Given a scientific question, generate a correct answer to it.

Ex Input:
Would you find cells that contain a cell wall, a large central vacuole, and plastids in plant or animal cells?

Ex Output:
plant cells

Ex Input:
What model postulates that electrons orbit the nucleus at fixed energy levels?

Ex Output:
bohr

Ex Input:
When oxygen is not bound to heme and the partial pressure of oxygen is low, hemoglobin readily binds to what?

Ex Output:
carbon dioxide