Test tube and funnel experiment, Ganong’s light screen experiment
12th botany neet school

Test tube and funnel experiment, Ganong’s light screen experiment

EXPERIMENTS ON PHOTOSYNTHESIS

Test tube and funnel experiment

Test tube and funnel experiment procedure is explain below.

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The test tube funnel experiment demonstrates that oxygen is evolved during photosynthesis.

A few branches of Hydrilla are kept in a beaker containing pond water in which a small amount of sodium bicarbonate is dissolved.

The branches are covered with a glass funnel and a test tube full of water is kept inverted over the stem of the funnel as shown in the figure.

test tube and funnel experiment

Now the apparatus is kept in sunlight for 4 to 6 hours.

The gas bubbles may be observed from the ends of hydrilla branches kept within the glass funnel.

These gas bubbles are collected in the test tube by the downward displacement of water.

The gas is tested for oxygen.

When a burnt splinter is taken near the mouth of the tube, it glows brightly and proves that the gas is oxygen.

The test tube and funnel experiment demonstrates that oxygen evolves during photosynthesis.

Ganong’s light screen experiment

Ganong’s light screen experiment


Ganong’s light screen experiment demonstrates that light is essential for photosynthesis.

When a pot plant is kept for 48 hours in dark room, the leaves become free from starch.

Thus dark treated plant is called destarched plant.

Ganong’s light screen is a clip like instrument with a tin foil disc having a star shaped opening through which light can enter.

This closes the lower hollow cylindrical box like structure.

The advantage of light screen is to allow free ventilation and at the same time it cuts off light.

The light screen is fixed to a leaf of the destarched potted plant as shown in the figure.

The entire experimental setup is placed in sunlight for 4 to 6 hours.

Ganong’s light screen experiment

The leaf subjected for experiment is tested for starch.

Only the star shaped part of the leaf exposed to the sunlight turns blue.

The Ganong’s light screen experiment demonstrates that light is essential for photosynthesis.

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For more detail about Test tube and funnel experiment click here

Other links 

Plant tissue culture – origin and techniques


Plant physiology – photosynthesis and its significance


Site of photosynthesis and Mechanism of photosynthesis


Electron transport system and photophosphorylation types


Dark reaction


C3 and C4 pathways


Photorespiration or C2 cycle


Factors affecting photosynthesis


 

Mode of nutrition – Autotrophic, Heterotrophic


Chemosynthesis


Mechanism of Respiration – Glycolysis


Mechanism of Respiration – Oxidative decarboxylation , Krebs cycle


Mechanism of Respiration – Electron Transport Chain, Energy Yield


Ganong’s respiroscope, Pentose phosphate pathway


Anaerobic respiration, Respiratory quotient, Compensation point, Kuhne’s fermentation tube experiment


Plant growth and Measurement of plant growth


Phytohormones Auxins


Phytohormones Gibberellins


Phytohormones Cytokinin, Ethylene, Abscisic Acid, Growth Inhibitors – Physiological Effects


Photoperiodism and vernalization, Phytochromes and flowering

 

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