Project description for participation
in the European Science on Stage festival
from 25 – 28 April 2013 in Słubice – Frankfurt (Oder)
Project title: How colors of visible light affect the activity of photosynthesis, and why
LED lights are interesting for production in greenhouses.
Main contact person
Title (Dr, Prof, etc.): Teacher First Name: Anne
Surname: Appe
E-Mail: [email protected]
School / institution: Midtfyns Gymnasium
Town: Ringe
Country: Denmark
Abstract: (max. 700 characters incl. spaces):
The project aims to investigate the dependence of photosynthesis on light quality /
light color. This should be done by measuring CO2 - consumption and O2 development over time in a 2L's Vernier bio-chamber, wherein a plant is illuminated
with white light, with blue light (450 nm) and red light (625 nm) and green light (520
nm). Photosynthesis activity is measured both as CO2 consumption and O2
production. It is measured by different light sources (LED) that emits light at the
right wavelengths.
Involved disciplines: Biology, chemistry and physics
Keywords: Photosynthesis - plant production - plant production by low energy
consumption.
Age group (Age of the students): 15 - 20
Materials used in this project: Vernier Bio chambers 2L, electronic CO2 sensor,
electronic O2 sensor, LED lamps, plants (in growth)
What is innovative about your project?
In classical photosynthesis experiments with aquatic plants you can detect
photosynthesis and respiration by a chemical method. pH changes caused by CO2
consumption or CO2 production are recorded by means of acid-base indicators.
In this study, photosynthesis and respiration in terrestrial plants are demonstrated
by measuring the CO2 consumption and the O2-production. The measurements are
performed with gas sensors (Vernier).
In this study the photosynthetic activity of the plants is coupled to the quality of the
light source.
Students are given an introduction to the use of light sources (conventional and
LED light sources), as well as how light quality (wavelength) affects photosynthetic
activity.
What can other teachers implement from your project in their class?
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To the extent that the teacher has data recording equipments and various light
sources available to him, the project could be implemented directly.
Personal quotation concerning your project:
Project description: (max. 12.000 characters incl. spaces / approx. 2,5 pages)
The experimental part of this project has to be put into a broader context where the
student must relate to the current (local) production of vegetables which takes place
in greenhouses. The production is based on an energy consumption
• Biological energy consumption - the photosynthesis
• Energy consumption in the operation of a greenhouse - illumination of the plants,
heating of the greenhouse etc.
Energy consumption for operation of the greenhouses must be as low as possible.
The greenhouses are "experimental units", where crop production is dependent on
various parameters such as light quality, temperature, humidity, nutrients etc.
The present photosynthesis project will demonstrate how to maintain a number of
parameters, and interact with one variable (wavelength).
Photosynthesis activity is dependent on the wavelength of the light.
In the leaves of the plants there is chlorophyll pigments which absorb light having a
wavelength in the range of 420 -480 nm (blue light), and light having a wavelength
in the range of 610 -690 nm (red light). The green light (520 to 600 nm) is reflected.
By using LED lights, it will be ensured that the plants will only be illuminated with
specific wavelengths.
FIG. 1 shows examples of LED lamps spectrum
Experiments are already carried out with greenhouse plants which are illuminated
with LED light (see Fig. 2).
FIG. 2 Greenhouse experiments at DTU (source: OpdagFotonikken, Fig. 8, Chapter
10,
http://www.fotonik.dtu.dk/OpdagFotonikken/Camps_boger_film_og_mere/BeyondOptical
Horizons/chapters/Chapter%2010.aspx)
In a small scale, it is possible in a closed chamber to measure plant photosynthesis
and respiration.
Photosynthetic activity is measured on basis of the photosynthesis reaction:
6 CO2 + 6 H2O + Light energy
C6H12O6 + 6 O2
Where CO2 - consumption and O2 - production is recorded
Respiration can be measured in the plants when they are not illuminated.
C6H12O6 + 6 O2
6 H2O + 6 CO2 + ATP (energy)
In the respiratory process correspondingly the CO2 - production and the O2 consumption is measured.
By having knowledge of these two biological processes, students can find an
expression of the net production of the plant.
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The plants used in this study are small plants growing well. The plant is placed in a
2L's bio- chamber (Vernier). The bio-chamber is fitted with a CO2 sensor and an O2
sensor. In a series of experiments the plant is exposed to blue light between 420 to
480 nm, and red light with a wavelength in the range 610 -690 nm, the green light
(520-600 nm), as well as by halogen light and white light. The correlation between
the wavelength of light and the photosynthetic activity is recorded by data collection
(logger-pro).
These data provide the basis for a discussion of plant’s optimal growth conditions.
Greenhouse production and energy consumption will be put into a larger
perspective where the benefits of LED lighting can be discussed. To obtain an
understanding of this, physical measurements are used to compare LED lamps with
traditional lighting (halogen bulbs/ fluorescent tubes).
This teaching project can be adapted for secondary education at different levels.
The correlation and collaboration between biology and physics is obvious.
NV-teaching (The Scientific basic course) in the 1.grade:
The project's interdisciplinary dimensions are in focus, and collaboration between
biology, chemistry and physics are supporting the project. The course will be put
into a context of energy consumption and sustainable production.
Biology at B-level:
The project's individual academic dimension is brought into focus.
Photosynthetic dependence on light wavelength and photosynthesis biochemistry is
the academic focus.
In the perspectivating part of the teaching, this project is put into a context where
biological production in relation to energy consumption is put into a larger societal
perspective.
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