Following are the two statements regarding the origin of life: (i) The earliest organisms that appeared on the earth were non-green and presumably anaerobes. (ii) The first autotrophic organisms were the chemoautotrophs that never released oxygen. Of the above statements which one of the following options is correct?
Answer: (C) Both (i) and (ii) are correct. Answer: (C) Both (i) and (ii) are correct.
- A.(i) is correct but (ii) is false
- B.(ii) is correct but (i) is false
- C.Both (i) and (ii) are correct✓
- D.Both (i) and (ii) are false
Correct Answer
(C) Both (i) and (ii) are correct
Solution & Explanation
Answer: (C) Both (i) and (ii) are correct. The earliest organisms on the early, oxygen-free reducing earth were non-green (non-photosynthetic) and anaerobic, consistent with NCERT's account that the first non-cellular and cellular forms arose in a water environment before any oxygen-releasing cells appeared. The first autotrophs were chemoautotrophs that synthesised organic matter from inorganic sources without releasing oxygen; oxygen-releasing (photosynthetic) life came only later. Hence both statements are correct. NCERT Reference: Ch 6 Evolution, p.121, lines 40–44: "About 2000 million years ago (mya) the first cellular forms of life appeared on earth. ... Some of these cells had the ability to release O2."