Pop quiz

Megan called me today. She pesters Marie to answer questions about the body. Marie does really well, but Meg always follows up with the question "Why?". I told Marie she could call me anytime she wants and I will answer those questions. She finally took me up on the offer.

Today it went like this:
"Mom, why do we need to breathe?"
"Because we need oxygen in our blood.
"Why?"
"It carries the oxygen to our cells and they need it."
"Why?"
"I don't know. Your aunt Miriam would."
"Let's call her."
"She might be teaching right now."
"Let's call her and see."
"Okay."

So she called.

On the phone:

"Aunt Miriam, why do we need to breathe?"
(My heart melted right then.)
"Welllll, when our cells are making energy that they can use, they make a lot of electrons and we need oxygen to accept those electrons and then the oxygen gets turned into water and it makes us have to go potty. And the other reason is that when our cells are making energy that they can use, they produce carbon dioxide and we have to breathe that out."
"And that's why we have to breathe?"
"Yes?"
"Okay, bye!"

Now I am all worried that I told her something wrong and I think I had better freshen up on glycolysis and electron transport because it has been 13 years since I have studied it.