Question

Pneumococcus experiment proves that

• A. DNA is genetic material.
• B. Bacteria undergo binary fission.
• C. Bacteria do not reproduce sexually.
• D. At times, RNA controls production of DNA and proteins.

Answer 1

The correct option is A DNA is genetic material.

Griffith proved that DNA is genetic material by his transformation experiment on virulent (SIII) and non-virulent strains (RII) of Diplococcus pneumoniae. Griffith infected mice with a mixture of virulent (SIII) and non-virulent strains (RII) of pneumococcus bacteria, Diplococcus pneumoniae. Heat killed SIII did not cause any infection but a mixture of heat-killed SIII and living RII strains caused infection because a transforming substance was transferred from heat-killed strain to non-virulent strain causing non-virulent strain to transform into a virulent form which was identified as DNA by McCleod and McCarty; option A is correct. Binary fission is the method of asexual reproduction in bacteria; option B is incorrect with respect to the question. Sexual reproduction in bacteria occurs by conjugation, transformation and transduction; option C is the false statement. RNA retroviruses have reverse transcriptase enzyme that synthesizes a DNA copy (cDNA) of viral RNA which is then transcribed and translated; the viral RNA controls the synthesis of DNA and protein; option D is incorrect. The correct answer is A.