What is diffusion?
Diffuse – to spread/ disperse/flow out or move in all directions.
Diffusion Definition Biology – Diffusion is the movement of particles (Ions, atoms or molecules) of different substances (solid, liquid and gases) from a region of higher concentration to a region of lower concentration due to their inherent kinetic energy till they get distributed uniformly and a dynamic equilibrium is attained.
Diffusion is a method of passive transport.
In plant diffusion Passive transport is a phenomenon which occurs naturally and doesn’t require expenditure of energy.
In passive transport, the substances move from a region of higher concentration to a region of lower concentration till they get uniformly distributed.
Mechanism of Diffusion
- Diffusion Pressure (DP) – The pressure exerted by the diffusing particles is known as Diffusion Pressure.
- Diffusion Pressure is directly proportional to the number/concentration of diffusing particles.
- Diffusion is the net movement of molecules from a region of their greater diffusion pressure to the region of lower diffusion pressure.
- Principal of Independent Diffusion – The direction of diffusion of one substance is independent of the movement of another substance and depends upon the difference in diffusion pressure.
- Oxygen (O2) moves and Carbon Dioxide (C02) moves out from the stomata simultaneously during respiration.
Factors Affecting Diffusion
- Diffusion Pressure Gradient
- Diffusing Medium
- Larger molecules diffuse slowly compared to smaller molecules.
- Graham’s law of diffusion – Rate of diffusion of a gas is inversely proportional to the square root of its density.
- Gas having higher density will move slowly compared to the gas with lower density.
- Increase in temperature increases the rate of diffusion because the kinetic energy increases.
Diffusion Pressure Gradient
- Higher the diffusion pressure more rapid is the rate of diffusion.
- Diffusion Pressure Gradient is directly proportional to diffusion pressure and inversely proportional to the distance.
- Higher the concentration of the diffusing medium lower is the rate of diffusion.
- Diffusion is faster in vacuum and slower in air.
Importance of Diffusion
- Exchange of gases – Carbon dioxide enters the leaves through the stomata because the concentration of carbon dioxide is higher outside the leaves as compared to the air spaces within the leaves.
- Similarly, oxygen given off during photosynthesis diffuses out of the leaf air spaces through the stomata as the concentration of oxygen is comparatively lower outside the leaves.
- Transpiration occurs due to diffusion.
- Fragrance of flowers spreads to large distances through diffusion of volatile aromatic compounds and attracts pollinators (e.g. Insects).
- The substances get uniformly distributed within the cell cytoplasm through diffusion.
People also ask about Diffusion
1. What is diffusion?
Ans – Diffusion is the movement of particles (Ions, atoms or molecules) of different substances (solid, liquid and gases) from a region of higher concentration to a region of lower concentration due to their inherent kinetic energy till they get distributed uniformly.
2. What are the types of diffusion?
Ans – Their are mainly two types of diffusion named as simple diffusion and facilitated diffusion.
3. What are the factors affecting diffusion?
Ans – Density, Temperature, Diffusion Pressure, Gradient Diffusing Medium are the factors affecting on diffusion process.
References and Sources