Question

Question: The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the

1. oxidation of glucose and other organic compounds.
2. flow of electrons down the electron transport chain
3. H⁺ concentration gradient across the membrane holding ATP synthase.
4. transfer of phosphate to ADP.

Short answer

1. The statement “Oxidation of glucose and other organic compounds” is false.
2. The statement “Flow of electrons down the electron transport chain” is false.
3. The statement “H⁺ concentration gradient across the membrane holding ATP synthase” is true.
4. The statement “Transfer of phosphate to ADP” is false.

Step-by-step solution

Meaning of ATP

ATP is an essential chemical substance that is produced in the body for energy requirements. The process of the formation of ATP is known as ATP synthesis. It is mediated by the enzyme called ATP synthase.

Explanation of option ‘(A)’

Kreb’s cycle is the chemical process that involves the oxidation of organic molecules. The glucose gets oxidized into pyruvate via the process of glycolysis.

Thus, the oxidation of glucose is not the driving force for ATP synthesis during oxidative phosphorylation.

Therefore, the given statement is false.

Explanation of option ‘(B)’

The transfer of electrons down the gradient happens in the electron transport chain. The transport of electrons causes the movement of hydrogen ions which acts as a proton motive force.

Thus, the flow of electrons is not directly linked to the synthesis of ATP.

Therefore, the given statement is false.

Explanation of option ‘(C)’

During the process of oxidative phosphorylation, the electron transport chain is connected with the process of chemiosmosis. The electron from the electron transport chain moves the hydrogen ions outside the mitochondria.

These hydrogen ions travel back to the matrix with the help of ATP synthase, which facilitates the conversion of ADP to ATP.

Thus, chemiosmosis that facilitates the hydrogen ion gradient across the ATP synthase promotes ATP synthesis.

Therefore, the given statement is true.

Explanation of option ‘(D)’

The combination of phosphate with the ADP results in the formation of ATP. There is a hydrogen ions requirement for the conversion of ADP to ATP with phosphate molecules.

The transfer of phosphate to the ATP molecule is the final step that requires the proton motive force as a driving force.

Therefore, the given statement is false.