How many ATP and NADPH molecules are required to make one molecule of glucose through the Calvin pathway?

Core Logic

Let's analyze the statements:

• Statement A is incorrect. The water splitting complex (photolysis of water) is physically associated with PS II on the inner side of the thylakoid membrane, not PS I.
• Statement B is correct. The C₃$C_{3}$ pathway (Calvin cycle) is the main biosynthetic pathway for CO₂$CO_{2}$ fixation in ALL photosynthetic plants, including C₄$C_{4}$ plants (occurs in bundle sheath cells).
• Statement C is correct. C₄$C_{4}$ plants possess mechanisms that concentrate CO₂$CO_{2}$ at the RuBisCO enzyme site, suppressing the oxygenase activity and thus preventing photorespiration.
• Statement D is incorrect. It is the C₄$C_{4}$ plants that exhibit 'Kranz' anatomy (wreath-like arrangement of bundle sheath cells), not C₃$C_{3}$ plants.
• Statement E is correct. ATP synthesis in chloroplasts (photophosphorylation) operates via chemiosmosis.

Step 1: Final Conclusion

The incorrect statements are A and D.

Pattern Recognition

Water splitting = PS II (p680). Kranz anatomy = C₄$C_{4}$ hallmark. Statements A and D are fundamental inversions of core facts.

Chapter Mix

Class 11 Biology: Photosynthesis in Higher Plants

Core Logic

The Calvin cycle (C3 pathway) begins with the carboxylation of Ribulose-1,5-bisphosphate (RuBP). This crucial step is catalyzed by the enzyme RuBP carboxylase-oxygenase, commonly known as RuBisCO. It fixes atmospheric CO₂$CO_{2}$ into a stable organic intermediate.

Step 1: Analyzing Other Options

• PEP carboxylase is the primary carboxylation enzyme in the C₄$C_{4}$ pathway.
• Carboxypeptidase is a digestive enzyme.
• Hexokinase is involved in the first step of glycolysis.

Step 2: Final Conclusion

The required enzyme is RuBP carboxylase-oxygenase (RuBisCO).

Pattern Recognition

Calvin cycle carboxylation = RuBisCO. Hatch-Slack (C₄$C_4$) carboxylation = PEPcase.

Chapter Mix

Class 11 Biology: Photosynthesis in Higher Plants