Question

How many molecules of pyruvic acid are produced at the end of glycolysis from 206 molecules of glucose?

• A. 412
• B. 206
• C. 309
• D. 103

Hint:

To avoid confusion during respiratory stoichiometry calculations, always rely on conservation of carbon atoms: \[ \text{Total Initial Carbon Atoms} = \text{Total Final Carbon Atoms} \] \[ \text{Number of Glucose molecules} \times 6 = \text{Number of Pyruvate molecules} \times 3 \] This basic arithmetic rule prevents errors under exam pressure!

Answer 1

The Correct Option is A

Step 1: Understand the question.
We must find how many pyruvic acid molecules come out of glycolysis when 206 glucose molecules are broken down.
Step 2: Recall the glycolysis ratio.
In glycolysis one glucose molecule with 6 carbons is split into two pyruvic acid molecules, each with 3 carbons.
Step 3: Confirm carbon balance.
No carbon is lost as carbon dioxide during glycolysis, so 6 carbons neatly give two 3 carbon pyruvate molecules. The fixed ratio is 2 pyruvate per glucose.
Step 4: Set up the calculation.
Total pyruvic acid equals number of glucose molecules multiplied by 2.
Step 5: Plug in the number.
$206 \times 2 = 412$.
Step 6: State the final value.
So 412 molecules of pyruvic acid are produced, matching the first option.
\[ \boxed{412} \]