Biology Bioenergetics SZABMU 2024
PMDC Verified Question 3 of 67
What is the product formed at the end of the respiratory chain in inner membrane of mitochondria?
A
NADH
B
Oxygen
C
Water
D
Carbon dioxide
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Water
Concept:

The electron transport chain ends when the depleted electrons are finally accepted by a terminal molecule.

Solution:

  • At the very end of the respiratory chain (Complex IV), electrons are passed to molecular Oxygen (\( O_2 \)).
  • The oxygen atoms accept these electrons and combine with protons (\( H^+ \)) from the surrounding matrix.
  • This chemical combination yields Water (\( H_2O \)) as the final metabolic product of the chain.


Why other options are incorrect:

  • Oxygen is the reactant (acceptor), not the product.
  • \( CO_2 \) is produced earlier during the Krebs cycle and link reaction, not the ETC.

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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