Organisms and Populations · Question 87

Choose the correct sequence of stages of growth curve for bacteria.

1. Lag, log, stationary, decline phase
2. Lag, log, decline, stationary phase
3. Stationary, lag, log, decline phase
4. Decline, lag, log phase, stationary

Answer

(1) Lag, log, stationary, decline phase

Solution

When bacteria are inoculated into a fresh medium, the growth curve shows four phases:

Lag phase – cells adjust to the medium; little or no increase in number.

⇒ Log (exponential) phase – cells divide at the maximum rate.

⇒ Stationary phase – nutrients decrease and wastes accumulate, so the rate of division = rate of death.

⇒ Decline (death) phase – death rate exceeds division rate.

∴ Correct sequence: lag, log, stationary, decline phase.

Answer: (1)