Question

Which of the following were first evolved organisms?

• A. Chemoautotrophs
• B. Heterotrophs
• C. Cyanobacteria
• D. Bacteria

Answer 1

The correct option is B

Heterotrophs

Correct option is (b)-

The explanation of the correct option

1. The early atmosphere of Earth had no oxygen, so the life form in an oxygen-free atmosphere could be only anaerobic.
2. Chemoheterotrophs are like bacteria. They are anaerobic prokaryotes found in an oxygen-free atmosphere,
3. They are dependent on an external supply of organic compounds.

The explanation of the incorrect option

Option (a)-

Chemoautotrophs are organisms that can make their own food through a chemical process. They were not the first evolved organisms.

Option (c)-

Cyanobacteria were the first oxygenic photoautotroph, and they produce energy in the presence of sunlight.

Option (d)-

First, nonoxygenic photoautotrophs were bacteria; they were not the first evolved organisms.

Final Answer: Heterotrophs were the first evolved organisms.