What prevents life from developing on land before Earth’s atmosphere contained a significant portion of oxygen?
(1) All land locations were too hot for life to exist.
(2) All terrestrial environments were too cold for life to even exist.
(3) All forms of life require atmospheric oxygen for their vital processes.
(4) The land received too much harmful solar radiation.
My answer is 2, thinking of the ice age.
Actually, the correct answer is (3) - all forms of life require atmospheric oxygen for their vital processes.
Life on Earth originated in the oceans, where the conditions were suitable for the evolution of simple organisms. These early life forms were anaerobic, meaning they could survive in an environment without oxygen. However, the evolution of more complex life forms, including those capable of living on land, required the presence of atmospheric oxygen.
Before Earth's atmosphere contained a significant portion of oxygen, the atmosphere was mostly composed of carbon dioxide, nitrogen, and small amounts of other gases. Photosynthetic organisms, such as cyanobacteria, gradually evolved and released oxygen as a byproduct of their metabolic processes. This oxygen eventually accumulated in the atmosphere, leading to the development of aerobic organisms that could utilize oxygen for energy production.
Considering the other options:
- Option (1) states that all land locations were too hot for life to exist, which is inaccurate. There are many habitats on land with varying temperatures that can support life.
- Option (2) suggests that all terrestrial environments were too cold for life to exist, which is also incorrect. Life can adapt to and thrive in a wide range of temperatures, including cold environments.
- Option (4) claims that the land received too much harmful solar radiation, but this is not the main reason why life could not develop on land before the presence of atmospheric oxygen.
Therefore, option (3) is the most accurate explanation for why life did not develop on land until Earth's atmosphere contained a significant portion of oxygen.