KEY TAKEAWAYS •
There are different cycles of nutrients with the nitrogen cycle being an important one as nitrogen is a limiting nutrient in the formation of living things.
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There are nitrogen fixing bacteria that take nitrogen from the atmosphere and denitrification bacteria that put the nitrogen back into the atmosphere.
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Ecosystems can be large or small but involve the interaction of organisms in a specific area with the physical characteristics of the environment.
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Population ecology is the study of different organisms and their growth or lack of growth in numbers in a specific area.
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The biosphere is the totality of the ecosystems and encompasses areas deep within the earth and parts of the atmosphere but not in deep space.
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Climate change has happened for billions of years, even when humans did not inhabit it the earth
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Humans have affected the climate in irreversible ways through an increase in greenhouse gases, deforestation, and other human activities.
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