Answer: 
Cells that need to perform high amounts of work, such as muscle cells in the heart and legs, fat cells and liver cells. Mitochondria are organelles which contain their own DNA. Animal cells generally have approximately 1,000 to 2,000 mitochondria.
Explanation:
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C the earth because that is the only planet around so he thought that the sun and everything else rotated around us.
        
                    
             
        
        
        
A substance that provides nourishment essential for the maintenance of life and for growth.
If you do not gain enough nutrients, a nutritional deficiency occurs (when the body doesn't absorb or get from food the necessary amount of a nutrient). Deficiencies can lead to a variety of health problems. These can include digestion problems, skin disorders, stunted or defective bone growth, and even dementia.
 
        
                    
             
        
        
        
the electron transport chain is responsible for generating the most ATP within cellular respiration. The electron transport chain is responsible for generating the most ATP within cellular respiration. This answer has been confirmed as correct and helpful.