Which of the following statements best describes a receptor potential?

• A. It is the resting membrane potential maintained by all cells in the absence of stimulation.
• B. It is the potential difference generated by the sodium-potassium pump during active transport.
• C. It is a graded change in membrane potential that occurs in response to a stimulus at a sensory receptor.
• D. It is an all-or-nothing electrical signal that travels along the axon of a neuron.

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of a receptor potential. A receptor potential is a graded change in the membrane potential of a sensory receptor cell in response to a stimulus. It is not an all-or-nothing signal like an action potential, but rather varies in magnitude depending on the strength of the stimulus.
2. Step 2: Compare the receptor potential to the resting membrane potential. The resting membrane potential is the baseline electrical charge across the membrane of a cell when it is not being stimulated. This is different from a receptor potential, which occurs specifically in response to a stimulus.
3. Step 3: Examine the role of the sodium-potassium pump. The sodium-potassium pump actively transports sodium (Na⁺) out of the cell and potassium (K⁺) into the cell, maintaining the resting membrane potential. However, this is not directly related to receptor potentials, which are caused by ion channel activity in response to a stimulus.
4. Step 4: Distinguish receptor potentials from action potentials. Action potentials are all-or-nothing electrical signals that propagate along the axon of a neuron. In contrast, receptor potentials are localized, graded changes in membrane potential that occur at sensory receptor cells.
5. Step 5: Conclude that the correct description of a receptor potential is: 'It is a graded change in membrane potential that occurs in response to a stimulus at a sensory receptor.' This definition highlights the key characteristics of receptor potentials and distinguishes them from other types of electrical signals in cells.