Across
- 3. Presence of harmful substances in the environment.
- 6. Ability to do work.
- 7. Teaching-learning process.
- 10. Surface layer of the Earth where plants grow.
- 11. Transformation or modification of something.
- 12. Property that distinguishes living beings from non-living ones.
- 13. Essential substance for life.
- 14. Mixture of gases that we breathe.
Down
- 1. Time to come.
- 2. Transform used materials into new products.
- 4. Large area covered by trees.
- 5. Set of all living beings and the physical environment in which they live.
- 6. Science that studies the relationships between living beings and their environment.
- 8. Large expanses of salt water that cover most of the Earth.
- 9. State of complete physical, mental and social well-being.