2.21: Describe the Structure of the Leaf and Explain How it is Adapted for Photosynthesis

DIAGRAM OF LEAF STRUCTURE:

                                    

Diagram showing the Structure of a Leaf

STRUCTURE OF THE LEAF:

STRUCTURE	DESCRIPTION
WAX CUTICLE	Outermost protective layer that prevents Water loss via evaporation
UPPER EPIDERMIS	Thin and transparent layer of cells to allow light to enter Palisade Mesophyll
PALISADE MESOPHYLL	Layer tightly packed with Chloroplasts to maximise light absorption for Photosynthesis
SPONGY MESOPHYLL	Layer containing internal air spaces to increases surface area to volume ratio for the diffusion of gases (mainly Carbon Dioxide)
LOWER EPIDERMIS	Layer containing: Guard cells: cells that flank and control the opening and closing of Stomata by absorbing and losing Water to regulate gas exchange and prevent water loss (via transpiration) Stomata: mouth-shaped opening flanked and controlled by Guard cells to regulate gas exchange and prevent Water loss (via transpiration)

*ADAPTATIONS FOR PHOTOSYNTHESIS (FEATURES):

FEATURE	ADAPTATION
LARGE SURFACE AREA (LEAF)	Increases surface area to volume ratio (SA:V) for diffusion of Carbon Dioxide and absorption of light for Photosynthesis
THIN	Short diffusion length which increases the rate of diffusion of Carbon Dioxide into leaf cells, e.g Chloroplasts
CHLOROPHYLL	Tightly packed and present in large amounts in Palisade Mesophyll to maximise light absorption for Photosynthesis
NETWORK OF VEINS	Supports the leaf and transports Water for Photosynthesis and Transpiration (via Xylem), and Carbohydrates produced by Photosynthesis (via Phloem) from sources to sinks
STOMATA	Regulates gas exchange by allowing Carbon Dioxide to diffuse into the leaf for use in Photosynthesis, and Oxygen to diffuse out as waste product of Photosynthesis