b. streak plate method.

            c. serial dilution method.

            d. MPN method.

The solidifying agent used most successfully in bacterial nutrient media is

            a. gelatin.

            b. peptone.

            c. agar.

            d. starch.

Prokaryotic cells divide by a process known as

            a. conjugation .

            b. mitosis.

            c. binary fusion.

            d. binary fission.

In the growth curve of a bacteria population, the bacteria are rapidly increasing in number in

the

            a. lag phase.

            b. exponential (log) phase.

            c. stationary phase.

            d. decline phase.

            e. boomer phase.

A urine sample with more than 100,000 organisms is considered indicative of infection. If a urine sample containing 5,000 bacteria with a generation time of 30 minutes, sits for 3 hours before finally being assayed, how many bacteria will then be present?

            a. 10,000

            b. 64,000

            c. 100,000

            d. 320,000

In a rapidly multiplying bacterial population, cell numbers increase

            a. arithmetically.

            b. logarithmically.

            c. geometrically.

            d. indirectly.

The speed of enzymatic reactions approximately doubles for each

            a. 5º C rise in temperature.

            b. 10º C rise in temperature.

            c. 20º C rise in temperature.

            d. 30º C rise in temperature.

Generally the proteins of thermophiles

            a. resist denaturation.          

            b. react more efficiently with DNA.

            c. are easily denatured.

            d. have a particular amino acid sequence that restricts bond formation.

            e. c and d

A hot tub would most likely contain

            a. psychrophiles.

            b. partiers.

            c. thermophiles.

            d. mesophiles.

The optimal temperature for most human pathogens might be expected to range from

            a. 35-40 º C.         

            b. 20-45 º C.

            c. 15-25 º C.

            d. 93-98.6 º C.

Bacteria on fish caught in the Arctic Ocean would

            a. be psychrophiles.

            b. be mesophiles.

            c. continue to grow while the fish is in the refrigerator.

            d. not grow very well in the refrigerator.

            e. a and c

Organisms that require gaseous oxygen for metabolism are referred to as

            a. facultative aerobes.

            b. obligate aerobes.            

            c. facultative anaerobes.

            d. microaerophiles.

Mycobacterium leprae is typically found infecting the ears, toes and fingers of its host due to

 its

            a. requirement for well-oxygenated blood.

            b. easy access to those parts.

            c. need for cooler temperatures.

            d. long incubation period.

The virus causing the common cold preferentially grows on cells of the upper respiratory

epithelium due to

            a. its requirement for well oxygenated blood.

            b. easy access to that region.

            c. a need for cooler temperatures.

            d. its long incubation period.

Which of the following is/are obligate aerobes?

            a. Clostridium botulinum

            b. Escherichia coli

            c. Pseudomonas aeruginosa

            d. Helicobacter pylori

Organisms that are indifferent to the presence of oxygen and do not use it are

            a. aerotolerant anaerobes.

            b. facultative anaerobes.

            c. obligate aerobes.

            c. microaerophiles.

The enzymes that deal with toxic oxygen-containing molecules is/are

            a. glycolase.

            b. superoxide dismutase.

            c. catalase.

            d. hydrogen peroxidase.

            e. b and c

The optimum pH for growth of most species of bacteria is

            a. pH 5.

            b. pH 7.

            c. pH 9.

            d. pH 6.

High concentrations of salt and sugar in foods

            a. are useful in preserving the food.

            b. tend to draw water out of a cell.

            c. tends to force water into a cell, causing plasmolysis.

            d. have no effect on water availability.

            e. a and b

Shake tubes are used to determine the

            a. pH requirements for bacterial growth.

            b. temperature requirements for bacterial growth.

            c. oxygen requirements for bacterial growth.

            d. salt requirements for bacterial growth.

The prefix photo-  indicates that an organism will make use of

            a. chemicals.

            b. organics.

            c. light.

            d. inorganics.

Organisms that use organic molecules as their source of carbon are called

            a. chemotrophs.

            b. organoheterotrophs.

            c. heterotrophs.

            d. autotrophs.

Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur may be considered

            a. minor elements.

            b. major elements.

            c. neutral elements.

            d. acidic elements.

Trace elements

            a. include zinc, copper and manganese.

            b. are required in large amounts.

            c. may be needed for enzyme function.

            d. are involved in maintaining pH in the cell.

            e. a and c

Growth factors are

            a. compounds that must be synthesized by the organism.

            b. compounds that must be provided to the organism.

            c. physical factors such as temperature.

            d. inorganic molecules.

Small organic molecules that must be provided to bacteria in order for them to grow are called

            a. minerals.

            b. growth factors.

            c. water.

            d. vitamins.

Organisms may derive energy from

            a. sunlight.

            b. metabolizing chemical compounds.

            c. little tiny AAAAAAAA batteries.

            d. temperature gradients.

            e. a and b

Organisms that use CO₂ as their source of carbon are called

            a. organotrophs.

            b. heterotrophs.

            c. autotrophs.

            d. chemotrophs.

Chemoheterotrophs

            a. use sunlight as an energy source.

            b. use pre-formed organic molecules as a carbon source.

            c. use pre-formed organic molecules as an energy source.

            d. use inorganic chemicals as an energy source.

            e. b and c

E : B use preformed organiz molecules as a carbon source and C use preformed organic molecules as an a energy source.

An organism called Bacillus fastidiosus

a. might be expected to be very flexible as to growth requirements.

b. might be expected to be very strict as to its growth requirements.

c. would probably be grown on a chemically defined media.

d. might be expected to have a rod shape.

e. b, c and d

E (b) might be expected to be very strict as to its growth requirements and woul dprobably be frown on a chemically defined media and (D) Might be expected to have a rod shape.

Peptone

a. refers to a hydrolysate of carbohydrates used in growth media.

b. refers to a hydrolysate of proteins used in growth media.

c. consists of a water extract of beef.

d. consists of a mix of monosaccharides and oligosaccharides.

e. b and c

Medically important bacteria are often

            a. grown on agar containing blood.

            b. grown at 37 º C.

            c. grown on agar containing chocolate.

            d. grown at a pH of 5.

            e. a and b

Products which limit pH changes are often incorporated into media and are referred to as

            a. enzymes.

            b. bases.

            c. buffers.

            d. acids.

A medium that enhances the growth of one particular organism in a mixed population is

termed a(n)

            a. synthetic medium.

            b. specific culture medium.

            c. complex medium.

            d. enrichment medium.

A medium that inhibits the growth of organisms other than the one being sought is termed

a(n)

            a. synthetic medium.

            b. specific culture medium.

            c. selective medium.

            d. enrichment medium.

Blood agar

            a. is a chemically defined medium.

            b. is often used to culture clinically relevant bacteria.

            c. may be used as a selective media.

            d. may be used as a differential media.

            e. b and d

MacConkey agar is

            a. a selective agar.

            b. a differential agar.

            c. a selective and differential agar.

            d. used to distinguish between bacteria by the type of hemolysis observed.

Candle jars are usually used to

            a. store  candles.

            b. provide an atmosphere with CO₂.

            c. stimulate the growth of obligate anaerobes.

            d. prevent the growth of obligate aerobes.

            e. b and c

In the cultivation of microaerophilic and anaerobic bacteria,  

a. a(n) candle/anaerobe jar is sufficient.

b. atmospheric oxygen in a(n) candle/anaerobe jar is used to produce water.

c. a catalyst is used that makes hydrogen and carbon dioxide in a(n) candle/anaerobe jar.              

d. oxidizing agents are incorporated into the media that react with oxygen.

During which phase of growth are bacteria most susceptible to antibiotics?

            a. lag

            b. stationary

            c. exponential (log)

            d. decline

When doing experiments with bacteria

a. it is usually not necessary to standardize which stage of growth is used.

b. it is best to use colonies as all the bacteria in a colony are at the same stage of growth.

c. it is best to use bacteria from the same stage of growth.

d.  the age of the bacteria is not important.

During which phase of the bacterial growth curve does the total number of viable cells             decline?

            a. stationary

            b. lag

            c. exponential

            d. death

The lag phase of the bacterial growth curve is marked by

            a. a decrease in cell mass.

            b. dormant, metabolically inactive cells.

            c. metabolically active cells.

            d. vigorously dividing cells.

Late log phase of the bacterial growth curve

            a. is marked by the production of primary metabolites.

            b. is marked by the production of secondary metabolites.

            c. is a transition into the death phase.

            d. shows a decline in cell numbers.

During which phase of the bacterial growth curve does a bacterial population become much more resistant to harmful conditions?

            a. lag phase

            b. exponential phase

            c. stationary phase

            d. late log phase

Agar

            a. is a useful nutrient source for most bacteria.

            b. is a hydrolysate of proteins.

            c. stays liquid through the typical range of incubation temperatures.

            d. has chemical and physical properties that make it almost ideal for solidifying media.

Bacteria may be stored

            a. on a slant in the refrigerator.

            b. frozen in glycerol solution.

            c. lyophilized.

            d. in broth at 37 º C.

            e. a, b and c

In nature, bacteria

            a. often grow in close association with many other kinds of organisms.

            b. may remain in a prolonged exponential phase.

            c. frequently synthesize structures such as slime layers.

            d. may adhere to surfaces by means of pili and slime layers.

            e. all of the above

Biofilms

            a. are a haphazard mixture of bacteria.

            b. are a polysaccharide-encased community of microorganisms.

            c. may enhance bioremediation efforts.

            d. may protect organisms against harmful chemicals

            e. b, c and d

Matching

53. Obligate aerobe (b)                  a. Streptococcus pyogenes

54. Obligate anaerobe (e)               b. Pseudomonas aeruginosa

55. Facultative anaerobe (d)            c. Helicobacter pylori

56. Microaerophiles (c)                   d. Escherichia coli

57. Aerotolerant anaerobes (a)       e. Clostridium botulinum

53. Obligate aerobe

Obligate anaerobe

are the only organisms able to use atmospheric nitrogen as a nitrogen source.

Secondary metabolites may be antibiotics.

 In microbiology, growth usually refers to an increase in size of the bacteria.

Answer:  When first placed in growth media, the bacteria are very active adapting to the media and preparing for replication. This is known as the lag period. After this lag period, the bacteria enter a period of growth know as the log phase or exponential phase. There is plenty of food, oxygen, space and very little waste has built up yet. Eventually the waste level begins to build, the food levels dwindle, and there is very little space. The bacteria then enter the stationary phase, when the number of bacteria dying balances the number being created. Eventually conditions deteriorate to the point where the bacteria are no longer actively dividing and the numbers start to decrease. Physiologically, bacteria are very different in each of these stages, typically being more “sensitive” during the actively growing phase and “tougher” during the death phase. Therefore bacteria from one stage may behave differently in an experiment than bacteria from a different stage of growth. Usually, bacteria used in many experiments come from the mid to late log phase of the growth curve. However, depending on the area of study it might be useful to use bacteria from the other stages of growth. The key is to standardize the stage used.

69.  Discuss the growth of bacteria in nature vs artificial culture?

Typically in nature bacteria grow in association with many other organisms while in artificial culture they are usually grown in pure culture. The bacteria in nature may produce a slime layer that is not usually seen when grown in artificial culture. In certain circumstances, growth in nature may mimic growth in continuous culture and remain in a prolonged exponential phase, however, they generally multiply more slowly than in the artificially favorable artificial culture.