B1.4.2 - Photosynthesis Experiments Flashcards Preview

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Flashcards in B1.4.2 - Photosynthesis Experiments Deck (16):

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


How can you prove oxygen is given off during photosynthesis?

Place an upturned test tube above an aquatic plant. Put the apparatus in light for maximum photosynthesis.
Once you have collected a full tube of gas, place a glowing splint inside the tube. It will relight because of the oxygen present.