Which of the following events occur during the stationary phase of bacterial growth?
P. Rise in cell number stops.
Q. Spore formation in some Gram-positive bacteria such as Bacillus subtilis.
R. Cell size increases in some Gram-negative bacteria such as Escherichia coli.
S. Growth rate of bacterial cells nearly equals their death rate.
T. Decrease in peptidoglycan cross-linking.

Which of the following techniques is best suited for immobilizing an affinity ligand?

Which one of the following can not be a limiting substrate if Monod's growth kinetics is applicable?

During cultivation of microorganisms in a fermenter, various parameters are controlled by appropriate sensor (probe). Match each probe in Group I with the appropriate response mechanism in Group II.

Group I (Probe)	Group II (Response)
P. Thermistor	1. Activation of acid/alkali pump
Q. Oxygen electrode	2. Activation of vegetable oil pump
R. Metal rod	3. Activation of hot/cold water pump
S. pH electrode	4. Increase/decrease in stirrer motor speed

The kinetics of the disintegration of baker's yeast cells in a bead mill is described as $$\frac{{dp}}{{dt}} = K\left( {{P_m} - P} \right)$$   , where P is the concentration of protein released, m is the maximum protein concentration achievable, K is the first order rate constant and is 0.5 h⁻¹ for the system studied. The time required for the release of 90% of the intracellular proteins will be: