Answer:
muscle cells in the legs of a marathon runner 
Explanation:
Mitochondria are the powerhouse of cells and serve as a site for the aerobic stage of cellular respiration. Cellular respiration is complete oxidation of nutrients in the presence of oxygen to produce a large number of ATP molecules. Therefore, the cells that require more ATP molecules as an energy source would most likely have a greater number of mitochondria.
Muscle cells are responsible for body movement. Muscle cells in the legs of a runner would require a constant supply of ATP during running since muscle contraction requires ATP. To sustain the continuous muscle contraction during the marathon, the muscle cells in the legs of the runner would have most number of mitochondria.  
 
        
             
        
        
        
If a person uses up his or her reserve supply of glycogen and still does not eat, sugar comes from the muscle.
Although only liver glycogen directly contributes to the release of glucose into circulation, maintaining a healthy blood glucose concentration is one of the glycogen's key functions. Since skeletal muscles lack glucose 6-phosphatase, they are unable to release glucose, and muscle glycogen primarily serves as a local energy source for activity rather than a source of fuel to keep blood glucose levels stable while fasting. 
In fact, the breakdown of muscle glycogen into lactate allows for its delivery to the liver, where it participates in the maintenance of euglycemia through the process of gluconeogenesis (Cori cycle). 
To learn more about glycogen click here
brainly.com/question/13082214
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Answer: i need this answer also 
Explanation:
 
        
             
        
        
        
Answer:
They teach you the purpose of condoms (or you learn the hard way.)
how to prevent stds
Explanation:
That's all I can think of.