Intake of carbon dioxide and water by plants for photosynthesis

Question 1

Explain the entry of carbon dioxide to the leaf

Answer 1

When photosynthesis occurs (In daylight), carbon dioxide in the leaf is rapidly used up. Carbon dioxide concentration in the leaf becomes lower than that in atmospheric air, thus a diffusion gradient exist
Carbon dioxide diffuses into the systems of air spaces in the leaf (Sub-stomatal air chamber).
The surface of the mesophyll cells are covered by a thin film of water, so that carbon dioxide dissolve into the plant

Question 2

Explain the entry of water and mineral salts to the leaf

Answer 2

Veins which contain xylem and phloem in the leaf (Form fine branches which end among the mesophyll cells)
Xylem vessel brings water and dissolved mineral salts to the leaf from the soil via roots.
Once out of the veins, water diffuses from cell to cell through the mesophyll of the leaf.
Sugars manufactured from photosynthesis are transported via the phloem sieve tube to all plant cells.