diffusion m[blank_start]olecules[blank_end] with c[blank_start]oncentration[blank_end] gradient no [blank_start]energy required[blank_end]
osmosis [blank_start]water[blank_end] with concentration gradient [blank_start]no[blank_end] energy required
[blank_start]active transport[blank_end] molecules against concentration gradient [blank_start]energy[blank_end] required