Question

Q26). During photosynthesis and mitochondrial respiration, energy is temporarily stored as an "electrochemical gradient." Which statement best describes this gradient?

A) It is a gradient of protons, which creates both a charge differential and chemical gradient across a membrane.

B) It is a gradient of electrons, which diffuse from one side of a membrane to other and thereby build a charge differential across a membrane.

C) It is a gradient of sodium ions, which creates both a charge differential and chemical gradient across a membrane.

D) It is a dual gradient of sodium and potassium, each of which is stored on a different side of a membrane

Answer 1

The electrochemical gradient created during photosynthesis and mitochondrial respiration is an uneven distribution of protons (hydrogen ions) across a membrane. This proton gradient, which includes both an electrical charge and a concentration difference, is used to generate ATP through oxidative phosphorylation.

Step-by-step explanation:

The statement that best describes the electrochemical gradient during photosynthesis and mitochondrial respiration is A) It is a gradient of protons, which creates both a charge differential and chemical gradient across a membrane. During these processes, energy is used to pump hydrogen ions (protons) across a membrane, leading to an uneven distribution of these ions. This creates an electrochemical gradient as a result of both the positive charge of the hydrogen ions and their higher concentration on one side of the membrane.

The electrochemical gradient serves as a form of potential energy that is harnessed by ATP synthase. As protons flow through ATP synthase, down their gradient, the enzyme synthesizes ATP from ADP and phosphate, a process known as oxidative phosphorylation.