Type s streptococcus pneumoniae bacterium is lethal and will kill its host. if heated, the inactivated s strain dies and becomes nonlethal. type r streptococcus pneumoniae is a nonvirulent strain of bacteria. what would occur if one were to inject both the r strain and heat-killed s strains into a host organism such as the mouse?

Transformation of live R strain would make it a virulent S strain and the host organism would die of infection.

Explanation:

Transformation is one of the mechanisms of genetic recombination in bacteria. Here, the bacterial cell obtains foreign DNA from the medium. The incorporation of foreign genetic material changes its phenotype.

In the given experiment, when heat-killed S strain and live R strain are injected together in the host cell, the DNA of heat-killed S strain would be taken up by live non-virulent R strain bacterial cells. The take up of genetic material of S strain would transform the R strain into S strain which in turn will infect the host organism and kill it.

answer: a. a gene that causes a specific trait.