Biology 4

Leaves are desiged for making food by photosynthesis.

Layer of the leaf structure

1. Waxy cuticle 2. upper epidermis 2. palisade mesophyll layer (middle layer) with chloroplast 4.spongy mesophyll layer with vein with air space 5. lower epidermis with waxy cuticle and guard cells the stoma is found at the bottom 

Leaves are broad- large surface area- exposed to more light

thin structure so CO2 + water can travel a short distance

air spaces in the spongy layer help CO2 + O2 pass easily (internal surface area to volume ratio)

Leaves-chlorophyll-pigment that absorbs light-energy for photosynthesis - found in pallaside layer 

upper epidermis-transparet-light pass through- pallaside layer

lower epidermis-holes-stoma-CO2 +O2 through - water to escape- called transpiration

veins-help leaf structure-delievers water + nutrients- take food away from leaf

Leaf palisade cells designed for photosynthesis - tall shape- surface area exposed down for absorbing CO2 - good chance of hitting light 

Plants exchange gases by diffusion

plant photosynthesise- use CO2- from atmosphere- produce O2- during respiration plants se O2 ad produce CO2 as a product- called diffusio

DIFFUSION IS THE PASSIVE MOVEMENT OF PARTICLES FROM A HIGH CONCENTRATED AREA TO A LOW CONCENTRATED AREA