The correct answer is electrons.  
Electron transport chain refers to an array of complexes, which mediates electrons from electron donors to electron acceptors through redox reactions, and combines the transfer of electrons with the transfer of protons through a membrane.  
This produces an electrochemical proton gradient, which instigates the production of ATP. The ultimate electron acceptor in the electron transport chain is oxygen in aerobic respiration and sulfate in anaerobic respiration.  
 
        
             
        
        
        
Answer:
Phenotypic ratio= 1 Brown : 1 Gray
Explanation:
Genotype of brown snake= BB
genotype of gray snake= Bb
A cross between brown (BB) and gray (Bb) snake obtains progeny in following phenotypic ratio= 1 Brown : 1 Gray
Here, the heterozygous parent, gray snake (Bb) forms two types of gametes in 1:1 ratio while the homozygous dominant parent, brown snake (BB) forms only one type of gamete. 
 
        
             
        
        
        
A The observed differences in plants height are due to genetics.
        
                    
             
        
        
        
Answer:
Volcanic degassing of volatiles, including water vapour, occurred during the early stages of crustal formation and gave rise to the atmosphere. When the surface of Earth had cooled to below 100 °C (212 °F), the hot water vapour in the atmosphere would have condensed to form the early oceans.
Explanation:
 
        
             
        
        
        
Since chloroplast use energy to make food for plant cells (Photosynthesis) I could compare it to lunch money, and how you have to keep refilling up, and up, just to use it again for food, for yourself.