The oxygen content in the atmosphere of the early earth is thought to have increased significantly once which of these developed?

Oxygen content increased after photosynthetic algae developed.

The algae is able to use solar energy, water, and carbon dioxide to synthesize sugars for its own energy. During the process, oxygen is released as a byproduct.

this protocol describes a detailed procedure for intracellular flow cytometry staining.

the offspring would all be white. if the parents are both white flowers then they have the genotype rr, which when crossed results in an all white punnet square.