Direction for: In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
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.
B) If both assertion and reason are true but the reason is not the correct explanation of the assertion.
C) If assertion is true statement but reason is false.
D) If both assertion and reason are false.
Correct Answer: B
Solution :
Primitive earth was devoid of oxygen so, only those organisms that were able to survive within anaerobic conditions developed. All these were heterotrophic organisms (taking nutrients from outside). Then after autotrophic organisms were developed that used inorganic sources such as \[{{H}_{2}}S,\,N{{H}_{3}},\,C{{H}_{4}}\] as the principle sources of energy. These oganisms are called chemo-autotrophs.
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