B4a Leaves

Epidermis

No chloroplasts

Secretes wax to protect leaf and stop from drying out (wax - Cuticle)

Stomata and guard cells

Thin layer of cells that completely covers the leaf, top and bottom

Mesophyll layer

Palisade layer

Tall and thin, stacked close together.

Contain lots of chloroplasts

Spongey layer

Contains cells with some chloroplasts

Big air spaces between cells for reactions

Veins

Veins lie between palisade and spongey layer

xylem vessels

Dead cells carry water up plant by cappilary action

Phloum tubes

Living cells carry sucrose down plant by diffusion

Stomata and guard cells

Pores between some cells in lower epidermis

Each stomata surounded by two guard cells, which open or close stomata

Leaves are broad, so more sunlight absorbed by chloroplasts

Thin, so sunlight reaches most cells in the mesophyll - also, less distanced for diffusion

Chloroplasts absorb sunlight

Network of veins transport water to leaf and sucrose around plant. Veins also support leaf

Stomata allow gas exchange to take place. When leaf is photosynthesising, CO2 diffuses in and Os out

Transparent epidermis allows most light through to palisade layer

Air spaces in spongy layer allow diffusion af gasses