Across
- 2. blood vessels that return blood to the heart; have valves.
- 3. smallest blood vessels with one-cell-thick walls.
- 4. pores in plant leaves through which gases are exchanged.
- 5. Known as the "energy currency" of the cell.
- 8. Branches of trachea entering lungs
- 9. Tissue that moves water and minerals upward.
- 12. Tiny air sacs where gas exchange occurs.
- 13. acid causes muscle cramps when oxygen is lacking.
- 15. six-carbon molecule — starting point of respiration.
- 16. The liquid part of blood transporting CO2 and nutrients.
- 18. main artery carrying oxygenated blood from the heart.
- 20. Blood vessels carrying blood away from the heart
- 21. The protein in RBCs that carries oxygen.
Down
- 1. loss of water vapour from aerial parts of plants.
- 6. The end-product of glycolysis.
- 7. Cell fragments that help blood to clot.
- 10. Tissue that transports products of photosynthesis.
- 11. Lower chamber of heart
- 14. Respiration that happens without oxygen.
- 17. upper chamber of the heart
- 19. Organ where exchange of gases takes place in humans.