Describe how the evolution of photosynthesis changed the atmospheric and oceanic composition. Provide one example of evidence that proves this event took place

Answer 1

The evolution of photosynthesis, specifically the development of oxygenic photosynthesis by cyanobacteria and later plants, had a profound impact on the atmospheric and oceanic composition of the Earth. Prior to the evolution of photosynthesis, the Earth's atmosphere was primarily composed of carbon dioxide and nitrogen, with little to no oxygen present. However, as photosynthetic organisms began to release oxygen as a byproduct of their metabolic processes, the atmospheric oxygen levels began to rise.

This increase in atmospheric oxygen had significant consequences for the Earth's environment. It allowed for the development of aerobic organisms, which could utilize oxygen for respiration and obtain more energy from their food sources. This led to a diversification and expansion of life forms on Earth, ultimately resulting in the complex ecosystems that exist today.

In addition to changing the composition of the atmosphere, the evolution of photosynthesis also had a major impact on the oceans. The release of oxygen by photosynthetic organisms led to the oxidation of iron and other minerals in the oceans, which created banded iron formations and other sedimentary deposits.

One example of evidence for the evolution of photosynthesis and its impact on the Earth's environment is the presence of stromatolite fossils. Stromatolites are layered structures formed by cyanobacteria and other photosynthetic organisms, and the oldest known examples date back over 3.5 billion years. These fossils provide direct evidence of early photosynthetic activity and the role of these organisms in changing the Earth's atmosphere and oceans.