Basic Microbiology Mock Exam (MICROCORE)

The isolated organism must cause the disease when inoculated into healthy resistant animals

Which of the following is NOT included in Koch’s postulates?

• The disease-causing organism must always be present in animals suffering from the disease but not in healthy animals

• The organism must be cultivated in a pure culture away from the animal body

• The isolated organism must cause the disease when inoculated into healthy resistant animals

• The organism must be isolated from newly infected animals

• The organism isolated from the newly infected animal must be cultured again in the laboratory and should be seen to be the same as the original organism

Ignaz Semmelweis

Described as the “savior of mothers,” he introduced handwashing in obstetrical wards using calcium hypochlorite

• Joseph Lister

• Ignaz Semmelweis

• Paul Elrich

• Edward Jenner

• Charles Chamberland

Anton van Leewenhoek

Who was the first to describe microorganisms?

• Zacharias Janssen

• Robert Hooke

• Anton van Leeuwenhoek

• Robert Koch

• Louis Pasteur

Spontaneous generation theory

which theory states that life emerges from non-living matter?

• biogenesis theory

• germ theory of disease

• spontaneous generation theory

• abiotic theory

• none of the above

One pathogen only causes one disease

Which of the following statements is/are NOT limitation(s) of Koch’s postulates?

• Some microbes are obligate intracellular parasites and are very challenging, or even impossible, to grow on artificial media

• Some diseases have variable signs and symptoms between patients

• One disease may be caused by a variety of microbes

• One pathogen only causes one disease

Provides a 2D image only

which of the following statement does not describe a scanning electron microscope (SEM)?

• beam of electrons is transmitted through an ultra-thin specimen, interacting with the specimen as it passes through it

• SEM has lesser magnification than TEM

• SEM is used to observe the internal structures of the specimen under a vacuum

• only a small amount of sample can be analyzed at a time

• Provides a 2D image only

all of the above

what is/are the challenges in using wet mount and hanging drop technique to observe microorganisms as compared to staining?

• refractive index of the cells is almost like that of water

• if the organism is pathogenic, there is possibility of danger to the person in handling the viable organisms on a slide

• wet mount and hanging drop technique preparations can’t be stored for longer period

both b and c

why can’t you stain Mycobacterium tuberculosis with Gram stain?

• a. they do not contain a peptidoglycan layer which is present in Gram-positive and Gram-negative bacteria

• b. they contain mycolic acids complexes with a portion of the cell wall, thereby giving the cell surface a waxy, hydrophobic consistency

• c. they have a net positive charge, therefore the dyes used in Gram staining cannot penetrate the cell

semi-solid

in which type of culture medium would you BEST observe apparent motility?

• broth

• semi-solid

• solid

• liquid

• none

Fluid Thioglycolate Agar

which of the following culture media is the BEST one to use to determine the oxygen requirement of an organism?

• Triple Sugar Iron Agar

• Fluid Thioglycolate Agar

• de Man, Rogosa, and Sharpe Agar

• Hugh and Leifson Agar

smallpox virus

the first successful vaccine was made against which pathogen?

• chickenpox virus

• cowpox virus

• smallpox virus

• influenze virus

• rabies virus

high limit of resolution

which is NOT a characteristic of a good microscope?

• adequate magnifying power

• provides good contrast

• high limit of resolution

• serves your purpose

• high resolving power

light and electron

what are the two types of microscope based on the illumination source?

• bright field and dark field

• light and electron

• fluorescence and UV

• differential interference and phase-contrast

• simple and compound

gram staining

you are given two pathogens, Escherichia coli and Staphylococcus aureus. What is/are the best method(s) to observe morphology?

• gram staining

• gram staining and hanging drop technique

• acid-fast staining and wet mount

• acid-fast staining and hanging drop technique

• none of the above

aseptic technique

what do you call these series of steps to prevent contamination during the manipulation of cultures of sterile culture media?

• aseptic technique

• serial dilution

• streak for isolation

• spread plating

• pour plating

differential

which medium is the BEST to use to find out if the water sample has E. coli or non-fecal coliforms?

• enrichment

• selective

• differential

• assay

• general purpose

serial dilution and plating

what technique is BEST to use when isolating Bacillus species from soil?

• serial dilution and plating

• membrane filtration

• enrichment

• single-cell isolation

enrichment

which isolation technique is BEST to use when isolating nitrogen-fixing bacteria from the soil?

• serial dilution and plating

• membrane filtration

• enrichment

• single-cell isolation

endospores can be destroyed using moist and dry heat

which of the following statements is NOT TRUE about moist and dry heat as methods of sterilization?

• the main mode of action of moist and dry heat is protein denaturation and oxidation, respectively

• steam is more effective than dry heat at the same temperature because it has more penetrating power

• dry and moist heat can be used to sterilize glassware but only moist heat can be used to sterilize culture media

• endospores can be destroyed using moist and dry heat

lyophilization

which method of culture preservation involves flash-freezing and the moisture inside evaporates without melting?

• freezing

• lyophilization

• use of liquid nitrogen

• overlaying mineral oil

• none of the choices

UV rays

which of the following antimicrobial agents do not denature proteins?

• phenolics

• UV rays

• alcohols

• ethylene oxide

• none of the choices
  

all of the above

which of the following factors influences the effectiveness of antimicrobial agent activity?

• population density

• duration of exposure

• temperature

• population composition

• all of the above

gram-positive

which of the following microorganisms/structures is most susceptible to chemical agents of control?

• gram-positive

• fungi

• gram-negative

• non-enveloped viruses

• endospores

both a and b

which of the following is/are INCORRECT?

• a. potato dextrose agar with 30 ppm rose bengal was sterilized using hot air oven

• b. nutrient agar with 100 ppm streptomycin was sterilized at 121 °C, 15 psi, for 15 minutes

• sterilization of the glass plates is done using hot air oven

bacteria, archaea, eukarya

what are the three domains of organisms?

ribosomal RNA

what is the basis for the three-domain system of classification?

more stable classification

what is/are the advantage(s) of artificial over natural classification?

• more stable

• only few characters considered

• related phylogenetically

• members of different groups are usually not similar in hereditary pattern

candidatus

refers to a microorganism that is well characterized but remains uncultured (Latin name)

A strain is a taxonomic category

which of the following is NOT true regarding a strain?

• a strain is a taxonomic category

• population of organisms that descend from a pure culture isolate or from a species

• may be typical or atypical representative of a species

aerotolerant anaerobe

which of the following types of microorganisms has no difference in its growth with or without the presence of oxygen?

• obligate aerobe

• microaerophilic

• obligate anaerobe

• aerotolerant anaerobe

• facultative anaerobe

Gram-positive bacteria have teichoic and lipoteichoic acids unlike Gram-negative bacteria.

What is/are the difference(s) between Gram-positive and Gram-negative bacteria?

chemoautotroph

which type of microorganism uses carbon dioxide and inorganic chemicals, as carbon and energy source, respectively?

thermoduric

which of the following types of microorganisms can survive milk pasteurization?

• mesophilic

• thermoduric

• psychrophilic

• psychotroph

• hyperthermophilic

cardinal

what pertains to the temperature range by which Clostridium botulinum can grow?

Most are filamentous, but some are unicellular.

Which of the following is TRUE about fungi?

• fungi are represented by both prokaryotes and eukaryotes

• most are filamentous, but some are unicellular

• not all are chemoheterotrophic

• they are obligate symbionts with plants

• they are only capable of asexual reproduction through sporulation

Glomeromycetes

Which of the following groups have members that are mutualistic

symbionts that form arbuscular mycorrhizal (AM) associations

intracellularly within the roots of the vast majority of herbaceous plants

and tropical trees?

opportunistic mycoses

Candidiasis and Aspergillosis are examples of ---

• opportunistic mycoses

• systemic mycoses

• cutaneous mycoses

• subcutaneous mycoses

• superficial mycoses

Conidia

What do you call the non-motile sporangiospores?

• zoospores

• blastospores

• conidia

• aplanospores

• arthrospores

Mycelium

What do you call the macroscopically visible tuft formed by the network of filaments of fungi?

• hyphae

• soredia

• mycelium

• conidia

• sporangia

Chitin

What do you call the polymer of N-acetylglucosamine which is the composition of most fungal cells?

Haustoria

What do you call the appendage or portion of a parasitic fungus that penetrates the host's tissue and draws nutrients from it?

Chytridiomycetes

Based on the phylogenetic tree of fungi, which of the following is the most primitive?

• Chytridiomycetes

• Zygomycetes

• Glomeromycetes

• Ascomycetes

• Basidiomycetes

Superficial

Which group of mycoses do piedras and Tinea versicolor belong?

• cutaneous

• superficial

• subcutaneous

• opportunistic

• systemic

Cutaneous

Which group of mycoses do dermatophytes belong to?

Saprophytic

What do you call an organism that takes up non-living organic nutrients in dissolved form and usually grows on decomposing organic matter?

Asexual stage of a fungi is produced only once a year.

Which of the following is NOT one of the reasons why asexual reproduction is important for the propagation of species?

• Asexual reproduction results in the production of numerous individuals

• Asexual stage of a fungi is produced only once a year.

• Asexual cycle is repeated several times during the season.

Plasmogamy, karyogamy, meiosis

In order, what are the three stages of sexual reproduction in fungi?

Somatogamy

Which of the following is NOT a mode of asexual reproduction in fungi?

a. Budding

b. Fusion

c. Fragmentation

d. Somatogamy

e. Conidia/Sporangia

Conidia

What do you call the reproductive structures of lichens?

a. Chlamydospores

b. Conidia

c. Soredia

d. Ascopores

e. Sporangia

None of the choices

Which of the following products do NOT use fungi?

a. Chocolate

b. antibiotics

c. Biofertilizer

d. Cortisones

e. None of the choices

Anaerobic respiration

The ability to use compounds and ions other than oxygen as terminal oxidants in respiration is a widespread microbial trait. What is this capacity called?

a. Photosynthesis

b. Fermentation

c. Aerobic respiration

d. Substrate phosphorylation

e. Anaerobic respiration

A, B and C are correct.

Which of the following tests/media will differentiate Staphylococcus

aureus and Streptococcus cremoris?

a. Gram staining

b. Lactose utilization

c. Mannitol salt agar

d. B and C are correct.

e. A, B and C are correct.

Electronic particle counter

Microalgal biomass can be quantified in the laboratory using the following techniques, EXCEPT

a. Direct microscopic count

b. Optical density measurement

c. Electronic particle counter

d. Cell dry weight

e. Standard plate count

Anabaena

The following organisms are protists EXCEPT

a. Amoeba

b. Gonyaulux

c. Euglena

d. Diatoms

e. Anabaena

Type of pigments

Which of the following characteristics can be used for algal classification?

a. type of photosynthesis

b. Choice of host

c. energy source

d. Spore formation

e. Type of pigments

gas

This type of vacuole is not found in protozoa.

a. contractile

b. gas

c. secretory

d. phagocytic

e. None of the above

Prevents dehydration by accumulating moisture

All of the following are functions of the phycobiont in lichens EXCEPT

a. Nitrogen fixation

b. Provides growth substances

c. Supplies organic nutrients

d. Prevents dehydration by accumulating moisture

e. None of the above

Chlorophyll a

Which photosynthetic pigment is present in all algae?

a. Carotene

b. Chlorophyll b

c. Chlorophyll a

d. Phycoerythrin

e. Chlorophyll a and b

None of the above

Which of the following is NOT true about Pseudomonas aeruginosa?

a. Biofilm former

b. Lacks tryptophanase enzyme

c. Pigment producer

d. Penicillin-resistant

e. None of the above

trophozoite

The invasive stage of a protist is called

a. cyst

b. sporozoite

c. merozoite

d. trophozoite

e. None of the above

a and b

Which statement/s best describe/s protists?

a. Most are motile by means of cilia, flagella, and pseudopodia.

b. Some members are pathogenic, some parasitic, some are autotrophic.

c. They are either holozoic or saprozoic.

d. a and b

e. b and c

conjugation

The method of sexual reproduction where there is exchange of gametes between paired protozoa of complementary mating types

a. conjugation

b. gametangy

c. gametoangiogamy

d. somatogamy

e. None of the above

Gonyaulax

The motile, photosynthetic protist that is capable of producing saxitoxin, the primary toxin for paralytic shellfish poisoning is

a. Amoeba

b. Euglena

c. Trichomonas

d. Plasmodium

e. Gonyaulax

Membrane filtration and plating

Which method is appropriate for quantifying possible contaminating heterotrophic microorganisms from a bottled distilled water?

a. Enrichment

b. Serial dilution and pour plating

c. Membrane filtration and plating

d. All methods are appropriate

e. No method is appropriate

e. All of the above

Which is a characteristic of lag phase?

a. There is no immediate increase in cell number and cell mass.

b. This is an adaptation phase of the microorganism when inoculated to a fresh

medium.

c. This is the period when cells are synthesizing new components.

d. Stressed microorganisms are undergoing repair.

e. All of the above

e. a,b, and c

During exponential phase in bacteria

a. population is growing at regular intervals

b. cells are at their healthiest hence sampling is best at this stage

c. population is uniform in terms of metabolic and physiological properties

d. a and b

e. a,b, and c

b. I, II, IV

Stationary phase is reached when-

I. there is a change in pH due to formation of organic acids

II. a required nutrient is exhausted

III. dividing cells is higher than the number of dying cells

IV. inhibitory end products accumulate in the medium

b. LPS

The structure in a Gram-negative bacteria which induces fever is

a. teichoic acids

b. LPS

c. Braun’s proteins

d. glycocalyx

e. b and d

They possess chlorophyll a and chlorophyll b.

The following are characteristics of red algae EXCEPT

a. They possess chlorophyll a and chlorophyll b.

b. Some genera are edible, and some can produce carrageenan.

c. They are aquatic.

d. Their major accessory pigment is phycoerythrin.

e. None of the above.

Pour plate method

Simon was asked to isolate a pure culture of Bacterium R using his own choice of method. After overnight incubation at optimum conditions, he observed both surface and subsurface colonies on the plates typical for the bacterium. Simon used:

a. Spread plate method

b. Pour plate method

c. Streak plate method

d. All of the above

e. None of the above

e. a, b, and c

Which statement/s is/are TRUE regarding temperature?

a. Beyond the maximum temperature requirement, enzymes are denatured.

b. Below the minimum temperature requirement, cytoplasm gels.

c. Optimum temperature is normally near the maximum than the minimum.

d. a and b

e. a, b, and c

e. Only obligate aerobes and facultative aerobes

Which of the following groups of microorganisms can carry out aerobic respiration as a type of metabolism?

a. Obligate aerobes, facultative aerobes and microaerophilic aerobes

b. Facultative aerobes, microaerophilic aerobes and aerotolerant aerobes

c. Obligate aerobes and facultative aerobes only

d. Obligate aerobes, facultative aerobes and aerotolerant anaerobes

e. Only obligate aerobes and facultative aerobes

e. A and C

Petri dishes for the isolation of bacteria are incubated in an inverted position so that

a. the colonies will not spread over the surface of the agar medium.

b. the medium will not dry out.

c. contamination will be avoided.

d. incubation temperature will be maintained.

e. A and C

a. Viable counts only determine the number of cells in the sample capable of growth.

Which of the following is true about viable count procedures?

a. Viable counts only determine the number of cells in the sample capable of growth.

b. Variations in viable count is heavily influenced by the length of incubation.

c. Viable counts may often be erroneously high.

d. The procedure gives less information on the number of viable cells than direct microscopic counts and turbidimetric methods.

e. Only A and B are correct.

The sample is inoculated on a solid medium.

Which is NOT true regarding pour plating?

a. Surface colonies are observed.

b. Only a swirling motion is used to disperse the inoculum.

c. The sample is inoculated on a solid medium.

d. Sub-surface colonies are observed.

e. None of the above.

c. Brilliant Green Lactose Bile Broth

Culture medium used in the Confirmatory MPN test for coliforms

a. Nutrient broth

b. Lauryl Sulfate Tryptose Broth

c. Brilliant Green Lactose Bile Broth

d. Eosin Methylene Blue Agar

e. A and C

d. Endospore

The Schaeffer-Fulton staining procedure is used for the observation of what bacterial structure?

a. Capsule

b. Glycogen granules

c. Ascopores

d. Endospore

e. Lipid granules

c. they are present in high numbers

Pathogens are not used as indicators of water quality for the following reasons EXCEPT

a. time required for their detection is too long

b. they do not survive in water for extended periods

c. they are present in high numbers

d. they are not constantly present in polluted waters

e. they are likely to escape detection

b. After decolorization, Gram-positive bacteria appear blue while Gram-negative bacteria appear colorless.

Which among the following is true about Gram staining?

a. After decolorization, both Gram-positive and Gram-negative bacteria appear colorless.

b. After decolorization, Gram-positive bacteria appear blue while Gram-negative bacteria appear colorless.

c. After counterstaining, both Gram-positive and Gram-negative bacteria appear pink.

d. After application of the mordant, Gram-positive bacteria remain blue while Gram-negative bacteria become colorless.

e. After primary staining, both Gram-positive and Gram-negative bacteria are stained red.

d. Hydrogen sulfide production and Lysine decarboxylation test

Which of the following tests/ media will differentiate Escherichia coli and Proteus vulgaris?

a. Methyl red test and Triple Sugar Iron Agar

b. Gram staining and Catalase test

c. Indole test and Motility Medium

d. Hydrogen sulfide production and Lysine decarboxylation test

e. B and C are true.

d. It has changed drastically throughout evolution.

Which is not true of the 16S rRNA?

a. This molecule is universally distributed.

b. Its function is constant for all microorganisms.

c. It contains highly conserved and variable regions/ domains.

d. It has changed drastically throughout evolution.

e. None of the above.

d. it prevents engulfment of the bacteria by the phagocytes.

The capsule or slime found in some pathogenic bacteria serve as defense mechanism because

a. it has lytic activity against phagocytes.

b. it releases toxins against phagocytes.

c. it engulfs and digests the phagocytes.

d. it prevents engulfment of the bacteria by the phagocytes.

e. None of the above

d. endospores

The following cytoplasmic inclusions are used for nutrient storage EXCEPT

a. polyhydroxybutyrate granules

b. glycogen

c. starch

d. endospores

e. volutin granules

a. Capsule

The Maneval’s staining procedure is used for the observation of what bacterial structure?

a. Capsule

b. Endospore

c. Flagella

d. Glycogen granules

e. Lipid granules

b. It ferments lactose and sucrose but not glucose.

Which of the following is not true about Escherichia coli?

a. It produces indole from tryptophan.

b. It ferments lactose and sucrose but not glucose.

c. It is a butanediol fermentor.

d. A and B

e. B and C

d. Flagella

Which of the following structures is not part of the bacterial cell envelope?

a. Peptidoglycan

b. Lipopolysaccharide

c. Capsule

d. Flagella

e. S-layer

d. A and C are correct.

Both aerobic and anaerobic respiration

a. can generate a proton motive force to drive ATP synthesis.

b. utilize compounds or molecules other than oxygen as terminal electron acceptor.

c. utilize an organic compound as the major source of carbon for biosynthetic

reactions.

d. A and C are correct.

e. All of the statements are correct.

c. It is an anabolic process.

Which of the following is not true about fermentation?

a. It is used to create new food products.

b. It makes use of microorganisms to transform organic compounds.

c. It is an anabolic process.

d. It is an energy-yielding reaction.

e. None of the above

c. Intracellular proteins and enzymes of halophiles are physiologically functional at high osmolarity.

Which of the following is true about halophiles?

a. Halophiles can increase their intracellular solute concentration by synthesizing compatible solutes.

b. Halophiles can increase their intracellular solute concentration by pumping inorganic ions into the cell.

c. Intracellular proteins and enzymes of halophiles are physiologically functional at high osmolarity.

d. High solute concentration is an absolute requirement of halophiles for growth.

e. All statements are true.

d. Uniport/facilitated diffusion

Which of the following transport mechanisms functions without requirement for energy?

a. Binding-protein dependent

b. Group translocation

c. Symport

d. Uniport/facilitated diffusion

e. antiport

photoheterotrophs

Nutritional type of organisms which require organic compounds and light energy.

a. photoautotrophs

b. chemolithotrophs

c. chemoheterotrophs

d. photoheterotrophs

e. A and D

c. ATP is derived mainly by oxidative phosphorylation.

Which of the following statements about chemoautotrophs is incorrect?

a. They use the electrons from reduced inorganic compounds.

b. They use CO2 as carbon source.

c. ATP is derived mainly by oxidative phosphorylation.

d. They use organic compounds as carbon source.

e. All statements are correct.

b. Diaminopimelic acid

Amino acids are found in the protein, peptidoglycan and capsule of bacteria. Which of the following amino acids is found only in the peptidoglycan?

a. L-lysine

b. Diaminopimelic acid

c. D-glutamate

d. L-alanine

e. None of the above

c. silent mutation

Which of the following point mutations does not cause phenotypic change?

a. missense mutation

b. nonsense mutation

c. silent mutation

d. all of the aforementioned

e. a and b only

b. transformation

Which of the following gene transfer methods does not require a viable donor cell?

a. conjugation

b. transformation

c. transduction

d. all of the above

e. A and C only

e. A and B only.

Which describes a transposable element?

a. They carry genes encoding a transposase.

b. They have short inverted repeats at the end of their DNA.

c. They are mutagenic.

d. All of the above.

e. A and B only.

d. Deoxyribonucleic acid

The synthesis of which of the following cell components is dependent upon a template?

a. Lipopolysaccharide

b. Peptidoglycan

c. Capsular polysaccharide

d. Deoxyribonucleic acid

e. Phospholipids