Question

Which phase of microbial growth is characterized by a balance between cell division and cell death?

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

Hint:

• Lag phase Adaptation, no significant growth.
• Exponential (log) phase Maximum, constant growth rate.
• Stationary phase Net growth is zero (division rate = death rate or division stops). Caused by nutrient depletion or waste accumulation.
• Death phase Death rate>division rate. Viable cell count declines.

Answer 1

The Correct Option is C

In a batch culture, microbial growth typically follows four phases: 1. Lag Phase: Cells adapt to the new environment; little or no cell division. 2. Exponential (Log) Phase: Cells divide at a constant, maximal rate; number of cells increases exponentially. Cell division rate is much higher than cell death rate. 3. Stationary Phase: Growth rate slows down and becomes zero. The rate of cell division equals the rate of cell death, or cells stop dividing but remain viable for some time. This phase is usually reached due to nutrient depletion, accumulation of toxic waste products, or other limiting factors. There is no net increase in the number of viable cells. 4. Death (Decline) Phase: The rate of cell death exceeds the rate of cell division (if any). The number of viable cells decreases. The phase characterized by a balance between cell division and cell death, resulting in no net change in viable cell population, is the stationary phase. \[ \boxed{\text{Stationary phase}} \]