Composition of the primitive Earth atmosphere

Composition of the present atmosphere of the Earth

EARTH ATMOSPHERE

LAYERS OF THE ATMOSPHERE

PROCARIOTIC CELL

BACTERIA CAN BE USEFUL

Bacteria can be useful to human beings in a few ways, for example:

1. Bacteria in human intestines (gut flora) help with the digestion of certain foods, mainly complex carbohydrates. Lactobacillus species convert milk protein to lactic acid in the gut.
2. They are used in the production of cheese, yogurt, and other foods 
3. They are essential for the decomposition and recycling of dead organisms
4. Fixation of nitrogen from the atmosphere into useable nitrogen in soils 
5. Many are used in the production of antibiotics and other substances as insulin, hormones...
6. Photosynthetic bacteria (Cyanobacteria) produce free oxygen
7. They synthesize vitamins such as folic acid (B9 vitamin), vitamin K and biotin (B7 vitamin)