I) As storage form in leaf cells: Starch

Here's the breakdown of the photosynthesis question:

a)

i) As storage form in leaf cells: Starch

ii) To make plant cell walls: Cellulose

b)

i) Name one of these materials: Sucrose

ii) Describe transport of the material named in (b)(i) from the leaves to the roots.
The sucrose is transported through the phloem vessels. It is actively loaded into the sieve tubes in the leaves, creating a high solute concentration. Water then moves into the phloem by osmosis, building up pressure. This pressure drives the mass flow of the sucrose solution down to the roots, where it is unloaded.