Re: A Graph About Moldy Bread
Nichole Wernett
Most of us know that food seems to become moldy more quickly in the summer than in the winter when it is colder. Food in refrigerators seems to keep longer than food left out in the sun. Is this true? Does temperature really affect the rate at which mold grows?
Because each square of bread is 100 cm2, you can express your results as a percentage. For each of the bread types, A, B or C average the amount of mold grown over the ten days and write these figures into a table.
You can then plot this information onto a graph and begin to explore your results. You can plot the amount of mold on each bread sample and compare it to the number of days, like in the diagram below. This can be done with a sheet of graph paper and colored pens or on a computer.
The food industry spends millions of dollars every year on refrigeration and it is very important that they know what temperature they need to stop mold from growing. Moldy food must be thrown away and this costs restaurants and manufacturers a lot of money.
Now that you have finished and obtained some results, maybe you want to see if other variables affect the rate at which mold grows. Maybe you could keep the temperature the same for all of the samples but use different types of bread.
You could try adding moisture to the slices or putting different amounts of sugar or lemon juice onto the slices. As long as you only vary one thing at a time, you can make some interesting studies about mold.
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For many semesters, my nonmajors biology lab did a lab called chicken wing microbiology. You can download it here, from the wonderful Association for Biology Laboratory Education website (Walvoord and Hoefnagels, 2006). In the lab, students devised a method to kill the bacteria on chicken wings, carried out an experiment (including serial dilutions) to test their proposed method, collected plate count data the following week, and wrote a short lab report on their results.
That turned out to be the inspiration I needed for our new lab. Sarah (my capable undergraduate assistant) and I unleashed the Summer of Mold to figure out whether we could have students test predictions about mold growth by spraying spore suspensions or sterile water control solutions on various baked goods. The first step was to figure out what type of baked goods would work the best. Sarah scoured the stores and came back to the lab with a huge variety of treats, including cookies, Twinkies, muffins, sweet breads, sandwich breads, garlic breads, and more. We sprayed, and then we waited. As you can see in the photos below, some baked goods got moldy. A lot of them did not.
During week 2, each group had to figure out how to quantify the mold growth on their bread slices. We gave them plastic transparencies marked with 1-cm2 grids and asked them to figure out how to use the grids to generate their data (without opening their baggies). Once a TA approved their proposed methods, they collected their data, produced their graphs, and wrote their reports.
What did the students think? They liked it! It was not overly complicated, but it was reasonably challenging. The TAs told me that students would have liked more freedom to test different types of natural preservatives, but I confess that I am not sure how to do that without introducing confounding variables. However, it would not be difficult to add refrigeration as a treatment to substitute for (or add to) store-bought bread with artificial preservatives. In our July pilot studies, refrigeration substantially inhibited mold growth.
Hi, thanks for the comment! I will email you the materials shortly. Our labs are just under 3 hr long, and we dedicate two lab periods to the project. Students get out a little bit early from the first period (setup), and data collection (in the second period) does not take long at all. We use that time to help students begin to write their lab reports.
Description: Line graph titled, Accumulated Rainfall, Las Vegas, Nevada. Horizontal axis, day of the year 2017, from 0 to 60, by 10's. (There are 4 equally spaced hashmarks/tickmarks between each labeled number.) Vertical axis, rainfall in inches, from 0 to 1 point 6 by 0 point 2's.The graph begins at 0 comma 0 and moves horizontally and to the right until it reaches 11 comma 0. It then slants upward and to the right until it reaches 13 comma 0 point 1. The graph then moves horizontally and to the right until reaching 19 comma 0 point 1. It then slants upwards and to the right until it reaches 20 comma 0 point 4. The graph moves horizontally and to the right until reaching 21 comma 0 point 4. It then slants upwards and to the right until it reaches 22 comma 0 point 9. It slants upwards and to the right again until it reaches 23 comma 0 point 95. The graph then moves horizontally and to the right until reaching 41 comma 0 point 95. It slants upwards and to the right until 43 comma 1. It moves to horizontally and to the right until 47 comma 1. It slants upwards and to the right until 48 comma 1 point 02, and slants upwards and to the right again until 49 comma 1 point 45. The graph moves horizontally and to the right until 60 comma 1 point 45.
Clare noticed mold on the last slice of bread in a plastic bag. The area covered by the mold was about 1 square millimeter. She left the bread alone to see how the mold would grow. The next day, the area covered by the mold had doubled, and it doubled again the day after that.
If there were 100,000 bacteria at the time it was initially measured and the population decreases so that \(\frac15\) of it remains after each passing hour, we can use function notation to model the bacteria population:
An exponential function is a function that has a constant growth factor. Another way to say this is that it grows by equal factors over equal intervals. For example, \(f(x)=2 \boldcdot 3^x\) defines an exponential function. Any time \(x\) increases by 1, \(f(x)\) increases by a factor of 3.
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This biology experiment requires you to gather some background information before starting with the research. Once you know what the organisms called molds are, understanding the activity would be easy.
For accurate measurements, you can take the help of a plastic grid to check how many squares or cm of it gets covered by the mold. While creating the lab report for your science experiment you can plot that data along the Y-axis and the no. of days along the X-axis on a graph paper.
Mold is a fungus that best grows in dark, moist and warm conditions. It feeds on organic matter like bread while decomposing the same. Hence it is harmful to consume the moldy bread or even inhale the smell as mold spores could enter the body in that way. Adding salt inhibits the development whereas sugar enhances the method. Types of bread with high moisture content like rye, oat, Boston and other dark breads mold faster than the drier and denser varieties.
Many food industries depend on molds to produce food materials like soy sauce, country cured ham, certain types of cheese, etc. They need to know the favorable conditions for fast culture. On the other hand, there are other food industries that take measures to preserve the produce from molds. They utilize the knowledge of the unfavorable situations of infestation.
If you are planning to demonstrate molds growing on bread at a science fair, it is best to perform the experiment beforehand and exhibit the resulting samples for all to see with due explanation of the method adopted.
Hello! Our names are Bella and Mary. We are both 14 years old and in 8th grade. We are participating in our school's annual Big Science Day. When we were planning our project, we were thinking of topics that interested us. We thought about things like rotting apples, plant growing and mould growth on bread. We eventually landed on mould growth on bread because we both thought that although it is disgusting, it can be quite fascinating as well.
We really wanted to know which place(s) in the school is/are the dirtiest, so that's what we did our topic about. We put these two ideas together and that formed our Big Science Day topic! We used bread and rubbed them on to different places in the school, then, put them in separate Ziploc bags and let them sit for a few days until some mould started to grow. During those days, we observed the growth and took pictures for our data collection. Each day, we would come back and take a look at the pieces of bread to see how much mould grew on them.
As a result of our experiment, we hope that people realize that some places in the school are dirtier than they might think and once they know this information we hope they wash their hands more, use hand-sanitiser more often, and sanitise their desks or belongings that they borrowed. This will help the impact of covid-19 on our school and will help the school be a cleaner and more disease-safe place.
In the end, we discovered that every single piece of bread grew mould except for the controlled bread, not even a speck of mould grew on that piece of bread! According to the graph, the bread with the most mould spots is the vending machine buttons bread. But, if you look at the actual piece of bread, the bread that has the most mould on it is the cafeteria table bread. The piece of bread that grew the fastest was the vending machine buttons bread. The bread that grew the slowest was the doorknob bread. And, the controlled bread grew no mould at all! We noticed that in our graph, the mould was growing a lot in the middle and not really at the start. In our hypothesis, we said that we thought the dirtiest places in the school would be the doorknobs, cafeteria tables, and vending machine buttons. We were right about the cafeteria tables and the vending machine buttons, those were the two pieces of bread that grew the most mould. However, we were a little shocked that the doorknob bread did not have that much mould on it. But we thought it was a little reasonable because most of the time the door is open and plus not many people touch it. Also, in our hypothesis, we said that we think that the toilet seats, whiteboards and teacher's desks will be some of the cleanest places. We were right about the toilet seats and the whiteboards. For the whiteboard bread, we thought that people do not really touch whiteboards with their hands so we do not think that there will be much mould on the whiteboard bread. However, for the teacher's desk bread, it was quite dirty!
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