DNA ligase is an enzyme that repairs irregularities or breaks in the backbone of double-stranded DNA molecules. It has important role in the process of DNA replication and DNA repair. It has three general functions: It seals repairs in the DNA, it seals recombination fragments, and it connects Okazaki fragments (small DNA fragments formed during the replication of double-stranded DNA). DNA ligase functions by forming a bond between the end of a “donor” nucleotide and the end of an “acceptor” nucleotide.
        
                    
             
        
        
        
Answer:
How traits/characters were passed down and inherited from parents to offspring.
 
        
             
        
        
        
Answer:
Dopamine.
Explanation:
Cocaine is used as a recreational drug and addictive in nature. It can be smelled or directly inhaled in the veins. This drug causes the feeling of restless and happiness. 
The dopamine is the important neurotransmitters that regulates the mood and other biological activity of the body. The cocaine inhibit the reuptake of dopamine and leads to its accumulation in the brain. This might also break the blood brain barrier.
Thus, the answer is dopamine.