g Which complexes in the electron transport chain contribute to the pumping of protons in to the intermembrane space

Complex I, Complex III, and Complex IV contribute to the pumping of protons into the intermembrane space.

Explanation:

In the electron transport chain, the energy of electron transfer is conserved in the transfer of protons from the inner mitochondrial matrix which becomes negatively charged, into the intermembrane space which becomes positively charged. The complexes involved in this process of pumping protons are Complexes I, III, and IV.

Complex I (also called NADH dehydrogenase): It pumps four protons into the intermembrane space simultaneously with the transfer of a hydride ion from NADH to ubiquinone.

Complex III (also called cytochrome bc₁ complex): It pumps four protons into the intermembrane space for every pair of electrons it transfers to cytochrome c.

Complex IV (also called cytochrome oxidase): For each electron pair transferred to molecular oxygen, it pumps two protons into the intermembrane space.

the correct answer to this question is 2