Across
- 4. Determines the condition of life
- 7. They are part of the animal kingdom
- 9. They are essential for life
Down
- 1. They are complex creatures
- 2. An essential substance in life
- 3. Provides the necessary oxygen
- 5. It is the interaction of living beings
- 6. It sustains life on earth
- 8. They play a fundamental role