Photosynthesis is the process by which green plants make their food by tue help of sunlight and chlorophyll using carbondioxide and water to form oxygen and glucose 
cellular respiration-cellular respiration definition. The chemical process that generates most of the energy in the cell, supplying molecules needed to make the metabolic reactions of an organism run. Note: The main carrier of energy in metabolism is the molecule ATP.
 
        
        
        
Hey There!
Here is your answer:
Your answer is that a experiments should be controlled because the experiment could go out of control which could harm or hurt someone.
Also the definition of a controlled experiment is a part of the experiment that's not touched.
Ex: Water is your controlled experiment that's because our not doing anything to the water.
If you need anymore help just ask me!
Hope this helps!
        
             
        
        
        
Explanation:
To find the number of atoms in each specie, we consider the coefficient and the subscript of each of the given atoms. 
1. NaCl: 
Na  = 1 atom
Cl = 1 atom 
2. CO₂
C = 1 atom
O = 2 atom 
3. O₂ 
O = 2 atoms 
4. C₆H₁₂O₆ 
C = 6 atoms 
H = 12 atoms 
O = 6 atoms  
For the second part; 
1. 2NaCl 
Na = 2 atoms 
Cl = 2 atoms 
2. 3CO₂ 
C = 3 atoms 
O = 6 atoms 
3. 4O₂ 
O = 8 atoms 
4. 2C₆H₁₂O₆ 
C = 12 atoms 
H = 24 atoms 
O = 12 atoms
 
        
             
        
        
        
The experiment conducted by Paul was not a waste of his time and resources even though he could not accomplish the experiment he initially prepared to conduct. The reluctance of the penguins to eat burgers even though they were starving and losing weight pointed towards the fact that they do not find junk food appealing. It could be concluded from their reluctance that they will eat only their normal diet rather than something they have never eaten before.