Question

Arrange the following in proper sequence of their formation
A) Photo autotrophs
B) Anaerobic heterotrophs
C) Free genes
D) Chemo autotrophs

• A. C - D - B - A
• B. C - B - D - A
• C. C - B - A - D
• D. A - D - B - C

Answer 1

The correct option is A C - D - B - A

The primitive earth conditions were highly reduced due to the absence of oxygen. Due to the polymerization of the simple organic compounds, the biomolecules like proteins. carbohydrates, nucleic acids evolved first. So, genes were the first to have evolved. As there was no oxygen and no producer of organic carbon. So, chemoautotrophic bacteria that synthesized their organic carbon from the inorganic compounds like iron, sulfur or magnesium. They did not use the carbon dioxide and also did not release the oxygen. Methane, organic sulfur etc. were the by-products of chemosynthesis. Now, due to chemoautotrophs, anaerobic heterotrophs evolved as they did not need to have oxygen for their energy production and the food was already available from the chemoautotrophs, anaerobic heterotrophs were next to evolve. Gradually, photoautotrophs like cyanobacteria evolved that could the atmospheric carbon dioxide and released the oxygen as the by-product in the presence of the sunlight.

Hence, the correct answer is 'C -D - B - A'