The leopard frog and the pickerel frog are two closely related species. in areas where their ranges overlap, the frogs will remain separate species if they

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.

this is more of a statement than a question. is there answers to go along with this, or is it opinion based?

the answer is d p: cell, q: organ, r: organ system, s: tissue