The Living World

Introduction

We know that everything in the living world is related to each other significantly. The vast range of life forms on Earth makes the planet an amazing place to live and flourish. The flourishing diversity implies the existence of numerous organisms with distinctive features. The most indicative characteristic of any organism is the fact that it is either a living or a non-living thing. Therefore, to distinguish between a living and a non-living thing, we need to understand what exactly is considered as a ‘living being’.

What is ‘Living’?

Generally, anything that moves and breathes and makes changes around itself is said to be a living thing. The easiest example is a human being, but what if a person is brain-dead, has been lying still in the hospital for days, and shows no physical movement? Would you then claim them to be a non-living thing? But aren’t they still breathing? Their heart is still pumping and all the organs within their body still work. Thus, we need to understand that the living world is way more complex than just what we have seen. To distinguish between a living and a non-living thing, the following features should be considered:

Characteristic Features:

•       Growth
•       Reproduction

Defining Features:

•       Metabolism
•       Cellular Organisation
•       Consciousness

Growth

An increase in the mass and number of any organism is known as growth. The division of the cell in both multicellular and unicellular organisms exhibit growth. It can be seen in all living things, occurring from the inside. But non-living-things grow in terms of numbers. Although it is seen in both living and non-living organisms, it is not considered a defining feature because all ‘living things’ don’t grow forever. Thus, making it an uncommon feature yet having the same characteristics.

Reproduction

Reproduction means the production of offspring. It is categorised as:
• Sexual Reproduction – Production of offspring possessing varied features, in which both the male and female parents are involved
• Asexual Reproduction – Production of offspring in which only one parent is involved to reproduce
In unicellular organisms, growth and reproduction are the same things, as they merely increase in number. Reproduction is also not a defining feature because all organisms do not reproduce.

Metabolism

It is the sum total of all the chemical reactions occurring in living organisms. It involves the process by which the body turns our food into energy to grow and reproduce. However, non-living-things do not reproduce. Hence, metabolism distinguishes the living from the non-living; therefore, it is a defining feature.

Cellular Organisation

The process of the making up of cells in an organism and their arrangement inside it is called cellular organisation. Since the cell is the basic structural and functional unit of life, its presence initiates cellular organisation in all organisms. It is found in all living organisms without exception; therefore, it is a defining feature.

Consciousness

Consciousness is being aware of the surroundings and responding to an external stimulus. All organisms sense the stimuli through sense organs and respond accordingly. For example, plants respond to the direction of the sun. However, humans are the only organism who are aware of themselves.

Diversity in the living world

There are 1.7-1.8 million known and described species on this planet. Together, we call that Biodiversity. But there are even more undetected species and constant discovery of new species that are continuously added to the list. To understand what these species are and how they affect the surrounding, we need to study each of them. Since the species are large in number, they are divided into similar categories and classified under common features. This process is called Taxonomy.

Taxonomy

All the organisms are arranged into different categories based on their characteristics. The process of taxonomy includes the following steps:
1. Identification –Recognition of an organism by a specific feature
2. Classification – Grouping of organisms with similar characteristics
3. Binomial Nomenclature – Naming an organism according to its group

Nomenclature

Often, the organisms around us are given local names, which differ from place to place and language to language. Therefore, it was required to standardise their names. Scientists formulated some methods to assign a scientific name to each organism. The International Code for Botanical Nomenclature (ICBN) and International Code for Zoological Nomenclature (ICZN) were introduced to assign scientific names for plants and animals, respectively. The scientific name has two components–a generic name known as ‘Genus’ and the specific epithet known as ‘Species’. This system of naming is called Binomial Nomenclature. It was given by Carolus Linnaeus and is used by biologists all over the world.

Conclusion

The Earth consists of diverse forms of life. Variations in them are so diverse that they make us wonder about defining the characteristics of living beings. To facilitate the study of diverse organisms, biologists evolved rules for identification, nomenclature, and classification. This process is called taxonomy. Each organism is identified and assigned a scientific name with two words as per the binomial system of nomenclature.