What is Living?

The living world is vast and diverse. The key characteristics that define living organisms include growth, reproduction, ability to sense the environment (consciousness), and metabolism. While growth and reproduction are also exhibited by non-living objects (e.g., mountains grow, sand dunes reproduce), consciousness and metabolism are considered the defining properties of life.

🌿 Introduction to Biodiversity

Biodiversity refers to the variety of living organisms on Earth, encompassing all plants, animals, microorganisms, and the ecosystems in which they occur.The Earth hosts a vast number of living organisms. The number of species that are known and described ranges between 1.7-1.8 million.

It includes diversity at three levels:

  1. Genetic Diversity – Variation in genes within a species. Example: different varieties of mango (Mangifera indica), rice (Oryza sativa), or dogs (Canis familiaris).
  2. Species Diversity – Variety of species within a habitat or region. Example: Tropical rainforests show maximum species diversity.
  3. Ecosystem Diversity – Variety of ecosystems in a geographical area, such as deserts, grasslands, forests, wetlands, and coral reefs.

🧬 Nomenclature and Identification

  • Need for Standardization: To study this diversity, we need a standardized system. Organisms are known by local names that vary from place to place, creating confusion. Therefore, there is a need for a standardized naming system so that an organism is known by the same name all over the world.
  • Nomenclature: The process of providing a standardized scientific name to an organism is called nomenclature.
  • Identification: Nomenclature is only possible when the organism is described correctly. This process of correct description, which allows us to know what organism the name is attached to, is called identification.

🧾 Introduction to Binomial Nomenclature

Before standardized naming, the same organism had multiple local names in different regions and languages, creating confusion in communication among scientists. To resolve this, a universal system of naming organisms was introduced — the Binomial System.

  • The system of providing a name with two components is called Binomial Nomenclature.
  • This system was given by Carolus Linnaeus and is practiced by biologists worldwide.

🌿 Concept

Binomial nomenclature is the system of naming organisms with two names:

  1. Generic name (Genus) – indicates the group or genus to which the organism belongs.
  2. Specific epithet (Species) – indicates the species within the genus.

Together, they represent the scientific name of the organism.

Example:

  • Homo sapiens → Homo (Genus) + sapiens (Species)
  • Mangifera indica → Mangifera (Genus) + indica (Species)

📜 Rules of Binomial Nomenclature (ICZN / ICBN)

Binomial nomenclature follows rules laid down by:

  • ICBN – International Code of Botanical Nomenclature (for plants)
  • ICZN – International Code of Zoological Nomenclature (for animals)

Key Rules:

  1. Each scientific name has two parts – Genus and species.
  2. Genus name starts with a capital letter, and species name starts with a small letter.
  3. Both names are italicized (when printed) or underlined separately (when handwritten).
  4. The name of the discoverer or author may be written after the species name (e.g., Mangifera indica Linn.).
  5. The names are Latinized regardless of their origin.
  6. No two organisms can share the same name.

Taxonomy and Systematics

  • Classification: It is the process by which organisms are grouped into convenient categories (taxa) based on easily observable characters.
  • Taxonomy: This is the science and process of classification. The processes basic to taxonomy are characterisation, identification, classification, and nomenclature.
  • Systematics: This is a broader branch of study. It includes taxonomy but also takes into account the evolutionary relationships (phylogeny) between organisms. Linnaeus used Systema Naturae as the title of his publication.

💡 Solved Examples

Q1. Define biodiversity.
A1. Biodiversity is the totality of genes, species, and ecosystems in a given region. It includes genetic, species, and ecosystem diversity.

Q2. Name the three levels of biodiversity.
A2. (i) Genetic diversity
(ii) Species diversity
(iii) Ecosystem diversity.

Q3. Why is biodiversity important?
A3. Biodiversity maintains ecological balance, provides economic benefits, and holds cultural and aesthetic value.

Q4. Give two examples of ecosystem diversity in India.
A4. Desert ecosystem (Rajasthan) and mangrove ecosystem (Sundarbans).

Q5. What is meant by species diversity? Give one example.
A5. Species diversity is the variety of species within a region. For example, the Western Ghats show very high species diversity compared to the Gangetic plains.