Question

Oxidative phosphorylation occurs in
A. Outer membrane of mitochondria
B. Inner membrane of mitochondria
C. Stroma of chloroplast
D. Grana of chloroplast

Answer 1

Oxidative phosphorylation is the process by which the energy of the electron transport chain (respiratory chain) is used to produce ATP, and is the peak energy metabolism in aerobic organisms. Oxidative phosphorylation involves the reduction of ${O_2}$ to ${H_2}O$ using the electrons released by $NAD{H_2}$ and $FAD{H_2}$.

Complete answer:
Let's study each mcq points:

The outer membrane of the mitochondria does not contain any components of the electron transport chain. It consists of proteins called porins, which assists in the permeability of ions in and out of mitochondria.
Hence option A is incorrect.

The Stroma is the colorless fluid that surrounds the grana in the chloroplast. The dark reaction of photosynthesis takes place in the Stroma. Grana or granum is nothing but a stalk of thylakoid discs. The light reactions of the Photosynthesis takes place in the grana.
Hence options C and D are incorrect.

Oxidative phosphorylation is a process in which ATP is synthesized from ADP and Pi using the energy released from the oxidation of $NAD{H_2}$ and $FAD{H_2}$ . The electrons released from the

Oxidation of $NAD{H_2}$ and $FAD{H_2}$ are passed through a chain of carriers like Flavoprotein and Cytochrome called electron transport chain. Oxygen is the final electron acceptor. The components of the electron transport chain are arranged in the inner membrane of mitochondria.

Hence, the correct answer is option (B).

Additional information:
Since the phosphorylation of ADP occurs because of energy released during the oxidation of $NAD{H_2}$ and $FAD{H_2}$ this phosphorylation is called Oxidative phosphorylation.

Note: Many chemicals inhibit ATP synthesis and can even kill cells at fairly high concentrations. Two types of chemicals are known as inhibitors and disintegrants. Inhibitors directly block the electronic transmission chain. The antibiotic pyricidin competes with coenzyme Q. The antibiotic is antimycin. It blocks the transfer of electrons between cytochromes b and c, and carbon monoxide $\left( {CO} \right)$ and cyanide $\left( {C{N^ - }} \right)$ strongly bind to certain cytochromes, disrupting their function.