When a potato chip is put into salt water, the potato cells become flaccid (soft and floppy). This is because there is a higher concentration of water molecules inside the potato cells than outside. If more water enters the cell, it becomes turgid. This is important in supporting plants.
a bird feather is biotic because it was made on a living thing. fog is abiotic because its not living or was never living. i might be wrong about the feather tho.