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Organism Research Worksheet

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Organism Research Worksheet

In a cooking class, Mele and Rawiri are investigating how baker’s yeast affects dough. Yeast is a single-celled fungus. It uses sugars for respiration and produces a gas; the gas forms bubbles that can make dough rise. Temperature affects how quickly yeast carries out this process. The class compares yeast mixtures at different temperatures, keeping the amounts of yeast, sugar and water the same. Use the results below as secondary data: they were collected by another group, not by you.

Water temperature (°C)

Gas collected (mL)

Understand the organism and evidence

Use the scenario and data to explain what the investigation can—and cannot—show.

1.Which group of organisms does baker’s yeast belong to? Select one answer.

Bacteria
Fungi
Protists
Viruses

2.Complete the statement: In this investigation, yeast uses sugar in respiration and releases gas, which can help dough rise.

3.Match each investigation feature to its role.

Water temperature
Gas volume after 10 minutes
Amount of sugar in each mixture

Variable kept the same
Independent variable
Dependent variable

4.At which tested temperature was the greatest volume of gas collected? Give the volume as well.

5.Compare the results at 10°C and 25°C. What pattern do they suggest about temperature and yeast activity over this range?

6.True or false: The results prove that yeast activity will keep increasing as temperature rises above 35°C. Explain your choice using the data.

7.Identify one limitation of using the gas volume as evidence of yeast respiration. Suggest one improvement to the method.

Plan a follow-up investigation

Use your understanding of variables, measurement and evidence to design a safe, fair test.

8.Mele wants to test how sugar availability affects yeast respiration. State a testable question and identify the independent variable and one factor she should keep the same.

9.Write a measurement plan for Rawiri’s test. Include what he will measure, the units, when he will measure it, and how many repeats would make the evidence more reliable.

10.The data show 0 mL of gas at 60°C. Give one cautious explanation for this result and one additional observation or measurement that could help investigate it.

11.Explain one way yeast respiration could affect another part of its environment during dough-making.