How long ago did two species of birds share an ancestor
        
                    
             
        
        
        
The Answer is A.) Carbon dioxide 
Cause it is produced as a waste product during respiration in the cells of the body tissues, diffuses into the blood.
 
        
                    
             
        
        
        
Answer:
Can't see the 1st question but the 2nd is C
Explanation:
 
        
             
        
        
        
DNA replication occurs in the synthesis phase. And one of the main actors are DNA polymerase which helps make a new copy of a DNA strand. Occasionally, they make errors and pair incorrect bases because of the process and repetition. A is sometimes paired with G is because they are both purines nucleotides and are produced with the same nucleotide components.