Food Micro - credit qs

2023, 2021 (Foodmicro biology-credittest), 2020(Food Micro credit test old Qs)

In STAR protocol, the test bacterium Bacillus cereus is used for the detection of

Select one:

macrolides

beta-lactams

tetracyclines

aminoglycosides

Tetracyclines

The following culture medium is used for enumeration of yeasts and mould in food products with water activity equal or less than 0.95

a. DRBC

b. TBX

c. DRBG

d. DG-18

DG-18

In STAR protocol, the test bacterium Bacillus cereus is used for the detection of

Select one:

macrolides

beta-lactams

tetracyclines

aminoglycosides

Tetracyclines

The following culture medium is used for enumeration of yeasts and mould in food products with water activity equal or less than 0.95

a. DRBC

b. TBX

c. DRBG

d. DG-18

DG-18

To detect the presence/absence of Salmonella, the initial suspension is prepared by mixing?

a. 25 grams of the test portion with 225 ml of peptone salt solution

b. 10 grams of the test portion with 90 ml of buffered peptone water

c. 10 grams of the test portion with 90 ml of peptone salt solution

d. 25 grams of the test portion with 225 ml of buffered peptone water

25 grams of the test portion with 225 ml of buffered peptone water

In terms of food safety, staphylococcus aureus is a?

a. Potentially (conditionally) pathogenic bacterium

b. Pathogenic bacterium

c. Commensal bacterium

d. Toxigenic bacterium

Toxicogenic bacterium

Enumeration of Enterobacteriaceae Count in Food Sample:

• Dilution 10⁻¹: 148 to 156 colonies

• Dilution 10⁻²: 10 to 15 colonies

• Dilution 10⁻³: 1 to 2 colonies

The count of Enterobacteriaceae in 1 gram of the test sample was:

Options:

• □ N = 1.4 × 10³ CFU·g⁻¹

• □ N = 1.4 × 10⁴ CFU·g⁻¹

• □ N = 1.5 × 10³ CFU·g⁻¹

• □ N = 1.5 × 10⁴ CFU·g⁻¹

correct: N = 1.4 × 10³ CFU·g⁻¹

in food microbiology, the following diluent(s) is(are) used for decimal dilutions"

Options:

• sterile distilled water

• sterile peptone water

• sterile peptone salt solution

• sterile buffered peptone water

• sterile demineralized water

• sterile deionized water

all of these are used as diluents in food micro. Most common are peptone water and buffered peptone water.

"In STAR protocol, the test bacterium Kocuria varians (Micrococcus luteus) is used for the detection of"

Selected options:

• macrolides

• aminoglycosides

• sulphonamides

• quinolones

• tetracyclines

• beta-lactams

beta-lactams, macrolides

Culture media for microbiological testing are sterilized in the

Options:

1. sterilizing oven with forced-air convection

2. steamer

3. incubator without forced-air convection

4. autoclave

5. incubator with forced-air convection

6. sterilizing oven without forced-air convection

Autoclave, steamer

The following storage temperatures are recommended for samples of technological swabs awaiting microbiological testing

18-27 °C

2-8 °C

1-4 °C

0-2 °C

1-4 °C

The following culture medium must be used for testing antimicrobial resistance by the disk diffusion method

Rappaport-Vassiliadis agar

Müller-Hinton agar

Müller-Kauffmann agar

Kirby-Bauer agar

Müller-Hinton agar

In food microbiology, the pour plate technique is not used for enumeration of

Select one:

- Total plate count

- β-glucuronidase-positive Escherichia coli

- yeasts and moulds

- Enterobacteriaceae

yeasts and moulds

The following temperatures are recommended for the transport of products not stable at ambient temperature to the laboratory

Select one:

below-15 °C,

preferably below-18 °C

1–8 °C

18–27 °C

0–5 °C

2 ± 2 °C

1–8 °C

The most common type of homogenizer in microbiological laboratory is that

Select one or more:

vibrationa

peristaltic

rotary

vortex mixer

peristaltic

Culture medium TBX is used for enumeration of

Select one:

coagulase-positive staphylococci

Salmonella sp.

Enterobacteriaceae

β-glucuronidase-positive E. coli

β-glucuronidase-positive E. coli

On the surface of ALOA agar, bacteria Listeria monocytogenes grow in

Select one:

- greyish green or olive green colonies, sometimes with black centres, but always with black halos

- pink, red, or purple colonies with or without precipitation haloes

- black or grey colonies surrounded by a clear zone which may be partially opaque, sometimes an

- 11 palescent ring immediately in contact with the colonies may appear in this clear zone

- green-blue colonies surrounded by an opaque halo

- green-blue colonies surrounded by an opaque halo

The name of culture medium enabling stressed and damaged micro-organisms tore pair and recover their capacity for normal growth without necessarily promoting their multiplication is

Select one:

- preservation medium

- suspension medium

- resuscitation medium

- transport medium

resuscitation medium

To determine the total count of psychrotrophic micro-organisms, inoculated plates are incubated

Select one:

at 5 °C for 10 days

at 20 °C for 5 days

at 30 °C for 3 days

at 10 °C for 7 days

at 5 °C for 10 days

All genera in the Enterobacteriaceae family are

Select one:

1. Gram-positive, glucose-positive and oxidase-negative

2. Gram-negative, glucose-positive and oxidase-positive

3. Gram-positive,glucose-positive and oxidase-positive

4. Gram-negative, glucose-positive and oxidase-negative

Gram-negative, glucose-positive and oxidase-negative

Negative result of PREMI®test (no residues of inhibitory substances are present in the test sample) is manifested by

Select one:

1. yellow colouration of the tube content

2. green colouration of the tube content

3. violet colouration of the tube content

4. black colouration of the tube content

1. yellow colouration of the tube content

When eating Enterobacteriaceae using the colony count method, the initial suspension is prepared by mixing

Select one:

10 grams of the test portion with 90 mL of buffered peptone water

10 grams of the test portion with 90 mL of EE broth

10 grams of the test portion with 90 mL of peptone salt solution

25 grams of the test portion with 225 mL of peptone salt solution

25 grams of the test portion with 225 mL of peptone salt solution

Enumeration of enterococci provided the following counts of colonies

Enumeration ofβ-glucuronidase-positive E. coli provided the following counts of colonies:

Enumeration of lactobacilli provided the following counts of colonies

correct: 1.0 × 10³

NE < 10 / 0.1 × 10`-1

In food microbiology, Baird-Parker agar is used for enumeration of

Select one:

1. yeasts and moulds

2. Enterobacteriaceae

3. beta glucuronidase-positive E. coli

4. coagulase-positive staphylococci

coagulase-positive staphylococci

The following culture medium is used for enumeration of yeasts and mould in food products with water activity greater than 0.95

Select one:

1. TBX

2. DRBC

3. DRBG

4. DG-18

DRBC

The following diluent is used to prepare the initial suspension and further decimal dilutions during quantitative microbiological examination of food samples by colony count method

Select one:

1. sterile nutrient broth

2. sterile buffered peptone water

3. sterile distilled water

4. sterile peptone salt solution

5. sterile peptone water

6. sterile demineralized water

sterile peptone salt solution

Ready-to-eat foods that do not support the growth ofListeria monocytogenesare those with

Select one:

1. aw<0.95, regardless of pH

2. pH< 4.4,regardless of water activity (aw)

3. a combination of pH< 5.0 and water activity (aw)< 0.96

4. 'pH< 5.0,regardless of water activity (aw
   

2. pH< 4.4,regardless of water activity (aw)

Typical colonies of Salmonella sp. on the surface of XLD agar

Select one:

are pink, red, or purple with or without precipitation haloes

have black centers sorrounded by lightly transparent reddish zones

are green-blue, surrounded by an opaque halo

are black orgrey, surrounded by a clear zone which may be partially opaque, sometimes an oppalescent ringimmediately in contact with the colonies may appear in this clear zone

have black centers sorrounded by lightly transparent reddish zones

Egg yolk emulsion added to Baird-Parker agar medium indicates

Select one:

1. coagulase activity

2. lipolytic activity

3. glycolytic activity

4. proteolytic activity

lipolytic activity

The following quantity of the test sample is used for preparation of the initial suspension during qualitative microbiological examination

Select one:

10 grams

20 grams

1 gram

25 grams

10 grams

To determine the total aerobic count of mesophilic micro-organisms, the inoculated PCA plates are incubated

Select one:

at 30 °C for 3 days

at 20 °C for 5 days

at 37 °C for 2 days

at 44 °C for 1 day

at 30 °C for 3 days

Determination of Total Plate Count provided the following counts of colonies:

2,8 × 10⁴

The name of culture medium designed to preserve and maintain the viability of micro-organisms whilst minimising numerical change in the time period between sampling and laboratory processing of the samples is

Select one:

1. suspension medium

2. resuscitation medium

3. transport medium

4. preservation medium

transport medium

In microbiological laboratory, the following method is preferably used for sterilization of culture media

Select one:

1. autoclaving at 121 °C and pressure 0.15 MPa for at least 30 minutes

2. dry heat in a sterilizing oven at 150 °C for at least 2 hours

3. dry heat in a sterilizing oven at 170 °C for at least 1 hour

4. autoclaving at 121 °C and pressure 0.15 MPa for at least 15 minutes

autoclaving at 121 °C and pressure 0.15 MPa for at least 15 minutes

The following bacteria can be found in both the fresh water and seawater

Select one:

Yersinia sp.

Aeromonas sp

Pseudomonas sp.

Vibrio sp

Vibrio sp

The enumeration of Enterobacteriaceae using the most probable number (MPN) is applicable when the expected number of Enterobacteriaceae is

Select one or more:

below 100 CFU/mL of the test sample

below 10 CFU/g of the test sample

below 10 CFU/mL of the test sample

below 100CFU/g of the test sample

below 10 CFU/mL of the test sample

below 100CFU/g of the test sample

-

If they ask for 2 coorect this

if ask for 1 correct: below 10 CFU/mL of the test sample

The genus Clostridium includes

Select one:

lipolytic bacteria

saccharolytic bacteria

proteolytic bacteria

proteolytic and lipolytic bacteria

proteolytic and saccharolytic bacteria

proteolytic and saccharolytic bacteria

The culture medium TBX contains the following selective agent

Select one:

- X-glucuronide

- Bile salts

- Tryptone

- Crystal viole

(not - X-glucuronide)

Bile salts - selective agent

The devitalization of micro-organisms by high temperatures results from

Select one or more:

- inactivation of enzymes

- melting of lipids in the cytoplasmic membrane

- ionizing of water molecules

- acid-base disbalance within the cell

inactivation of enzymes

melting of lipids in the cytoplasmic membrane

The following micro-organisms belong to obligate aerobes

Select one or more:

Escherichia coli

Pseudomonas sp.

Clostridiumsp.

Penicillium sp.

Pseudomonas sp.

Penicillium sp.

The following tests are used to confirm Listeria spp. (The genus Listeria).

Select one or more:

- heamolysis test

- utilization of rhamnose

- CAMP test

- Gram-staining

- Henry illumination test

- catalase reaction

motility test

utilization of xylose

Gram-staining

Henry illumination test

catalase reaction

also motility test

The following tests are used to confirm Campylobacter spp.

select one or more:

catalase reaction

aerobic growth at 25 °C

aerobic growth at 41.5 °C

motility test

oxidase reaction

formation of hydrogen sulphide

aerobic growth at 25 °C

Motility test - checking for corkscrew motility

oxidase activity - positive

in the microbiological laboratory, sterilization of heat-labile culture media is preferably done by

Select one:

- dry heat in a sterilizing oven

- moist heat in an autoclave

- dry heat in a microwave oven

- moist heat in a steamer

moist heat in a steamer

The subspecies of Salmonella enterica do not include

Select one:

ssp.bongori

ssp.enterica

ssp.salamae

ssp.arizonae

ssp.indica

ssp.bongori

The resolution of the balance used for weighing the test portion, components of the culture media and reagents should achieve a tolerance of

Select one or more:

0.1 %

0.1 gram

0.01 %

1 gram

0.01 gram

1 %

1%

In microbiological laboratory, freezers shall be available to achieve separation for the storage of

Select one or more:

- uninoculated culture media

- microbial cultures

- inoculated culture media

- food samples for analysis

microbial cultures

food samples for analysis

Micro-organisms converting monosaccharides to organic acids and gases in the process of fermentation are known as

Select one:

saccharolytic

lipolytic

glycolytic

proteolytic

glycolytic

The preservation effect of salting is based on the following

Select one or more:

- decrase in water activity(aw)

- increase in osmotic pressure

- increase in pH-value

- decrease in redox potential

decrase in water activity(aw)

increase in osmotic pressure

The culture medium Plate Count Agar (PCA)

Select one or more:

- is used for determination of the Total plate count

- is a solid, chromogenic and differential medium

- is a solid, synthetic medium which contains one indicator and two selective agents

- is a solid, synthetic medium which contains growth factors

- is used for determination of the Total plate count

- is a solid, synthetic medium which contains growth factors

The name of selective agents present in VRBA are

Select one or more:

bile salts

crystal violet

potassium tellurite

lithium chloride

bile salts

crystal violet

The following culture bacteria are used for yoghurt preparation

Select one or more:

Leuconostoc mesenteroidesssp.dextranicum

Streptococcus termophilus

Streptococcus lactisssp. cremoris

Lactobacillus delbrueckiissp. bulgaricus

Streptococcus termophilus

Lactobacillus delbrueckiissp. bulgaricus

Typical strains of enterohaemorrhagic E. coli O157 are

Select one:

glucose-negative, sorbitol-negative, glucuronidase-negative and oxidasepositive

glucose-negative, sorbitol-positive, glucuronidase-positive and oxidase positive

glucose-positive, sorbitol-negative, glucuronidase-positive and oxidase negative

glucose-positive, sorbitol-negative, glucuronidase-negative and oxidase negative

glucose-positive, sorbitol-negative, glucuronidase-negative and oxidase negative

The group of lactic acid bacteria (LAB) includes

Select one or more:

Staphylococcus sp.

Lactobacillus sp.

Leuconostoc sp.

Enterobacter sp.

Streptococcus sp.

Micrococcus sp

Lactobacillus sp.

Leuconostoc sp.

Streptococcus sp.

Multiplication of micro-organisms is retarded, generation time is prolonged and a slow decrease in viable cell numbers is observed in the following growth phase

Select one:

Stationary phase

Logarithmic decline phase

Phase of negative acceleration

Lag phase

Phase of positive acceleration

Logarithmic phase

Phase of negative acceleration

In the PCR method, the cycles of DNA amplification include the following three basic steps

Select one:

extraction, purification and extension

denaturation, annaeling and extension

neutralization, annaeling and extraction

denaturation, extraction and purification

denaturation, annaeling and extension

The following nitrogen-fixing bacteria are found in the soil

Select one:

Nitrobacter spp.

Nitrosomonas spp.

Rhizobium spp.

Achromobacter spp

Rhizobium spp.

In food microbiology, the pour plate technique is used for enumeration of

Select one or more:

- coagulase-positive staphylococci

- β-glucuronidase-positive Escherichia coli

- Total plate count

- Enterobacteriaceae

- enterohaemorrhagic Escherichia coli O157

- yeasts and moulds

β-glucuronidase-positive Escherichia coli

Total plate count

Enterobacteriaceae

When enumerating coagulase-positive staphylococci by the colony count method, the initial suspension is prepared by mixing

Select one:

10 grams of the test portion with 90 mL of buffered peptone water

25 gram of the test portion with 225 mL of peptone salt solution

1 gram of the test portion with 9 mL of buffered peptone water

10 grams of the test portion with 90 mL of peptone salt solution

10 grams of the test portion with 90 mL of peptone salt solution

The following type(s) of biosafety cabinets is (are) used for work with risk category 3 pathogens

Select one:

Class I biosafety cabinets

Classes I and II biosafety cabinets

Class II biosafety cabinets

Classes II and III biosafety cabinets

Class III biosafety cabinet

Class II biosafety cabinets

In the STAR protocol, the test-bacterium Escherichia coli ATCC 11303 is used to detect the residues of

Select one:

- sulphonamides

- aminoglycosides

- β-lactams

- quinolones

- tetracyclines

- macrolides

quinolones

Inoculated DG-18 plates are incubated aerobically

elect one:

at 10 °C for 7-10 days

at 30 °C for 3-5 days

at 25°C for 5-7 days

at 5 °C for 10-12 days

at 25°C for 5-7 days

A condition in which the growth and metabolism of one micro-organism alter the environment to allow the growth of another miro-organism is known as

Select one:

metabiosis

mutualism

commensalism

amensalism

antibiosi

metabiosis

The group of thermotolerant enteropathogenic campylobacters does not include

Select one:

Campylobacter jejuni

Campylobacter mucosalis

Campylobacter lari

Campylobacter upsaliensis

Campylobacter col

Campylobacter mucosalis

Sublethal injury of Salmonella cells is manifested by the following

Select one or more:

decrease in enzymatic activity

inability of bacteria to form visible colonies

changes in the cell antigenic structure

false-positive results of microbiological testing

decrease in enzymatic activity

inability of bacteria to form visible colonies (part. on selective media)