Assertion: Glycolysis is the first step of respiration in which glucose completely breaks into `CO_(2)" and "H_(2)0`.
Reason: In this process. there is net gain of twenty four molecules of ATP.

Options

A. Only statement-I is correct .
B. Only Statement-II is correct .
C. Both statement-I and statement -II are correct .
D. Both statement-I and statement-II are incorrect .

Answer

To solve the question, we need to evaluate both the assertion and the reason provided.

### Step 1: Analyze the Assertion
The assertion states that "Glycolysis is the first step of respiration in which glucose completely breaks into CO₂ and H₂O."

- **Understanding Glycolysis**: Glycolysis is indeed the first step of cellular respiration. However, it does not completely break down glucose into carbon dioxide (CO₂) and water (H₂O). Instead, glycolysis converts one molecule of glucose (a six-carbon sugar) into two molecules of pyruvate (a three-carbon compound). Therefore, the assertion is **incorrect**.

### Step 2: Analyze the Reason
The reason states that "In this process, there is a net gain of twenty-four molecules of ATP."

- **Understanding ATP Production in Glycolysis**: During glycolysis, a net gain of 2 ATP molecules is produced directly. Additionally, 2 NADH molecules are generated, which can be converted to ATP during oxidative phosphorylation. Each NADH can yield about 2.5 ATP (depending on the cell type), leading to a total of around 8 ATP from glycolysis (2 ATP from substrate-level phosphorylation + 6 ATP from NADH). Therefore, the reason is also **incorrect**.

### Conclusion
Both the assertion and the reason are incorrect. Therefore, the correct answer is that both statements are incorrect.

### Final Answer
Both the assertion and the reason are incorrect.

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