leaf structure

• carbon dioxide enters the leaf through the stomata
• water and oxygen exits the leaf through the stomata
• the waxy cuticle prevents uncontrolled water loss as it is waterproof
• palisade cells have lots of chloroplasts near the top end to trap as much light as possible
• the cells of the spongy mesophyll layer are not tightly packed together for efficient gas exchange
• guard cells open and close the stomata
• the xylem vessels transport water and dissolved mineral ions from the roots to the leaves
• the phloem vessels transport sugars produced in photosynthesis to the rest of the plant
• the waxy cuticle prevents water loss and allows light through
• the upper epidermis is a narrow layer with few chloroplasts and sunlight passes directly through
• the palisade mesophyll has many chloroplasts, so most photosynthesis occurs here
• the spongy mesophyll contains some chloroplasts and the walls are saturated with water
• the lower epidermis is a thin layer with few chloroplasts and many stomata and guard cells
• air spaces are where gases diffuse freely eg oxygen, carbon dioxide, water vapour
• the guard cells open or close the stomatal pore
• the phloem take soluble food from the leaf to where it is needed
• the xylem brings water and dissolved minerals to the leaf from the root
• stomata are mainly on the lower surface and they allow gases to diffuse in and out