What does natural selection cause

the mechanism that darwin proposed for evolution is natural selection . because resources are limited in natural organisms with heritable traits that favour survival and reproduction will tend to more offspring than their peers ,causing the traits to increase in frequency over generation .

Explanation:

hope it helps :)

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.