1. The prototrophs are the organisms which are not capable of synthesizing all growth requirements for themselves.
a) true
b) false
Explanation: The prototrophs are the organisms which are capable of synthesizing all the growth requirements by themselves whereas auxotroph is dependent on prototrophs.
2. Which of the following method is useful for isolation and detection of organisms having the ability to produce organic acids?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Indicator dye technique
Explanation: The use of Indicator Dye Technique is used for detection and isolation of the organisms which are organic acid producers. The organic acid producers produce acid which changes the colour of media and is thus detected easily.
3. What is the pH range of Bromophenol blue?
a) 3.0 – 4.6
b) 8.0 – 10.0
c) 5 – 8
d) 6.4 – 8.0
Explanation: The pH range of Bromophenol blue is 3.0 – 4.6. It changes from yellow at pH 3.0 to blue-violet at pH 4.6. It works best in this range and is also used as a tracking dye in Agarose-Gel Electrophoresis.
4. Which of the following method proceeds with 2-plate preparation?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Indicator dye technique
Explanation: Auxanographic technique proceeds with 2-plate preparation. The 1st plate is used to isolate and detect prototrophs whereas 2nd plate is used for identification of auxotrophs.
5. Which of the following dye is colourless at acidic pH and becomes red at basic pH?
a) Methyl red
b) Thymol blue
c) Phenolphthalein
d) Phenol red
Explanation: Phenolphthalein has a pH range between 8.0 – 10.0. It is colourless at pH 8.0 and becomes red at pH above 10.0. It belongs to the phthalein family that is employed as an acid-base indicator.
6. Which of the following plate is used to detect and isolate organic acid producers?
a) Phenol red plate
b) Potato Dextrose Agar plate
c) MacConkey’s Agar plate
d) Rose Bengal Agar plate
Explanation: Phenol Red plate is used to detect and isolate organic acid producers. The colour of plate changes from red to yellow in the zone of organisms producing organic acid.
7. A test tube contains 9ml distilled water. 1g of soil is added to that test tube and the soil is allowed to settle down. Now, 1ml of that stock solution is taken and transferred to the 2nd test tube containing 9ml of distilled water. The process is repeated several times until the requirement is met. For this dilution, it may be said that the solution was diluted _______
a) 100-fold
b) 10-fold
c) 1000-fold
d) 2-fold
Explanation: The transfer of a 1ml solution to 9ml d/w is called as serial 10-fold dilution. It is used to reduce the dense culture of cells to usable concentration.
8. Which of the following method is useful for detection and isolation of those microorganisms which are capable of growing on a particular nutrient medium?
a) Crowded plate technique
b) Auxanographic technique
c) Enrichment Culture technique
d) Indicator dye technique
Explanation: The Enrichment culture technique is useful for the detection and isolation of those microorganisms which are capable of growing on a particular nutrient medium. For e.g., cellulose producers grow on nutrient medium supplied with cellulose.
9. Which scientists gave the details of the techniques of preservation?
a) Jacob and Monod
b) Kirsop and Doyle
c) William and Wilkins
d) Boliver and Rodriguez
Explanation: Kirsop and Doyle in 1991 gave the full details of the preservation techniques. The preservation techniques were used to store the microbial culture for a longer period of time.
10. Which of the following is NOT the technique of preservation?
a) storage on agar slants
b) storage under liquid nitrogen
c) dried cultures
d) storage in water
Explanation: The techniques of preservation include – storage on agar slants, storage under liquid nitrogen, dried cultures, lyophilization. Storage in water is not a technique for the preservation of microbes.