The structure of a leaf
The leaves are the organ for photosynthesis. It is where photosynthesis takes place. The structures of leaves are adapted for efficient photosynthesis as shown in the table below.
|Large surface area||Most leaves are broad and so have a large surface area allowing them to absorb more light.|
|A thin shape||A thin shape means a short distance for carbon dioxide to diffuse in and oxygen to diffuse out easily.|
|Chlorophyll||This chemical gives the leaves their green colour and transfers light energy to chemical energy.|
|Veins||Networks of veins support the structure of the leaf and transport substances to and from the cells in the leaf.|
|Stomata||These are small holes on the underside of the leaf that allow gases to diffuse in and out.|
The cellular structure of a leaf
|Layer & Adaptation||Function|
|The cuticle is a waxy, waterproof layer which cuts down the water lost by evaporation and protects against parasitic fungi.|
|A single layer of cells that are transparent and contain no chloroplast allowing light to pass straight through.|
|This layer is made up of palisade cells which contain chloroplasts. This is where most of the photosynthesis takes place.|
|Vein:||The vein contains tubes called the xylem and phloem. The xylem brings water and salts to the leaf for photosynthesis. The phloem transports the dissolved foods away.|
Irregularly shaped cells with air spaces between them.
|This layer consists of irregularly shaped cells with large air spaces between them allowing gas exchange (diffusion) between stomata and photosynthesising cells.|
Contains lots of tiny holes.
|This layer contains lots of tiny holes or pores called stomata at regular intervals. These allow gases to diffuse in and out of the leaf.|