Humans cannot convert the sun's energy into glucose for themselves because humans lack <span>chlorophyll.</span>
        
                    
             
        
        
        
Answer
primary function of cell membrane is protecting organelles because cell membrane acts as a physical barrier allowing a very few molecules across it while fencing the majority of chemicals inside cell in this way it maintains the internal composition of cell and protect the organelles from the attack of bacteria and viruses
Explanation:
i hope this will help you:)
 
        
             
        
        
        
Diseases that can affect the circulatory system include:
Atherosclerosis. Atherosclerosis is a hardening of the arteries. ... 
Heart attack. ... 
Mitral valve prolapse. ... 
Mitral valve regurgitation. ... 
Mitral stenosis. ... 
Angina pectoris. ... 
Arrhythmia and dysrhythmia. ... 
Cardiac Ischemia.
        
             
        
        
        
As you talk in animals 
nucleus/ plasma membrane / mitochondria
if you talk in plants 
nucleus / the cell / plastid / mitochondria