Transport across membranes

Question 1

channel

Answer 1

protein with an empty centre through which ions can pass by facilitated diffusion

Question 2

facilitated diffusion

Answer 2

1. movement down the concentration gradient / from high to low concentration;
2. through channel proteins/ion channels;
3. passive transport / it requires no energy from the cell / no ATP;
4. for molecules that cannot pass through the phospholipid bilayer;
5. channel is specific/selective to the ion/molecule being transported;