A) If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B) If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C) If the assertion is true but the reason is false
D) If both the assertion and reason are false
E) If the assertion is false but reason is true
Correct Answer: A
Solution :
In 1944, Avery, Mc Carty and Mac Leod, fractionated the killed S-type bacteria into three components-DNA, carbodhydrate and protein. DNA fraction was further divided into two parts : one with deoxyribonuclease (DNA-ase) and the other without it. The four components were then added to separate culture tubes containing R-type bacteria. The culture tubes were allowed to remain undisturbed for some time. They were then analysed for bacterial population. Only DNA of S-type can change R-type of bacteria into S-type. Therefore, the character of gene of virulence is located in this chemical. Hence, DNA forms the chemical or molecular basis of heredity.
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