5 November 2025

Summary

This video demonstrates an experiment using Wilmod's bubbler to measure photosynthesis rates under different light wavelengths. Using a 100 mL conical flask, water reservoir tube, rubber cork, modified dropper, and a hydraula aquatic plant in 1% sodium bicarbonate solution, the setup traps oxygen bubbles produced by photosynthesis. Students count bubbles per minute under white (control), red (620–750 nm; ~670 nm most effective), blue (450–495 nm), and green (495–570 nm) light. Results show highest rates in white light; among monochromatic lights red produces the most, blue next, and green yields negligible bubbles because chlorophyll reflects green. The video concludes with averaged observations and interpretation.

Takeaways

• 😀 The aim of the experiment is to study the rate of photosynthesis at different wavelengths of light using Wilmod's bubbler apparatus.
• 😀 The materials required for the experiment include a 100ml conical flask, water reservoir tube, rubber cork, disposable dropper, Hydraula plant, and cellophane colored paper (red, green, and blue).
• 😀 The procedure involves assembling the bubbler with the rubber cork, inserting the Hydraula plant stem, and adding a 1% sodium bicarbonate solution to serve as a carbon source.
• 😀 The experimental setup uses monochromatic light (red, blue, green) and a control (white light) to observe the rate of photosynthesis.
• 😀 The control setup (white light) allows for counting the number of air bubbles produced per minute to measure photosynthesis rate.
• 😀 Red light (620-750 nm) is most effective for photosynthesis, with the highest rate of bubble formation observed.
• 😀 Blue light (450-495 nm) also promotes photosynthesis, but at a slightly lower rate compared to red light.
• 😀 Green light (495-570 nm) shows little to no bubble formation, as chlorophyll reflects this wavelength and absorbs less light.
• 😀 The experiment encourages wrapping the conical flask in cellophane color paper to isolate the plant under specific light conditions.
• 😀 Conclusion: Photosynthesis is most effective under white light, with red light yielding the highest rate of photosynthesis, while green light has minimal effect.

Q & A

What is the aim of the experiment described in the script?

The aim of the experiment is to study the rate of photosynthesis at different wavelengths of light using an apparatus called Wilmott's bubbler.

Which materials are required for this experiment?

The materials required include a 100 ml conical flask, a water reservoir tube, a one-hole rubber cork, a disposable dropper (with the lower part cut off), a Hydrilla plant, and cellophane color papers in red, green, and blue.

What is the purpose of using sodium bicarbonate solution in the conical flask?

Sodium bicarbonate solution serves as a carbon source for photosynthesis by providing carbon dioxide to the plant.

How is the Wilmott's bubbler apparatus assembled?

The bubbler is inserted into the lower portion of the rubber cork, and the water reservoir tube is inserted into the upper portion. The assembled cork is then fitted tightly to the conical flask containing water and sodium bicarbonate solution.

What role does the Hydrilla plant play in the experiment?

The Hydrilla plant acts as the photosynthetic organism whose rate of photosynthesis is measured by counting the number of air bubbles it releases under different light conditions.

How is the rate of photosynthesis measured in this setup?

The rate is measured by counting the number of air bubbles evolved per minute from the Hydrilla plant under different wavelengths of light.

What are the wavelength ranges used for the red, blue, and green lights in the experiment?

Red light: 620–750 nm, Blue light: 450–495 nm, and Green light: 495–570 nm.

Which light wavelength shows the highest rate of photosynthesis, and why?

Red light shows the highest rate of photosynthesis because the wavelength around 670 nm is most effectively absorbed by chlorophyll, maximizing photosynthetic activity.

Why is the rate of photosynthesis very low under green light?

The rate is low because chlorophyll reflects green light instead of absorbing it, resulting in minimal photosynthetic activity.

What conclusion can be drawn from the experiment regarding light wavelength and photosynthesis?

The rate of photosynthesis is highest in white light (which contains multiple wavelengths), high in red light, moderate in blue light, and very low or nearly zero in green light.

What is the significance of repeating the experiment for three trials and taking an average?

Repeating the experiment and averaging the results ensures accuracy and reduces the effect of experimental errors or random variations.

How can the experiment be simulated at home or in a classroom setting?

It can be simulated by wrapping the conical flask with cellophane papers of different colors (red, blue, and green) to filter light of specific wavelengths and observing the bubble count.