Answer:
The correct answer is nitrogen base
Explanation:
The nucleotide sequence of one codon differ from that of another codon by the presence or absence of specific nitrogen base.The nucleotide sequence of different codons contain different nitrogen bases.
        As a result change in genetic code result from the change in the nitrogen bases  of the codons present in the genetic code.
   In simple words change in single nitrogen base of a codon will change the entire codon.
 
        
             
        
        
        
Smoking and drinking can cause major birth defects. It can also cause the baby to be very sick when it is born, and have a near death experience. 
depending on the amount of intake, the baby could also be born addicted to either one. It is very dangerous to drink or smoke during the development of a child.
Hope this is helpful!:))))
 
        
             
        
        
        
What defines a plant is if it alive, and leaves or contains pollen or seeds I hope this helps and is correct
 
        
                    
             
        
        
        
Answer:
2)
Explanation:
The positive control is the treatment where bacteria grew without lead. Since positive control indicates the presence of bacteria in the experimental conditions, it is possible to confirm that they only death in presence of this metal. However, it is important to note that it is imperative to repeat this experiment three times and also to include a negative control in order to confirm these results.