Tag: respiration in plants

In lactic acid fermentation, the 3-carbon pyruvate is converted to the 3-carbon lactic acid. Also NAD$^{+}$ is regenerated in the process, allowing glycolysis to continue to make ATP in anaerobic conditions. Hence lactate and NAD$^{+}$ are the direct products and ATP is the indirect product of lactic acid fermentation. NADH act as a reducing agent here, while CO$ _{2}$ is a product of alcohol fermentation.

A) Lactic acid fermentation is the process that occurs after glycolysis when there is lack of oxygen.

Fermentation is a type of anaerobic respiration in which the glucose is broken down into pyruvic acid in the absence of oxygen. During fermentation of sugars, this pyruvic acids coverts to a 2C acetaldehyde and then to ethanol and CO₂. All this takes place in the cytoplasm.

Unicellular organisms like yeast undergo an alternate pathway of respiration in which an organic substrate is broken down in absence of oxygen. The end products are alcohol and CO$ _2$. Such a process is called alcoholic fermentation. In Yeast, the fermentation products are ethyl alcohol and carbon dioxide.

Conversion of sugar to alcohol directly was found in yeast fermentation in which glucose was converted to ethyl alcohol and CO$ _2$. The conversion happens in presence of an enzyme called zymase which is found naturally in yeast. So, the answer is 'Zymase'.

Cellular respiration in animals is predominantly aerobic in nature. However in stressful conditions, the respiration turns anaerobic to meet the energy demands. End products of anaerobic respiration are lactic acid and water. End products in plants for aerobic respiration are alcohol and carbon dioxide.

The given process is alcoholic respiration and is done by the yeast in which two molecules of ATP, carbon dioxide and alcohol is released and the process takes place in the absence of oxygen.

Alcoholic fermentation employs the conversion of pyruvic acid to ethanol for the release of energy. This is an incomplete oxidation in which aldehyde is first formed as an intermediate which is then further oxidised to alcohol. Pyruvic acid to acetaldehyde conversion is brought about by pyruvate decarboxylase which releases CO2.

Alcoholic fermentation occurs in the absence of O2 and is a type of anaerobic respiration in which the end products are CO2 and alcohol. Aldehyde is an intermediate product in fermentation and is further oxidised to alcohol with the help of an enzyme called dehydrogenase. So ethanol is formed from acetaldehyde with the help of alcohol dehydrogenase.

In lactic acid fermentation which occurs in the absence of oxygen like fermentation after glycolysis form lactate which gets deprotonated to form lactic acid while in fermentation acetaldehyde converts into alcohol by deprotonation of it.