6.2 leaf structure

• most leaves have a large surface area and are thin
• large surface area because...

  it helps allow more diffusion of CO2 & more absorption of light for photosynthesis
• thin because...

  it allows faster diffusion of CO2 to palisade mesophyll cells
• chloroplasts - contain chrolophyll that absorbs light enegy for photosynthesis
• cuticle - is waxy but thin, so it protects the leaf from water loss without blocking sunlight
• guard cell & stomata - guard cells open & close the stomata to control and allow CO2 to diffuse into leaf and O2 to diffuse out
• upper epirdemis - thin & transparent so it allows more light to reach palisade cells
• palisade mesophyll - on top of leaf so the chloroplasts in the cells are able to absorb more light
• spongy mesophyll w/ air spaces - air spaces allow CO2 to easily diffuse through the leaf
• xylem vessels - bring water & minerals to the leaf
• phloem vessels - transport sugars & amino acids away from the leaf to the rest of the plant
• stomata is only in the lower epirdemis to reduce rate of water loss
• pathway of CO2 from atmosphere to chloroplasts by diffusion:

  atmosphere > air spaces around spongy mesophyll > leaf mesophyll cells > chloroplast