The living world is a complex network of interconnected organisms that engage in metabolism, reproduction, and response to environmental cues. We are aware of how intricately connected everything in the living world is. The diversity of living forms on earth gives it a wonderful environment to live and thrive. The abundance of diversity suggests the presence of numerous species with unique characteristics. The fact that an organism is either a living thing or a non-living entity is its most striking characteristic. As a result, in order to distinguish between a living item and a non-living one, we first need to define what a “living being” actually is.

What is ‘Living’?

Any organism that breathes and moves is considered ‘Living’. Any life form that exhibits or possesses the qualities of life or being alive is referred to as a living thing. The basic traits include having an organized structure, requiring energy, reacting to stimuli and changing their surroundings, and having the ability to reproduce, grow, move, metabolize, and die. The three Domains that make up the current classification of living things are Bacteria, Archaea, and Eucarya.

Characteristics of Living World

All living organisms grow and increase in mass and number of individuals. Growth, reproduction, ability to sense the environment and mount a suitable response is unique features of living organisms. Given below are some characteristic features of the Living world:

Respiration

• Aerobic respiration: Aerobic respiration is a chemical process in which oxygen is used to make energy from sugars. Aerobic respiration is also known as aerobic metabolism and cell respiration.
• Anaerobic respiration: Anaerobic respiration takes place in the absence of oxygen. examples include alcohol fermentation and lactic acid fermentation.

Nutrition

• Autotrophic Nutrition: It is a type of nutrition in which plants make their own food .they are interdependent on themselves. example- plants. Autotrophic nutrition is of two types: phototrophic, and chemotrophic.
• Heterotrophic Nutrition: It is a type of nutrition in which an organism is dependent on another organism for food. example -humans. Heterotrophic nutrition is of three types: herbivorous, carnivorous, and omnivorous.

Excretion

The process of moving out waste material from the body is known as excretion.

Locomotion/Movement

Locomotion is a term used to describe a movement of an organism from one place to another.

Reproduction

• Asexual Reproduction: A process where a single gamete is responsible for reproduction to take place i.e., new offspring is produced from a single parent. Examples: hydra and paramecium.
• Sexual Reproduction: Process where both the gametes take part in reproduction. Examples: fishes, and mammals.

Structural Organisation

• Unicellular: It is also known as a single-celled organism and only single cells perform all the functions needed for an organism to live. example- protozoa and Protista.
• Multicellular: Multicellular organisms consist of many cells to perform different functions. example-Dogs, cows.

Diversity

A large variety of anything is known as diversity. Diversity is a vast term to include different species, genes, and ecosystem levels. Thomas Lovejoy introduced the term biological diversity in 1980.

Biodiversity

A large variety of organisms or terms used to refer to the number of varieties of plants and animals on earth is termed biodiversity. there are three types of biodiversity: genetic, species, and ecological diversity. There are over 15 Lakh species in the world of which 10 Lakh are animals(8 Lakh of insects and 2 Lakh of others) and 5 Lakh of plants.

Nomenclature

The scientific naming of organisms is known as nomenclature. Nomenclature is defined as the language of sculpture. The scientific name of mango is written as Mangifera indica.

Rules of Nomenclature

• Latinised names are used.
• The first word represents the genus and the second word is the species name.
• Printed in italics, if handwritten then underline separately.
• The first word starts with a capital letter while the species name is written in small letters.

ICBN  International Code of Botanical  Nomenclature (This is for giving scientific names to plants).

ICZN International Code of Zoological Nomenclature(This is for giving scientific names to animals).

Classification

Grouping organisms into categories on the basis of similarities and differences is known as classification. classification is the process by which anything is grouped into systematic categories based on some easily observable characteristics. For example, we easily recognize groups such as plants or animals, dogs or cats, insects, or reptiles.

Need of Classification

Classification is done to organize the vast number of plants and animals into categories that could be named, remembered, studied, and understood. classification avoids confusion among the different varieties of organisms. Moreover, it makes the study of organisms easier.

Given below are some scientist’s contributions to biology

• Carolus Linnaeus (Father of Taxonomy): He gives the 2 kingdoms system.
• Hackel: He gave the 3 kingdom systems.
• Copeland: He gave the 4 kingdom systems.
• R.H Whittaker: He gave the 5 kingdom system which is the popular one.
• Carl Woese: He gave the 6 kingdom system and is the latest.

Taxonomy

The study of principles and procedures of classification is termed taxonomy. Based on characteristics, all living organisms can be classified into different taxa. This process of classification is taxonomy.

Taxonomic Categories

A. P. Candolle is credited with coining the term “taxonomy,” which refers to the seven main taxonomic categories. It is the listing of categories from the top-most kingdom to the bottom-most species, either in ascending or declining orders. There are two kinds in the hierarchy: intermediate and mandatory. From kingdoms to species, Obligate is rigidly adhered to, yet Intermediate is the exact reverse.

• Species: The smallest and most fundamental distinction in classification is the species. It describes a population that is comparable in terms of form, shape, and reproductive characteristics. Similar reproductive characteristics can lead to the formation of fertile siblings.
• Genus: This is the grouping of a number of closely related species that share linked features and are thought to have shared ancestors. For instance, the genus Panthera is where the leopard and cat belong.
• Family: Families are associations of connected genera. The vegetative and reproductive characteristics are used to categorize the families. The Felidae family includes animals like tigers and lions as examples.
• Order: It is the combination of one or more common families, which is regarded as a higher category. Felidae family members participate in the Carnivora order.
• Class: A class designates a division in a phylum made up of one or more orders. All mammals, including gorillas, monkeys, humans, and gibbons, are included in the Mammalia class.
• Phylum: It contains a group of related classes. Mammalia, along with reptiles, fish, amphibians, and birds, make up the phylum Chordata.
• Kingdom: The highest taxonomic classification known as a kingdom is given to every animal that belongs to various phyla. The kingdom Animalia and Plantae encompasses all living things, including both plants and animals. A taxon is a classification that identifies an organismal group based on external characteristics.

FAQs on Living World

Q1: Define the following terms: Phylum, and Class.

Answer:

• Phylum– Classes comprising animals like fishes, amphibians, reptiles, and birds along with mammals constitute the higher category called phylum. All these, based on the common features like the presence of notochord and dorsal hollow neural system, are included in phylum Chordata.
• Class– This category includes related orders. For example- the order primate comprising monkey, gorilla, and gibbon is placed in class Mammalia along with the order Carnivora which includes animals like tiger, cat, and dog.

Q2: How is a key helpful in the identification and classification of organisms?

Answer:

 The key is defined as the taxonomical aid used to identify and classify plants and animals based on their similarities and differences. Keys are generally analytical in nature.

Q3: Define a taxon.

Answer:

 Taxon is plural of taxa, it is the taxonomic unit of any rank. ARISTOTLE is known as the father of taxonomy.

Q4: Why are living organisms classified?

Answer:

Living organism are classified due to the following reasons:

• To make study of organism easy.
• To avoid confusion.
• To learn the interrelationship among the various organisms.