Bacterial growth occurs most rapidly during the ____________.

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

Answer: (B)

Rapid growth happens during the exponential (log) phase. After cells acclimate in a brief lag, they begin dividing at a constant, maximal rate because nutrients are abundant and waste isn’t yet inhibitory. This leads to a swift, exponential increase in population. In the lag phase, cells aren’t dividing much as they adjust. In the stationary phase, resources become limited and waste products accumulate, so the birth and death rates balance. In the death phase, nutrients are exhausted and toxins build up, causing a net loss of cells. So the period of fastest multiplication is the log phase.