How does water enter the plant and get into the leaves?

water passes by osmosis from the inner cell similarly the water passes from the inner cell to the cortex. this transfer process continues till water enter xylem vessel and travels up the plants.

how does co2 enter the leaf?

co2 diffuses through small holes in the under side of the leaf called stomata.

where does photosynthesis occur in the plant?

takes place inside plant cells in small things called chloroplasts

What are the final products of photosynthesis and how are they important to life on thes planet?

glucose and oxygen. Both ingredients called celleur respiration to make energy.