Glucagon. It stimulates the liver to convert stored glycogen to glucose.
        
             
        
        
        
The following are the environmental factors that can damage genes that code for these enzymes. radiation from sun, various chemicals and x-rays. these agents are referred to as environmental mutagens. they result to changes in the genetic make up of the organism and in  turn affect the production of enzymes. enzymes are protein in nature and once the DNA has been compromised their production is affected. in most cases mutated DNA produces enzymes with lost or abnormal function. 
        
                    
             
        
        
        
The natural succession of a small farm pond will tend to make the pond more likely to freeze solid in winter time,the nature of things helps them to merge more quickly and adapt to their environment.