Question

Arrange the following in sequence in relation to the origin of living organisms
A. Chemo-autotrophs
B. Oxygenic photoautotrophs
C. Anaerobic heterotrophs
D. Anoxygenic photo-autotrophs

• A. A, C, D, B
• B. B, A, D, C
• C. C, A, D, B
• D. D, C, B, A

Hint:

Order: Anaerobic heterotrophs → Chemoautotrophs → Anoxygenic → Oxygenic photoautotrophs.

Answer 1

The Correct Option is C

- First life forms were anaerobic heterotrophs (no oxygen).
- Chemoautotrophs appeared next, using inorganic chemicals.
- Then came anoxygenic photoautotrophs (photosynthesis without oxygen release).
- Finally, oxygenic photoautotrophs evolved, contributing oxygen to atmosphere.