Question

Assertion The earliest organisms that appeared on the earth were non-green and presumably anaerobes.
Reason The first autotrophic organisms were the chemo-autotrophs that never released oxygen.

• A. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion, then mark
• B. If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion, then mark
• C. If Assertion is true statement but Reason is false, then mark
• D. If both Assertion and Reason are false statements, then mark

Answer 1

Answer: (B)

Primitive earth was devoid of oxygen so, only those organisms that were able to survive within anaerobic conditions developed. All those were heterotrophic organisms (taking nutrients from outside). Then after autotrophic organisms were developed that used inorganic sources such as $ H_{2}S,\,NH_{3},\,CH_{4} $ as the principle sources of energy. These organisms are called chemo-autotrophs.