Leaf organisation Flashcards
Layers of a leaf`starting from the bottom
Lower epidermis, spongy mesophyll, palisade mesophyll, upper epidermis, waxy cuticle.
Role of lower epidermis
CO2 taken in from stomata, contains guard cells to control water loss and co2 levels.
Role of spongy mesophyll
Has lots of gaps between cells, to allow co2 to diffuse to the palisade cells.
Role of Palisade mesophyll
This is where most photosynthesis happens, as there are lots of chloroplasts
Role of upper epidermis
They are almost transparent to allow sunlight through easily to palisade cells for photosynthesis
Role of waxy cuticle
It’s a thin layer of lipids that prevents water loss.
How is water loss reduced in a leaf?
The top reduces water loss by having a waxy cuticle on top of the leaf, that water can’t get through.
The bottom reduces water loss by having stomata open for as short as possible, to maximise Co2 absorption and minimise water loss.
What are guard cells
Guard cells surround stoma ,
They go turgid to allow Co2 to diffuse through by making gap bigger
They go flacid to conserve water vapour and reduce Co2 that can diffuse through
Why do guard cells close the stoma at night?
Because they are sensitive to light.
What happens once photosynthesis has occured in the leaf
Once sugar molecules are produced, They are transported to the rest of the plant through the phloem.
What does the Xylem contribute to photosynthesis?
The xylem brings water molecules to palisade cells for photosynthesis.
