Question

Which of the following is responsible for transforming the R strain into the S strain?

(a) Purified bio-chemicals from S-strain

(b) Purified bio-chemicals from R-strain

(c) Purified bio-chemicals from heat killed S-strain

(d) Purified bio-chemicals from heat killed R-strain

I had been asked this question during an interview.

Origin of the question is The Search for Genetic Material topic in chapter Molecular Basis of Inheritance of Biology – Class 12

Answer 1

Correct answer is (c) Purified bio-chemicals from heat killed S-strain

To elaborate: S-strains are the virulent ones which have the ability to kill a mouse when injected into it. But, when the heat killed S-strain is injected into the mouse along with the R-strain, the mouse happens to die due to transformation. The purified bio-chemicals (protein, DNA and RNA) from the heat killed S-strain, transforms the R-strain into the S-strain (virulent).