Question

which of the following best explains the process illustrated?
a passage of water molecules through a semi - permeable membrane to equalize concentration
b transport of molecules across a membrane from a high to low concentration gradient by means of a carrier molecule
c movement of molecules against a concentration gradient expending energy
d separation of suspended particles from a fluid environment through a porous membrane

Explanation:

• Option A: Osmosis is the passage of water molecules through a semi - permeable membrane to equalize concentration. The image does not show water molecules specifically.
• Option B: Facilitated diffusion is the transport of molecules across a membrane from a high to low concentration gradient by means of a carrier molecule. This matches the illustration where molecules are moving through a carrier protein in the membrane from an area of higher concentration (outside the cell) to an area of lower concentration (inside the cell).
• Option C: Active transport is the movement of molecules against a concentration gradient expending energy. There is no indication of energy expenditure (like ATP) in the image.
• Option D: Filtration is the separation of suspended particles from a fluid environment through a porous membrane. This is not what is depicted in the image.

Answer:

B. Transport of molecules across a membrane from a high to low concentration gradient by means of a carrier molecule