Consider the following statements :
- 1. The Earth’s magnetic field has reversed every few hundred thousand years.
- 2. When the Earth was created more than 4000 million years ago, there was 54% oxygen and no carbon dioxide.
- 3. When living organisms originated, they modified the early atmosphere of the Earth.
Which of the statements given above is/are correct ?
1 only
2 and 3 only
1 and 3 only
1, 2 and 3
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC IAS – 2018
2. When the Earth formed over 4 billion years ago, the atmosphere was primarily composed of volcanic gases like water vapor, carbon dioxide, and nitrogen, with little to no free oxygen. An atmosphere with 54% oxygen is not consistent with early Earth conditions; oxygen became abundant much later due to biological activity. Statement 2 is incorrect.
3. The origin and evolution of life, particularly photosynthetic organisms like cyanobacteria, fundamentally altered the Earth’s atmosphere. Through photosynthesis, these organisms consumed carbon dioxide and produced oxygen, leading to the gradual oxygenation of the atmosphere over billions of years (the Great Oxidation Event). Statement 3 is correct.
Therefore, statements 1 and 3 are correct.