Principle Of Inheritance And Variation Question 609
Question: Assertion : Avery et al. found that DNA is the molecular basis of heredity. Reason : Transformation is caused by DNA.
Options:
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
Show Answer
Answer:
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.
BETA
