Question

What was the outcome when mice were injected with a mixture of live R strain and heat-killed S strain in Griffith's fourth experiment?

Options

• Mice died with live S strain bacteria recovered

• Mice survived with no bacterial recovery

• Mice died with dead S strain bacteria recovered

• Mice survived with live R strain bacteria recovered

Answer 1

In Experiment 4, the injection of a mixture of live R strain and heat-killed S strain resulted in mice dying of pneumonia. Live S strain bacteria were recovered from the dead mice, indicating that the R strain had been transformed into the virulent S strain phenotype by the Transforming Principle from the heat-killed S strain.