Fermentation vs. Cellular Respiration: Yeast Lab Study Guide

Q2. What is the overall net equation for cellular respiration?

Background

Topic: Cellular Respiration

This question tests your understanding of the chemical process by which cells convert glucose and oxygen into energy, carbon dioxide, and water.

Key Terms and Formulas

• Glucose ($C_6H_{12}O_6$)

• Oxygen ($O_2$)

• Carbon dioxide ($CO_2$)

• Water ($H_2O$)

• ATP (energy molecule)

The net equation for cellular respiration is:

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy (ATP)}$

Step-by-Step Guidance

1. Recall that cellular respiration is a process where glucose is broken down in the presence of oxygen.

2. Identify the reactants: glucose ($C_6H_{12}O_6$) and oxygen ($O_2$).

3. Identify the products: carbon dioxide ($CO_2$), water ($H_2O$), and energy (ATP).

4. Balance the equation so that the number of atoms for each element is equal on both sides.

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Q3. What is the overall net equation for alcohol fermentation?

Background

Topic: Alcohol Fermentation

This question tests your understanding of how yeast converts glucose into ethanol and carbon dioxide in the absence of oxygen.

Key Terms and Formulas

• Glucose ($C_6H_{12}O_6$)

• Ethanol ($C_2H_5OH$)

• Carbon dioxide ($CO_2$)

• NAD$^+$ (regenerated during fermentation)

The net equation for alcohol fermentation is:

$C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2$

Step-by-Step Guidance

1. Recall that fermentation occurs when oxygen is not available.

2. Identify the reactant: glucose ($C_6H_{12}O_6$).

3. Identify the products: ethanol ($C_2H_5OH$) and carbon dioxide ($CO_2$).

4. Balance the equation so that the number of atoms for each element is equal on both sides.

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Q4. What gas was being produced at the very beginning of the experiment? How do you know that a gas was being produced?

Background

Topic: Gas Production During Cellular Respiration

This question tests your ability to connect the observed experimental results (balloon inflation) to the metabolic processes occurring in yeast.

Key Terms

• Cellular respiration

• Carbon dioxide ($CO_2$)

• Balloon inflation as evidence of gas production

Step-by-Step Guidance

1. Consider which metabolic process is occurring when oxygen is present (aerobic respiration).

2. Recall that carbon dioxide ($CO_2$) is a waste product of aerobic respiration.

3. Think about how the balloon attached to the bottle would respond to gas production (it would inflate).

4. Use your observations from the experiment to infer which gas is being produced.

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Q5. For each molecule of glucose oxidized in aerobic respiration:

Background

Topic: Stoichiometry of Cellular Respiration

This question tests your understanding of the quantitative relationships between reactants and products in aerobic respiration.

Key Terms and Formulas

• Glucose ($C_6H_{12}O_6$)

• Oxygen ($O_2$)

• Carbon dioxide ($CO_2$)

• Stages: Glycolysis, Krebs cycle, Electron Transport Chain

Relevant equation:

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$

Step-by-Step Guidance

1. Look at the balanced equation to determine how many $O_2$ molecules are consumed per glucose.

2. Identify where in the process oxygen is used (hint: Electron Transport Chain).

3. Determine how many $CO_2$ molecules are produced per glucose.

4. Recall at which stage $CO_2$ is released (hint: Krebs cycle).

5. Consider whether there is an even exchange between $O_2$ and $CO_2$.

6. Think about whether the total amount of gas in the flask changes and how this affects the balloon.

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Q6. When all of the O2 in the bottle is used up, the yeast switches to fermentation. For each molecule of glucose metabolized in anaerobic respiration:

Background

Topic: Anaerobic Respiration (Fermentation)

This question tests your understanding of the stoichiometry and gas production during fermentation.

Key Terms and Formulas

• Glucose ($C_6H_{12}O_6$)

• Ethanol ($C_2H_5OH$)

• Carbon dioxide ($CO_2$)

• Oxygen ($O_2$)

Relevant equation:

$C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2$

Step-by-Step Guidance

1. Refer to the balanced equation to determine how many $O_2$ molecules are consumed per glucose (hint: none).

2. Determine how many $CO_2$ molecules are produced per glucose.

3. Consider whether the total amount of gas in the flask changes during fermentation.

4. Think about whether the type of gas in the flask changes (from $O_2$ to $CO_2$).

5. Predict whether the balloon will increase in size during fermentation and explain your reasoning.

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Q7. After 30 minutes, observe the balloon and answer the following questions:

Background

Topic: Experimental Observation and Interpretation

This question tests your ability to interpret experimental results and connect them to the metabolic processes occurring in yeast.

Key Terms

• Balloon inflation

• Respiration type (aerobic vs. anaerobic)

• Gas production ($CO_2$)

Step-by-Step Guidance

1. Observe the balloon and note any changes in size or shape.

2. Determine which type of respiration the yeast is carrying out based on the presence or absence of oxygen.

3. Use your observations (such as bubbles) to infer which gas is being produced.

4. Explain how the gas production relates to the metabolic process (cellular respiration or fermentation).

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Q8. What do you think would happen to the yeast and to the balloon if you left the setup for a week? Explain your answer.

Background

Topic: Yeast Metabolism Over Time

This question tests your ability to predict the outcome of a long-term experiment based on your understanding of yeast metabolism.

Key Terms

• Yeast viability

• Substrate depletion

• Gas production

Step-by-Step Guidance

1. Consider what happens to yeast when the sugar (substrate) runs out.

2. Think about how gas production would change over time.

3. Predict what would happen to the balloon as yeast activity decreases.

4. Explain your reasoning based on yeast metabolism and environmental conditions.

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Q9. What would the bottle smell like at the end of the week? Explain.

Background

Topic: Byproducts of Fermentation

This question tests your understanding of the metabolic byproducts produced by yeast during fermentation.

Key Terms

• Ethanol

• Fermentation

• Metabolic waste

Step-by-Step Guidance

1. Recall that ethanol is a byproduct of alcohol fermentation.

2. Consider how the accumulation of ethanol and other waste products would affect the smell.

3. Think about any other possible odors from yeast metabolism or spoilage.

4. Explain your reasoning based on the chemical processes involved.

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