Describe the half-leaf experiment on photosynthesis

CBSE Class 11
1

Describe the half-leaf experiment on photosynthesis.

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  • A potted plant is kept in the dark for 48-72 hours for destarching.
  • A part of a leaf is enclosed in a test tube containing some KOH solution, and the other half is kept out exposed to air.
  • It is made sure that the leaf does not break off from the plant body while the experiment is going on.
  • The setup is then kept in sunlight for some time.
  • Later, the leaf is tested for the presence of starch.
  • The starch test shows that the exposed part of the leaf tests positive for starch, while the part in the test tube tests negative for starch.
  • This shows that carbon dioxide is necessary for photosynthesis.