Glycerol enters some cells by simple diffusion and other cel

Glycerol enters some cells by simple diffusion and other cells through a carrier protein. On the plot below, indicate which line represents passive diffusion and which represents diffusion through a channel Why do the rates of the two processes differ at low substrate concentration? Why do the rates of the two processes differ at high substrate concentration?

Solution

Ans. a) In the given plot, line A showed the carrier mediated or facilitated diffusion and line B showed simple diffusion.

b.) In both the diffusion methods, rate of diffusion depends upon the properties of the cell, diffusing molecule and the surrounding solution. Hence the rate of diffusion varied in both the process.

c.) Actually, in simple diffusion, the rate of diffusion depends on the concentration gradient while in carrier mediated diffusion, molecules and ions move down their concentration gradient and it changes with the with increasing solute concentration outside the cell.