Q.14 Which of the following are energy transducing membranes?
[P] Plasma membrane of bacteria
[Q] Inner membrane of chloroplasts
[R] Inner membrane of mitochondria
(A) P and Q only
(B) P and R only
(C) Q and R only
(D) P, Q and R

Energy transducing membranes convert chemical energy into ATP through electron transport chains and proton gradients. These specialized membranes house protein complexes for oxidative or photophosphorylation. The correct answer is (B) P and R only.​

Option Analysis

[P] Plasma membrane of bacteria qualifies as an energy transducing membrane. In prokaryotes lacking mitochondria or chloroplasts, this membrane embeds the electron transport chain and ATP synthase to generate ATP via proton motive force during respiration.​
[Q] Inner membrane of chloroplasts does not qualify. Chloroplasts perform photophosphorylation on thylakoid membranes, not the inner envelope membrane, which mainly handles metabolite transport.​
[R] Inner membrane of mitochondria qualifies. It contains respiratory complexes and ATP synthase for oxidative phosphorylation, creating a proton gradient essential for ATP synthesis.​

Core Functions

Energy transducing membranes maintain proton impermeability to build electrochemical gradients. Bacterial plasma and mitochondrial inner membranes drive respiration, pumping protons outward. ATP synthase harnesses proton flow back across the membrane to produce ATP.​
Thylakoids in chloroplasts, often confused with the inner membrane, perform analogous light-driven proton pumping.​

Exam Relevance

This question tests chemiosmotic theory distinctions across organelles, common in IIT JAM Biotechnology. Bacterial plasma membranes evolved as precursors to eukaryotic inner mitochondrial membranes via endosymbiosis. Avoid mistaking chloroplast inner envelope for thylakoids.​