Final answer:
The genetic material from the dead S strain (DNA) was transferred to the R strain during Griffith's transformation experiment, transforming the R bacteria into a pathogenic S strain and causing the death of the mice.
Step-by-step explanation:
When the R strain of bacteria uptakes genetic material from the dead S strain, the R bacteria are transformed into the pathogenic S strain. This phenomenon was discovered by Frederick Griffith and is known as Griffith's transformation.
The "something" that was transferred from the killed S strain to the R strain is DNA, the substance responsible for the transformation. DNA, or deoxyribonucleic acid, is the genetic material that determines the characteristics of organisms. The outcome of Frederick Griffith's experiment, where a combination of dead S and live R bacterial strains were injected into mice, resulted in the death of the mice.
The reason for this is that the genetic material from the dead S strain (DNA) transformed the non-pathogenic R strain into a pathogenic S strain, subsequently causing the death of the mice.