Across
- 3. How do humans influence the carbon cycle
- 4. A common source of carbon
- 6. How many electrons do carbons have
- 9. What humans breath out
- 10. A type of fuel that releases CO2
Down
- 1. How plants make oxygen
- 2. How plants and animals get rid of CO2
- 5. What plants make when they take in carbon
- 7. How does carbon get to humans
- 8. What plants and animals are made of