When oxygen is not available (anaerobic condition) yeast and some other microbes convert pyruvic acid into ethyl alcohol. It is a two step process. In the first step pyruvic acid is decarboxylated to yield acetaldehyde and CO2.


( or)
In aerobic respiration or biological oxidation of one glucose molecules, 38 ADP molecules change into 38 ATP molecules, where donor phophate is inorganic phosphate . ATP molecules are the energy currency of the cell, i.e., the common immediate source of energy in cellular activity

Explanation:

When one glucose molecule is completely oxidized, it goes through a series of biochemical reactions known as cellular respiration. This process occurs in the mitochondria of cells and involves the breakdown of glucose to produce energy in the form of ATP (adenosine triphosphate).

Step 1: Glycolysis
The first step of glucose oxidation is glycolysis, which occurs in the cytoplasm of cells. During glycolysis, one glucose molecule is broken down into two molecules of pyruvate. This process requires the input of two ATP molecules but produces four ATP molecules through substrate-level phosphorylation. Therefore, the net production of ATP during glycolysis is two molecules.

Step 2: Pyruvate Decarboxylation
The two molecules of pyruvate produced in glycolysis are transported into the mitochondria. In the mitochondrial matrix, each pyruvate molecule undergoes decarboxylation and is converted to a molecule called acetyl-CoA. This step does not directly produce ATP but is essential for the next stage of glucose oxidation.

Step 3: Krebs Cycle
The acetyl-CoA molecules produced from pyruvate decarboxylation enter the Krebs cycle, also known as the citric acid cycle. This cycle takes place in the mitochondrial matrix and involves a series of chemical reactions that result in the release of carbon dioxide and the production of high-energy electron carriers (NADH and FADH2). Although the Krebs cycle does not directly produce ATP, it generates electron carriers that participate in the next step of glucose oxidation.

Step 4: Electron Transport Chain
The high-energy electron carriers (NADH and FADH2) produced in the Krebs cycle donate their electrons to the electron transport chain (ETC), located in the inner mitochondrial membrane. As the electrons pass through the ETC, a series of redox reactions occur, generating a proton gradient across the membrane. This gradient is used by ATP synthase to produce ATP through oxidative phosphorylation.

Final ATP Yield
For each glucose molecule that undergoes complete oxidation, the net production of ATP is as follows:
- Glycolysis: 2 ATP
- Krebs cycle: 2 ATP (from GTP, which is later converted to ATP)
- Electron transport chain: 34 ATP

Therefore, the total ATP yield from one glucose molecule is 2 + 2 + 34 = 38 ATP molecules.

Conclusion:
Option B, which states that the complete oxidation of one glucose molecule changes 38 ADP molecules into 38 ATP molecules, is the correct answer.