The energy for building a proton gradient is provided by

The energy for building a proton gradient is provided by the oxidation of food.

Explanation:

The electrons from from NADH and FADH2 flow through the electron transport chain in the inner mitochondrial membrane generating a H+ buildup in the inner membrane space. This proton gradient (gradient of H+) flowing through the membrane enzyme complex ATP synthetase is the direct energy source for producing ATP.

Explanation:

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.