Testing leaves

Read the information below about testing a leaf with iodine solution.
 

Put the leaf in boiling water for 30 seconds. Carefully remove the leaf from the water and put it into a boiling tube which contains methylated spirits. Heat the boiling tube in a water bath for 5 minutes. Then wash the leaf and spread it onto a petri dish. Add a few drops of iodine solution.

 
 
a) Draw a line from each step of testing a leaf with iodine solution, to the purpose of that step. One of the purposes is not needed.
 

Step       Purpose
 
i) Leaf in hot water
  •  
 
  •  
 
Remove the methylated spirits
 
ii) Leaf into methylated spirits
  •  
 
  •  
 
Remove any proteins
 
iii) Wash the leaf
  •  
 
  •  
 
Remove the chlorophyll
     
  •  

Break down the cell walls

 
b) 
 
If the iodine solution turned blue-black, what substance is present in the leaf? ____________________
 
 
c)
 
A leaf was removed from a plant and left beside the plant for a week. Explain what would happen if this leaf was now tested with iodine solution.

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