Important Notes For NEET Biology – The Living World

The Living World

Understanding the characteristics that define living organisms is fundamental. Here are the essential features that denote life:

• Growth
• Reproduction
• Tactile sensation and environmental responsiveness
• Metabolism
• Self-organization
• Mortality

All these processes occur in the protoplasm, making it the physical basis of life, as stated by Huxley.

Biodiversity

Biodiversity represents the variety and variability of life on Earth. The key terms used in classification include:

• Nomenclature: This is the process of assigning scientific names to organisms. The International Code of Botanical Nomenclature (ICBN) and the International Code of Zoological Nomenclature (ICZN) provide guidelines. The system of binomial nomenclature, introduced by Carolus Linnaeus, uses two names: the genus and the specific epithet (e.g., Homo sapiens).

Rules for Nomenclature:

1. Each name has two parts – the genus and the specific epithet.
2. Names should be underlined when written by hand and italicized when printed.
3. They should be Latinized.
4. The generic name starts with an uppercase letter, while the specific name starts with a lowercase letter.

• Classification: This involves grouping organisms into categories based on shared characteristics. These groups are called taxa.
• Taxonomy: This is the science of identifying, naming, and classifying organisms based on various criteria such as cellular structure, biological data, and evolutionary history.
• Systematics: This branch of biology deals with classification and the evolutionary relationships among organisms. Linnaeus’s Systema Naturae was a pioneering work in this field.

Taxonomic Categories

These categories represent the hierarchical levels of classification in ascending order:

1. Kingdom – Groups different phyla.
2. Phylum/Division – Includes related classes (phylum for animals, division for plants).
3. Class – Comprises related orders.
4. Order – Contains related families.
5. Family – An assembly of related genera.
6. Genus – A group of related species.
7. Species – The fundamental unit of classification, representing a group of closely related individuals that can interbreed to produce fertile offspring.

Taxonomic Aids

These are tools and techniques used for the identification and classification of organisms:

• Herbarium: A collection of preserved plant specimens. These are dried, pressed, and mounted on sheets with detailed labels.
• Museums: Repositories for preserved plant and animal specimens, which are stored as dry samples or in preservative solutions.
• Zoological Parks: Protected areas where wild animals are kept in natural-like conditions.
• Botanical Gardens: Places where a wide variety of living plant species are cultivated for scientific study and conservation, each labeled with its scientific name and family.

Keys

These are tools used for identifying plants and animals based on their characteristics.

Types of Taxonomy

• Alpha Taxonomy: Involves collecting and identifying organisms based on gross morphology and herbarium studies.
• Beta Taxonomy: Incorporates morphological evidence along with anatomical, genetic, and physiological data.
• Omega Taxonomy: Utilizes microscopic and biochemical evidence for classification, synonymous with new systematics based on phylogenetic classification.

Notable Figures in Taxonomy

• Father of Indian Taxonomy: H. Santapau
• Father of Indian Botany and Indian Herbaria: William Roxburgh
• Term ‘Taxonomy’ Coined By: A.P. de Candolle
• Father of Taxonomy: Carolus Linnaeus

Key Books and Authors

• Lamarck: Philosophie Zoologique
• Alexander Oparin: The Origin of Life
• Ernst Mayr: Principles of Systematic Zoology
• Linnaeus: Systema Naturae, Philosophia Botanica, Species Plantarum, Genera Plantarum

Additional Terminologies

• Cohort: A group of individuals of the same age within a population.
• Sympatric Species: Two related species living in the same geographic region.
• Allopatric Species: Genetically related species with different geographic distributions.
• Polytypic Species: A species with two or more varieties or subspecies.
• Monotypic Species: A species without any variety, race, or subspecies.

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