Microbiology Theory Paper

  1. Which of the following is a substitute for crystal violet used in the gram-staining procedure?

a) Methylene blue

b) Bromocresol green

c) Safranin

d) Phenolpthalene


  1. The cocci which mostly occur in single or pairs are:

a) Streptococci

b) Diplococci

c) Tetracocci

d None of these


  1. Which of the following medium are used to differentiate the colonies of Vibrio cholerae and V. parahaemolyticus?

a) Alkaline bile salt

b) Thiosulphate-citrate-bile-sucrose

c) MacConkey

d) All of the above


  1. Which of the following can be identified by the milk ring test?

a) Brucellosis

b) Salmonellosis

c) Bovine tuberculosis

d) All of these

  1. Which of the following specimen is not expected to have any bacteria in normal conditions?

a) Urethral swab

b) Sputum

c) Pus

d) Cerebrospinal fluid


  1. Which of the following methods is not suitable for sterilization of bacteriological media?

a) Tyndillization

b) Autoclaving

c) Steaming at 100oC

d) disinfecting in Lysol


  1. The most pathogenic Brucella spp for man is:

a) B melitensis

b) B abortus

c) B suis

d) B canis


  1. Which of the following disinfectant is NOT effective against viruses?

a) Hydrogen peroxide

b) Hypochlorite

c) Formaldehyde

d) methylated spirit


  1. Salmonella typhi is an association with?

a) Botulinum

b) Brucellosis

c) Amoebic dysentery

d) Enteric fever


  1. Cryptococcus neoformans is an opportunistic pathogen commonly isolated from?

a) Slool

b) Urine

c) CSF

d) Blood


  1. Which of the following is best used for long term storage of microbial specimens when carried out properly?

a) Storage in a freezer at -10°C

b) Storage in a freezer at ultra-low temperatures (-70°C)

c) Storage in a refrigerator on an agar slant

d) Storage on a Petri plate at room temperature


  1. The concept of putting microbes to help clean up the environment is called:

a) Pasteurization

b) Bioremediation

c) Fermentation

d) Biolistics


  1. The nature of the poliovirus given for oral vaccination (satin vaccine) as part of the eradication program is:

a) Heat killed virus

b) Live attenuated strains of all three immunological types

c) A small dosage of wild-type live viruses

d) Formalin-inactivated viruses


  1. For most bacteria, the optimum pH for growth lies between:

a) 5-7.5

b) 5-4.5

c) 5-5.5

d) 5-6.5

  1. Suspension cultures consist of cells and cell aggregates, growing dispersed in:

a) Liquid medium

b) Solid nutrient medium

d) Solid or liquid medium

e) None of these


  1. Which of the following is not the characteristic of a growth curve?

a) Shows development of microbial population under relatively stable environmental conditions

b) Plotted with logarithmic numbers

c) Graphs numbers of microbes versus time

d) Each growth curve consists of four distinct phases

  1. The organism which obtains their energy from chemicals are designated as:

a) Prototrophs

b) Chemotrophs

c) Organotrophs

d) Autotrophs


  1. Which of the following media is selective for Salmonella?

a) Thiosulphate citrate bile salt agar

b) Wilson and Blair’s brilliant-green bismuth sulphite agar medium

c) Bile salt agar

d) All of the above


  1. Xylose lysine deoxycholate (XLD) agar is better selective medium than the deoxycholate citrate agar (DCA) because:

a) It is selective

b) It imparts better growth

c) It contains a high salt concentration

d) It is less inhibitory to Dysentriae and S. flexneri


  1. The viruses that attack bacteria are:

a) Bacterial viruses

b) Bacterial pathogens

c) Bacteriophages

d) Various