EVOLUTION
THE ORIGIN OF LIFE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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cellular respiration in plants
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photosynthesis in blue-green bacteria
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eruption of many volcanoes in a short period
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decomposition of large amounts of organic matter
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Detailed explanation-1: -Such an atmosphere contains practically no oxygen. The modern atmosphere contains abundant oxygen, making it an oxidizing atmosphere. The rise in oxygen is attributed to photosynthesis by cyanobacteria, which are thought to have evolved as early as 3.5 billion years ago.
Detailed explanation-2: -Scientists think that algae first evolved approximately 2.7 billion years ago, and soon after this oxygen began to exist in the atmosphere. Photosynthesis by primitive plants and algae released oxygen, which gradually built up in the atmosphere.
Detailed explanation-3: -Earth’s original atmosphere was rich in methane, ammonia, water vapour, and the noble gas neon, but it lacked free oxygen.
Detailed explanation-4: -The oxygen did not build up in the atmosphere for a long time, since it was absorbed by rocks that could be easily oxidized (rusted). To this day, most of the oxygen produced over time is locked up in the ancient “banded rock” and “red bed” rock formations found in ancient sedimentary rock.
Detailed explanation-5: -Summary: New research has uncovered a direct link between changes in the earth’s crust three billion years ago and the introduction of free oxygen to the atmosphere. Without these changes, oxygen could have been suppressed in earth’s crust forever, so the findings help explain the emergence of life on our planet.