Origin of Life & Oxygen Release — NEET Biology
📚 Practice ConceptAbout 2000 million years ago (mya) the first cellular forms of life appeared on earth. The mechanism of how non-cellular aggregates of giant macromolecules could evolve into cells with membranous envelop is not known. Some of these cells had the ability to release O₂. The reaction
Which of the following statements are correct? S1: The Mesozoic era is widely recognized as the 'Age of Mammals' due to their rapid diversification. S2: Oxygen production on Earth began with the appearance of the first cellular forms of life approximately 2000 million years ago. S3: Amphibians evolved into reptiles, which successfully colonized land partly due to their ability to lay thick-shelled eggs that resist desiccation. S4: The extinction of dinosaurs, leading to the rise of mammals, occurred about 165 million years ago. S5: The emergence of modern Homo sapiens is associated with the period between 75,000-10,000 years ago, during the last ice age.
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Correct answer: B — S2, S3 and S5 only
The question pertains to the geological time scale and major evolutionary events as described in the NCERT text. S1: The Mesozoic era is incorrect. The Mesozoic era is known as the 'Age of Reptiles' (or Dinosaurs), while the Cenozoic era is referred to as the 'Age of Mammals' after the dinosaurs disappeared. Therefore, S1 is incorrect. S2: This statement is correct. According to NCERT, "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." S3: This statement is correct. NCERT states, "The amphibians evolved into reptiles. They lay thick-shelled eggs which do not dry up in sun unlike those of amphibians." S4: This statement is incorrect. Dinosaurs disappeared approximately 65 million years ago, not 165 million years ago. NCERT states, "About 65 mya, the dinosaurs suddenly disappeared from the earth." S5: This statement is correct. NCERT mentions, "During ice age between 75,000-10,000 years ago modern Homo sapiens arose." Based on the analysis, statements S2, S3, and S5 are correct. The final answer is B.
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