Question

what happened when griffith mixed heat - killed bacteria with the live harmless culture of bacteria? there was no change. the harmless bacteria died. the harmless bacteria caused pneumonia.

Explanation:

Griffith's experiment showed that when heat - killed pathogenic bacteria (which can cause pneumonia) were mixed with live harmless bacteria, the harmless bacteria took up the "transforming principle" from the heat - killed bacteria and became pathogenic. This led the harmless bacteria to cause pneumonia (and kill the mouse, as seen in the relevant part of the experiment's visual representation). The option "There was no change" is incorrect as the transformation occurred. The option "The harmless bacteria died" is also incorrect as the key was the transformation of the harmless bacteria, not their death.

Answer:

The harmless bacteria caused pneumonia.