Across
- 4. - Instrument for viewing objects too small for the naked eye
- 6. - Nerve cell transmitting electrical signals
- 9. - Process by which plants convert sunlight into energy
- 11. - Molecule containing genetic instructions
- 12. - Variety of life forms in a given area
- 13. - Basic unit of matter
- 16. - Process of species change over time
- 18. - Change in the DNA sequence
- 20. - Controlled procedure to test a hypothesis
Down
- 1. - Large systems of stars, gas, and dust
- 2. - Proposed explanation based on limited evidence
- 3. - Nuclear reaction combining atomic nuclei
- 5. - Transfer of heat through direct contact
- 7. - Force attracting objects to each other
- 8. - Substance with a distinct molecular composition
- 10. - Community of living organisms and their environment
- 14. - Physics theory describing subatomic particles
- 15. - Physicist famous for the theory of relativity
- 17. - Sun and all celestial objects orbiting it
- 19. - Substance composed of one type of atom