Rickettsia typhi is a species of infectious bacterium that is an obligatory intracellular parasite. This means that, similar to viruses, R. typhi cannot reproduce and survive outside of a eukaryotic cell. Why do we consider viruses nonliving, but rickettsia alive

Due to its characteristics.

Explanation:

We consider viruses are nonliving, but rickettsia are living because rickettsia have the characteristics of bacteria which is a living  and has unique structure. It also survives outside the living cell but not for long time. The rickettsia  remain in their shape and does not form crystalline structure like viruses outside the cell. If there is suitable environment for rickettsia, it can survive in that environment.

brain development. a child's brain undergoes an amazing period of development from birth to three—producing more than a million neural connections each second. the development of the brain is influenced by many factors, including a child's relationships, experiences and environment.

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