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Question #47596
The Question
An experimental herbicide selectively accumulates in the stroma lamellae of a C3 plant's chloroplasts, where it specifically targets and inhibits the P700 reaction center. Which of the following will be the most direct and immediate consequence of this inhibition?
Options
- A.
Immediate cessation of oxygen evolution, as the cyclic electron flow is directly coupled to the photolysis of water.
- B.
A stoichiometric deficit of ATP in the stroma, primarily bottlenecking the RuBP regeneration step of the Calvin cycle.
- C.
Direct halting of NADPH synthesis, because the stroma lamellae are the primary functional sites for the NADP reductase enzyme.
- D.
Accumulation of electrons in Photosystem II, leading to an immediate halt of the non-cyclic Z-scheme within the stroma lamellae.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Cyclic Photophosphorylation Pathways|Chlorophyll-a vs Accessory Pigments
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot & Location Trap: Tests the specific functional anatomy of chloroplasts.
Students often associate photosystem inhibitors solely with the non-cyclic Z-scheme.
The trap relies on knowing that stroma lamellae exclusively perform cyclic photophosphorylation to meet the extra ATP demand of the Calvin cycle, and explicitly lack PS II and NADP reductase.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Photosynthesis in Higher Plants - Class 11 |
| Concept | Cyclic Photophosphorylation Pathways |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |