Final answer:
A small percentage of R bacteria were transformed to S types due to factors like low uptake efficiency, DNA degradation before incorporation, or nuclease activity. Antibodies are essential for accurate experimental results to isolate transformed bacteria. Historical experiments by Avery, Macleod, McCarty, Hershey, and Chase, and Griffith's work, all provide evidence for DNA as the hereditary material.
Step-by-step explanation:
A student is querying the efficiency of bacterial transformation in a historical experiment and the necessity of using an antibody for removing untransformed bacteria. To begin with, several possible reasons why only a small percentage of type R bacteria were converted to type S might include low efficiency of uptake of DNA by R cells, the possible breakdown of S DNA before it could be incorporated, or the potential degradation of transforming DNA by R cell nucleases. As for the antibody usage, it is critical to remove untransformed bacteria to ensure the accuracy of the experiment's results. If an antibody was not used, the results would be confounded as the cultures could be overgrown by untransformed cells, making it difficult to identify and quantify the transformed ones.
Following these findings in historical experiments by Avery, Macleod, and McCarty, Hershey, and Chase, and Griffith's mouse experiments, it was concluded that DNA was the hereditary material necessary for bacterial transformation. The transformation experiment by Griffith revealed that dead S cells could transmit disease-causing ability to live R cells, highlighting that DNA carried genetic information. Hershey and Chase's work with bacteriophages labeled with radioactive isotopes provided further evidence to support the notion that DNA was the genetic material.