Answer:
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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One will be due to climatic change or it might be coz of evolution
B. Second level consumer because it is not a plant(producer). It is not a decomposed and it is eating the mouse , a first level consumer .
