Introduction to Biology

Biology is a subject that deals with the study of structures, functions and relationships of living organisms. The things around us can be divided into two groups as Living Things and Non-living Things. In Biology, the attention is majorly payed to the Livings Things category.

It has been unable for us to give an exact definition to "Life". But several characteristics that distinguish living things on Earth from non-living things could be observed. These characteristics help us to understand what a living thing or life means. These include: Order and Organization, Homeostasis, Metabolism, Growth and Development, Adaptation, Responsiveness, Reproduction, Movement, and Evolution.

Order and Organization

Order and Organization could be described as being structurally composed of one or more cells.

Homeostasis

Regulation of the internal environment of the body to maintain a constant state, despite the external environmental changes. Example: Contraction of muscles in the body to produce heat in cold conditions (shivering)

Metabolism

The metabolism of an organism is the total of all the chemical processes within its body.

Growth and Development

Growth is defined as an irreversible increase in size of the organism.

Example: Multicellular organisms start life from a single cell, and later develop into individuals containing many multicellular organs.

Adaptation

Particular innovations of structure and functions which help living things to maintain life by extracting energy and materials from the environment, and reproduce.

Responsiveness

All organisms are responsive, and they exhibit irritability. They receive information about their environment and react in appropriate ways.

Reproduction

Organisms give rise to others of the same type in order to perpetuate life despite the inevitability of death of the individual.

Movement

Energy produced during metabolism allows movement of an individual organism, parts of organisms and materials inside cells and tissues. Animal movements are usually associated with obtaining food, finding mates, migrating due to climatic changes or escaping from predators.

Evolution 

Living things change over time. This is evidence from fossil records of earlier organisms. All living things are from a common ancestor and arose as a result of genetic modification of species over time.