Biology: NCERT - THE LIVING WORLD

Biology

• Study of living organisms
• Covers a wide range of life forms and their processes
• Humans have always been interested in the living world, recognizing the difference between animate and inanimate objects

Categorizing & Naming Living Organisms

• Early classifications were based on the uses of organisms
• Standardized naming became necessary for communication and understanding
• Nomenclature - assigning scientific names to organisms
• Identification - describing organisms accurately
• Binomial nomenclature introduced by Carolus Linnaeus
  • Uses two words: genus and specific epithet
  • Written in Latin and italicized
  • First word (genus) capitalized, second (specific epithet) not
  • Author's name appears after specific epithet, e.g., Mangifera indica Linn.
• International Code for Botanical Nomenclature (ICBN) - for plants
• International Code of Zoological Nomenclature (ICZN) - for animals
• Scientific names ensure each organism has a unique, universally accepted name

Taxonomic Categories

• Taxonomy - science of classification
• Hierarchy of categories: Kingdom, Division/Phylum, Class, Order, Family, Genus, Species
• Species - group of organisms with fundamental similarities that can be distinguished from other species
• Genus - group of related species with more common characteristics than other species
• Family - group of related genera with fewer similarities than genus and species

What is Living?

• Distinguishing characteristics of living organisms:
  • Growth
  • Reproduction
  • Metabolism
  • Ability to sense and respond to environment
  • Cellular organization
  • Self-replication, evolution, and self-regulation
• Living organisms are complex, dynamic systems

Diversity in the Living World

• Earth harbors a vast diversity of living organisms
• Estimated 1.7-1.8 million species identified
• Biodiversity refers to the number and types of organisms on Earth
• New organisms are being identified continuously

### Systematics

•  Study of relationships among living organisms
•  Encompasses identification, nomenclature, and classification
•  Takes into account evolutionary relationships
•  Linnaeus used "Systema Naturae" to describe his systematic arrangement of organisms.

Emergent Properties

• Interactions among components at different levels of organization create new properties
• Example: Properties of cells arise from interactions among their molecular components
• Living organisms are self-replicating, evolving, and self-regulating interactive systems.

Taxonomy

• Taxonomy is the study of identification, nomenclature, and classification of organisms.
• The classification system is hierarchical, starting with species and moving up to kingdom.
• As you move up the hierarchy, the number of common characteristics decreases, making it more difficult to determine relationships.
• Taxonomic categories, also known as taxa, include species, genus, family, order, class, phylum, and kingdom.

Classification Hierarchy

• Species: A group of organisms that can interbreed and produce fertile offspring.
• Genus: A group of closely related species.
• Family: A group of related genera.
• Order: A group of related families.
• Class: A group of related orders.
• Phylum: A group of related classes.
• Kingdom: The highest taxonomic rank, grouping together all organisms sharing fundamental characteristics.

Taxonomic Aids

• Herbarium: A collection of dried, pressed plant specimens arranged and preserved on sheets, providing information on the date and place of collection, English, local, and botanical names, family, and collector’s name.
• Botanical Gardens: Specialized gardens containing living plants for identification and reference, with each plant labeled with its scientific name and family.
• Museums: Collections of preserved plant and animal specimens, often including skeletons, for study and reference.
• Zoological Parks (Zoos): Protected environments where wild animals are kept for observation and education, providing insights into their behavior and food habits.
• Keys: Tools used for identification based on similarities and differences, utilizing contrasting characters in a pair called couplets, leading to a choice between two options.

Taxonomic Tools & Resources

• Flora: Contains information on the habitat and distribution of plants in a particular area.
• Manuals: Provide guidance for identifying species in a given region.
• Monographs: Focused studies on a single taxon, providing in-depth information.
• Catalogues: Lists and descriptions of organisms.

Biology: The Science of Life

• Biology is the study of living organisms and their processes.

• The living world exhibits diverse organisms, which early humans recognized as distinct from inanimate objects.

• Anthropocentric views in biology limited progress in early biological knowledge.

• Systematic study of living organisms led to detailed identification, nomenclature, and classification systems.

• Recognizing shared similarities (horizontally and vertically) among organisms demonstrated the interconnectedness of life.

• This realization highlighted the importance of biodiversity and the interconnectedness of living organisms on Earth.

Ernst Mayr: The "Darwin of the 20th Century"

• Ernst Mayr, born in 1904, was a renowned Harvard University evolutionary biologist.

• He made significant contributions to ornithology, taxonomy, zoogeography, evolution, systematics, and the history and philosophy of biology.

• He redefined the concept of a biological species and emphasized the origin of species diversity as the central question in evolutionary biology.

• He received prestigious awards, including the Balzan Prize, International Prize for Biology, and Crafoord Prize.

Defining "Living"

• Determining what is "living" involves identifying distinct characteristics of living organisms.

• Growth, reproduction, response to stimuli, metabolism, self-replication, self-organization, interaction, and emergence are often considered defining features.

• Growth in living organisms refers to an increase in mass and number of individuals, originating from within.

• Reproduction involves the production of offspring with similar characteristics to parents, although some organisms don't reproduce.

• Metabolism encompasses the complex chemical reactions within living organisms, constantly converting and transforming biomolecules.

• All living organisms exhibit a sense of their surroundings and respond to environmental stimuli.

• Cellular organization is a defining feature of living organisms, emphasizing the complexity and interaction of cells and molecules.

Diversity in the Living World

• There is an abundance of living organisms, ranging from plants and animals to microscopic organisms.

• Biodiversity encompasses the number and types of organisms on Earth.

• Nomenclature refers to the standardized naming of organisms for clear communication and understanding.

• Scientific names, based on agreed principles and criteria, ensure that each organism has a unique and universally recognized name.

• Binomial Nomenclature, developed by Carolus Linnaeus, provides scientific names with two components: a generic name and a specific epithet.

• Rules of Binomial Nomenclature:

  • Names are typically in Latin and written in italics.
  • The first word represents the genus, and the second word denotes the specific epithet.
  • The genus name is capitalized, and the specific epithet starts with a lowercase letter.
  • The author's name is often included, abbreviated after the specific epithet.

Taxonomic Categories and Hierarchy

• Classification involves organizing organisms into categories based on shared characteristics.

• A taxonomic category, or taxon, represents a specific rank in the taxonomic hierarchy.

• Common taxonomic categories include: kingdom, phylum (or division for plants), class, order, family, genus, and species.

• Species is the lowest category, grouping individuals with fundamental similarities.

Examples of Taxonomic Categories

• Species: Mangifera indica (mango), Solanum tuberosum (potato), Panthera leo (lion).

• Genus: Mangifera, Solanum, Panthera

• Family: Solanaceae (includes Solanum, Petunia, Datura)

• Higher Levels: Taxonomic categories demonstrate a hierarchical relationship, with each category encompassing more inclusive groups.

  • For example, a genus includes multiple species, each belonging to a specific family.### Taxonomy - the science of classifying organisms

• Taxonomy is the branch of science focused on identifying, naming, and classifying organisms based on their similarities and differences.

Taxonomic Hierarchy - organizing life

• The taxonomic hierarchy consists of categories arranged in ascending order based on the number of shared characteristics, starting with a species and culminating with a kingdom.

• The higher the category, the more diverse the organisms. The lower the category, the more specific the common characteristics.

• Species: The basic unit of classification comprising organisms capable of interbreeding and producing fertile offspring.

• Genus: A group of closely related species sharing a common ancestor.

• Family: A collection of similar genera with shared evolutionary origins.

• Order: A grouping of related families exhibiting shared, less numerous traits compared to families.

• Class: A collection of related orders expressing more general, less specific attributes.

• Phylum: A group of related classes unified by shared characteristics at this higher level.

• Kingdom: The highest taxonomic category encompassing all organisms sharing fundamental characteristics.

Taxonomic Aids

• Herbarium: A collection of dried, pressed, and preserved plant specimens mounted on sheets.

• Botanical Gardens: Living plant collections for reference, maintained for identification and research purposes.

• Museums: Stores for preserved plant and animal specimens, providing valuable resources for research and education.

• Zoological Parks (Zoos): Sites for wild animal conservation, providing insights into their behavior and habits.

• A place where wild animals are kept in protected environments under human care.

• Key: A tool for identification based on contrasting characteristics, allowing for the distinction and classification of organisms.

Biology

• The study of life forms and living processes.

Diversity of Life

• The living world is incredibly diverse.
• Early humans recognized the difference between living and non-living things.
• Humans often expressed awe and fear toward both inanimate and animate objects.
• Societies with anthropocentric views of biology made limited progress in biological knowledge.
• Systematic and detailed descriptions of life forms led to systems of identification, nomenclature, and classification.
• Humans recognized similarities among living organisms both horizontally (across similar species) and vertically (between species).
• This realization led to a cultural movement for conservation of biodiversity.

Ernst Mayr (1904-2004)

• A renowned evolutionary biologist who was called "The Darwin of the 20th Century".
• Joined Harvard's Faculty of Arts and Sciences in 1953 and retired in 1975.
• Made the origin of species diversity a central question in evolutionary biology.
• Pioneered the currently accepted definition of a biological species.
• Received three prestigious prizes: the Balzan Prize in 1983, the International Prize for Biology in 1994, and the Crafoord Prize in 1999.

What is Living?

• Distinctive characteristics of living organisms are used to define life, including:
  • Growth: An increase in mass and number of individuals.
  • Reproduction: The production of progeny with similar features to the parents.
  • Metabolism: Ongoing chemical reactions in the body.
  • Self-organization: All living organisms have a cellular structure.
  • Response to Stimuli: The ability to sense surroundings and react to them.
  • Homeostasis: Maintaining a stable internal state.
  • Adaptation/Evolution: Changes over generations that allow organisms to survive in their environment.
• Living organisms are self-replicating, evolving, and self-regulating interactive systems that respond to external stimuli.

Biodiversity

• Refers to the number and types of organisms present on Earth.
• The number of known and described species ranges between 1.7-1.8 million, but new organisms are continuously being discovered.

Nomenclature

• The standardization of names given to living organisms to facilitate scientific communication.
• Plants are named according to the International Code for Botanical Nomenclature (ICBN).
• Animals are named according to the International Code of Zoological Nomenclature (ICZN).

Binomial Nomenclature

• A system of naming organisms using two words: genus and specific epithet.
• This system was created by Carolus Linnaeus.
• Examples:
  • Mangifera indica (mango)
  • Solanum tuberosum (potato)
  • Panthera leo (lion)

Rules of Nomenclature

• Scientific names are generally in Latin and written in italics.
• The first word represents the genus (capitalized) and the second word represents the specific epithet (lowercase).
• If handwritten, both words are underlined separately.
• The author of the name is sometimes included in an abbreviated form after the specific epithet (e.g., Mangifera indica Linn.).

Classification

• The process of grouping organisms into categories based on easily observable characters.
• Facilitates the study of a vast number of living organisms.
• Each category is a taxonomic category or taxon, forming a taxonomic hierarchy.

Taxonomic Categories

• The hierarchical levels of classification, from the broadest to the most specific:
  • Kingdom: The broadest category, including all living organisms.
  • Phylum or Division (for plants): A major grouping within a kingdom.
  • Class: A grouping of related orders.
  • Order: A grouping of related families.
  • Family: A grouping of related genera.
  • Genus: A grouping of closely related species.
  • Species: The most specific category, representing a group of individual organisms with fundamental similarities.

Systematics

• The study of the diversity of life and the evolutionary relationships between organisms.
• Encompasses identification, nomenclature, and classification.
• Seeks to understand how organisms are related to each other.
• The term "systematics" is derived from the Latin word "systema," which means systematic arrangement.

Taxonomy

• Taxonomy is a branch of biology that deals with the identification, nomenclature, and classification of organisms.
• The basic principles of taxonomy include:
  • Identification
  • Nomenclature
  • Classification

Taxonomy Hierarchy

• Taxonomy hierarchy arranges organisms into increasingly inclusive categories based on shared characteristics.
• The major categories in this hierarchy are:
  • Species: A group of organisms that can interbreed and produce fertile offspring.
  • Genus: A group of closely related species.
  • Family: A group of related genera.
  • Order: A group of related families.
  • Class: A group of related orders.
  • Phylum: A group of related classes.
  • Kingdom: The highest taxonomic category, grouping all organisms that share fundamental characteristics.

Taxonomic Aids

• Taxonomic aids are tools and resources used to facilitate and complement the study and classification of organisms.
  • Herbarium: A collection of dried, pressed, and preserved plant specimens arranged systematically for reference and study, often mounted on sheets with labels providing information about the species.
  • Botanical Gardens: Specialized gardens with collections of live plants grown for identification and reference.
  • Museum: Collections of preserved plant and animal specimens, including skeletons, insects, and larger animals, for study and reference. These specimens are preserved in various ways, such as containers with preservative solutions or as dried specimens.
  • Zoological Parks (Zoos): Secure environments where wild animals are kept under human care, enabling observation of their behavior and food habits.
  • Key: A set of dichotomous choices based on contrasting characteristics for distinguishing and identifying organisms. These keys typically use pairs of opposing statements, leading to the acceptance of one choice and the rejection of the other.

Classification of Organisms

• Housefly: Musca domestica (Order: Diptera, Class: Insecta, Phylum: Arthropoda)
• Man: Homo sapiens (Order: Primata, Class: Mammalia, Phylum: Chordata)
• Mango: Mangifera indica (Order: Sapindales, Class: Dicotyledonae, Division: Angiospermae)
• Wheat: Triticum aestivum (Order: Poales, Class: Monocotyledonae, Division: Angiospermae)

Understanding Taxonomic Categories

• Phylum: A major taxonomic group within a kingdom, consisting of organisms with a common body plan and shared derived characteristics.
• Class: A group of related orders.
• Family: A group of related genera.
• Order: A group of related families.
• Genus: A group of closely related species.

Binomial Nomenclature

• Binomial nomenclature is a system of naming organisms with two components: the generic name and the specific epithet.
• The system was introduced by Carolus Linnaeus and is used worldwide by biologists.
• Example: Mangifera indica - Mangifera represents the genus, and indica is the specific epithet.
• Rules of binomial nomenclature:
  • Scientific names are written in Latin and italicized.
  • The first word (genus) is capitalized, and the second word (specific epithet) is lowercase.
  • The author's name may be abbreviated after the specific epithet (e.g., Mangifera indica Linn. indicates Linnaeus described the species).

Classification

• Classification is the process of organizing organisms into groups based on shared characteristics.
• Allows for easier study and understanding of the diversity of life.
• Recognizable groups include: plants, animals, dogs, cats, insects.

Biodiversity

• Refers to the variety of life on Earth.
• Estimated 1.7-1.8 million species currently described.
• New species are constantly being discovered.

Nomenclature

• Standardizes the naming of organisms, allowing for consistent communication between scientists worldwide.
• Involves identifying and describing organisms accurately.

International Codes

• International Code for Botanical Nomenclature (ICBN) provides rules for naming plants.
• International Code of Zoological Nomenclature (ICZN) establishes naming conventions for animals.

Taxonomy

• Branch of biology focused on identifying, naming, and classifying organisms.
• Utilizes various tools and methods including herbaria, museums, botanical gardens, and zoological parks.
• Taxonomists also use taxonomic keys to aid in identification.
• Taxonomic studies are crucial for understanding biodiversity and its applications in fields like agriculture, forestry, and industry.

Explore the foundations of biological nomenclature and classification in this quiz. Learn about the historical context, the development of binomial nomenclature by Carolus Linnaeus, and the standards set by various International Codes for naming living organisms. Test your knowledge on the identification and classification of life forms.