Q: What is the overall net equation for aerobic cellular respiration in yeast?

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

Q: Which of the following is the correct net equation for alcohol fermentation in yeast?

$$\mathrm{C_6H_{12}O_6$} \rightarrow 2\,\mathrm{C_2H_5OH} + 2\,\mathrm{CO_2$} + \text{energy}$$

Question 1

Which of the following best describes why yeast are considered facultative anaerobes?

Accepted Answer

They can switch between aerobic respiration and fermentation depending on environmental oxygen availability.

Question 2

What is the overall net equation for aerobic cellular respiration in yeast?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\,\mathrm{O_2$} ightarrow 6\,\mathrm{CO_2$} + 6\,\mathrm{H_2O} + 	ext{energy}$$

Question 3

During the experiment, a balloon was attached to the bottle containing yeast and apple juice. What gas caused the balloon to inflate during fermentation?

Accepted Answer

Carbon dioxide ($$\mathrm{CO_2$})$$

Question 4

Which of the following is the correct net equation for alcohol fermentation in yeast?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} ightarrow 2\,\mathrm{C_2H_5OH} + 2\,\mathrm{CO_2$} + 	ext{energy}$$

Question 5

In aerobic respiration, for each molecule of glucose oxidized, how many molecules of oxygen are consumed by yeast?

Accepted Answer

6

Question 6

At which stage of aerobic respiration is carbon dioxide ($$\mathrm{CO_2$}) $$released?

Accepted Answer

During the Krebs cycle (citric acid cycle)

Question 7

If the yeast in the experiment used up all the oxygen in the bottle, what would happen next?

Accepted Answer

The yeast would switch to fermentation to continue producing energy.

Question 8

During anaerobic fermentation, for each molecule of glucose metabolized, how many molecules of carbon dioxide are produced?

Accepted Answer

2

Question 9

Why does the balloon continue to inflate even after all the oxygen is used up in the bottle?

Accepted Answer

Fermentation produces carbon dioxide as a waste product, which accumulates and inflates the balloon.

Question 10

After a week, what would you expect the smell of the bottle to be and why?

Accepted Answer

It would smell like alcohol due to ethanol production from fermentation.

Question 11

Which of the following best explains why there is not an even exchange between oxygen consumed and carbon dioxide produced during aerobic respiration?

Accepted Answer

Oxygen is used to form water, while carbon dioxide is released from the breakdown of glucose.

Question 12

If you observed bubbles forming in the yeast mixture, what is the most likely explanation?

Accepted Answer

The yeast are producing carbon dioxide as a result of metabolic activity.

Question 13

Which of the following is a key difference between aerobic respiration and fermentation in yeast?

Accepted Answer

Aerobic respiration requires oxygen and produces more ATP than fermentation.

Question 14

Suppose you set up two identical bottles, one with oxygen and one without. After 30 minutes, which bottle would have a larger balloon and why?

Accepted Answer

The bottle without oxygen, because fermentation produces carbon dioxide that accumulates in the balloon.

Question 15

Which of the following best explains why yeast produce ethanol during fermentation?

Accepted Answer

To regenerate NAD+ needed for glycolysis to continue.

Question 16

If you left the yeast and balloon setup for a week, what would most likely happen to the yeast population?

Accepted Answer

The yeast would eventually die as sugar is depleted and ethanol accumulates.

Question 17

Which of the following is a metabolic waste product of alcohol fermentation in yeast?

Accepted Answer

Ethanol

Question 18

Why is NAD+ regeneration important during fermentation?

Accepted Answer

NAD+ is required for glycolysis to continue producing ATP.

Question 19

Which of the following best describes the fate of glucose during yeast fermentation?

Accepted Answer

It is partially broken down to ethanol and carbon dioxide.

Question 20

In the context of the experiment, why is apple juice added to the yeast mixture?

Accepted Answer

To supply sugar for yeast metabolism.

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