Describe how two processes of chemical weathering and one process of physical weathering may cause rocks to break up.

Physical Weathering would be nature related like the wind or rain. Chemical Weathering would be anything caused by a chemical reaction like acids or acidic rain. 
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When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.