Question

describe the following with an examples 1) diffusion

Answer 1

Diffusion is a physical process that refers to the net movement of molecules from a region of high concentration to one of lower concentration. The material that diffuses could be a solid, liquid or gas. Similarly, the medium in which diffusion occurs could also be in one of the three physical states.


For example, oxygen is at a higher concentration inside arteries and arterioles, when compared with the oxygen levels in actively respiring cells. By the time blood flows into capillaries in the muscle or liver, for instance, there is only a single layer of cells separating this oxygen from hepatocytes or skeletal muscle fibers. Through a process of passive diffusion, without the active involvement of any other molecule oxygen passes through the capillary membrane and enters cells.

Cells utilize oxygen in the mitochondria for aerobic respiration, which generates carbon dioxide gas as a byproduct. Once again, as the concentration of this gas increases within the cell, it diffuses outwards towards capillaries where the force of flowing blood removes the excess gas from the tissue region. This way, the capillaries remain at a low carbon dioxide concentration, allowing the constant movement of the molecule away from cells.