Eukaryotic Microbes, Parasitology, & Viruses Microbes, Parasitology, & Viruses ... 12. Record your...
Transcript of Eukaryotic Microbes, Parasitology, & Viruses Microbes, Parasitology, & Viruses ... 12. Record your...
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Eukaryotic Microbes, Parasitology, & Viruses
Experiment 1: Mold Growth on Bread and Fruit--What are Optimal Conditions for Fungal Growth? Fungi are unable to ingest food. Instead, they must absorb nutrients (like bacteria) rather than ingesting
them (as is the case for animals). Fungi secrete enzymes into their surroundings to help breakdown their
food source and facilitate the absorption process. Fungi frequently have different growth requirements than
bacteria. This can sometimes enable them to grow in places bacteria cannot. For example, fungi can grow
at a pH of 5, which is too acidic for most bacteria. Some fungi can also tolerate higher osmotic pressures
than bacteria can. This enables them to grow in areas with higher solute concentrations. Further, some fun-
gi can use carbohydrate sources (such as those from wood) for energy that most bacteria cannot use. In
this experiment, you will determine which factors encourage mold (filamentous fungi) growth on pieces of
bread and apples.
Procedure: 1. Add 120 mL of water to a saucepan or large microwaveable bowl and mix in 1/2 cup of sugar.
2. Gently heat the water/sugar mixture on the stove or in the microwave, stirring occasionally until all of the
sugar is dissolved. Use caution when removing the solution from the microwave/stove as it will be hot.
Allow the solution to cool.
3. Label the plastic bags with these titles: “bright, control”, “bright, water”, “bright, sugar”, “bright, lemon”,
“bright, vinegar”, “dark, control”, “dark, water”, “dark, sugar”, “dark, lemon”, and “dark, vinegar”.
4. Cut the two slices of bread into 10 total pieces (5 pieces from each slice).
5. Cut the apple into 10 slices.
6. Place one piece of bread and one slice of apple into a plastic bag. Repeat this process until you have
10 bags, each with one piece of bread and one slice of apple.
2 tsp. Lemon juice
1/2 C. Sugar
2 tsp. White vinegar
Plastic bags
Measuring spoon
250 mL Beaker
Permanent marker
*2 Slices of bread
*Apple
*Sharp utensil to cut the apple and bread
*Sauce pan
*Stove or microwave
*Large microwavable bowl
*Water
*You must provide
Materials
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Eukaryotic Microbes, Parasitology, & Viruses
7. Measure 120 mL of plain water in a clean, separate bowl.
8. Add 1 tsp. plain water to the bags labeled as water; add 1 tsp. of the sugar-water solution (prepared in
Step 1) to the bags labeled sugar; add 1 tsp. of lemon juice to the bags labeled lemon; add 1 teaspoon
white vinegar to the bags labeled vinegar. Do not add anything to the bags labeled control.
9. Find a well-lit, warm location in which to place the bags labeled bright (for example a windowsill or un-
der a lamp).
10. Find a dark, warm location in which to place the bags labeled dark (for example a warm closet).
11. Examine the bags every 1 - 2 days for 2 weeks and look for mold formation on the bread and apple
pieces. Take particular note to which environmental condition(s) mold formed in first and last. Also,
make sure to note which environmental condition(s) grew the most and least mold. Use the following
scale to assess the extent of mold growth:
0 = none
1 = little/some (1-25%)
2 = moderate (26-50%)
3 = heavy (51-75%) 4 = extensive (76-100%)
12. Record your results in Table 1.
13. Do not open the bags when you are finished with the experiment. This will disperse mold spores and
contaminate your work/living area. Dispose of the sealed bags in the trash and remove the trash bag
from your living area.
Condition Extent of Growth
Bright, Control
Bright, Water
Bright, Sugar
Bright, Lemon
Bright, Vinegar
Dark, Control
Dark, Water
Dark, Sugar
Dark, Lemon
Dark, Vinegar
Table 1: Growth Results