Compared to bacteria cells, viruses are

Viruses have to invade the body of a host organism in order to replicate their particles. Therefore, most viruses are pathogenic. The main difference between bacteria and virus is that bacteria are living cells, reproducing independently and viruses are nonliving particles, requiring a host cell for their replication.

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the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.