Question

When 54 molecules of \(CO_2\) are fixed by RuBisCo in a \(C_3\) plant, number of G3-P exported to cytosol and number of G3-P participating in regeneration respectively are:

• A. 90 and 18
• B. 54 and 54
• C. 60 and 48
• D. 18 and 90

Hint:

For every 3 \(CO_2\), one G3P exits Calvin cycle while five regenerate RuBP.

Answer 1

The Correct Option is D

Concept: For every 3 molecules of \(CO_2\): \[ 6G3P \] are formed. Out of these: \[ 1G3P \] is exported and \[ 5G3P \] are utilized for regeneration.

Step 1: For 54 molecules of \(CO_2\).
\[ 54/3=18 \] cycles.

Step 2: Calculate exported G3P.
\[ 18\times1=18 \]

Step 3: Calculate regeneration G3P.
\[ 18\times5=90 \] \[ \boxed{18 \text{ and } 90} \]