Question

Oxidative phosphorylation is the production of _____________.

• A. ATP during respiration
• B. ATP during photosynthesis
• C. NADH during respiration
• D. NADPH during photosynthesis

Answer 1

The correct option is A ATP during respiration

Oxidative phosphorylation is a process in which ATP is formed during respiration as a result of the transfer of electrons from $NADH+H^{+}$ and $FAD{H}_2$ to $O_2$ by a series of electron carriers. The electron transport chain occurs in the inner mitochondrial membrane that has four complexes that accept and carry electrons from $NADH+H^{+}$ and $FAD{H}_2$.

As the electrons move through different complexes, they release energy. This energy is utilized to pump protons from the matrix to the intermembrane space. The protons accumulate in the intermembrane space and this increases the concentration of protons in the intermembrane space and creates a driving force.

The protons move through the complex V (ATP synthase) into the matrix from the intermembrane space. Complex V has two components, $F_0$ and $F_1$.
$F_0$ forms the channel for the passage of protons and $F_1$ has a site for the synthesis of ATP from ADP and inorganic phosphate. Hence, during oxidative phosphorylation, ATP is synthesised.

The production of ATP during photosynthesis is called photophosphorylation.

The reduced coenzyme NADH stores the energy produced during the Krebs cycle and utilizes it during oxidative phosphorylation to produce ATP.

NADPH is a product of the light reaction. It is utilised during the Calvin cycle.