What is correct about the electron transport system ?

Options

A. Energy stored in ATPs is utilised for synthesis of `NADH+H^+`
B. Energy stored in ATPs is utilised for synthesis of `FADH_2`
C. Energy stored in `NADH+H^+ and FADH_2` is utilized for synthesis of ATPs.
D. Energy stored in glucose is utilized for synthesis of `NADH + H^+ , and FADH_2` only.

Answer

To determine what is correct about the electron transport system (ETS), we need to analyze the statements provided in the question. Here is a step-by-step breakdown of the solution:

### Step 1: Understand the Electron Transport System
The electron transport system is a series of protein complexes located in the inner mitochondrial membrane. It plays a crucial role in cellular respiration by transferring electrons from electron donors (like NADH and FADH2) to electron acceptors (like oxygen) through a series of redox reactions.

**Hint:** Familiarize yourself with the components and function of the electron transport system.

### Step 2: Analyze the First Statement
The first statement claims that "Energy stored in ATP is utilized for the synthesis of NADH + H⁺." This statement is incorrect. ATP is produced during the electron transport chain, and NADH + H⁺ is generated during glycolysis and the Krebs cycle, not synthesized from ATP.

**Hint:** Remember that ATP is produced as a result of the electron transport chain, not used to synthesize NADH.

### Step 3: Analyze the Second Statement
The second statement claims that "Energy stored in ATP is utilized for the synthesis of FADH₂." This statement is also incorrect. Similar to the first statement, FADH₂ is produced during the Krebs cycle and is not synthesized from ATP.

**Hint:** Consider where FADH₂ is produced and how it relates to ATP production.

### Step 4: Analyze the Third Statement
The third statement discusses that "Energy stored in NADH + H⁺ and FADH₂ is utilized for the synthesis of ATP." This statement is correct. The electrons from NADH and FADH₂ are transferred through the electron transport chain, leading to the production of ATP.

**Hint:** Focus on the role of NADH and FADH₂ in the electron transport chain and how they contribute to ATP synthesis.

### Step 5: Analyze the Fourth Statement
The fourth statement claims that "Energy stored in glucose is utilized for the synthesis of NADH + H⁺ and FADH₂ only." This statement is incorrect. While glucose is broken down to produce NADH and FADH₂, it also leads to ATP production directly through glycolysis and the Krebs cycle.

**Hint:** Remember that glucose metabolism leads to multiple products, not just NADH and FADH₂.

### Conclusion
Based on the analysis of the statements, the correct answer regarding the electron transport system is that the energy stored in NADH + H⁺ and FADH₂ is utilized for the synthesis of ATP. Therefore, the correct option is the third statement.

**Final Answer:** The correct statement about the electron transport system is that energy stored in NADH + H⁺ and FADH₂ is utilized for the synthesis of ATP.