6. The bubble column fermenter is usually limited to

A. aerobic fermentation

B. anaerobic fermentation

C. Both (a) and (b)

D. facultative fermentation

7. A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________ culture.

A. continuous

B. batch

C. fed-batch

D. semi-continuous

8. If the specific growth rate, μ. is constant with time during the exponential growth period, the equation correlating bacterial number density C_{n}), cell number concentration with respect to time can be expressed as

A. C_{n}= C_{n0}exp[μ (t – t_{0})]
B. C_{n0}= C_{n}exp[μ (t – t_{0})]
C. C_{n}/C_{n0}=(1/μ)exp(t-t_{0})

D. C_{n0}/ C_{n}= (1/μ)exp(t-t_{0})

9. The diameter of the baffles in a standard stirred tank bioreactor ranges from

A. 1/10^{th}– 1/12^{th}of the tank diameter

B. 1/3^{rd}– 1/4^{th} of the tank diameter

C. 1/15^{th}– 1/20^{th}of the tank diameter

D. 1/20^{th}– 1/25^{th}of the tank diameter

10. During the log phase cell numbers increase exponentially

A. because cells produce enzymes

B. because cells do not have cell membranes

C. because cells are autocatalysts

D. because the rate of cell division increases exponentially