Question

Give reason: On injecting a mixture of heat-killed S-bacteria and live R-bacteria, the mice died.

Answer 1

1. Griffith isolated live S-strain bacteria from deceased mice's blood.
2. In a mixture of live R-bacteria and heat-killed S-bacteria, the live R-strain bacteria took up something (the transforming principle) from the heat-killed S-bacterium and were transformed into S-type bacteria.
3. The transforming principle enabled R-type bacteria to synthesise capsules, allowing them to become virulent.
4. As a result, the mice died after being injected with a mixture of heat-killed S-bacteria and live R-bacteria.