Does Exposure to UV Light Affect the
Germination Rate of Phaseolus lunatus?
I.M. Smart
Hardee Junior High
Mr. Scienz
Ultra-Violet Light
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of
visible light, but longer than X-rays, that is, in the range between 400 nm and 10 nm,
corresponding to photon energies from 3 eV to 124 eV. It is so-named because the spectrum
consists of electromagnetic waves with frequencies higher than those that humans identify as the
color violet. These frequencies are invisible to most humans except those with aphakia. Near-UV
is visible to a number of insects and birds.
UV light is found in sunlight and is emitted by electric arcs and specialized lights such as
mercury lamps and black lights. It can cause chemical reactions, and causes many substances to
glow or fluoresce. A large fraction of UV, including all that reaches the surface of the Earth, is
classified as non-ionizing radiation. The higher energies of the ultraviolet spectrum from
wavelengths about 120 nm to 10 nm ('extreme' ultraviolet) are ionizing, but, due to this effect,
these wavelengths are absorbed by nitrogen and even more strongly by dioxygen, and thus have
an extremely short path length through air.[1] However, the entire spectrum of ultraviolet
radiation has some of the biological features of ionizing radiation: It does far more damage to
many molecules in biological systems than is accounted for by simple heating effects (an
example is sunburn). These properties derive from the ultraviolet photon's power to alter
chemical bonds in molecules, even without having enough energy to ionize atoms
Phaseolus lunatus
Phaseolus lunatus is of Andean and Mesoamerican origin. Two separate domestication
events are believed to have occurred. The first, taking place in the Andes around 2000 BC,[1]
produced a large-seeded variety (Lima type), while the second, taking place in Mesoamerica
around AD 800, produced a small-seeded variety (Sieva type).[1] By around 1300, cultivation had
spread north of the Rio Grande, and in the 1500s, the plant began to be cultivated in the Old
World.[1]
The small-seeded wild form (Sieva type) is found distributed from Mexico to Argentina,
generally below 1,600 metres (5,200 ft) above sea level, while the large-seeded wild form (Lima
type) is found distributed in the north of Peru, from 320 to 2,030 metres (1,050 to 6,660 ft) above
sea level.[citation needed]
The Moche Culture (0-800 AD) cultivated lima beans heavily and often depicted them in
their art.[2] During the Spanish Viceroyalty of Peru, lima beans were exported to the rest of the
Americas and Europe, and since the boxes of such goods had their place of origin labeled
"Lima – Peru", the beans got named as such.
The term "butter bean" is widely utilised for a large, flat and yellow/white variety of lima
bean (P. lunatus var. macrocarpus, or P. limensis[3]).
In some Southern United States areas the Sieva type are traditionally called butter beans,
also otherwise known as the Dixie or Henderson type. In that area, lima beans and butter beans
are seen as two distinct types of beans.
Research Plan
Question:
Does Exposure to UV Light Affect the Germination Rate
of Phaseolus lunatus?
Hypothesis:
UV light will affect the germination rate of Phaseolus
lunatus.
Independent variable:
Length of exposure to UV light in days
Dependent variable:
Number of seeds that germinate
Materials:
110 Phaseolus lunatus seeds
1 black light (UV source)
Paper plates
Aluminum foil
Paper towels
Plastic sandwich bags
Water
Journal
Pencil
Procedure:
1. Divide seeds up into 11 groups of 10
2. Set up blacklight in a dark space like a closet
3. Cover paper plates with foil
4. Place 10 seeds onto each foil covered plate
5. Place plates under blacklight
6. Turn on black light
7. Choose 10 seeds as a control.
8. Place seeds into damp paper towel
9. Place paper towel and seeds into plastic sandwich bag
10.
Place bag in drawer.
11.
Check daily for germination. Record in journal
12.
Every 24 hours, remove one plate
13.
Repeat steps 8-11
Data
Control 1 day 2 days 3days 4 days 5 days 6 days 7 days 8 days
10
10
9
9
8
7
5
GRAPHS
10
9
8
7
6
5
Series1
4
Series2
3
2
1
0
1
2
3
4
5
Analysis
Averages
T-test
CONCLUSION:
After much analysis, the hypothesis accepted. UV light
does affect the germination rate of Phaseolus lunatus.
Bibliography
References
Lima Beans. (n.d.). The World's Healthiest Foods. Retrieved January 6, 2014, from
http://www.whfoods.com/genpage.php?tname=foodspice&dbid=59
Phaseolus lunatus. (n.d.). Wikipedia. Retrieved January 6, 2014, from
http://en.wikipedia.org/wiki/Phaseolus_lunatus
Science Fusion Interactive Worktext Grade 7 Holt Mcdougal Science Fusion Florida.. (2010).
Orlando, FL: Houghton Miflin Harcourt.
Ultraviolet. (n.d.). Wikipedia. Retrieved January 7, 2014, from
http://en.wikipedia.org/wiki/Ultraviolet
Ultraviolet Light. (n.d.). Ultraviolet Light. Retrieved January 7, 2014, from
http://science.ksc.nasa.gov/mirrors/msfc/description/ultraviolet.html
APA formatting by BibMe.org.