6.2.2 Leaf Structure

Leaf Structure

• Identify and label the cuticle, cellular and tissue 

structure of a dicotyledonous leaf, as seen in 

cross-section under the light microscope, and 

describe the significance of these features in 

terms of functions, to include:

• distribution of chloroplasts – photosynthesis

• stomata and mesophyll cells – gas exchange

• vascular bundles (xylem and phloem) – transport 

and support

The cuticle prevents water loss via evaporation as it has a waxy layer which prevents water from getting too hot.

Chloroplasts (chlorophyll inside them) trap sunlight and carry out the process known as photosynthesis - more chloroplasts and enough raw materials and light to support them will mean a higher rate of photosynthesis 

Stomata open to allow gases to diffuse inside the plant leaf, the mesophyll cells all contain chloroplast and so C02 which has diffused into the leaf through the Stomata will eventually reach the Mesophyll cells and contribute to photosynthesis.

Xylem are involved in water uptake. There is always a lower pressure level at the top of the Xylem as a result of transpiration, this means that water is constantly moving up the Xylem tubing towards the leaves from the soil/root hair cells.

Phloem transport sucrose around the plant from places of production to sinks.