Microbiology Theory Paper

  1. Which of the following is NOT used as a disinfectant?

a) Ethylene oxide gas

b) Glutaraldehyde

c) Chlorine

d) Phenol red


  1. False-positive catalase test can be due to

a) Prolonged incubation

b) Presence of staphylokinase

c) Short incubation time

d) Use of metallic wire loop


  1. Which of the following are components of indole reagent?

a) Sodium hydroxide

b) Amyl alcohol

c) Urea

d) Alpha naphthol


  1. The phase at which bacteria population dying is higher than the number dividing is known

a) Logarithmic phase

b Decline phase

c) Stationary phase

d) Lag phase


  1. Anaerobic conditions can be achieved by the use of the following method EXCEPT

a) Anaerobic jar

b) Robertson cooked meat media

c) Not using commercially obtained sachet containing oxygen removing chemicals

d) Thioglycollate broth


  1. Organisms that only grow in small concentrations of oxygen are called

a) Aerobes

b) Strict anaerobes

c) Capnophiles

d) Facultative anaerobes


  1. The following is true about optochin disc;

a) It is useful in the diagnosis of S. pneumoniae

b) H. influenza is sensitive to the disc

c) S. pyogenes growth is inhibited around the disc

d) It can be used in identifying S. agalactiae


  1. The following is true about gram-positive cell wall

a) It contains teichoic acid

b) It contains lipopolysaccharide

c) It contains a thin peptidoglycan

d) It contains periplasm


  1. What is the difference between stationary phase and the death phase?

a) The growth rate accelerates in stationary phase; the growth rate declines in the death phase

b) The concentration of viable cells increases in stationary phase; the concentration of viable cells decreases in the death phase

c) There are viable cells in stationary phase; there are no viable cells in the death phase

d) There are more viable cells in stationary phase than in the death phase


10. Which statement best characterizes the behavior of a bacterial culture during exponential growth

a) Minimum generation time

b) Have reached maximum concentration

c) A maximum generation time

d) A minimum growth rate

e) Cells numbers are increasing at a constant arithmetic rate


11. Which of the following is/are used to identify Salmonella typhi carriers

a) Stool

b) Blood

c) Urine

d) Bile

e) Rectal swab


12. Exotoxins are produced by

a) Salmonella typhi

b) Staphylococcus aureus

c) Shigellasonnei

d) Proteus mirabilis

e) Shigelladysentriae


13. Arrangement of flagella all round the bacterium is called

a) Monotrichous

b) Peritrichous

c) Amphitrichous

d) Lopotrichous

e) Atrichous


14. Which of the following are oxidase positive

a) Staphylococcus aureus

b) Neisseriaegonorrhoeae

c) Streptococcus pyogenes

d) Neisseria meningitides

e) Enterococcus faecalis


15. The following organisms are/are used as biological controls when sterilizing with autoclave

a) Serratiamarcescens

B) Pseudomonas aeuruginosa

C) Staphylococcus aureus

d) Bacillus stearothermophilus


16. Which of the following break down fibrin

a) Staphylococcus epidermidis

b) Staphylokinase

c) Streptokinase

d) Coagulase

e) Catalase


17. Mucoid colonies of Klebsiella species are due to its

a) ‘K’ antigen

b) ‘O’ antigen

c) ‘H’ antigen

d) ‘K’ antibody

e) ‘O’ and ‘H’ antigens


  1. Hydrogen sulfide could be detected in which media

a) TSI

b) DCA



e) MacConkey


  1. Cerebrospinal fluid whose processing is expected to delay is stored at

a) 370C

b) 250C

c) 2-80C

d_) H20 bath

e) 180C-250C


  1. The counterstain used in gram staining technique is

a) Neutral red

b) Diluted carbolfuchsin

c) Malachite green

d) Methylene blue

e) Eosin red