[Campbell Biology P.1042] The driving forces behind ion movement across a cell's plasma membr... | Practice Question

The driving forces behind ion movement across a cell's plasma membrane are described as an "electrochemical gradient." Which of the following best explains why this term is used?

  • A: It refers only to the chemical concentration difference of ions across the membrane.
  • B: It encompasses both the chemical concentration difference and the electrical potential difference (voltage) across the membrane that influence ion movement.
  • C: It refers specifically to the movement of electrons during chemical reactions that generate electricity.
  • D: It indicates that ion movement is always powered by ATP, which is a chemical energy source, and generates an electrical signal.

Explanation

The text asks to explain why ion movement is described as an electrochemical electrical and chemical gradient, referring to Concept 7.4. An electrochemical gradient combines two components: a chemical gradient concentration difference of a substance across a membrane and an electrical gradient charge difference, or membrane potential, across the membrane . Both forces act together to determine the net movement of an ion.