Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.
Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.
About 2.4 billion years ago, Earth experienced one of the most dramatic environmental transformations in its history: the Great Oxygenation Event (GOE). Before this time, Earth’s atmosphere contained almost no free oxygen
Diagram 1.
Source: https://www.biologyonline.com/dictionary/great-oxygenation-event
This rising oxygen level fundamentally altered Earth’s systems. Many anaerobic species could not tolerate oxygen, leading to widespread extinctions - sometimes called the “oxygen crisis.” But for other organisms, oxygen opened the door to new metabolic pathways. Aerobic respiration, which uses oxygen to break down molecules for energy, is much more efficient than anaerobic processes. This increase in available energy allowed for greater biological complexity and set the stage for multicellular life.
The GOE also triggered major changes in Earth’s geosphere and climate. Increased atmospheric oxygen reacted with methane, a powerful greenhouse gas, decreasing its concentration. This likely contributed to planet-wide glaciation events (“Snowball Earth”) that reshaped Earth’s climate system. At the same time, oxygen combined with UV radiation in the atmosphere to form ozone
Evidence for the GOE comes from many scientific fields: geology (iron formations and sulfur isotopes), atmospheric science (models of gas composition), and biology (genetic and fossil evidence for early oxygen-producing organisms). Together, these data sets show a clear coevolution of Earth’s systems and life. Life changed the atmosphere, and the atmosphere changed life in return - including which organisms survived, diversified, or went extinct.
Diagram 2.
Source: https://nephicode.blogspot.com/2017/08/what-do-we-know-about-noahs-flood-part-i.html
Today, aerobic organisms - including humans - depend on the oxygen-rich atmosphere shaped by ancient microbes. The GOE remains an iconic example of how biological evolution and Earth system processes are linked across time.
Table 1.
Time (billion years ago) | Atmospheric O |
|---|---|
3 | 0.001 |
2.8 | 0.002 |
2.6 | 0.005 |
2.45 | 1 |
2.3 | 4 |
2 | 10 |
Graph of Information - Figure 1.
Table 2.
Time (billion years ago) | Cyanobacteria Abundance Index | Mass-Independent Sulfur Fractionation (%) |
|---|---|---|
3 | 5 | 12 |
2.8 | 9 | 11 |
2.6 | 18 | 9 |
2.45 | 40 | 3 |
2.3 | 65 | 1 |
2 | 80 | 0 |
Graph of Information - Figure 2.
According to Table 1, which time period shows the first major rise in atmospheric oxygen?
Using Figure 1, describe how atmospheric oxygen levels changed between 2.6 and 2.0 billion years ago. What overall trend is shown in the data?
Using Diagram 1, explain how cyanobacteria changed Earth’s atmosphere and how these changes affected anaerobic organisms. Base your response only on information in the diagram and reading.
Construct an argument explaining how interactions between early photosynthetic life and Earth’s atmosphere during the GOE demonstrate coevolution of Earth’s systems and life.
Your response should include a clear claim, supporting evidence, and reasoning.
According to Table 2, how does cyanobacteria abundance change from 3.0 to 2.0 billion years ago?
Based on Figure 2, describe the relationship between cyanobacteria abundance and the decline of mass-independent sulfur fractionation (S-MIF). How does this pattern support changing atmospheric chemistry during the GOE?