<span>there’s another way to retroviruses is to make
more strong screening methods to tell if the transgene is functioning properly
in the embryo before it is implanted in the uterus. The approach leads to fewer
problems with development, but it has raised concerns about the possibility.</span>
        
                    
             
        
        
        
Yes. They do it to escape the winter. Hope it helps.
 
        
                    
             
        
        
        
Answer:
miRNA ( micro RNA )
Explanation:
The small RNA molecule that interfere with gene expression are miRNA. The miRNA is micro RNA that are non-coding molecules of RNA. These small RNA regulate gene expression after transcription (post transcription). 
The miRNA binds to 3' UTR region (untranslated region ) and halt the process of protein production and thereby silencing mRNA.
 
        
             
        
        
        
It is Chemistry. 
Cu+AgNO3=Ag+Cu(NO3)2
==>
Cu+2AgNO3=2Ag+Cu(NO3)2