Question

Net ATP yield in glycolysis is

• A. 1
• B. 2
• C. 4
• D. 6

Hint:

Remember the glycolysis summary: \[ \boxed{\text{Glucose} \longrightarrow 2\text{Pyruvate} +2\text{ATP (Net)} +2\text{NADH}} \] A common exam trick is asking between gross ATP (4) and net ATP (2). Always remember: \[ \boxed{\text{Gross ATP}=4,\qquad \text{Net ATP}=2} \]

Answer 1

The Correct Option is B

Concept: Glycolysis is the first stage of cellular respiration. It occurs in the cytoplasm and converts one molecule of glucose into two molecules of pyruvate through a series of ten enzyme-catalyzed reactions. During glycolysis, ATP is both consumed and produced.

Step 1: ATP investment phase.
In the initial steps of glycolysis, ATP is required to activate glucose. \[ \boxed{\text{ATP Consumed} = 2} \] These ATP molecules are used during phosphorylation reactions.

Step 2: ATP payoff phase.
In the later steps, ATP is generated by substrate-level phosphorylation. \[ \boxed{\text{ATP Produced} = 4} \] Since two molecules of glyceraldehyde-3-phosphate are formed, ATP-producing reactions occur twice.

Step 3: Calculate the net ATP gain.
\[ \text{Net ATP} = \text{ATP Produced} - \text{ATP Consumed} \] \[ =4-2=2 \] Thus, \[ \boxed{\text{Net ATP Yield}=2} \] In addition to ATP, glycolysis also produces:
• 2 Pyruvate molecules
• 2 NADH molecules
• 2 Water molecules Final Answer: \[ \boxed{Option (B) is correct \]