Arrange the following steps of experiments performed by Griffith in correct series.
(A) 'S' strain → injected into mice → Mice died
(B) 'S' strain (Heat killed) → injected into mice → Mice lived
(C) 'R' strain → injected into mice → Mice lived
(D) 'S' strain (Heat killed) + 'R' Strain (Live) → injected into mice → Mice died
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A), (C), (B), (D)
(A) ‘S’ strain → injected into mice → Mice died — first. The live smooth (S) strain is virulent.
(C) ‘R’ strain → injected into mice → Mice lived — second. The rough (R) strain has no capsule and is harmless.
(B) ‘S’ strain (Heat killed) → injected into mice → Mice lived — third. Killing the S strain by heat makes it harmless.
(D) ‘S’ strain (Heat killed) + ‘R’ Strain (Live) → injected into mice → Mice died — last. Something from the dead S cells transformed the R cells into virulent S cells; this “transforming principle” was later shown to be DNA.