Bacterial growth occurs most rapidly during the ______.

• A. Lag phase
• B. Log phase
• C. Stationary phase
• D. Death phase

Answer: (B)

Bacteria go through distinct growth phases on a growth curve, and the fastest increase in numbers happens during the log phase. In this phase, nutrients are plentiful and wastes haven’t yet built up to inhibitory levels, so cells are metabolically active and dividing at their maximum rate. Each cell splits, leading to exponential increase in the population.

In contrast, the lag phase involves adaptation with little or no net growth as cells gear up; the stationary phase occurs when resources become limiting and growth slows to balance with death; and the death phase sees more cells dying than are formed.