Given below are two statements: Statement I: In the RNA world, RNA is considered the first genetic material evolved to carry out essential life processes, RNA acts as a genetic material and also as a catalyst for some important biochemical reactions in living systems. Being reactive, RNA is unstable. Statement II: DNA evolved from RNA and is a more stable genetic material. Its double helical strands being complementary, resist changes by evolving repairing mechanism. In the light of the above statements, choose the most appropriate answer from the options given below:

Solution & Explanation

Answer: (C) Both statement I and statement II are correct. RNA was the first genetic material, acting both as a genetic material and as a catalyst, but being reactive it is unstable; DNA evolved from RNA as a more stable, double-stranded molecule whose complementary strands resist change via repair. NCERT Ch 5, p.88, lines 011-022: "RNA was the first genetic material... RNA used to act as a genetic material as well as a catalyst... But, RNA being a catalyst was reactive and hence unstable. Therefore, DNA has evolved from RNA with chemical modifications that make it more stable. DNA being double stranded and having complementary strand further resists changes by evolving a process of repair."