Why do we have six different crystal structures?

The earth consists of a variety of different organisms. despite their diversity, however, some similarities on the structural and metabolic levels may be seen. these similarities can be attributed to a. similarities among organisms in their proteins and nucleic acids. b. the ability of organisms to readily adapt to sudden environmental changes. c. similarities in organisms' habitats and niches. d. the ability of all organisms to interbreed and produce new species.

Aboy jumps into a cold swimming pool and his body tempature goes down hus muscles ,blood vessels

Sequence how oxygen accumulated in the atmosphere and the effect it had on life by completing the flowchart