Answer:
<em><u>D. Cytoskeleton</u></em>
Explanation:
It is really none of these answers. The correct answer would be a microtubule which is a component of the cytoskeleton which is in the cytoplasm. 
The Cell Walls are only in plant cells so that won't work.  So, A wouldn't work.
Chromosomes are the things that both your parents give you as genes. They have nothing to do with keeping the structure of the cell alright.
Cytoplasm cannot be a answer choice because, the thing is in it but, it doesn't do anything with it. So C wouldn't work either
The correct answer is microtubule however, it is a component of cytoskeleton so therefore, that is your answer.
<em><u>Reference the picture below:</u></em>
 
        
             
        
        
        
Answer:
I think its the third one :)
Explanation:
hope this helped :))
 
        
             
        
        
        
The diffusion of water through a cell membrane to reach dynamic equilibrium.
        
                    
             
        
        
        
Answer:
Oxygen
Explanation:
Oxygen is the by product of photolysis during photosynthesis whereby water molecules are split to form protons (H+ ions), electrons and oxygen (by product). 
Oxygen is not needed during any of the reactions in photosynthesis and Calvin cycle and will not affect the rate of photosynthesis or possibility of photosynthesis occurring. However, it will affect the process of aerobic respiration instead. 
Carbon dioxide is needed in carbon fixation during the Calvin cycle. Without it, 6 carbon sugars cannot be formed. 
Water is needed for photolysis to produce protons (maintain the electrochemical gradient) and electrons (to replenish lost electrons)
Chlorophyll are pigments that harvest light energy to excite electrons produced from photolysis of water to be passed down the electron transport chain. 
Light is needed as a source of energy to energise the electrons