In lactic acid fermentation, ______ is _______
a) lactate...oxidized
b) pyruvate...reduced
c) ethanol...oxidized
d) NAD+...oxidized
e) NADH...reduced
I think it's b.
In lactic acid fermentation, the correct answer is (a) lactate is oxidized.
To answer this question, we need to understand the process of lactic acid fermentation and the role played by different molecules.
Lactic acid fermentation is an anaerobic metabolic process that occurs in certain microorganisms, including bacteria and yeast. It also happens in our muscle cells when there is a lack of oxygen during intense exercise. In this process, glucose is converted into lactic acid, producing a small amount of ATP (energy).
During lactic acid fermentation, the molecule being reduced is pyruvate. Reduction is a chemical reaction that involves the gain of electrons or a decrease in oxidation state. Pyruvate, which is a three-carbon molecule produced during glycolysis, is reduced to form lactic acid.
Therefore, the correct answer to the question is:
b) Pyruvate is reduced.
In lactic acid fermentation, pyruvate is converted into lactic acid. This conversion involves the transfer of electrons, and pyruvate gains electrons to form lactic acid, making it the molecule that is being reduced.
It is important to note that oxidation and reduction always occur together, as electrons are transferred from one molecule to another. In this process, the molecule that donates electrons, such as NADH, is oxidized, while the molecule that accepts those electrons, such as pyruvate, is reduced. However, in lactic acid fermentation, NADH is not directly involved in the reduction process, so answer option e) NADH...reduced is not correct.
Understanding the concepts of redox reactions, electron transfer, and the specific metabolic pathways involved in a process like lactic acid fermentation allows us to determine the correct answer to the question.