Question 1

Which of the following best describes the main purpose of fermentation in cells?

Accepted Answer

To regenerate NAD+ so glycolysis can continue producing ATP in the absence of oxygen.

Question 2

Where in the cell does fermentation occur?

Accepted Answer

In the cytoplasm.

Question 3

During glycolysis, which is the correct net ATP yield per molecule of glucose?

Accepted Answer

$$2$$ net ATP

Question 4

Which of the following is a product of lactic acid fermentation in human muscle cells?

Accepted Answer

Lactate

Question 5

What are the reactants required for the fermentation step following glycolysis in yeast cells?

Accepted Answer

2 Pyruvate and 2 NADH

Question 6

Which of the following equations correctly represents the overall process of lactic acid fermentation?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 2\ \mathrm{ADP} + 2\ \mathrm{P_i} \rightarrow 2\ \mathrm{Lactate} + 2\ \mathrm{ATP}$$

Question 7

A yeast cell is placed in an anaerobic environment with abundant glucose. Which products will accumulate as a result of fermentation?

Accepted Answer

Ethanol, CO$$_2$$, and ATP

Question 8

Why is NAD+ regeneration critical during fermentation?

Accepted Answer

Because NAD+ is required for glycolysis to continue producing ATP.

Question 9

Which of the following best explains why fermentation is less efficient than aerobic respiration?

Accepted Answer

Fermentation produces only $$2$$ ATP per glucose, while aerobic respiration can produce up to $$36$$ ATP per glucose.

Question 10

A patient’s muscle cells are deprived of oxygen during intense exercise. Which metabolic pathway will their cells primarily use to generate ATP, and what byproduct will accumulate?

Accepted Answer

Lactic acid fermentation; lactate

Question 11

Which of the following is the correct sequence of steps in fermentation starting from glucose?

Accepted Answer

Glucose enters cell → Glycolysis → Pyruvate formation → Fermentation (lactic acid or ethanol)

Question 12

If a mutation prevents the regeneration of NAD+ during fermentation, what is the most likely consequence for the cell?

Accepted Answer

Glycolysis will stop, and ATP production will decrease.

Question 13

Which of the following is a key difference between lactic acid fermentation and ethanol fermentation?

Accepted Answer

Lactic acid fermentation produces lactate, while ethanol fermentation produces ethanol and CO$$_2.$$

Question 14

A scientist measures the products of fermentation in a culture of yeast cells. Which of the following would she expect to find?

Accepted Answer

Ethanol, CO$$_2$$, and NAD+

Question 15

Which of the following statements about glycolysis is correct?

Accepted Answer

Glycolysis converts one molecule of glucose into two molecules of pyruvate.

Question 16

In the absence of oxygen, what happens to the pyruvate produced by glycolysis in human muscle cells?

Accepted Answer

It is converted to lactate.

Question 17

Which of the following best explains why yeast cells produce CO$$_2$$ during fermentation, but human muscle cells do not?

Accepted Answer

Yeast cells perform ethanol fermentation, which releases CO$$_2$$, while human muscle cells perform lactic acid fermentation, which does not.

Question 18

A researcher blocks the transport protein that allows glucose to enter a cell. What is the most immediate effect on fermentation?

Accepted Answer

Fermentation will not occur because glucose cannot enter the cell.

Question 19

Which of the following is a correct summary of the reactants and products of ethanol fermentation?

Accepted Answer

Reactants: 2 Pyruvate, 2 NADH; Products: 2 Ethanol, 2 CO$$_2$$, 2 NAD+

Question 20

A cell is performing fermentation and you measure the following: high levels of NADH and low levels of NAD+. What is the most likely explanation?

Accepted Answer

The fermentation pathway is blocked, preventing NADH from being oxidized to NAD+.

Fermentation: Pathways, Steps, and Cellular Context

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