Answer:
1.Glycerol, alcohol and steroid hormones diffuse easily; because they are non-polar and soluble in the non-polar phospholipid tails of bilayer, (lipid solubility and composition of the membrane)
2.Oxygen and Carbon dioxide, pass easily through the lipid bilayer ; because they uncharged and non-polar.(lack of polarity)
3. Water because of small molecular size pass through the membrane
Ficks stated that the rate of diffusion is proportional to the surface area,concentration gradient and inversely proportional to the membrane thickness,
The larger the number of molecules at a point, the higher the concentration of the molecules at that particular direction. These molecules have higher kinetic energy than other molecules of smaller number and concentrations in the same environment. Thus move(diffuse) down their concentration gradients to a less crowded environment .The higher the concentration gradient the faster the rate of diffusion.
The larger the surface area available for molecules to get free from their intermolecular forces the faster the rate of diffusion. However, this varies with the size of organisms. For example small organism e.g Rat has large surface area to volume ratio, therefore the rate of diffusion of molecules is very high. Large organism like Elephant has low surface-area to volume with lower rate of diffusion.
The thicker the membrane the longer the diffusion distant the molecules need to pass across to move down the concentration gradient and therefore the lower the rate of diffusion
Explanation:
