Which growth phase is characterized by a death rate that exceeds the rate of new cell formation due to nutrient depletion?

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

Answer: (D)

When cells are growing in a closed environment, nutrients steadily get used up and waste products build up. Early on they divide rapidly (log phase) because resources are abundant, and later they enter a stationary phase where birth and death roughly balance as resources become limited. Once nutrients are exhausted and toxins accumulate, the death rate surpasses the formation of new cells. That causes the population to decline—the death (decline) phase. Some cells may linger in a dormant state, but overall viability decreases as conditions grow harsher.