Answer:
The  matrix  is the innermost compartment of a mitochondrion
. Here, the  
the Krebs cycle  occur(s), breaking down  pyruvic  acid into carbon dioxide in a series of reactions.
Explanation:
 
        
             
        
        
        
I'm not sure if this is exactly correct, but to complete photosynthesis, plants need carbon dioxide and water. Usually sunlight as well. If you are supposed to be specific, you could put H2O. I hope I answered your question!
        
                    
             
        
        
        
Energy flows through an ecosystem and cannot be recycled. 
        
             
        
        
        
Boys need 2,400 to 3,200 a day, while girls need 1,800 to 2,400 a day.
Hope this helps!