Final answer:
The statement is false; transforming material activity was not reduced by extracting lipids and proteins, but rather, it was reduced when DNA was degraded. The experiments conducted by Avery, MacLeod, and McCarty concluded that DNA was the transforming principle because only the degradation of DNA prevented the bacterial transformation.
Step-by-step explanation:
The statement in the student's question is false. According to the experiments conducted by Avery, MacLeod, and McCarty, transforming material (also known as the transforming principle) was not affected by extracting lipids and proteins. Instead, their research indicated that the transforming ability remained when lipids and proteins were removed but was lost when DNA was degraded. Using specific enzymes to degrade proteins, RNA, and DNA, they found that only the degradation of DNA prevented the transformation of the R strain of bacteria. This led them to conclude that DNA was the substance responsible for transformation and, therefore, the genetic material.
Had the results shown that proteases (enzymes that degrade proteins) prevented the transformation, it would suggest proteins as the transforming material rather than DNA. Since the transformation wasn’t affected by proteolysis, it reinforced their conclusion that DNA was the key molecule for heredity.