The document describes an experiment where bread was exposed to light or no light to determine the effect on mold growth. Over a 6 day period, the bread exposed to no light grew more mold than bread exposed to light, contrary to the hypothesis. The purpose of the experiment was to observe mold growth under different light conditions, and the results showed that mold grew more in the absence of light.

1. Kendrick Lee IB Biology 1/4/2011
Bread Mold Lab
Purpose
The purpose of the experiment was to find the amount of mold growth on a piece of bread under light
and with no light and to determine under what light intensity mold grows the most.
Research
Growing in the form of multicellular filaments, mold is a fungus which obtains its energy from
the organic matter it feeds and lives on. They possess enzymes that break down bipolynomers
which are absorbed by the hyphae. By decomposing organic material, they play a significant role
in the environment. Through small pores, they are able to reproduce asexually through mitosis or
sexually through meiosis. A colony of mold consist of intertwined hyphaes are able to grow at a
temperature of 39 degrees Fahrenheit, meaning that harsh conditions most of the time do not
prevent growth. Mold goes into a dormant state when the conditions do not allow growth and
then proceed to reproducing and growing when the conditions allow. The most common of the
fungi is the bread mold, Rhizopus stolonifer , which withdraws nutrients from the bread and
causes damage to the surface. Some common bread molds are Penicillium and Aspergillus. The
mold can be reproduced asexually when sporangia’s spores are released (usually by wind) and
land on a damp, humid place on the bread, forming hyphaes. The interconnected roots of the
mold called rhizoids anchor the fungus, absorb nutrients and disperse the enzymes needed to
breakdown the bread. Eventually, sporangiophores grow within the hyphae and the baby spores
are created and released. When they germinate, new mold forms, creating a colony of them.
Bread mold is a member of the zygomycota meaning that sexual reproduction is possible and
occurs when the two parents (hyphaes) give half of the DNA needed to produce an offspring,
causing a zygote to form. Depending on the environment conditions, humidity, temperature,
density, light intensity, and other variable vary the amount of bread mold growth.
Hypothesis
Under light, mold will be more abundant on the bread under light than the bread exposed to no light.

2. Kendrick Lee IB Biology 1/4/2011
Procedure
1. A laboratory table was chosen and cleaned appropriately so that unsatisfactory factors
would not influence the outcome of the experiment.
2. The scientist obtained six clean petri dishes and labeled three of the dishes “light” and
the other three “dark” with a wax pencil.
3. Using a knife, six 1 1/2 inch by 1 1/2 inch squares were cut out of the slices of bread
(without the crust) and each of the bread squares were placed inside of a petri dish.
4. A 50 mL beaker was filled with tap water.
5. The scientists used a pipette to suck up some of the water and then drop ten drops of
water on the bread squares in the petri dishes.
6. The petri dishes were sealed with the petri dish covers and organized by where they will
be placed; in light or in dark.
7. The petri dishes labeled “light” were placed on the laboratory desk where light is
abundant and present and the petri dishes labeled “dark” were placed in a concealed
laboratory cabinet where light is not available.
8. Throughout a six day period, the bread was observed for the amount of mold and color
(qualitatively) every two days and the data was recorded.
Data Collection
Four Day Period
Day 2 Light Dark
Trial 1 No mold visible, moist surface No mold visible, moist surface
Trial 2 No mold visible, moist surface No mold visible, moist surface
Trial 3 No mold visible, moist surface No mold visible, moist surface

3. Kendrick Lee IB Biology 1/4/2011
Day 4 Light Dark
Trial 1 Mold barely visible No mold visible
Trial 2 No mold visible Little spores of mold spot the
surface
Trial 3 Little amount of mold growing No mold visible
Day 6 Light Dark
Trial 1 Small colony of spores (mold) Small amounts of mold visible
cover the surface
Trial 2 Tiny spots of mold cover a small Large spots of mold appear
piece of the surface in the center throughout the whole surface of
bread
Trial 3 Little mold growing No mold visible(human eye) but
under the microscope, small
mold is obviously present
Conclusion
The purpose of the experiment was found with the bread exposed to no light growing more
mold than the bread exposed to light therefore, the results do not support my hypothesis. The control
of the experiment was the amount of water and temperature and the independent variable was the
light. Based on the colors of the mold, black and green, it was obvious that Rhizopus was present.
From observing the bread before the sixth day, spores were seen meaning that the molds were
constantly reproducing.
The procedure used was proven to be strong with the scientists maintaining the variables and
constants to the best of their abilities which is shown by the results allowing the scientists to state a
precise conclusion. There was a random error that occurred which was the not being able to monitor
the specific amount of water rather than drops used to moisten the bread. Although the procedure was
strongly designed and constructed there were some things that could be altered in the future. The
investigators should use a burette to accurately measure the amount of water put on the bread and put
it on a tissue paper to put on the surface instead of putting it straight on the bread.

4. Kendrick Lee IB Biology 1/4/2011
Bibliography
Riveside, Josh. "Bread Mold." EzineArticles Submission - Submit Your Best Quality
Original Articles For Massive Exposure, Ezine Publishers Get 25 Free Article Reprints.
2010. Web. 05 Jan. 2011. <http://ezinearticles.com/?Bread-Mold&id=405845>.
NCBI. "Bread Mold Fungus, Rhizopus Stolonifer." Backyard Nature with Jim Conrad. 9
May 2009. Web. 05 Jan. 2011. <http://www.backyardnature.net/f/bredmold.htm>.