TOPIC 05-TRANSPORT OF MATERIALS IN LIVING THINGS-01
Introduction
The basic characteristics of all living things are nutrition, respiration, excretion, growth and development, movement, reproduction and sensitivity. In order for these life processes to take place, there must be transportation of materials. Materials are transported either from the environment into the organism or from one part of the organism to another. They can also be transported from the organism into the environment.
For example, during nutrition, organisms take in food substances that they need to provide them with energy. The food must also be transported to all parts of the organism. Respiration requires oxygen, which must be taken in from the environment. During excretion, waste materials from the organism are transported to the excretory organs and removed from the body. Growth requires the production and transportation of growth hormones to the growing parts of the organism. Movement and locomotion are made possible by the transportation of impulses to the relevant organs. Reproduction requires the movement of gametes (sex cells) or the transportation of genetic material. Sensitivity is made possible by the transportation of messages about the presence of a certain thing in the environment.
Transportation is therefore very important for the survival of living things.
Transportation is therefore very important for the survival of living things.
Ways of transportation of materials
Life processes in organisms take place at the cell level. Therefore, it is necessary for substances to move in and out of the cells. There are two ways through which substances can move across the cell membrane:
Passive transport; which occurs spontaneously without the need of energy to transport materials through the cell membrane.
Active transport; where the cell has to use energy to move materials across the cell membrane.
Processes like diffusion, osmosis and mass flow involve passive transport.
Diffusion
Diffusion is the movement of particles from an area of high concentration to one of low concentration.
A difference in the concentration of a substance between two regions is known as a concentration gradient. Diffusion causes particles to move from the area of high concentration to a low concentration area. This process continues until the particles are distributed evenly throughout the liquid. Figure below shows the diffusion of potassium permanganate in water.