2 questions in 1: jimmy is running laps during his physical education class. As he is running, he starts to breathe harder as his body tries to get more oxygen. Which of the following best explains why Jimmy’s oxygen requirement increases?

1. His cells use oxygen as their primary source of energy.
2.His cells need oxygen to help break down sugars for energy.
3.His cells need oxygen to increase the levels of sugars in the blood.
4.His cells use oxygen to transport substances across their cell membranes

One of your cells has taken in a sugar molecule from a cookie you ate at lunch. The sugar molecule contains atoms of carbon. Which best explains what will happen to the carbon after your body processes it? *

1.It is recycled by the body to create CO₂ which will be stored for later use.
2.It is destroyed as the body breaks it down to use for energy.
3.It is returned to the environment through CO₂ or the decay of organic matter.
4.It is transformed into sugars which will be broken down and used for energy by the body.