1. Kendrick Lee IB Biology 1/4/2011 Bread Mold LabPurposeThe purpose of the experiment was to find the amount of mold growth on a piece of bread under lightand with no light and to determine under what light intensity mold grows the most.ResearchGrowing in the form of multicellular filaments, mold is a fungus which obtains its energy fromthe organic matter it feeds and lives on. They possess enzymes that break down bipolynomerswhich are absorbed by the hyphae. By decomposing organic material, they play a significant rolein the environment. Through small pores, they are able to reproduce asexually through mitosis orsexually through meiosis. A colony of mold consist of intertwined hyphaes are able to grow at atemperature of 39 degrees Fahrenheit, meaning that harsh conditions most of the time do notprevent growth. Mold goes into a dormant state when the conditions do not allow growth andthen proceed to reproducing and growing when the conditions allow. The most common of thefungi is the bread mold, Rhizopus stolonifer , which withdraws nutrients from the bread andcauses damage to the surface. Some common bread molds are Penicillium and Aspergillus. Themold can be reproduced asexually when sporangia’s spores are released (usually by wind) andland on a damp, humid place on the bread, forming hyphaes. The interconnected roots of themold called rhizoids anchor the fungus, absorb nutrients and disperse the enzymes needed tobreakdown the bread. Eventually, sporangiophores grow within the hyphae and the baby sporesare 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 andoccurs 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.HypothesisUnder light, mold will be more abundant on the bread under light than the bread exposed to no light.
2. Kendrick Lee IB Biology 1/4/2011Procedure 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 CollectionFour Day PeriodDay 2 Light DarkTrial 1 No mold visible, moist surface No mold visible, moist surfaceTrial 2 No mold visible, moist surface No mold visible, moist surfaceTrial 3 No mold visible, moist surface No mold visible, moist surface
3. Kendrick Lee IB Biology 1/4/2011Day 4 Light DarkTrial 1 Mold barely visible No mold visibleTrial 2 No mold visible Little spores of mold spot the surfaceTrial 3 Little amount of mold growing No mold visibleDay 6 Light DarkTrial 1 Small colony of spores (mold) Small amounts of mold visible cover the surfaceTrial 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 breadTrial 3 Little mold growing No mold visible(human eye) but under the microscope, small mold is obviously presentConclusion The purpose of the experiment was found with the bread exposed to no light growing moremold than the bread exposed to light therefore, the results do not support my hypothesis. The controlof the experiment was the amount of water and temperature and the independent variable was thelight. 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 wereconstantly reproducing. The procedure used was proven to be strong with the scientists maintaining the variables andconstants to the best of their abilities which is shown by the results allowing the scientists to state aprecise conclusion. There was a random error that occurred which was the not being able to monitorthe specific amount of water rather than drops used to moisten the bread. Although the procedure wasstrongly designed and constructed there were some things that could be altered in the future. Theinvestigators should use a burette to accurately measure the amount of water put on the bread and putit on a tissue paper to put on the surface instead of putting it straight on the bread.
4. Kendrick Lee IB Biology 1/4/2011Bibliography 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>.