Hi!!
So Rosa eats a peanut butter sandwich, which gives her protein and starch, right? She also goes on a run and breathes normally, which gives her a good amount of oxygen. Based on this, we can conclude...
1. Cells need the protein and starch to make energy.
A cell uses proteins to keep itself alive and functioning. Because the proteins keep the cell working, the cell can change the starch into sugars, which in turn becomes food for the cells. The sugar is used to keep Rosa running.
2. The cell also needs oxygen.
The cell gets oxygen through the bloodstream. When Rosa breathes well, she is making sure that she is providing her body with enough oxygen to run.
Rosa's body systems give the cells protein, starch, and oxygen, which allows the cells to function. This, in turn, allows Rosa to run and play without worry.
I really hope this helps!!