Diffusion

What is Diffusion?

Diffusion of gases and liquids is a very common phenomenon in nature. We see that the storms move, the cloud flies,sugar crystals dissolve in water forming solution, the fragrance of a flower spread to a distant place and so on. All these happen because of the movement of their component molecules from one place to the other, which is nothing but a process of diffusion.
 
When a solute is dissolved in a solvent it forms a solution. In a solvent the molecules or ions are having a random and spontaneous movement and when a solute is put into in the solute molecules or ions also move spontaneously. This random and spontaneous movement of ions throughout the medium is known as diffusion.Diffusion of molecules from a region of  its  higher concentration or pressure to a region of its lower concentration or pressure without the use of any external energy is a common tendency of any fluid substance.

Diffusion pressure

Diffusion pressure can be defined as a physical force of a substance by virtue of which its molecules or ions move from one place to another,if other conditions do not resist the movement.

Factors affecting Diffusion

Diffusion or the rate of movement of any molecules is dependent on following factors.

1. Temperature: Increase in the temperature increase the  speed of the molecules, and thereby,the rate of diffusion too. In a similar way at lower temperature the rate of diffusion also decreases.    
2. Kinetic Energy of the Solvent Molecules: When the amount of surrounding medium or solution of a cell is increased the kinetic energy of a solvent molecules will be considerably more. As a result there will be  more diffusion of solvent  into the cell.                                                                                             
3. Density: Density is defined as the amount of material that exists within a given volume. Regions of high density contain a  greater number of particles per unit  volume then regions of lower  density. An increase number of particles leads to a greater chance of  collisions, and this leads to an increased rate of diffusion. A lower number of particles leads to  reduced chance of collisions and this lower the rate of diffusion. Therefore high density regions have a greater rate of diffusion than low density region.                                                                                               
4. External  Pressure: External pressure also determines the direction and rate of diffusion. If the external pressure on the surrounding medium of a cell increase the  rate of diffusion of solvent molecules into the cell will also increase  and the vice-versa.                                                                  
5. Size of the Molecules: With the increase of the size of the molecules the rate of diffusion decrease. The smaller the molecules the more is the rate of diffusion.

    

introduction to biology

What is biology?

          

              Biology is the natural science that studies life and living organism, including their physical structure, chemical composition, function, development and evolution. Shortly biology is the science of life.

              It is concerned with the characteristic and behaviors of organism; how individuals come into existence, and how species evolve, and the interactions they have with each other and with their environment.

Discovery of biology

         

             The term biology is derived from the greek word- bios (life) and logia (study of) . The  latin- language  form  the term first appeared in 1736 when swedish scientist
Carl Linnaeus used biologi in his bibliotheca botanica.  The term biology was first coined by Jean-Baptiste Lamark and  Gottfried -Reinhold Treviranus in 1802.
              In 384-322 BC Aristotle dicover biology, especially important are his history of animal.Aristotle's successor at the lyceum, Theophrastus, wrote a series of books on botany in 371-287 BC.

Branches of biology

  Biological science is divided in  two types of branches; that is botany and zoology.

              Botany is also called as plant science , plant biology or phytology: is the science of plant life and a branch of biology,
that studies the plant kingdom, including structure, growth and differentiation, reproduction ,biochemistry and primary metabolism, chemical products, development ,diseases, evolutionary relationship, systematics and plant taxonomy. There are 26 branches of botany also have.
            Zoology is also called animal science or animal biology;that studies the animal kingdom, including the structure, embryology, evolution, classification, habits and distribution of all animals, both living and extinct, and how they interact with their ecosystem.