Question 1

Which of the following best describes the process shown in the first image, where ethanol is converted to acetaldehyde?

Accepted Answer

Oxidation, where ethanol loses electrons and protons to form acetaldehyde.

Question 2

In the second image, the term 'dehydrogenation' is used to describe the conversion of ethanol to acetaldehyde. What does dehydrogenation specifically refer to in biological oxidation reactions?

Accepted Answer

The removal of hydrogen atoms (proton and electron) from a molecule.

Question 3

Referencing the third image, which reaction is catalyzed by alcohol dehydrogenase during alcoholic fermentation in yeast?

Accepted Answer

Reduction of acetaldehyde to ethanol using [2H].

Question 4

In the fourth image, which molecule acts as the electron acceptor during glycolysis in the absence of oxygen?

Accepted Answer

Pyruvate

Question 5

Which of the following statements about the conversion of ethanol to acetaldehyde is correct?

Accepted Answer

It is an oxidation reaction, where ethanol loses hydrogen atoms.

Question 6

During alcoholic fermentation, which step is responsible for regenerating NAD+ from NADH?

Accepted Answer

Reduction of acetaldehyde to ethanol.

Question 7

Which enzyme catalyzes the conversion of acetaldehyde to ethanol in yeast cells?

Accepted Answer

Alcohol dehydrogenase

Question 8

In glycolysis, what is the fate of pyruvate under anaerobic conditions in muscle cells?

Accepted Answer

It is reduced to lactate.

Question 9

Which of the following best explains why fermentation is necessary in the absence of oxygen?

Accepted Answer

To regenerate NAD+ so glycolysis can continue.

Question 10

Which of the following equations correctly represents the reduction of acetaldehyde to ethanol during alcoholic fermentation? (Use double backslashes for LaTeX formatting)

Accepted Answer

$$\mathrm{CH_3CHO} + [2H] \rightarrow \mathrm{CH_3CH_2OH}$$

Question 11

Which of the following is a key difference between oxidation and reduction reactions in biological systems?

Accepted Answer

Oxidation involves the removal of electrons and protons, while reduction involves the addition of electrons and protons.

Question 12

Which of the following best describes the role of NAD+ in glycolysis and fermentation?

Accepted Answer

NAD+ serves as an electron acceptor, becoming reduced to NADH.

Question 13

During glycolysis, which step is directly responsible for substrate-level phosphorylation?

Accepted Answer

Transfer of phosphate from 1,3-bisphosphoglycerate to ADP.

Question 14

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation regenerates NAD+ without net oxidation of the substrate.

Question 15

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

Accepted Answer

Lactate

Question 16

Which of the following best explains why cancer cells often rely on aerobic glycolysis?

Accepted Answer

To produce carbon skeletons for biosynthesis needed by proliferating cells.

Question 17

Which of the following reactions is catalyzed by pyruvate decarboxylase during alcoholic fermentation?

Accepted Answer

$$\mathrm{Pyruvate} \rightarrow \mathrm{Acetaldehyde} + \mathrm{CO_2$}$$

Question 18

Which of the following best describes the fate of NADH produced during glycolysis under anaerobic conditions?

Accepted Answer

It is reoxidized to NAD+ by transferring electrons to pyruvate or acetaldehyde.

Question 19

Which of the following is a correct summary equation for alcoholic fermentation? (Use double backslashes for LaTeX formatting)

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} \rightarrow 2\mathrm{CH_3CH_2OH} + 2\mathrm{CO_2$}$$

Chemotrophic Energy Metabolism: Glycolysis and Fermentation – Study Notes

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