What is living?

The dog I can hear barking is alive, and so is the tree outside my window. However, snow falling from the clouds is not alive. The computer you’re using to read this article is not alive, and neither is a chair or table.

What is living?

Anything which shows characteristics of life is called living. The fundamental characteristics of life are- growth, reproduction, metabolism, cellular organization and consciousness. Living things are highly organized, meaning they contain specialized, coordinated parts.

Growth

Living things tend to grow in size. The increase in the number and mass of individuals are two unique characteristics of growth. Multicellular organisms exhibit growth by cell division. Growth varies in plants and animals. If we consider unicellular organisms, they tend to grow in size by cell division. Moreover, this can be easily detected by counting the cells during in vitro cultures under a microscope.

Reproduction

Reproduction is the process by which organisms replicate themselves.

Reproduction can primarily be of two types- sexual reproduction and asexual reproduction.   

Reproduction generally refers to sexual reproduction. Asexual reproduction is used by the lower organisms like Bacteria that divide asexually via Binary fission, Virusestake control of host cells to produce more viruses; Hydras (invertebrates of the order Hydroidea) and Yeast are able to reproduce by Budding.

Sexual reproduction is a biological process that creates a new organism by combining the genetic material of two organisms in a process that starts with, meiosis a specialized type of Cell division

 

budding of Hydra

Metabolism

Metabolism is the sum of the chemical reaction that takes place within each cell of a living organism and that provides energy for vital processes and for synthesizing new organic material.

All living organisms are made up of chemicals. These chemicals, small and big belonging to various classes, size and function, etc are constantly being made and changed into other biomolecules.

There are thousands of metabolic reactions occurring simultaneously inside all living organisms, be they unicellular or multicellular.

Cellular organization

Cellular organization – All living organisms are made up of cells that perform all functions inside the body. The cellular organization is the components that make up the cell and how they are arranged inside it. Each component called an organelle, performs a specific function vital for the cell.

Consciousness

All living organisms have an inherent ability to sense their surroundings or environment and respond to their environmental stimuli which could be physical, chemical, or biological. Plants and animals both respond to external stimuli. Human beings are the only organisms who are aware of themselves, i.e., have self-consciousness.

Diversity in the Living World

Diversity in the Living World 

Diversity in the world can be experienced everywhere on the earth. Each different kind of plant, animal, or organism that you see represents a species. The number of species that are known and described ranges from 1.71.7 to 1.81.8 million, which is referred to as biodiversity. Every individual is unique with respect to structure, body functions, genetic make-up, etc

Living organisms inhabiting different habitats have different structural organs or functions developed according to the conditions of the habitat. The warm and humid regions of the earth have diverse organisms and thus are known as the region of mega biodiversity.

Terminology utilized as a part of classification includes Nomenclature, Classification, Taxonomy and Systematics.

The process of naming an organism is known as nomenclature. A principle and criterion were given for naming the organisms, by scientists known as International Code for Botanical nomenclature (ICBN). For animals, International Code of Zoological Nomenclature. This helps scientists from all over the world to interact with each other using the same name.

Each name consists of two parts the first part is the generic name and the second part is the name of the species. This is known as Binomial Nomenclature. This was given by a scientist known as Carolus Linnaeus. 

Examples: Mangifera Indica (Mango); Homo sapiens (Man)

In this case, Mangifera and Homo are the generic names; indica and sapiens are specific epithets.

Rules of Nomenclature:

  • Each biological name has two words-The principal word speaks about the genus and the second speaks to the specific epithet.
  • The expressions of the name ought to be independently underlined when manually written and ought to be in italics when printed.
  • The generic name ought to begin with a capital letter and the specific epithet ought to begin with a little letter.
  • The names ought to be either Latin or Latinized.

Classification: It is the process of assigning creatures to particular groups or classes taking into account some defined characters. These classes are called Taxa (sing. taxon)

Taxonomy: It is the investigation of identification, nomenclature and arrangement of life forms taking into account outer and inside the structure with cell structure, advancement process and biological data.

 systematics: It is the investigation of life forms with reference to identification, nomenclature, arrangement and evolutionary correspondence.

Taxonomic Categories

Taxonomy

Taxonomy Definition

Taxonomy is the branch of biology that classifies all living things. It was developed by the Swedish botanist Carolus Linnaeus, who lived during the 18th Century, and his system of classification is still used today. Linnaeus invented binomial nomenclature, the system of giving each type of organism a genus and species name. The Father of taxonomy was Carolus Linnaeus. He also developed a classification system called the taxonomic hierarchy, which today has eight ranks from general to specific: domainkingdomphylum, class, order, family, genus, and species.

The Taxonomic Hierarchy

A taxon (plural: taxa) is a group of organisms that are classified as a unit. This can be specific or general. The hierarchy has two categories i.e., obligate and intermediate. Obligate is the one that is followed strictly and ranges from kingdom to species. Intermediate is not observed strictly and they. Also, they are added to the obligate lists like subdivision, superfamily, superclass, suborder, subspecies etc.

The following is a brief description of the taxonomic ranks of the taxonomic hierarchy.

Domain

A domain is the highest (most general) rank of organisms. Linnaeus did invent some of the taxonomic ranks, but he did not invent the domain rank, which is relatively new. The term domain wasn’t used until 1990, over 250 years after Linnaeus developed his classification system in 1735.

The three-domain system of Carl Woese, introduced in 1990, with top-level groupings of ArchaeaBacteria, and Eukaryota domains.

Kingdom

Before domains were introduced, the kingdom was the highest taxonomic rank. In the past, the different kingdoms were Animalia, Plantae, Fungi, Protista, Archaea, and Bacteria (Archaea and Bacteria were sometimes grouped into one kingdom, Monera)

Phylum

Phylum (plural: phyla) is the next rank after kingdom; it is more specific than kingdom but less specific than class. There are 35 phyla in the kingdom Animalia, including Chordata (all organisms with a dorsal nerve cord), Porifera (sponges), and Arthropoda (arthropods).

Class

Class was the most general rank proposed by Linnaeus; phyla were not introduced until the 19th Century. There are 108 different classes in the kingdom Animalia, including Mammalia (mammals), Aves (birds), and Reptilia (reptiles), among many others.

Order

Order is more specific than class. Some of Linnaeus’ orders are still used today, such as Lepidoptera (the order of butterflies and moths). There are between 19-26 orders of Mammalia, depending on how organisms are classified—sources differ. 

Genus

Genus (plural: genera) is even more specific than family. It is the first part of an organism’s scientific name using binomial nomenclature; the second part is the species name. An organism’s scientific name is always italicized, and the genus name is capitalized while the species name is not. Genus and species are the only taxonomic ranks that are italicized. The scientific name for humans is Homo sapiensHomo is the genus name, while sapiens is the species name. 

Species

Species are the most specific major taxonomic rank; species are sometimes divided into subspecies, but not all species have multiple forms that are different enough to be called subspecies. There are an estimated 8.7 million different species of organisms on Earth, While each genus name is unique, the same species names can be used for different organisms. For exampleUrsus americanus is the American black bear, while Bufo americanus is the American toad.

Taxonomical Aids

Taxonomic Aids: Taxonomic studies of animals, plants, microorganisms and other species are highly useful in the field of forestry, industry, agriculture and the study of biodiversity. Hence, the organism should be identified, and classified and information about the organism should be stored for future studies and references. This storehouse of information and specimens that helps in taxonomic studies are called Taxonomic Aids.

Herbarium: A herbarium is the storehouse of plant specimens.
It is a collection of dried, pressed, plant specimens that are arranged systematically according to a universally accepted system of classification. The Bentham and Hooker system is followed in most of Herbaria. The sheets on which the specimens are mounted are called Herbarium
 sheets 

The total number of plant specimens are about 6.56.5 million.
 Another Botanical Herbarium called Central National Herbarium is at Indian Botanical Garden, Howrah, Kolkata.

Some of the other examples are as follows:
a. National Botanical Garden, Lucknow
b. Lalbagh Botanical Garden, Bangalore, Karnataka
c. Government Botanical Garden, Ooty
d. Tropical Botanical Garden and Research Institute, Trivandrum, Kerala
.

Herbarium of flowers

Botanical Garden: Botanical gardens are the place where varieties of plants collected from different places of the world are grown together in a protected environment. It may consist, of many rare, elite, exotic species. It shows rich biodiversity and plays an important role in germplasm conservation. In the Botanical Garden, all plants carry identification plates, having a common name, botanical name and the name of the family that belongs

Botanical Garden

Museum: It is the collection of preserved plants and animal specimens for study and reference. Specimens are preserved in jars using preservative solutions of alcohol and formalin. Only those plants that cannot be kept in the herbarium are preserved. Some of the specimens include algae, fungi, mosses, ferns, succulents, fruits, etc. Even fishes, reptiles, amphibians, etc., are stored. Large animals are preserved in skeleton forms. Insects are dried out and mounted over pins inside the insect boxes. Others are preserved as dry specimens in the Biological Museum.

Biological museum

Zoological Park: Zoological Park is an enclosed area where wild animals are kept in an open, natural, but protected environment under human care. Zoological parks are the best places to study the behavior and food habitats of wild animals. Zoological parks help in conserving endangered animals and their multiplication through captive breeding. In India, there are around 200200 Zoological parks.
Zoological Parks are also important spots for children, students and the public to see wild animals

Zoological park

Keys: Key is another taxonomical aid used for the identification of plants and animals based on similarities and dissimilarities.Keys are of two types, i.e., dichotomous keys (bracketed key and indented key) and poly clave keys. Dichotomous Keys is the one in which the choices allow only two alternative couplets. There are two types of dichotomous keys – Indented Keys, also called yoked and Bracketed Keys. Poly clave key is relatively a new alternative to dichotomous keys and becoming increasingly popular, especially because of the ease of computerizing them and is also termed multiple access or synoptic key. This key is based on the identification of species by the process of elimination.

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