Question

Why do scientists think the first living cells to appear on earth were probably anaerobic heterotrophs?

Answer 1

The atmosphere had no oxygen it thereby created an environment where only anaerobic organisms could exist. They couldn't make there own food due to lake of oxygen in the atmosphere

Explanation:

During the archaea period 3.4 billion years ago after amino acids develop the first living cells the prokaryotes with no nuclei , simple design and no organelles. According to Miller Urey and Sagan these cells were anaerobic as no oxygen was present in atmosphere and they were heterotrophs using fermentation as the process to obtain energy from the molecules formed by the heat and light in early atmosphere this is why these organisms are said to be anaerobic and heterotrophs