Question

Question: Most CO₂ from catabolism is released during

1. glycolysis.
2. citric acid cycle
3. lactate fermentation
4. electron transport

Short answer

1. The option “glycolysis” is false.
2. The option “citric acid cycle” is true.
3. The option “lactate fermentation” is false.
4. The option “electron transport” is false.

Step-by-step solution

Metabolism

Metabolism is the chemical reaction that occurs in the body to facilitate the process of living. In metabolism, the catabolic reaction involves the breakdown of complex organic molecules into simpler absorbable forms.

Explanation of option ‘(A)’

Glucose is the precursor molecule that is essential for the glycolysis process. It is converted into pyruvate, which is a three-carbon compound that is produced from glucose.

Thus, the glycolysis mechanism creates two pyruvate molecules, 2 ATP and 6 NADH molecules, as the end products.

Therefore, the given statement is false.

Explanation of option ‘(B)’

The second step followed by glycolysis in the aerobic oxidation process is the citric acid cycle. The precursor for this process is acetyl CoA. There is the formation of 2 molecules of carbon dioxide produced from a single acetyl CoA and an ATP molecule.

Thus, the catabolic process that creates carbon dioxide is the citric acid cycle. The method of respiration removes it.

Therefore, the given statement is true.

Explanation of option ‘(C)’

Fermentation is a word that refers to the process that takes place in the absence of oxygen. The production of lactate via the fermentation process is lactate fermentation. It happens in the skeletal muscles.

Thus, the products produced in lactate fermentation are NAD and lactate.

Therefore, the given statement is false.

Explanation of option ‘(D)’

Electron transport happens via the series of redox reactions that occur in the mitochondria. It is a common mechanism for cellular respiration as well as photosynthesis. In this transport, oxygen acts as a terminal electron acceptor, and energy is released in each step.

Thus, the product produced from the electron transport is the water and ATP. ATP acts as an energy molecule for the body.

Therefore, the given statement is false.