Other reasons are
Not finishing the antibiotics.
Or
Taking antibiotics too often
Each cell in the human body contains about 25,000 to 35,000 genes.
According to a source the answer is <span><u>Cyanobacteria were the first organisms to produce oxygen in water, which then escaped into the atmosphere.</u>
These cyanobacteria species were the first ones to "produce" oxygen as a by-product of the photosynthetic mechanisms which enables organisms to make their own food. </span>
Natural system is former when various components get grouped together for a particular function
