Well to begin with this process is called genetic engineering, the scientists altered the DNA of the chickens instead of altering a protein already in the chickens because when you alter the DNA the offsprings  of the chicken will will have the same qualities while if you only alter the protein already in that chicken only that chicken will be able to do the job 
        
             
        
        
        
Answer:
the complex of nerve tissues that controls the activities of the body. In vertebrates it comprises the brain and spinal cord.
Explanation:
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Answer:
A disease model is an animal or cells displaying of the pathological process that are observed in the actual human or animal disease.
 
        
                    
             
        
        
        
Answer:
Freedom of choice and action