Answer:
ACROSS
1. sugar
4. carbon cycle
8. stomata
11. leaves
13. photosynthesis (!)
15. carbon dioxide
17. ATP
18. thylakoid
19. green (that's why leaves appear green!)
DOWN
1. stroma
2. herbivore
3. photophosphorylation
5. carotenoids
6. grana
7. water
9. oxygen
10. chlorophyll
11. light
12. food chain
14. six
16. dark
THESE ARE ALL RIGHT. I GOT AN A. HAVE FUN CHEATING(;