Up until the end of the Proterozoic Eon, Earth\'s biosphere was dominated by ___
ID: 291221 • Letter: U
Question
Up until the end of the Proterozoic Eon, Earth's biosphere was dominated by _____________.
marine animals
land plants
prokaryotic plant-like organisms
no living organisms until the beginning of the Cambrian Period
How do banded iron formations (BIFs) tell us that conditions on Earth were very different before about two billion years ago?
They represent a time of extensive continental crust across Earth.
These rock types form only during glacial periods.
BIF require the prime deposition conditions of deep marine waters.
These rock types formed in a very oxygen-poor atmosphere at that time.
Evidence of a former "supercontinent" Rodinia during the early Proterozoic Eon can be seen in old mountain rocks of the _______________.
Grenville Orogeny
East African Rift
Marianas Trench
Antler Orogeny
One chemical change that occurred in the late Proterozoic Period and led to the adaptation of the first shelled organisms was _____________.
increase in plant photosynthesis
increased plate tectonic activity
decrease in oxygen in the atmosphere
higher calcium concentration in oceans
It is hypothesized that Earth's atmosphere during the Archean Eon had only 2% oxygen. How does this compare to the modern atmosphere, and what process eventually started to increase the oxygen levels?
10 times less than today; photosynthesis
5 times greater than today; volcanism
2 times less than today; erosion
the same as today; plate tectonics
marine animals
land plants
prokaryotic plant-like organisms
no living organisms until the beginning of the Cambrian Period
Explanation / Answer
1] no living organisms until the beginning of the Cambrian Period is the correct option.
2] These rock types formed in a very oxygen-poor atmosphere at that time is the correct option.
3] Grenville Orogeny is the correct option.
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