Measuring photosynthesis via the production of oxygen. Oxygen can be measured by counting bubbles evolved from pondweed, or by using the Audus apparatus to measure the amount of gas evolved over a period of time.
 
        
             
        
        
        
Answer:
the two reactants of cellular respiration are oxygen and glucose.
 
        
             
        
        
        
the correct answer is the first one. density = mass / volume.
i hope this helped!
 
        
             
        
        
        
1) Chloroplast 
 -converts solar energy into food for the plant. 
2) Cell Wall 
 -provides protection and structure.