Answer - Cyanobacteria aka Algae that contributed in creating O2 for the atmosphere as a byproduct thru Photosynthetic.
Reason - Of course Algae make up mainly the whole world in waters and they do photosynthesis to give off oxygen in the atmosphere.
Classification systems are essential to science; they act as the scaffolding that enables scientists to stand up close and get to know plants
Firstly, humans did not evolve from monkeys. Instead, monkeys and humans share a common ancestor from which both evolved around 25 million years ago. This evolutionary relationship is supported both by the fossil record and DNA analysis. A 2007 study showed that humans and rhesus monkeys share about 93% of their DNA.
The force of gravity affects all objects on Earth by pulling them towards the centre. The Earth is close to spherical in shape as this is the geometry gravity prefers. Without gravity, objects would be floating in space. The atmosphere would not exist as the air particles would have no force pulling them towards the planet. Gravity means when you throw something up, most of the time it will come down. It is a force, which causes objects to accelerate when they fall.
