Which statement best defines the lag phase in a bacterial growth curve?

• A. Period of rapid cell division with exponential increase
• B. A period of adaptation with little or no net increase in cell number
• C. A phase of rapid death due to waste accumulation
• D. A phase of sporulation

Answer: (B)

Lag phase is the initial adjustment period after bacteria are placed in a new environment, during which cells gear up for growth. They synthesize the enzymes, ribosomes, and transport systems they’ll need, repair any prior damage, and acclimate to the medium and conditions, so there is little or no net increase in cell number during this time. This preparation sets the stage for rapid multiplication in the following exponential phase. The rapid division described here is the exponential (log) phase, the rapid death from waste accumulation corresponds to the death phase, and sporulation is a separate survival response not characteristic of the lag period.