Guillermo was finding it difficult to walk up the steps to his family’s apartment. His doctor thinks that his cells might not be getting enough oxygen or glucose.

Why does having low levels of glucose or oxygen in his cells make it difficult for
Guillermo to walk up steps?

Which body systems should the doctor test in order
to find out whether Guillermo’s cells are getting enough oxygen and glucose
and why?

How do Rosa's body systems work together to get the molecules she needs into her cells? How do hair cells use these molecules to release energy for her body to run?