The short answer is that cells respond to the chemical environment in which they find themselves. The cells around them, the specific conditions, and feedback from the environment all create specific chemical cues that inform the cells to which genes should be expressed, and in what amounts. Chemicals include hormones, cytokines, general signaling molecules, such as cAMP, etc.
i literally hopped on google for this, lol.
i hope this helps though. :)
        
             
        
        
        
hey the answer polytechnic traits my friend :)   
        
             
        
        
        
Answer:
I think it is the variable.
Explanation:
 
        
                    
             
        
        
        
The following are the statements that accurately demonstrate the electron transport chain:
1. The electron transfer in the electron transport chain is combined with the proton transfer from the matrix to the intermembrane space.
2. The prosthetic groups, like Fe-S centers, directly take part in the transfer of electrons.
3. The electron carriers in the electron transport chain comprise cytochrome C and ubiquinone (coenzyme Q).
4. The electron carriers are arranged into four complexes of prosthetic groups and proteins.
5. The reactions of the electron transport chain occur in the inner membrane of mitochondria.