SCIENCE
ENVIRONMENTAL SCIENCES
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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absorbing carbon dioxide and releasing oxygen, warming the planet
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producing large amounts of methane, causing global warming
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absorbing carbon dioxide and releasing oxygen, cooling the planet
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producing more carbon dioxide and cooling the planet
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Detailed explanation-1: -Before about 2.4 billion years ago, Earth was a virtually oxygen-free environment. The appearance of cyanobacteria, or blue-green algae, changed all that. Cyanobacteria injected the atmosphere with oxygen, setting the scene for the development of complex life as we know it.
Detailed explanation-2: -Cyanobacteria carry out oxygen-evolving, plant-like photosynthesis. Earth’s oxygen-rich atmosphere and the cyanobacterial origin of plastids in plants are the two major evolutionary contributions made by cyanobacteria. Certain cyanobacteria are able to carry out nitrogen fixation.
Detailed explanation-3: -The release of oxygen by cyanobacteria was thus responsible for changes in the earth’s atmospheric composition, the rise of aerobic metabolism and, ultimately, the evolution of multicellularity. Oxygen is the primary molecule that makes Earth what it is today, far more hospitable and beautiful than the early earth.
Detailed explanation-4: -Cyanobacteria are microorganisms that live in water and, like plants, they capture energy from the sun to convert carbon dioxide into sugars and other useful compounds. This process-called photosynthesis-releases oxygen as a by-product.