Answer:
Because oxygen is the combustion  fuel and glucose  is the substrate needed for synthesis of energy as ATPs during cellular respiration.Therefore Guillermo lacks enough energy as ATPs in her  body cells, especially skeletal muscles cells to complete the task of ascending the s steps.
For all the mitochondrial in cells(sites of energy production)   to receive needed glucose,and other metabolites needed for  energy synthesis; an efficient transport system is needed, so that  these materials   are available  immediately, in required amount. This system is called circulatory system.
And for the the supply of combustion fuel (oxygen) needed for the completion of the ATP synthesis mechanisms;  respiratory systems which  convey oxygen from the external environments to the circulatory system through breathing mechanisms, for distribution is needed.
Thus the  doctor needs to test both the circulatory and respiratory systems.
Explanation:
 
        
             
        
        
        
Everything on Earth can be easily described in terms of one of four forms of matter: solid, liquid, gas, and plasma. Students are familiar with the three common forms of matter: solids, liquids, and gases. A solid is an object that has a form.
plz mark me as brainliest if this helped :)
 
        
                    
             
        
        
        
How do cells get ATP through Cellular Respiration. 
Cellular respiration takes place in the mitochondria. The Mitochondria use oxygen (O2) to convert broken-down glucose (at type of sugar) into carbon dioxide (CO2) and water (H2O).
The reactants of CR are oxygen and glucose.
The products of CR are ATP, carbon dioxide, and water.
        
             
        
        
        
The first statement (Matter is neither created nor destroyed) is correct.
The second statement would violate the law of conservation of mass (I will refer to this as LCM), as it would mean matter can "flow" into the universe, but not out, meaning the total matter will never be less than it was before.
The third statement violates LCM because it means matter is created during a reaction, which is not true.
The last statement violates LCM because it means matter is lost during a reaction, which is not true.