Question

Which of the following describes the effect of the electron transport chain and chemiosmosis on the intermembrane space and the matrix of mitochondria?

1. The electron transport chain and chemiosmosis increase the acidity of intermembrane space and mitochondrial matrix, respectively.

2. The electron transport chain decrease the pH of the mitochondrial matrix; chemiosmosis does not change the acidity of intermembrane space.

3. The electron transport chain does not change the pH of the mitochondrial matrix; chemiosmosis increases the acidity of intermembrane space.

4. The electron transport chain decreases the pH of the mitochondrial matrix, and chemiosmosis increases the pH of intermembrane space.

5. The electron transport chain and chemiosmosis decrease theacidity of intermembrane space and mitochondrial matrix, respectively.

Answer 1

Answer

The electron transport chain and chemiosmosis increase the acidity of intermembrane space and mitochondrial matrix, respectively.

Explanation - When the NADH + H and FADH2 get oxidised through the electron transport chain, protons ( H+ ions ) are pumped into the intermembrane space. The increased concentration of H+ ions in the intermembrane space causes an increase in the acidity. Now the mitochondrial matrix have lower concentration of H+ ions and so decrease in acidity.

During the ATP synthesis (as explained by chemiosmosis), the protons accumulated in the intermembrane space are transported to the mitochondrial matrix through F0 part of ATP synthase enzyme. Now the comcentration of H+ ions increase in the matrix. This means an increase in acidity in the mitochondrial matrix.