Question

What is diffusion in a nutshell?

I'm really unsure and I could barely grasp any idea.

Answer 1

When something diffuse then it doesn't require energy.

Explanation:

Diffusion is movement of molecules in & out of plasma membrane from higher to lower concentration that doesn't require energy.*

Diffusion involves the movement of molecules along their concentration gradient i.e from higher to lower. So no energy is required for the process & hence it is the simplest type of transport across the membrane.

The hydrophobic molecules being non-polar and small sized polar molecules e.g `C_2H_5OH` simply slide through the phospholipid bilayer(because it's also hydrophobic) of plasma membrane along their concentration gradient. This process is called diffusion.

For better comprehension, give a read to the link below:
https://socratic.org/questions/explain-passive-diffusion?source=search

Hope it helps!

Answer 2

Diffusion is the phenomenon of particles moving from an area of high concentration to a low concentration area. This is a general explanation of the phenomenon.

Explanation:

Diffusion is defined as the phenomenon of particles moving from an area of high concentration to a low concentration area. This process is completely passive, ie., it does not require any energy to move from a high concentration to low concentration.

Here is a video where you can observe that the food dye is being diffused from a high concentration region (the drop) to whole glass of water. this whole process is very slow but can be accelerated by providing energy to the system. In the coming video, you see that when the host of video mix two solution diffusion happens at almost instantly.