Which of the following best describes simple diffusion?

• A. Movement of molecules from an area of lower concentration to an area of higher concentration without the use of energy.
• B. Movement of molecules against their concentration gradient using energy and transport proteins.
• C. Movement of molecules through a membrane using transport proteins but without energy.
• D. Movement of molecules from an area of higher concentration to an area of lower concentration without the use of energy or transport proteins.

Answer: (D)

Verified step by step guidance

1. Understand the concept of diffusion: Diffusion is the process by which molecules spread from areas of high concentration to areas of low concentration. This movement is driven by the concentration gradient and does not require energy.
2. Identify the characteristics of simple diffusion: Simple diffusion involves the passive movement of molecules directly through the lipid bilayer of a cell membrane, without the assistance of transport proteins or the expenditure of energy.
3. Analyze the given options: Evaluate each option based on the definition and characteristics of simple diffusion. Look for key phrases such as 'without the use of energy' and 'from an area of higher concentration to an area of lower concentration'.
4. Eliminate incorrect options: Discard options that mention movement against the concentration gradient, the use of energy, or the involvement of transport proteins, as these do not align with the definition of simple diffusion.
5. Select the correct description: Choose the option that accurately describes simple diffusion as the movement of molecules from an area of higher concentration to an area of lower concentration without the use of energy or transport proteins.