Question

“3. Would these conditions apply to all fungal growth? Why or why not?”

“4. How would changing the type of bread (fresh from a bakery, no preservatives vs. prepackaged with preservatives) affect the results? Describe an experiment that would test your hypothesis.”

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“5. How would changing the incubation temperature of the bags affect the results? Describe an experiment that would test your hypothesis.”

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“6. Look up the pH of lemon juice and vinegar. Based on your results and your knowledge of favorable environmental conditions for fungal growth, what can you conclude about the effect of pH on growth? How would making the pH more basic affect growth?”

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“7. What is the source of the mold that grew on the samples?”

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Answer 1

“4. How would changing the type of bread (fresh from a bakery, no preservatives vs. prepackaged with preservatives) affect the results? Describe an experiment that would test your hypothesis.”

Answers: Bakery bread contains two preservatives calcium propanoate and propionic acid. Both of these preservatives inhibit the growth of the fungi on the bread. Therefore, the fungus will grow fast on the bread with no preservatives as compared to the bread contains preservatives.

Experiment designing to prove the hypothesis: Keep both, bread which contains and do not contains preservative at 25-degree celsius (optimal temperature for the growth of fungus). Monitor the blackening of the bread after every one hour of incubation. The growth of fungus turns bread black.

5. How would changing the incubation temperature of the bags affect the results? Describe an experiment that would test your hypothesis.”

Answers: The optimal temperature for the growth of the fungus is 25-degree celsius. Decreasing or increasing the temperature value from the optimal temperature will affect the growth of the fungus on the bread (food).

Experiment designing: Incubate bread that does not contain a preservative is incubated at three different temperatures viz 10, 25 and 37-degree celsius. Monitor the growth of the fungus in all three temperatures. Alternatively, experiment at three different temperatures can also perform by taking bread which contains preservatives.

6. Look up the pH of lemon juice and vinegar. Based on your results and your knowledge of favorable environmental conditions for fungal growth, what can you conclude about the effect of pH on growth? How would making the pH more basic affect growth?”

Answers: Optimal pH for the fungal growth is 5 to 6. Therefore, if you are going above 8 or below 2 (acidic), then only growth of the fungus will be inhibited. At alkaline pH above 8, the growth of the fungus is inhibited. The pH of lemon and vinegar is 2-3 and 3.7, respectively. Therefore at these acidic pH, the growth of the fungus will be slow but not inhibited. The growth would be much slower in case of lemon than the vinegar; as the pH of lemon is close to 2.

“7. What is the source of the mold that grew on the samples?”

Answers: Mould is present in the air, plant and animal tissues. Therefore food should be kept in the close container to prevent contamination from mold.