Final answer:
Mice injected with bacteria from smooth (S) colonies indeed died, confirming the statement as true. Frederick Griffith's experiments with the S strain and R strain of Streptococcus pneumoniae led to the discovery of the transforming principle, which indicated that genetic material from the heat-killed S strain transformed the nonvirulent R strain into a virulent S strain.
Step-by-step explanation:
Frederick Griffith's experiments involved two strains of Streptococcus pneumoniae, the S (smooth) strain and the R (rough) strain. Mice injected with the S strain, which was pathogenic, succumbed to infection and died. In contrast, mice that were injected with the R strain survived because this strain was not virulent. Griffith's groundbreaking work continued with mice being injected with heat-killed S cells, which resulted in no harm to the mice, as the heat treatment killed the bacteria, rendering them nonvirulent. In a pivotal set of experiments, Griffith injected mice with a mixture of live R strain and heat-killed S strain. Surprisingly, these mice died, and upon examination, only live S strain bacteria were recovered from their blood, indicating that something from the heat-killed S strain had transformed the R strain into a virulent S strain. This phenomenon was termed the transforming principle, serving as a foundation for understanding genetic transformation in bacteria.