Several experiments were required to demonstrate how traits are inherited. Which scientist or team of scientists first demonstrated that cells contain some components that can be transferred to a new population of cells and permanently cause changes in the new cells?

a. Griffith

b. Watson and Crick

c. Avery, MacLeod, and McCarty

d. Hershey and Chase

a. Griffith

Explanation:

Frederick Griffith used two strains of the bacterium Streptococcus pneumoniae. The S strains were pathogenic while the R strains were nonpathogenic. He added the heat-killed virulent bacteria to the live nonvirulent strain and infected mice with it. He showed that the mice developed the disease and were killed. He concluded that a substance from the heat-killed S strains transformed the live R strains into the virulent form that killed mice. However, he could not identify the substance responsible for the process of transformation.