Sin título

Página 1

TESTING A LEAF FOR STARTCH

create a water bath- half fill a beaker with water set up tripod , gauze , bunzen burner + heatproof mat

heat water until it boils then remove the leaf from a plant place leaf in water and boil for 30 seconds .

heat leaf to remove the waxy cuticle.

turn Bunsen burne off because alcohol is flammable

take leaf out and place it in boiling tube

leaf is boiled in ethanol to remove colour

leave until leaf goes white

take leaf out and dip it into water in beaker to soften it and make it easier to spread

test leaf with a few drops of iodine and record colour change

conclusion - iodine changes from yellow brown to blue black .

adapted for light absorption

flat and thin to allow light to pass quickly

large surface area

cuticle - thin transparent layer prevents water loss

palsied mesophyll - packed full of chloroplast containing chlorophyll to help maximum light absorption