The correct answer is - cyanobacteria.
The atmospheric oxygen came from the cyanobacteria. These were one of the earliest living organisms on Earth. The cyanobacteria was using photosynthesis in order to create its own food. The photosynthesis process requires sunlight, carbon dioxide, water, and oxygen. The oxygen is mostly released as a waste product from the process of photosynthesis, thus the cyanobacteria were literally releasing oxygen that was ending up into the atmosphere. As more and more cyanobacteria there were across the planet, more and more oxygen they were releasing into the atmosphere, slowly changing the composition of the atmosphere, and setting the basis of it as we know it now.
Answer:
An eon
Explanation:
The first broad division of the geologic timescale is the eon. Others are Eras, Periods and Epoch.
Eons are the most broad and the largest of divisions of the timescale. There are two categories of the eons which are:
- Hadean eon
- Archean eon
- Proterozoic eon
- Phanerozoic eon
The Phanerozoic eon is the most recent. The Hadean eon is the is the oldest eon.
I think that the two regions would be the Temperate Zone and the Polar Zone, as they're the only climate regions to the south of the 20<span>°S latitude. Check a world latitude map and compare it with a climate map if you're still unsure.</span>
Answer:
The very cold winters are associated with the country's high latitudes, lack of topographic barriers, and the extensive size of land. In the northern parts of Russia, the winters are milder and characterized by frequent precipitation all through the year. These parts of the country are influenced by the Baltic Sea.
Explanation:
