Question
With the help of an experiment explain how germinating seeds respire.
✓
Answer
- Seed coats of a few germinating seeds (peas, beans or gram) are removed and are then put in a test tube filled with mercury.
- After closing the test tube with the thumb, it is vertically inverted in a trough of mercury and the thumb is carefully removed.
- Being lighter than mercury, the seeds rise to the closed upper end of the test Uibe. No gas is seen at first in the test tube.
- As germination proceeds, a gas begins to collect at the top of the mercury in the test tube.
- On introducing a pellet of potassium hydroxide into the tube, it rises to the top and absorbs the gas. The mercury again fills the tube.
- The potassium hydroxide reacts with carbon dioxide gas to produce potassium carbonate and water.
- The gas therefore disappears. Evidently germinating seeds produce carbon dioxide by anaerobic respiration in the absence of oxygen in the mercury column.
[Note: Mercury is toxic chemical. Proper precautions must be taken while performing this experiment ]
[Note: Students can scan the adjacent QR code to get conceptual clarity with the aid of a relevant example.]
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