Question

in griffiths experiments, multiple choice mice infected with live nonvirulent bacteria developed pneumonia and died. mice infected with heat - killed virulent bacteria and heat - killed nonvirulent bacteria developed pneumonia and died. nonvirulent bacteria transformed the virulent bacteria into a nonvirulent variety. mice infected with heat - killed virulent bacteria and live nonvirulent bacteria developed pneumonia and died.

Explanation:

In Griffith's experiments, when a mixture of heat - killed virulent bacteria and live non - virulent bacteria was injected into mice, the non - virulent bacteria were transformed by a substance from the heat - killed virulent bacteria, becoming virulent and causing the mice to develop pneumonia and die. Live non - virulent bacteria alone do not cause the mice to die. Heat - killed bacteria (both virulent and non - virulent) do not cause death as they are dead. It is the transformation of non - virulent bacteria by the virulent factor from heat - killed virulent bacteria that is the key finding.

Answer:

mice infected with heat - killed virulent bacteria and live nonvirulent bacteria developed pneumonia and died.