6. How did Earth's atmosphere change during Precambrian time?
O The amount of oxygen increased greatly.
O Precambrian oxygen was quickly used up by algae and plants.
O The amount of carbon dioxide increased.
Torrential rains never reached the surface until the Paleozoic era.

Precambrian oxygen was quickly used up by algae and plants.

Explanation:Around three billion years ago, the atmosphere of earth during the Precambrian time was virtually devoid of oxygen. The oxygen was produced as the byproduct of the photosynthetic activities of the cyanobacteria. The level of the gas raised and reached upto one percent about 2 billion years ago

explanation:

mitosis is used to produce daughter cells that are genetically identical to the parent cells. the cell copies - or 'replicates' - its chromosomes, and then splits the copied chromosomes equally to make sure that each daughter cell has a full set.