Biology: Class 11 — Chapter 1: The Living World

• Known as 'The Darwin of the 20th century'.
• Pioneered the currently accepted definition of a biological species.
• Awarded the triple crown of biology: the Balzan Prize (1983), the International Prize for Biology (1994), and the Crafoord Prize (1999).

• Nomenclature: The process of standardising the naming of living organisms such that a particular organism is known by the same name all over the world.
• Identification: Determining whether an organism is described correctly to assign its correct name.
• Scientific names for plants are based on principles provided by the International Code for Botanical Nomenclature (ICBN).
• Scientific names for animals are based on principles provided by the International Code of Zoological Nomenclature (ICZN).

Proposed by Carolus Linnaeus, Binomial Nomenclature is a system of providing a scientific name with two components: the Generic name and the specific epithet.

Universal Rules of Nomenclature:

1. Biological names are generally in Latin and written in italics. They are Latinised or derived from Latin irrespective of their origin.
2. The first word represents the genus, while the second component denotes the specific epithet.
3. Both words, when handwritten, are separately underlined, or printed in italics to indicate their Latin origin.
4. The genus name starts with a capital letter, while the specific epithet starts with a small letter (e.g., Mangifera indica).
5. The name of the author appears after the specific epithet in an abbreviated form (e.g., Mangifera indica Linn., indicating it was first described by Linnaeus).

• Taxonomy: The process of classifying all living organisms into different categories or taxa based on their characteristics. Characterisation, identification, classification, and nomenclature are basic to taxonomy.
• Systematics: Derived from the Latin word 'systema' (systematic arrangement of organisms). It deals with systematic arrangements and evolutionary relationships between organisms. Linnaeus used Systema Naturae as the title of his publication.

1. Species: A group of individual organisms with fundamental similarities (e.g., Mangifera indica, Solanum tuberosum, Panthera leo).
2. Genus: Comprises a group of related species which has more characters in common in comparison to species of other genera (e.g., Panthera includes leo, tigris, and pardus).
3. Family: A group of related genera with still less number of similarities (e.g., family Solanaceae includes Solanum, Petunia, and Datura; family Felidae includes Panthera and Felis).
4. Order: The assemblage of families exhibiting a few similar characters (e.g., order Polymoniales includes Solanaceae and Convolvulaceae; order Carnivora includes Felidae and Canidae).
5. Class: Includes related orders (e.g., class Mammalia includes order Primata and order Carnivora).
6. Phylum / Division: Classes comprising animals with common features like a notochord and dorsal hollow neural system are placed in phylum Chordata. For plants, classes with similar characters are assigned to a higher category called Division.
7. Kingdom: The highest category in the classification system (e.g., Kingdom Animalia for animals, Kingdom Plantae for plants).

• Man: Homo sapiens | Genus: Homo | Family: Hominidae | Order: Primata | Class: Mammalia | Phylum: Chordata
• Housefly: Musca domestica | Genus: Musca | Family: Muscidae | Order: Diptera | Class: Insecta | Phylum: Arthropoda
• Mango: Mangifera indica | Genus: Mangifera | Family: Anacardiaceae | Order: Sapindales | Class: Dicotyledonae | Division: Angiospermae
• Wheat: Triticum aestivum | Genus: Triticum | Family: Poaceae | Order: Poales | Class: Monocotyledonae | Division: Angiospermae