Question

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

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

Assertion is correct as the earliest organisms that appeared on the earth were non-green and presumably anaerobes, because primitive earth was devoid of oxygen, so only those organisms that were able to survive within anaerobic conditions developed. These were heterotrophic organisms (taking nutrients from outside).

Reason is also correct but not correct explanation of assertion as first autotrophic organisms, which were developed were the chemoautotrophs that used inorganic substances, like hydrogen sulphide, ammonia, methane as the principal sources of energy which never released oxygen. Hence, option B is correct.