I think it’s organism since it already stated skeletal and respiratory then it means it cannot be tissue or organ because skeletal is included so i say go for organism
For giving you understanding ; we need Free O2 but Oxygen is also available in H20 right why dont we use it !!
As the early atmosphere was reducing as there was no free oxygen but it was later produced by chemoautotrophic bacteria !! Living thing release O2 in atmosphere thus making it oxidising in nature and then life evolves !!
Answer:
the bacteria is bad because with that one person it's in difficult time. hem need to take more careful.
Answer:
answer is 2 for both cuz they both have the 2 subscript next to hydrogen
