There are 3
exclusive mutually birth orders that could
make two
affecteds and 1 unaffected - unaffected child first born, unaffected child
second born,
and unaffected child third born. Thus, there is a 3/64 + 3/64 + 3/64
= 9/64
chance that 2 out of 3 children will be affected.
 
 
        
             
        
        
        
Answer:
Early cyanobacteria in stromatolites are thought to be responsible for increasing the amount of oxygen in the primeval Earth's atmosphere through their continuing photosynthesis. They were the first known organisms to photosynthesize and produce free oxygen. 
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