How are lactic acid and alcohol fermentation similar? They have the same products They have the same reactants They both require oxygen d. They occur in the same organisms
The Correct Answer and Explanation is:
Correct Answer:
b. They have the same reactants
Explanation:
Lactic acid fermentation and alcohol fermentation are two types of anaerobic respiration—processes that allow organisms to produce energy without using oxygen. Although they produce different end products, these two types of fermentation begin with the same reactant: glucose.
Both fermentation processes start with glycolysis, which is the breakdown of one molecule of glucose (C₆H₁₂O₆) into two molecules of pyruvate. This step takes place in the cytoplasm and generates a small amount of ATP (energy) and NADH. In the absence of oxygen, cells cannot use the electron transport chain to regenerate NAD⁺ from NADH. Therefore, they rely on fermentation to recycle NADH back to NAD⁺ so glycolysis can continue.
In lactic acid fermentation, which occurs in some bacteria and in muscle cells under low-oxygen conditions, the pyruvate is directly converted into lactic acid (or lactate). This process regenerates NAD⁺ without releasing carbon dioxide.
In alcohol fermentation, which occurs in yeast and some types of bacteria, the pyruvate is first converted into acetaldehyde and carbon dioxide, and then into ethyl alcohol (ethanol). This also regenerates NAD⁺.
Despite having different products—lactic acid versus ethanol and carbon dioxide—both fermentation types begin with glucose as the primary reactant, and both regenerate NAD⁺ to sustain glycolysis. Importantly, neither process requires oxygen, which is why they are both forms of anaerobic respiration.
Therefore, the correct answer is that they have the same reactants, even though they result in different products and may occur in different organisms (e.g., humans versus yeast).
