Final answer:
Diffusion is a spontaneous process where molecules move from an area of higher concentration to lower concentration, reaching equilibrium. Osmosis is a specific type of diffusion involving water through a semi-permeable membrane. The rate of diffusion can be affected by cell size, impacting large cells.
Step-by-step explanation:
The question relates to whether diffusion is a spontaneous change. Diffusion is indeed a spontaneous change because it results in the net movement of molecules from an area of higher concentration to an area of lower concentration without requiring an external energy source. This occurs due to the random motion of molecules and continues until equilibrium is reached, where there is a uniform distribution of matter.
When considering osmosis, it is a special type of diffusion that involves the movement of water across a semi-permeable membrane. Osmosis is a form of passive transport, which means that it does not require the input of external energy, similar to other types of diffusion.
The rate of diffusion can vary with the size of the cell; larger cells may encounter limitations because the surface area to volume ratio is less favorable compared to smaller cells. This implies larger cells may have to develop adaptations, like having more surface area through foldings, to facilitate efficient diffusion.