Boiled Leaf LabBoiled Leaf Lab

Preparation:Preparation:

Cut 2 one inch square pieces of thick Cut 2 one inch square pieces of thick cardboard (like cereal box)cardboard (like cereal box)

Clip the two pieces of cardboard to a leaf Clip the two pieces of cardboard to a leaf still growing and attached to a plantstill growing and attached to a plant

Label your squaresLabel your squares Write down a prediction about what you Write down a prediction about what you

will find under the cardboard squareswill find under the cardboard squares Sketch the leaf with the cardboard on itSketch the leaf with the cardboard on it

Put Label on paperPut Label on paper PredictionPrediction

1 2

3 4

5

SketchingSketching

LabelsLabels Size/ScaleSize/Scale Details – shadingDetails – shading ViewView

TopTop BottomBottom sideside

A day or two laterA day or two later

Prediction:Prediction: Sketch the leaf (1)-Label “Before”Sketch the leaf (1)-Label “Before”

Take off the cardboardTake off the cardboard Sketch the leaf noting any color changes Sketch the leaf noting any color changes

(2) – Label “After”(2) – Label “After”

Saga continues…Saga continues… Boil the leaf in water for 5 minutesBoil the leaf in water for 5 minutes Sketch the leaf noting any color changes (3) – Sketch the leaf noting any color changes (3) –

Label “Boiling Water”Label “Boiling Water” Note the change of color in the waterNote the change of color in the water

Boil in alcohol for 5 minutes MUST WEAR Boil in alcohol for 5 minutes MUST WEAR GOGGLES! AVOID INHALATION!GOGGLES! AVOID INHALATION!

Sketch leaf noting any color changes (4) – Label Sketch leaf noting any color changes (4) – Label “Boiling Alcohol”“Boiling Alcohol”

Lastly…Lastly…

Place iodine on the leafPlace iodine on the leaf Sketch the leaf noting changes in color Sketch the leaf noting changes in color

(5) Iodine(5) Iodine

How does the leaf compare to the original How does the leaf compare to the original leaf and cardboard and why?leaf and cardboard and why?

Results – Picture 2Results – Picture 2

What did it look like when you took the What did it look like when you took the shape off?shape off?

Should still be greenShould still be green Is it still alive?Is it still alive? Yes – chlorophyll still presentYes – chlorophyll still present

After boiling in Water (3)After boiling in Water (3)

Color change?Color change? Green to drab greenGreen to drab green Purpose: Break down cell walls – Purpose: Break down cell walls –

cellulose – paper – gets soft if you boil itcellulose – paper – gets soft if you boil it Water – yellowish-greenWater – yellowish-green

After boiling in alcohol After boiling in alcohol (4)(4)

Color? Texture?Color? Texture? Yellow and a bit crispyYellow and a bit crispy Liquid?Liquid? Green – removed the chlorophyllGreen – removed the chlorophyll Is chlorophyll soluble in water? Is chlorophyll soluble in water? No – if it were water and rain would wash No – if it were water and rain would wash

the chlorophyll awaythe chlorophyll away

After Iodine (5)After Iodine (5)

Iodine reacts with starch to turn Iodine reacts with starch to turn black/dark blueblack/dark blue

Where was the starch? How come?Where was the starch? How come? Shape – burns glucose – then starch Shape – burns glucose – then starch

(polymer made of glucose) – imports (polymer made of glucose) – imports glucose glucose

Roots and BarkRoots and Bark

Class of 09 leafClass of 09 leaf

Why do leaves change Why do leaves change color in the fall?color in the fall?

What triggers the leaf to What triggers the leaf to stop photosynthesis? stop photosynthesis?

Amount of sun lightAmount of sun light Shuts down photosynthesisShuts down photosynthesis Chlorophyll breaks downChlorophyll breaks down See what is leftSee what is left

Why do leaves drop off?Why do leaves drop off?

sunlight decreases -the veins that carry sap sunlight decreases -the veins that carry sap into and out of a leaf gradually close. into and out of a leaf gradually close.

A layer of cells, A layer of cells, separation layerseparation layer, forms at the , forms at the base of the leaf stem. base of the leaf stem.

When this layer is complete, the leaf is When this layer is complete, the leaf is separated from the tissue that connected it to separated from the tissue that connected it to the branch, and it falls. the branch, and it falls.

Oak leaves are the exception. The separation Oak leaves are the exception. The separation layer never fully detaches the dead oak leaves, layer never fully detaches the dead oak leaves, and they remain on the tree through winter.and they remain on the tree through winter.