15. Following statements are related to oxidative phosphorylation
A. Redox reactions of electron transport chain coupled with ATP synthesis are collectively called oxidative phosphorylation.
B.Three major processes: glycolysis, oxidative pentose phosphate pathway and citric acid cycle are related to oxidative phosphorylation.
C.Electron transport proteins are bound to outer of the two mitochondria! membranes.
D.In the electron transport chain electrons are transferred to oxygen from NADH.
Which one of the following combinations of above statements is correct?
(1) A and D                   (2) B and C
(3) C and D                            (4) A and C

Introduction

Oxidative phosphorylation is a central metabolic process in mitochondria, where electrons transferred through the electron transport chain drive ATP synthesis. Clarifying fundamental concepts about the electron transport location and involved pathways is crucial for understanding cellular respiration.

Explanation of Each Statement

(A) Redox reactions of the electron transport chain coupled with ATP synthesis are collectively called oxidative phosphorylation.

• Correct. This process uses energy from redox reactions to produce ATP via ATP synthase.

(B) Three major processes: glycolysis, oxidative pentose phosphate pathway, and citric acid cycle are related to oxidative phosphorylation.

• Incorrect. While glycolysis and the citric acid cycle provide substrates (NADH, FADH₂) for oxidative phosphorylation, the oxidative pentose phosphate pathway is not directly connected to oxidative phosphorylation.

(C) Electron transport proteins are bound to outer of the two mitochondrial membranes.

• Incorrect. Electron transport proteins reside in the inner mitochondrial membrane, not the outer membrane.

(D) In the electron transport chain, electrons are transferred to oxygen from NADH.

• Correct. NADH donates electrons that travel through the electron transport chain and ultimately reduce oxygen to water.

Why Option (1) A and D Is Correct

Statements A and D accurately summarize oxidative phosphorylation’s core concepts: energy coupling via redox reactions linked to ATP synthesis, and the role of NADH as an electron donor to oxygen.

Understanding these fundamental details is essential for students and researchers in bioenergetics and cellular metabolism.