Which of the following is NOT a standard phase of bacterial growth?

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

Answer: (D)

Understanding the bacterial growth curve is key. In a typical closed-system growth curve, there are four recognized phases: lag, where cells adapt with little or no division; the log (exponential) phase, where cells divide at a constant, rapid rate and the population grows quickly; the stationary phase, where growth levels off as nutrients become limited and wastes accumulate; and the death (decline) phase, where more cells die than are produced. The term “growth phase” isn’t a standard, distinct stage on this curve. Growth is what you observe during the log phase; there isn’t a separate labeled phase named growth. That’s why this option isn’t a standard phase.