51. An organism is completely dependent on atmospheric O2 for growth. This organism is
A. osmotolerant
B. acidophile
C. facultative anaerobe
D. obligate aerobe
52. Microaerophilic bacteria are those which require
A. 21 % oxygen for growth
B. low levels of oxygen for growth (lesser than O2 present in atmosphere)
C. oxygen for activation of enzymes
D. none of the above
53. The period between inoculation of bacteria in a culture medium and the beginning of multiplication is known as
A. stationary phase
B. log phase
C. lag phase
D. decline phase
54. The term aerotolerant anaerobe refers to an organism that
A. doesn’t use oxygen but can grow in the presence of oxygen
B. is killed by oxygen
C. requires less oxygen than is present in the air
D. prefers to grow without oxygen
55. The term obligate anaerobe refers to an organism that
A. doesn’t use oxygen but tolerates it
B. is killed by oxygen
C. uses oxygen when present or grows without oxygen when oxygen is absent
D. prefers to grow without oxygen