Question

The type of diffusion in which substances move across the membrane along their concentration gradient in the presence of certain carriers or transport proteins is called as
A. simple diffusion
B. facilitated diffusion
C. osmosis
D. active transport.

Answer 1

Correct Answer - B
The diffusion of hydrophilic substances along the concentration gradient through fixed membrane transport proteins without involving energy expenditure, is called facilitated diffusion. Facilitated diffusion is very Specific as it allows cell to select substances for uptake. It is sensitive to inhibitors as well as show saturation effect. Two major types of transport proteins are known viz, carrier proteins carriers, transporters) and channel proteins. Carrier proteins bind the particular solute to be transported and deliver the same to the other side of the membrane.