Question

Refer to the paragraph and diagram to answer questions 20 to 22. Griffith

investigated how certain types of bacteria produce pneumonia in mice.

*2 points

The diagram outlines his experiments.

20. What did Griffith conclude from these experiments?

Heat-killed, disease-causing bacteria (5 type)

Disease-causing bacteria (S type)

Harmless bacteria (R type)

Heat-killed, disease-causing bacteria (S type)

Harmless bacteria (R type)

Mouse dies of pneumonia

Mouse lives

Mouse lives

Mouse dies of pneumonia

a. The S type bacteria produced a poison that made mice sick

b. The heat-killed S type bacteria transformed the harmless R type bacteria into disease-causing cells.

c. The R type bacteria produced a poison that caused disease in mice

d. The heat-killed S type bacteria became harmless when injected into the mice along with the R type bacteria

Answer 1

Griffith concluded from his experiments that:

**b. The heat-killed S type bacteria transformed the harmless R type bacteria into disease-causing cells.**

This conclusion is based on the observation that when the harmless R type bacteria were mixed with heat-killed S type bacteria, the mice developed pneumonia and died, indicating that the R type bacteria had somehow acquired the ability to cause disease.