Question

State what you would observe when: A green leaf is heated over a water bath in a test tube containing methylated spirit.

Answer 1

• A green leaf heated in a test tube with methylated spirit over a water bath, removes all chlorophyll from the leaf cells and makes them more permeable to Iodine solution.
• During the starch test, one can observe the color change of the leaf from brown to blue when iodine is put on the leaf as iodine reacts with the starch present in the leaf.
• However, because the leaf is initially green in color, it obscures the observation and does not provide an accurate conclusion of the test.
• As a result, the green-colored chlorophyll must be removed first.
• Methanol and ethanol are both alcohols found in methylated spirits.
• This organic solvent dissolves chlorophyll (alcohol). As a result, when a leaf is boiled in alcohol, the chlorophyll in the leaf is extracted, and the leaf turns pale yellow.
• Thus, one needs to heat the green leaf over a water bath in a test tube containing methylated spirit to remove chlorophyll from the green leaf and allows us to prove that photosynthesis occurs in the presence of sunlight, water, and carbon dioxide.