Question

The Activity

A team of researchers is interested in testing the amount of oxygen gas (O₂) produced when the same species of plant is exposed to different colors of visible light. The research team has developed a hypothesis to test and designed experimental conditions to run.

They have submitted the work to you for feedback and approval. Your job is to provide feedback concerning both the hypothesis and the experimental design. This will enable them to make the necessary changes to obtain approval for their research.

The Team’s Hypothesis:

The levels of oxygen gaswill be higher for plants exposed to visible red light.

Part 1:

Describe five ways in which the hypothesis can be improved.

Part 2:

Based on the improvements you listed in part 1, write an improved hypothesis for the team.

The new and improved hypothesis:

Answer 1

The hypothesis provided by the team is not satisfactory and can be put across in a better way.

HOW THE HYPOTHESIS CAN BE IMPROVED:

1. The reaction of plants (oxygen production) to different wavelengths can be mentioned.
2. Based on the results, the best out of them can be chosen.
3. Information about the visible light spectrum can be provided.
4. The pigments( in the leaves) involved in absorption of light can be mentioned.
5. The reactions occurring in the pigments on absorption of light can be mentioned.

NEW AND IMPROVED HYPOTHESIS:

VISIBLE LIGHT:

• The visible spectrum is the only part of electromagnetic spectrum that can be seen by the human eye.
• Its wavelength is between about 400nm to 700nm.
• The visible light from sun appears to be white in color, but it is made up of different colors(as we see in rainbows).
• The red light has the longest wavelength and least energy and the violet light has the shortest wavelength and the most energy.

PIGMENTS INVOLVED:

• The light absorbing molecules present in photosynthetic organisms are called pigments.
• They absorb only specific wavelengths of visible light, while reflecting others.
• The three key pigments in photosynthesis are : chlorophyll a, chlorophyll b, beta-carotene.
• The chlorophyll molecules absorb blue and red wavelengths.
• The carotenoids absorb violet and blue-green lights.

THE PROCESS:

• Photosynthesis reaction:
• It takes place in the leave of the plants.
• The leaves contain the above mentioned pigments.

RESULTS:

• White light is the most effective for photosynthesis, since it provides a wide range of colored lights for various pigments to use.
• When only a single colored light is used, red light is the most effective.
• Red has the longest wavelength, allowing it to radiate more energy and allow for an increased rate of photosynthesis.
• The length of the wavelength of light a plant is exposed to is directly related to the rate of photosynthesis.
• As the rate of photosynthesis increses, the oxygen production by the leaves also increses.