Question

In 1994 Avery, McCarty and MacLeod isolated a substance from a heat-killed virulent form of bacteria and added to the non-virulent form of bacteria which changed the non-virulent to virulent form this substance can be destroyed by
A. DNAse
B. Protease
C. Lipase
D. Amylase

Answer 1

Virulent is defined as the capacity of an organism to contaminate the host and result in death and non-virulent means an organism that doesn't contaminate the host. Bacteria comprise two strains: S strain i.e. Smooth strain with glycoprotein coat that destroys mice (virulent) and R strain i.e. Rough strain (non-virulent).

Complete answer:
Oswald Avery, Maclyn McCarty, and Colin MacLeod are the researchers who conducted the experiments which demonstrated that the transforming principle is the DNA, in a time when it had been broadly accepted that it was a protein that served the capacity of transmitting genetic information. They announced that DNA is a substance that results in the bacterial transformation from non-virulent to a virulent form.
DNAse functions as an endonuclease enzyme responsible for DNA fragmentation and causes devastation of the DNA. It also causes the cleavage of the nucleotides in the sequence of the DNA. The protease is the enzyme that causes the breakdown of protein into smaller molecules i.e. amino acid. Lipase is the digestive enzyme that catalyses the hydrolysis of fats. Amylase is the digestive enzyme that results in the breakdown of starch into smaller molecules.

So, the right answer is option A i.e. DNase.

Note:
Avery, MacLeod, and McCarty explaining the chemical nature of genes, during an experiment on Streptococcus pneumonia (microorganisms that cause pneumonia). The sequence of the experiment begins in 1920 to observe that DNA is the genetic material. The enzyme that is responsible for the degradation of protein, RNA, lipid, and starch didn’t demolish the transforming principle.