Question
The diagram shown below represents the sequence followed in the laboratory during the testing for starch in the leaf
a) What is the importance of the following stages
i) Boiling leaf in water
ii) Boiling leaf in Ethanol
iii) Heating the ethanol indirectly over a water bath
b) Fill in the table below to show the conclusion if the following colours are observed after placing drops of iodine onto the leaf at the end of the experiment
| COLOUR OBSERVED | CONCLUSION |
|---|---|
| Blue Black | (I) |
| Brown | (II) |
Answer
a)
i) Stop metabolic processes / Kill the cells
ii) Remove chlorophyll
iii) To avoid igniting the highly flammable Ethanol
(I) Starch present
(II) Starch absent
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