Question

How would you demonstrate that green plants release oxygen when exposed to light ?

Answer 1

• Place hydrilla plant (a water plant) in a beaker containing pond water and cover it by a short-stemmed funnel. (Make sure the level of water in the beaker is above the level of the stem of the funnel)
• Invert a test tube full of water over the stem of the funnel.
• Place the set up in the sun light for a few hours.

Observation:
Bubbles appear in the stem which rise and are collected in the test tube. When sufficient gas gets collected, a glowing splinter will be introduced in the test tube, which will burst into flames.

Inference:
The splinter glows due the presence of oxygen in the test tube which proves that the gas collected in the test is released by hydrilla during photosynthesis.