Question

Out of 35 ATP molecules produced per glucose, 30 ATP molecules are formed from NADH/FADH2 in
(A) Respiratory chain
(B) Krebs cycle
(C) Oxidative decarboxylation
(D) EMP

Answer 1

Hint: Oxidation of glucose results in the formation of 2 molecules of pyruvic acid and thus energy is stored in the form of NADH and ATP. The oxidation process is completed through the action of the citric acid cycle or Krebs cycle. More energy in the form of ATP is produced here.

Complete answer:
Let’s discuss the question and find the correct answer.
- Respiratory chain: Respiratory chain is also known as the electron transport chain or ETS. It is defined as the series of the complex where the electron is transferred from donor to acceptor through the redox reaction. An electrochemical gradient of the proton is formed from the redox reaction which in turn helps in ATP synthesis. Thus several molecules of ATP are formed in this state.
- Krebs cycle: Krebs cycle is also called the tricarboxylic acid cycle or TCA cycle. It is defined as a series of reactions that take place in all anaerobic organisms and thus energy is released through the oxidation of acetyl coenzyme A. 2 molecules of ATP is formed during the synthesis of succinyl coenzyme A.
- Oxidative decarboxylation: The process oxidative decarboxylation is defined as the removal of carbon from through the oxidation process. It is a part of the citric acid cycle or Krebs cycle.
- EMP: EMP is also called the Embden-Meyerhof-Parnas pathway. It is another name of the glycolysis pathway. Here, the glucose molecule goes through a series of reactions and ultimately forms pyruvic acid and two molecules of ATP.
Hence option A: Respiratory chain is the correct answer.

Note: ATP can also be formed from aerobic as well as anaerobic respiration process. Aerobic respiration takes place in mitochondria and requires oxygen whereas anaerobic respiration does not need oxygen to function.