Question

Select the correct statements about facilitated diffusion.

• A. There is a specific protein carrier for a specific substance to be transported.
• B. The same protein carrier transports all the substance through the membrane.
• C. There is no limit to the rate of transport of a substance by facilitated diffusion.
• D. The rate of transport is limited by saturation, i.e. when all protein carrier molecules are being used.

Answer 1

Answer: (A), (D)

The correct options are
A There is a specific protein carrier for a specific substance to be transported.
D The rate of transport is limited by saturation, i.e. when all protein carrier molecules are being used.

Facilitated diffusion involves a specific protein carrier which carries a specific substance through the membrane. When all the carrier molecules for a particular substance are being used, the carrier is said to be saturated, and the rate of transport becomes maximum.