Question

The different steps of aerobic respiration are

• A. Glycolysis and oxidative phosphorylation
• B. Glycolysis and Krebs cycle
• C. Glycolysis, Krebs cycle and terminal oxidation
• D. Krebs cycle and terminal oxidation

Answer 1

Answer: (C)

Glycolysis, Krebs cycle and terminal oxidation

Aerobic respiration is a biological process which produces energy from glucose in the form of ATP in the living cells. Aerobic respiration takes place in 4 stages:

1. Glycolysis- It is the first step of respiration which is anaerobic as it does not require oxygen and produces two molecules of pyruvate from 1 molecule of glucose. It takes place in the cytoplasm and produces two molecules of ATP and 2 NADH.

2. Formation of Acetyl Coenzyme A- In this step pyruvate is converted into 2 carbon acetyl group which then combines with coenzyme A to form Acetyl coenzyme A.

3. Krebs cycle- This step takes place in mitochondria where acetyl coenzyme A combines with oxaloacetate to produce citrate. The citrate undergoes several conversion steps and ultimately forms oxaloacetate to restart the cycle. Two turns of the citric acid cycle are required to break down acetyl coenzyme A from single glucose molecule and produce 2 ATP, 6 NADH, and 2 FADH.

4. Electron transport chain- This is the final step in which NADH and FADH donate their electrons to make large amounts of ATP. One molecule of glucose creates a total of 34 ATP. The step is also called as terminal oxidation stage which includes electron transport chain and oxidative phosphorylation.

Thus, the correct answer is option C.