During which growth phase does cell population increase logarithmically, showing exponential growth?

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

Answer: (A)

During the exponential (log) growth phase, cells have abundant nutrients and optimal conditions, allowing them to divide at a constant rate. Because each generation doubles the population, the total number grows exponentially, which appears as a straight line on a semi-log plot. This rapid, ongoing doubling contrasts with the lag phase, where cells are adapting and divide slowly; the stationary phase, where growth stops due to limited resources and buildup of waste; and the death phase, where more cells die than are produced. So the phase with a logarithmic, exponential rise in cell numbers is the exponential (log) growth phase.