Question

1.1.2 quiz: introduction to heredity
living s cells
living r cells
heat - killed s cells
heat - killed s cells and living r cells
which two experimental groups of mice died after griffith injected them with pneumococci bacteria?
a. the group exposed to heat - killed s cells
b. the group exposed to living s cells
c. the group exposed to living r cells
d. the group exposed to heat - killed s cells mixed with living r cells

Explanation:

In Griffith's experiment with pneumococci:

• Living S cells (virulent) cause mice to die (Option B).
• Heat - killed S cells alone don't kill, but when mixed with living R cells (non - virulent), the R cells are transformed by a factor from heat - killed S cells to become virulent, killing the mice (Option D).
• Living R cells are non - virulent, so mice don't die (Option C is wrong).
• Heat - killed S cells alone don't kill (Option A is wrong).

Answer:

B. The group exposed to living S cells
D. The group exposed to heat - killed S cells mixed with living R cells