Across
- 3. If a person studies _____ then he studies DNA.
- 5. ______ change isn't always caused by humans.
- 7. Garbage _______ the sea and kills animals.
- 8. _______ means different things.
- 9. _______ means when a species no longer exists.
- 10. ______ gases pollute the air.
- 11. ______ is plants, living forms and all kinds of things natural.
- 12. Global warming can ______ the ozone layer.
Down
- 1. ______ that grow give us more oxygen in the world.
- 2. _____ means life.
- 4. Humans are ______ every day, every second.
- 6. The place that surrounds you is called the _______.