General questions on photosynthesis

What does a plant need to photosynthesise?

Why would a plant need a healthy root system to photosynthesise?

When and why would plants carry out the reversal of photosynthesis.

Why is clearing large amounts of forest areas worrying scientists?

Why do plants look green?

In which direction does the water in the xylem travel?

Where in the cells does photosynthesis occur?

Why is excess sugar often stored as starch and not simple sugar?

Why are leaves often arranged so they do not shade each other?

What substances are made with photosynthesis?