Question

question 6 of 10
frederick griffith studied two strains of pneumococci bacteria: the s strain and the r strain. he wanted to know whether each strain was deadly to mice. the diagram below shows griffiths experimental setup.
which two experimental groups of mice died after griffith injected them with pneumococci bacteria?
a. the group exposed to living s cells
b. the group exposed to heat - killed s cells mixed with living r cells
c. the group exposed to heat - killed s cells
d. the group exposed to living r cells

Explanation:

Step1: Understand S and R strains

The S strain of pneumococci is virulent (deadly) because it has a capsule that protects it from the immune system of the mice. Living S cells will cause the mice to die.

Step2: Understand transformation

When heat - killed S cells are mixed with living R cells, the R cells can take up genetic material from the heat - killed S cells through a process called transformation. The transformed R cells then become virulent and can kill the mice.

Step3: Analyze other groups

Heat - killed S cells alone are not virulent as they are dead, and living R cells are non - virulent as they lack the protective capsule, so the mice in these groups will not die.

Answer:

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