B1.4.2 - Photosynthesis Experiments Flashcards
What can testing for starch prove?
That light, chlorophyll and carbon dioxide are essential for photosynthesis
What are the steps for testing for starch?
Get a leaf and use forceps to put it into a beaker of boiling water.
Then take the leaf and put it into a test tube with boiling ethanol.
Then wash the leaf with water and spread it out on a white tile.
Add a few drops of iodine solution, and the leaf should change colour.
Why should you use forceps to place the leaf into the boiling water?
So you don’t accidentally burn yourself.
Why do you need to place the leaf into the boiling water?
To kill it
Why do you need to place the leaf into boiling ethanol?
So the chlorophyll is removed
Why do you need to wash the leaf?
So you can remove the ethanol and soften it
What is iodine solution made of?
A mixture of iodine and potassium iodide
What colour should the leaf turn if starch is present?
Blue - black
What is a variegated leaf?
It is only coloured green in some areas
How can you prove chlorophyll is needed for photosynthesis?
Place a destarched variegated plant in sunlight for several hours. Then, test one of the leaves for starch.
Why do you need to destarch a plant before carrying out photosynthesis experiments?
So the starch can start from nothing
How can you destarch a plant?
You place it in total darkness for 24 hours
How can you prove light is needed for photosynthesis?
Get a destarched plant and cover one of its leaves with black card. Light can’t reach the area of this leaf. Place the plant in sunlight. Then, test the starch in the leaf.
How can you prove carbon dioxide is needed for photosynthesis?
Take a destarched bag and place it in a polythene bag. Before you seal the bag add a pot of soda lime. Place it in sunlight, and then test it for starch
What is soda lime?
A chemical that absorbs carbon dioxide and water
