Biology Bioenergetics UHS 2024
PMDC Verified Question 12 of 67
In the journey of electrons from photosystem II to photosystem I plastocyanin is reduced by:
A
Plastoquinone
B
Cytochrome complex
C
P700
D
Primary electron acceptor of PSI
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Cytochrome complex
Concept:

The thylakoid electron transport chain follows a strict, sequential order of electron carriers between the two photosystems.

Solution:

  • Electrons leave Photosystem II and are passed to Plastoquinone (PQ).
  • Plastoquinone passes them to the Cytochrome \( b_6f \) complex.
  • The Cytochrome complex then passes the electrons to Plastocyanin (PC).
  • Because Plastocyanin receives (gains) these electrons from the Cytochrome complex, it is technically reduced by the Cytochrome complex.


Why other options are incorrect:

  • Plastoquinone passes electrons to cytochrome, not directly to plastocyanin.
  • P700 and the primary acceptor of PSI are located after plastocyanin in the chain.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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