Question 1

Which of the following best describes the main purpose of lactic acid fermentation in human muscle cells during intense exercise?

Accepted Answer

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

Question 2

During alcoholic fermentation, which of the following is the correct sequence of major products formed from glucose?

Accepted Answer

Glucose $$ \rightarrow $$ Pyruvate $$ \rightarrow $$ Ethanol + CO$$_2$$ $$ \rightarrow $$ NAD$$ ^+ $$

Question 3

Why is lactic acid fermentation sometimes referred to as a 'short circuit' of aerobic respiration?

Accepted Answer

It allows cells to skip the Krebs cycle and electron transport chain, regenerating NAD$$ ^+ $$ directly from pyruvate

Question 4

Which of the following statements correctly compares lactic acid fermentation and alcoholic fermentation?

Accepted Answer

Both regenerate NAD$$ ^+ $$ from NADH, but only alcoholic fermentation produces CO$$_2$$

Question 5

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

Accepted Answer

Fermentation only uses glycolysis, yielding 2 ATP per glucose, while aerobic respiration uses glycolysis, Krebs cycle, and electron transport chain, yielding up to 38 ATP per glucose

Question 6

Under which condition might an aerobic organism switch to anaerobic respiration (fermentation)?

Accepted Answer

When oxygen is scarce or unavailable, such as during intense exercise

Question 7

Which type of organism is capable of surviving solely on anaerobic respiration, and what is a common example?

Accepted Answer

Obligate anaerobes; Clostridium species

Question 8

Which of the following is a key evolutionary reason supporting the idea that glycolysis evolved very early in the history of life?

Accepted Answer

Glycolysis occurs in the cytoplasm and does not require membrane-bound organelles, making it possible in primitive cells

Question 9

Which of the following is NOT a similarity between lactic acid fermentation and alcoholic fermentation?

Accepted Answer

Both produce lactic acid as a final product

Question 10

A scientist is studying a culture of yeast cells in a sealed, oxygen-free environment. Which products would she expect to find in high concentrations after several hours?

Accepted Answer

Ethanol and CO$$_2$$

Question 11

Which of the following equations correctly represents the net reaction for lactic acid fermentation?

Accepted Answer

$$C_6H_{12}O_6$ \rightarrow 2C_3H_6O_3$$

Question 12

Which of the following best explains why glycolysis is considered a universal metabolic pathway?

Accepted Answer

It is present in nearly all living organisms and occurs in the cytoplasm, independent of organelles

Question 13

A patient with a genetic defect that prevents the conversion of pyruvate to lactate would most likely experience which of the following during intense exercise?

Accepted Answer

Accumulation of pyruvate and decreased regeneration of NAD$$ ^+ $$, leading to muscle fatigue

Question 14

Which of the following is a major difference between lactic acid fermentation and alcoholic fermentation?

Accepted Answer

Alcoholic fermentation produces ethanol and CO$$_2$$, while lactic acid fermentation produces lactic acid only

Question 15

Which of the following data would best support the hypothesis that glycolysis evolved before the presence of oxygen in Earth's atmosphere?

Accepted Answer

Glycolysis occurs in the cytoplasm and does not require oxygen

Question 16

In a scenario where a facultative anaerobe is exposed to both oxygen and glucose, which metabolic pathway will it primarily use and why?

Accepted Answer

Aerobic respiration, because it yields more ATP per glucose molecule

Question 17

Which of the following is the correct net equation for alcoholic fermentation?

Accepted Answer

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

Question 18

Which of the following best describes the evolutionary advantage of glycolysis being present in both aerobic and anaerobic organisms?

Accepted Answer

It allows organisms to produce ATP regardless of the presence of oxygen

Question 19

A brewery is experiencing a problem where their yeast cultures are not producing ethanol. Which step in alcoholic fermentation is most likely being disrupted?

Accepted Answer

Conversion of pyruvate to acetaldehyde and then to ethanol

Question 20

Which of the following is a real-world example of lactic acid fermentation in humans?

Accepted Answer

Muscle soreness after sprinting due to accumulation of lactic acid

Fermentation Pathways and the Evolutionary Role of Glycolysis

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