Three different bacterial strains (P, Q, and R) when grown independently in a culture medium showed typical growth curves. Equal number of cells from all three actively growing cultures are mixed and grown together for 10 days. The number of bacteria ( N ) are counted each day and plotted. Assuming nutrients are not limiting, the correct explanation for the observed trend is:

Step-by-step solution

Based on the growth curves of the mixed culture: Strain Q exhibits a normal logistic growth curve, reaching a plateau. This indicates it is unaffected by the other strains and is likely the producer of an inhibitory substance (antibiotic). Strain P grows initially but experiences a continuous decline after day 4 . This suggests it is sensitive to the accumulating antibiotic produced by Q . Strain R shows an initial growth, followed by a decline (indicating sensitivity), and then a subsequent recovery and growth pha