Testing leaves for starch is an experiment that is usually performed in school science laboratories, by pupils grade 7-9. It is a simple experiment that works well in the summer but can be disappointing in the winter months when leaves make little starch. Variations include testing leaves destarched by lack of light, lack of carbon dioxide, or lack of chlorophyll (by using a variegated leaf). Starch is a complex carbohydrate which is insoluble in water. ... Chlorophyll is a green photosynthetic pigment found in plants, algae, and cyanobacteria. ...

Introduction

Leaves come in different shapes, sizes, colours, thicknesses and different types. The plant where the leaf is usually obtained is a geranium. Geranium can be: The genus Geranium of flowering plants, usually called the cranesbills Any of the garden plants called geraniums, which are members of the related genus Pelargonium. ...

Photosynthesis happens in the mesophyll cells of leaves. The mesophyll cells contain tiny bodies called chloroplasts, which contain chlorophyll, which is used to catch the light energy needed in photosynthesis. Glucose can be converted into starch and stored. Both starch and sucrose can be turned back into glucose and used in respiration. Most plants store starch. They can turn starch back into glucose when they need it for respiration. Leaf. ... Chloroplasts are organelles found in plant cells and eukaryotic algae which conduct photosynthesis. ... A space-filling model of glucose Glucose, a simple monosaccharide sugar, is one of the most important carbohydrates and is used as a source of energy in animals and plants. ... Respiration can refer to: Cellular respiration, which is the use of oxygen in the metabolism of organic molecules. ...

Aim

The aim of the experiment is to see if a green leaf that had been left in the dark for 48 hours would have starch.

Hypothesis

The prediction is that the green leaf will have starch present.The leaf will turn brown/black if starch is present.

Equipment

• Beaker
• Test tube
• Water
• cold water
• Ethanol
• Gauze
• White tile
• Tripod
• Iodine solution
• Bunsen burner
• Safety Goggles
• Heatproof mat
• Leaves
  • one that has been in light for 48 hours
  • one that has had no light for 48 hours

Illustration of a Beaker A beaker is a type of laboratory glassware which consists of a cylindrical cup with a notch on the top to allow for the pouring of liquids. ... A test tube (Sometimes culture tube) is a kind of laboratory glassware, composed of a fingerlike length of glass tubing, open at the top, sometimes with a rounded lip at the top, and a rounded U shaped bottom. ... Ethanol, also known as ethyl alcohol or grain alcohol, is a flammable, colorless chemical compound, one of the alcohols that is most often found in alcoholic beverages. ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ... A bunsen burner with needle valve. ...

Safety procedures

• Wear safety goggles
• Keep ethanol away from Bunsen burner; ethanol is flammable
• Tie Hair back
• Tuck ties,flies and loose material away

Watersport goggles Blowtorching goggles and safety helmet Goggles are a form of protective eyewear that usually enclose the eye area to prevent particulates or chemicals from striking the eyes. ... Flammable or Flammability refers to the ease at which a substance will ignite, causing fire or combustion. ...

Method

1. Set up the equipment.
2. Light the bunsen and boil the water. When the water had boiled add the first geranium leaf (the one that had been the light for 48 hours).
3. Wait one minute for the leaf to boil (this is to get rid of the waterproof layer and break the open cells and make it soft).
4. Turn off the Bunsen burner (for safety reasons, we are going to use ethanol), and take out the leaf.
5. Put the leaf in a boiling tube and cover with ethanol.
6. Put the tube of ethanol plus leaf into the beaker of hot water. Ethanol boiles at 80° so it should come to boil even though the bunsen is off.
7. Dip it back into the hot water so it can get the ethanol off.
8. Spread the leaf out on a tile. Add about five drops of iodine on to the leaf and observe. After about two minutes the iodine had soaked in.
9. Repeat using a leaf that had been in the dark for 48 hours.

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