Structure – Leaves Stem Roots Plants Structure – Leaves Stem Roots
Leaves
Function of leaves Trap light energy for photosynthesis Producing sugar from photosynthesis Exchange of gases – oxygen and carbon dioxide
Structure Helps to catch more light energy Wide Helps to catch more light energy Thin Help get carbon dioxide from bottom to top of leaf for photosynthesis
Leaf structure Greener on top CO2 gets in here
Leaf diagram – palisade layer Most chlorophyll CO2
Leaf cell - palisade Position? Upper surface of leaf Features? Box shape Chloroplasts Function? Photosynthesis
Gas exchange Leaves are designed to allow carbon dioxide to get to the main chlorophyll layer at the top of the leaf They have small holes called stomata on the under surface Each hole is open & closed by 2 guard cells
Leaf diagram – stoma and guard cells
Stoma position
Stoma is a small hole Its size is controlled by 2 guard cells closed open
Stoma function is for gas exchange in the leaf oxygen Guard cell Provided plant is photosynthesising Carbon dioxide
Stomata open and close at different times of the day When it is light the plant needs CO2 for photosynthesis so the stoma open At night (darkness) they close
Roots – function and structure Hold plant in position Absorb water and minerals from the soil Specialised cells to increase surface area for water intake
Wheat seed Root hairs Fragile parts of cells that grow from the main root They massively increase the surface area for absorption
Root hair cells (x150)
Root ‘B’ has had the hairs damaged -
Stem– function and structure Support of Leaf Display Support of Flower Display Support of Fruit Display Conduct water and minerals up from soil Conduct water and nutrients (sugar, amino acids) from leaf to rest of plant Photosynthesis (in some plants, eg. cacti) Storage of water, etc (cacti, underground stems (potato), swollen bases kohlrabi) Anchorage especially in vines
Differences in stem structure between monocots and dicots
Stem Tissues
Monocot Stem
Dicot Stem
Monocot Root
Dicot Root
Monocot Leaf
Dicot Leaf
Vascular Cambium Cork Cambium Area that produces xylem towards the inside of the vascular cambium and phloem towards the outside. Increases the thickness of the stem Cork Cambium Produces outer covering of stems (bark)