Year 7 test leaves for starch

As part of our topic on photosynthesis Year 7 have been testing leaves for starch in the labs this morning. They have written a blog post all about the experiment.

Testing a leaf for starch 

First we boiled the leaf to get rid of the waxy cuticle and stop the cell reactions.

Then we turned off the Bunsen burner because the chemical we are about to use is flammable.

We covered the leaf in ethanol and placed it in the boiling water. We did this to remove the green chlorophyll from the leaf.

We waited for ten minutes and took the leaf out. 

The ethanol had turned green and the leaf was colourless and brittle. We placed the leaf in warm water to soften it.

We spread the leaf out on a Petri dish and covered it in iodine. If it turned black it meant there was starch and if it did not change then there was no starch. 

And then we sat down wrote up the experiment.

By Miss Wybar's Year 7 Science class.