Adaptations in Leaf structure for photosynthesis:

The external and internal structure of the leaf is well adapted to its function i.e. photosynthesis. The leaves on the branches of plants are arranged in such a manner that they get maximum sunlight for photosynthesis. Similarly, the majority of the leaves are flat with a maximum surface area for maximum absorption of the fallen light.

The function of the Cuticle:

The upper surface of the leaves called the epidermis is thin and is composed of a single-cell layer. It is covered by a layer of cuticle, which lessens the evaporation of water from the surface.

The function of Stomata:

The epidermis contains tiny pores known as stomata through which the exchange of gases between leaf cells and the environment occurs.

The function of Mesophyll Cells:

Inside the thin epidermis, specialized photosynthetic cells of leaves, called mesophyll cells, are present. The upper layers of mesophyll cells are compact and are called palisade mesophyll while the lower layer, called spongy mesophyll, contains many air spaces among its cells.

Passage of Air through Leaf:

Air enters the leaf through stomata and diffuses into the air spaces in the leaf. The carbon dioxide present in the air first gets dissolved in the thin watery layer over the mesophyll cells and then diffuses into the cells. Mesophyll cells contain chloroplasts which are the chief organelles concerned with photosynthesis. In higher plants, leaves also contain vascular (xylem and phloem) supply. Xylem vessels transport water and salts to the leaves while phloem vessels transport food from leaves to other parts.