During which stage of a growth curve does the population remain relatively constant?

The stationary phase of a microbial growth curve is characterized by a balance between cell division and cell death, which leads to a relatively constant population size. During this stage, the growth rate slows down as resources become limited, and waste products accumulate. This means that while some cells are continuing to reproduce, others are dying, resulting in a stable number of viable cells overall. Factors such as nutrient depletion and toxic accumulation impact this stage significantly, causing the population to stabilize rather than increase or decrease.

In contrast, the other stages have distinct characteristics that do not align with a constant population size. The lag phase involves adaptation where cells are metabolically active but not yet dividing, leading to minimal population increase. The exponential phase marks rapid growth and increase in population size due to abundant resources. The decline phase, on the other hand, is characterized by a decrease in population as cells begin to die at a rate exceeding new cell formation. Therefore, the stationary phase is the only stage where the population remains relatively constant.