The mitochondria converts food into energy
        
             
        
        
        
I would say the scientific method?
        
                    
             
        
        
        
<span>Herbivores posses different digestive system than that of carnivores. In the course of evolution herbivory evolved with a complex digestive tract. There is no cannine teeth for herbivores. The stomach contains billions of bacteria. The intestine is 27 times longer in length than the length of its body.</span>
        
             
        
        
        
Your cardiovascular system is what moves blood through your body, delivering oxygen, nutrients, and more to its many cells. Those veins and arteries keep you alive. In your home, there are pipes that deliver water to different rooms of the house, helping you stay clean and hydrated.
        
                    
             
        
        
        
Nucleus, mitochondria, vacuole, cytoplasm, 
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