MCQ Bank
How lactic acid bacterial colonies appear on MRS agar paltes after incubation?
- A) Irregular, raised and dry
- B) Smooth, convex and translucent
- C) Wrinkled, concave and opaque
- D) Rough, flat and pigmented
Which agar medium is recommended for the growth of lactic acid bacteria?
- A) Blood agar
- B) MRS agar
- C) Mannitol salt agar
- D) Lactose agar
In the lipase extraction experiment, which agar is prepared for the assay?
- A) Blood agar
- B) Lactose agar
- C) Skim milk agar
- D) Tributyrin agar
What is routinely used to avoid contamination when sealing the agar media plates?
- A) Food wrap
- B) Polythene bag
- C) Parafilm
- D) Aluminium foil
What is purpose of heat fixing in Gram staing procedure?
- A) Kill the organism and make them adhere to slide
- B) Increase the sensitivity of specimen
- C) Improve the visibility of specimen
- D) Enhance bacterial motility
What is the main purpose of adding Gram's iodine to the starch agar plate?
- A) To visualize starch hydrolysis
- B) To nourish the bacteria
- C) To sterilize the plate
- D) To enhance bacterial growth
What does the presence of a clear zone around the bacterial growth indicate in this experiment?
- A) The bacteria are pathogenic
- B) Ineffective sterilization of the medium
- C) The bacteria are resistant to iodine
- D) Amylase production by the bacteria
What is the role of safranin in Gram staining procedure?
- A) Mordant
- B) Counter stain
- C) Primary stain
- D) Decolorizer
What is the significance of using a sterile loop for spreading the soil sample on agar plates?
- A) To alter the chemical composition of the soil
- B) To ensure even distribution of the sample
- C) To increase the growth rate of microbes
- D) To prevent contamination of the sample
Why is E. coli often used in experiments to identify amylase production?
- A) Because it is a common pathogen
- B) Due to its rapid growth rate
- C) It is easy to handle in laboratory conditions
- D) It produces a wide range of enzymes
Why is skim milk agar used in the protease extraction protocol?
- A) It neutralizes soil pH
- B) It enhances microbial growth
- C) It acts as an indicator for protease activity
- D) It provides a source of lipase
What is the purpose of dissolving starch in distilled water and boiling it?
- A) To sterilize the water
- B) To create a suitable medium for bacterial growth
- C) To activate the starch
- D) To dissolve the starch completely
In the procedure for extracting proteases, what is the first step after weighing the soil sample?
- A) Incubate at room temperature
- B) Add Tributyrin agar
- C) Dispense it into sterile water and dilute serially
- D) Spread it directly on skim milk agar plates
How does the appearance of a halo zone around the growth on skim milk agar plates indicate protease activity?
- A) By showing the digestion of fats
- B) By demonstrating carbohydrate breakdown
- C) By indicating bacterial contamination
- D) By illustrating protein hydrolysis
Why is it necessary to autoclave the starch solution?
- A) To enhance the color reaction with iodine
- B) To sterilize the medium
- C) To dissolve the starch completely
- D) To initiate the reaction of amylase
What does the presence of a clear zone around the bacterial growth indicate in this experiment?
- A) Ineffective sterilization of the medium
- B) The bacteria are pathogenic
- C) The bacteria are resistant to iodine
- D) Amylase production by the bacteria
What is the significance of using a sterile loop for spreading the soil sample on agar plates?
- A) To alter the chemical composition of the soil
- B) To increase the growth rate of microbes
- C) To prevent contamination of the sample
- D) To ensure even distribution of the sample
In the procedure for extracting proteases, what is the first step after weighing the soil sample?
- A) Spread it directly on skim milk agar plates
- B) Incubate at room temperature
- C) Dispense it into sterile water and dilute serially
- D) Add Tributyrin agar
What is purpose of heat fixing in Gram staing procedure?
- A) Kill the organism and make them adhere to slide
- B) Increase the sensitivity of specimen
- C) Enhance bacterial motility
- D) Improve the visibility of specimen
How lactic acid bacterial colonies appear on MRS agar paltes after incubation?
- A) Irregular, raised and dry
- B) Wrinkled, concave and opaque
- C) Smooth, convex and translucent
- D) Rough, flat and pigmented