Question

Chemiosmosis, the generation of a proton gradient across the inner mitochondrial membrane, is a crucial requirement for the synthesis of ATP in cellular respiration.
How does the cell power the movement of protons up its gradient?
A) A transporter on the outer membrane allows the diffusion of protons from the cytoplasm into the inner membrane space.
B) ATP synthase powers the movement of protons across the membrane while simultaneously generating ATP.
C) Electrons are transported into the inner membrane space drawing in protons due to electrostatic attraction.
D) Complexes of the Electron transport chain undergo a redox reaction that, in turn, generates the energy to pass protons up its gradient.

Answer 1

Hint: The electron transport chain is the main process involved in the synthesis of ATP. It takes place in the mitochondria. Chemiosmosis is the movement of the ions or protons along or against the concentration gradient resulting in the synthesis of ATP.

Complete Answer:
This process is also called oxidative phosphorylation. The complete process of oxidative phosphorylation can be summarised as
The protein complexes in the ETC accept and pass electrons to the next acceptor and undergo redox reaction. The electron thus moves down the energy gradient and releases free energy. This energy drives the movement of protons up their concentration gradient to the matrix of mitochondria.
The ATP synthase complex located in the inner mitochondrial membrane catalyses ATP synthesis on the membrane towards the matrix side.
This statement A, B, C is incorrect.

Hence the correct answer is option ‘D’.

Note: A bipolar neuron has two extensions- one dendrite and other axon. They are specialised sensory neurons for the transmission of senses like smell, sight, taste, hear, touch, and balance.