Across
- 3. The swapping of gases like oxygen and carbon dioxide.
- 4. When living things turn food into energy, usually using oxygen.
- 5. A substance that triggers an immune response in the body.
- 8. The part of a plant cell where photosynthesis happens.
- 10. A protein that speeds up chemical reactions in living things.
- 11. A substance that helps your body build immunity to a disease.
- 13. A germ, like a virus or bacteria, that causes disease.
Down
- 1. A process where a system's output affects its input.
- 2. The main energy currency of the cell.
- 3. Cells around stomata on leaves that control gas exchange.
- 6. A simple sugar that living things use for energy.
- 7. How plants use sunlight to make food from water and carbon dioxide.
- 9. Keeping a stable internal balance in a living organism.
- 12. A protein made by the immune system to fight off antigens.