1. Which of the following is not a method of sterilization?
a) Radiation
b) Chemical Treatment
c) Ultrasonic treatment
d) Cooling
Explanation: The alternative methods of sterilizations includes radiations, chemical treatment, ultrasonic treatment, heating, filtration. The medium which is to be sterilized is exposed to radiations or certain chemicals that will remove the contamination from the medium.
2. Which of the following is not an antimicrobial chemical agent?
a) Cresol
b) Formaldehyde
c) Acetone
d) Iodine
Explanation: The major antimicrobial chemical agents are phenols like cresol, orthophenylphenol and halogens like Iodine, chloramines. Formaldehyde and Ethylene oxide are also used as chemo sterilizers. Acetone is a cleaning agent used in laboratories.
3. Which of the following wavelengths of radiation has the highest bacterial efficiency?
a) 270 mm
b) 280 mm
c) 265 nm
d) 290 nm
Explanation: The wavelengths around 265 nm has the highest bacterial efficiency. The radiation of 265 nm is absorbed by cellular components, leading to DNA damage and cell death. X-rays and Gamma rays are considered to be more lethal.
4. Which of the following organism can grow with or without oxygen?
a) Obligate aerobes
b) Facultative anaerobes
c) Obligate anaerobes
d) Aerotolerant anaerobes
Explanation: Facultative anaerobes grow with or without oxygen. However, they grow better in the presence of oxygen and obtain their energy through aerobic respiration. If oxygen is absent, they utilize fermentation respiration.
5. Which of the following is the most preferable frequency for ultrasonic sterilization?
a) 500 kHz
b) 300 kHz
c) 600 kHz
d) 400 kHz
Explanation: The most preferable frequency for ultrasonic sterilization is 500 kHz. The ultrasonic vibrations are generated which create the cavitation microbubbles and sterilize the medium.
6. Which of the following is an advantage of continuous sterilization over batch sterilization?
a) Solid matter can be used in media
b) Reduction of fermenter corrosion
c) Lower risk of contamination
d) Easier control
Explanation: The advantages of continuous sterilization over batch sterilization is that the corrosion of the fermenter is reduced. This happens due to the usage of stainless-steel materials which prevents corrosion.
7. The steam is injected into the system via a nozzle.
a) true
b) false
Explanation: The steam is injected into the system via a nozzle. The media reaches the holding loop in the meantime and the steam sterilization occurs which removes the contaminants of the medium
8. Differential media allows the growth of a certain type of organism and will inhibit the growth of certain microorganisms.
a) true
b) false
Explanation: Differential media is mainly used for differentiation of closely related group of organisms whereas the selective media allows the growth of the certain type of organisms and will inhibit the growth of certain microorganisms.
9. Which of the following is the method of filter sterilization?
a) Osmosis
b) Diffusion
c) Double Diffusion
d) Sitting Drop
Explanation: Diffusion is the method of filter sterilization. The other mechanisms include Inertial impaction, Electrostatic attraction, Interception. Suspended particles are separated from the fluid by these mechanisms
10. In which of the following the large aerosol particles are deposited on the walls of airway conduit?
a) Inertial Impaction
b) Diffusion
c) Electrostatic attraction
d) Interception
Explanation: The large aerosol particles are deposited on the walls of airway conduit in inertial impaction. The impaction occurs where the airway changes. It is more significant in the filtration of gases than in the filtration of liquids.