Final answer:
Cells are dying faster than new cells are being produced during the death phase, which is when the cell population in a culture medium decreases due to depleted nutrients and accumulation of toxic waste.
Step-by-step explanation:
The direct answer to your question is: (C) death phase. This occurs when a culture medium accumulates toxic waste and nutrients are exhausted, leading to an exponential decrease in the number of cells. In the death phase, the number of dying cells exceeds the number of dividing cells, resulting in a decline in cell numbers. Antibiotics that inhibit cell-wall synthesis, such as penicillin, would be most effective during the death phase as they can target actively growing cells and prevent further cell division.
The death phase in a culture's growth cycle is when cells die at a faster rate than new cells are being produced, often due to toxic waste accumulation and exhausted nutrients. In contrast, the log phase occurs when cell numbers increase rapidly and their metabolic activity is uniform. Here, cells are highly susceptible to antibiotics like penicillin, which is most effective during this period because cells are rapidly dividing and forming new cell walls that penicillin can target. The lag phase is where cells acclimate and prepare for division but do not increase in number, while the stationary phase is characterized by an equilibrium between cell death and production, with no net increase in cell number.