During which growth phase is the population size decreasing logarithmically, nutrients are depleted, and death rate exceeds division rate?

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

Answer: (C)

This is describing the death phase. In this phase, nutrients are depleted and waste products accumulate, creating a hostile environment for the cells. As a result, the rate at which cells die surpasses the rate at which new cells are produced, so the population size declines. The decline is typically exponential, meaning the number of organisms falls by a roughly constant proportion over time, which is why you hear about a logarithmic decrease. By contrast, lag phase involves little growth, the log phase is rapid growth with plenty of nutrients, and the stationary phase has a balance between birth and death so the population size stays about the same.