Phylum, it is the second largest group.
Biology or Geology. These answers make the most sense to me.
They adapt because they can replicate quickly (have many generations within short period of time) and accumulate mutations. Mutations in their genetic information allows them to bypass the host's immune system or resist to antibiotics. These mutations are successfully carried to the next generations of bacteria and allows them to thrive in their new environments. <span />
Omnivore, as they eat both meat and plants
