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This question is about life, the Earth and its atmosphere - AQA - GCSE Chemistry - Question 3 - 2015 - Paper 1
Question 3
This question is about life, the Earth and its atmosphere. 3 (a) There are many theories about how life was formed on Earth. Suggest one reason why there are many ... show full transcript
Worked Solution & Example Answer:This question is about life, the Earth and its atmosphere - AQA - GCSE Chemistry - Question 3 - 2015 - Paper 1
Step 1
Suggest one reason why there are many theories.
Answer
One reason there are many theories about the origin of life on Earth is the lack of sufficient evidence or proof. The elusive nature of early life forms and the complex processes involved make it difficult for scientists to agree on a singular explanation.
Step 2
Describe and explain how the surface of the early Earth and its atmosphere have changed to form the surface of the Earth and its atmosphere today.
Answer
The surface of the early Earth was predominantly volcanic, with much of it covered by lava and ash. This active volcanic environment released significant amounts of gases, primarily carbon dioxide and water vapor, into the atmosphere. Over time, as the Earth cooled, these gases began to condense, leading to the formation of oceans.
Additionally, the early atmosphere was rich in carbon dioxide. As life forms like plants and algae evolved and conducted photosynthesis, they started to convert carbon dioxide into oxygen. This crucial process gradually changed the composition of the atmosphere, leading to a significant increase in oxygen levels while decreasing carbon dioxide concentrations.
Furthermore, tectonic activity caused the land to break apart, forming continents which would eventually support diverse ecosystems. The shift from a volcanic surface to one dominated by oceans, paired with the transition to a nitrogen and oxygen-rich atmosphere, illustrates the profound changes that have occurred since Earth's formative years.