Question

In both photosynthesis and respiration, protons are pumped across a membrane during ________?

1) glycolysis
2) electron transport chain
3) Krebs cycle
4) fermentation

Answer 1

Protons are pumped across a membrane during the electron transport chain, which occurs in the inner membrane of the mitochondria and contributes to ATP synthesis through oxidative phosphorylation.

Step-by-step explanation:

In the context of both photosynthesis and cellular respiration, protons are pumped across a membrane during the electron transport chain. This process occurs in the specialized protein complexes in the inner membrane of the mitochondria. During the electron transport chain, electrons are transferred from carriers such as NADH and FADH2 to a series of other carriers within the membrane, effectively creating an electrochemical gradient. The gradient established is then utilized to drive the synthesis of ATP through the process known as oxidative phosphorylation or chemiosmosis. Thus, the correct answer is (2) electron transport chain.