What color would plants have on another planet?

Introductory section and preparatory phase• Short Description: Plants as producers perform the process of

photosynthesis. Chlorophyll is the molecule – key to photosynthesis. What happens on a planet without enough light? Why the leaves of plants, are green? Are they green on any other planet? To answer all these questions we studied the chlorophyll. With the spectroscope we saw that absorbs red and blue, and reflects the green. With a clever experiment – game showed why the sky on Earth is blue and we associated this fact with the behavior of chlorophyll. We studied the growth of plants under radiation of different wavelengths, as well as in conditions of limited or poor lighting.

• Keywords: Chlorophyll, photosynthesis, spectroscopy, plants, polarized light, blue sky, color adsorption.

• Target audience: Students studying Natural Sciences (especially Physics, Biology, Chemistry and Astronomy)

• Age range: 14-18 years old

• Context: Natural Sciences School Lab, Computer School Lab, internet connection.

• Time required: 6 hours (preparation), 1-2 months for full project.

Introductory section and preparatory phase• Technical Requirements: Fully equipped Natural Sciences Lab, Internet

connection, Microsoft Office, Microsoft Windows, Computers, video projector could be useful.

• Author’s background: Knowledge of Physics, Chemistry, Biology and Astronomy. The project is mainly based on astrobiology and co-evolution of life in other planets. Photosynthesis, plants grow up, chlorophyll, light physics, polarization and optics are main science topics related to our project.

• Connection with the curriculum: Strongly related with Astronomy (Second Class of Greek High School), Physics (First, Second and Third Class of Greek High School) Biology (Second Class of Greek High School). Partly related with Chemistry (First Class of Greek High School).

• Learning Objectives: Hands on learning, Inquiry based learning, connection between Universities-Institutes and Schools, use of Open Science Resources, learn students to cooperate and act as researchers.

• Guidance for preparation: Study the biology of photosynthesis, the chemistry of chlorophyll reactions and physics of light. Observe polarization of light, the plants color and relate the green color of plant leaves with the blue color of the sky. Plant lentils and expose the plants under high and low light, and under color filters. Study the growth of plants under no sunny light.

Pre-Experiment / Observation– Teaching Phase 1:Questions Eliciting Activities – PROVOKE CURIOSITY

Teacher asks students why do they believe the leaves of the plants are green (and not black for instance)?

Teacher asks students why sky is blue?

Teacher presents to students the following video:https://www.youtube.com/watch?v=HIwOSbH8yD8&list=FLYcVaeaC8XYOprtynu9iRgQ

Pre-Experiment / Observation– Teaching Phase 1:Questions Eliciting Activities – DEFINE QUESTIONS FROM CURRENT KNOWLEDGE• The role of chlorophyll in

photosynthesis: (http://en.wikipedia.org/wiki/Photosynthesis )

• Photosynthesis: (http://www.youtube.com/watch?v=g78utcLQrJ4 )

• The wavelengths of chlorophyll’s adsorption.http://www.youtube.com/watch?v=WYKBEYRkhLg

Pre-Experiment / Observation– Teaching Phase 2: Active Investigation – PROPOSE PRELIMINARY EXPLANATION OR HYPOTHESES

• Why sky is blue?

• Scattering of light into atmosphere.

• Why during daytime sky is blue, whether at dawn and evening is red?

• Students are modeling the scattering procedure, following a clever game.

Pre-Experiment / Observation– Teaching Phase 2: Active Investigation – PLAN AND CONDUCT SIMPLE INVESTIGATION• Students are asked to extract chlorophyll from spinach leaves (boiling

spinach, stirring mixture of boiled spinach with ethanol, filtered the green suspension in test-tube and add gasoline, chlorophyll emerges in surface).

• Students are observing the adsorption spectrum, comparing it with a continuous one.

Pre-Experiment / Observation– Teaching Phase 2: Active Investigation – PLAN AND CONDUCT SIMPLE INVESTIGATION• Students are asked to study the chemical

compound that gives the green color in plants by techniques of chromatography (purring green leaves of spinach in acetone, mark filter paper, immerse the marked filter paper into the test-tube carrying amount of acetone

• Students are observing the two areas of different colour, green and yellow, corresponding to chlorophylls and carotenoids, respectively.

Experiment / Observation– Teaching Phase 3: Creation – GATHER EVIDENCE FROM OBSERVATION

• Students are asked to demonstrate the direct correlation of leave color to atmosphere colors. To study the behavior of chlorophyll students plant lentils in irrigated cotton and let it sprout in controlled conditions. We have lentils grown in poor lighting (absolute darkness), lentils grown in greenhouse conditions of glass and lentils under color filters (red, green, blue).

Experiment / Observation– Teaching Phase 4: Discussion – EXPLANATION BASED ON EVIDENCE

• Students are asked observe the growth rates of the plants (lentils) under different color filters.

• Also students asked to study the growth rates of plants growing in greenhouse.

Experiment / Observation– Teaching Phase 4: Discussion – CONSIDER OTHER EXPLANATIONS

• Additionally, students can study the growth of another plant (e.g. wheat) growing under greenhouse conditions (high CO2 concentration) and open air (low CO2 concentration)

Experiment / Observation– Teaching Phase 4: Discussion – CONSIDER OTHER EXPLANATIONS

• Finally, the most interesting finding is the color of plants in total darkness. Plants developed in complete darkness showed white stem in contra version to illuminated ones, that showed Green:

Post-Experiment / Observation– Teaching Phase 5:Reflection – COMMUNICATE EXPLANATION

• Students can now compare their findings with “white” plants in depth oceans with poor lighting conditions.

• As follow up activities, students can continue their experiments with more accurate and precise conditions (strictly defined color filters) and new experimental objects (e.g. algae).

Post-Experiment / Observation– Teaching Phase 5:Reflection – FOLLOW UP ACTIVITIES AND MATERIALS

• Furthermore, students can suggest astronauts (e.g. Timothy Peak) to perform such experiments in ISS.

Post-Experiment / Observation– Teaching Phase 5:Reflection – FOLLOW UP ACTIVITIES AND MATERIALS

Contact Information• Name Surname: Ioannis Chiotelis• Affiliation: www.pelopio-lykeio.gr • Address: Arakinthou 20, 26226, Patras, Greece• Telephone: +306948372341• Email: johnchiotelis@yahoo.gr

johnchiotelis@gmail.com johnchiotelis@icloud.com

http://johnchiotelis-yperlepth-yfh.blogspot.gr/