Consider the following statements regarding the formation of micromolecules and choose the correct answer:
1. The molecules which have molecular weight below 100 daltons are called micromolecules
2. According to Miller (1965), most of the glycine and many amino acids were formed from CO₂, CO, H₂ and NH₂ in gaseous state due to electric discharge
3. Purines and pyrimidines are thought to be originated from hydrogen cyanide in the primitive earth due to condensation reactions in the presence of heat or radiations
4. Pyrroles, the probable precursors of porphyrins, were likely formed at a very late stage of chemical evolution due to speculated reaction between ethylene and acetylene