Answer:
The respiratory system and the circulatory.
Explanation:
The respiratory system brings in the oxygen and the circulatory system brings all of the oxygen through out the body.
I think it’s DNA replication if i’m not mistaken
Answer: Atmosphere
Explanation:
Atmosphere is the part of the earth, known as the gaseous part, since it contains gases such as nitrogen (about 78%), oxygen (about 21%), Carbondioxide (about 0.03%), and rare gases to make the rest.
Thus, atmosphere contains the most whole of oxygen and carbon dioxide
The Cambrian explosion was a period at the Pre-Cambrian boundary of the geologic time scale at 542 Ma. At this boundary, the fossil record shows that animals suddenly appeared in a dramatic radiation of life. A radiation is the relatively rapid development of new types of organisms that derive from a common ancestor. The Cambrian explosion is important because it marks the origination of all major animal groups called phyla.
