2.3.6

Testing Leaves for Starch

Test yourself

Testing Leaves for Starch

Some of the glucose made by photosynthesis in the leaves is stored as starch. It is possible to test for starch stored in leaves.

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Boil

  • Boil a leaf to denature the enzymes and halt photosynthesis.
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Ethanol

  • Soak the leaf in ethanol to remove the green chlorophyll from the leaf, turning it white.
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Iodine

  • Add droplets of iodine onto the leaf.
  • The iodine will turn dark blue in the parts of the leaf where starch is present.
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Altering starch content

  • The starch content of leaves can be changed.
    • For example, keeping plants in the dark would decrease the rate of photosynthesis. This would force leaves to use up their starch stores, so if these leaves were tested, not as much of the leaves would turn dark blue with iodine.
    • Plants could also be kept in low carbon dioxide (using sodium hydroxide to absorb CO2) to reduce photosynthesis.

Jump to other topics

1The Nature & Variety of Living Organisms

2Structure & Functions in Living Organisms

3Organism Functions

3.1Respiration

3.2Gas Exchange

3.3Transport

3.4Excretion

3.5Coordination & Response

4Reproduction & Inheritance

5Ecology

6Biological Resources

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