State how facilitated diffusion is achieved describe ways in which organisms maintain concentration gradients across membranes

describe properties of an exchange surface that would facilitate rapid diffusion rates

Explanation:

The ion channels that are selective to only a certain ions,such as sofium and potassium ions.Transmembrance protiens actively push ions across the membrane and establish concentration gradient across the membrane,and ion channels allow ions to move across the membrane down those concentration gradients.

*DIFFUSION is a type of passive transport that transports substances from higher concentration going to lower concentration.The greater difference between the concemtration gradient,the faster the diffusion take place

*BARRIERS in the membrane also affects the rate of diffusion.More pores in the barrier will allow more substances to pass across speedily.

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.