Class 11 Biology Chapter 1 The Living World Notes
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| Class 11 Biology Chapter 1 The Living World Notes |
Class 11 The Living World Chapter 1 Biology Notes
TOPICS IN THE CHAPTER
- Definition of biology and its importance.
- Characteristics of living organisms.
- Levels of biological organization (cell, tissue, organ, organ system, organism, population, community, ecosystem, and biosphere).
- Definition and importance of taxonomy and systematics.
- Taxonomical hierarchy: Kingdom, Phylum, Class, Order, Family, Genus, and Species.
- Binomial nomenclature and rules for writing scientific names.
- Herbarium, botanical gardens, museums, and zoological parks as taxonomical aids.
- Introduction to Monera and their characteristics.
- Types of bacteria: Eubacteria and Archaebacteria.
- Structure and types of bacterial cells.
- Economic importance of bacteria.
- Introduction to Protista and their characteristics.
- Classification and examples of different protists.
- Introduction to Fungi and their characteristics.
- Structure and types of fungal cells.
- Classification and examples of different fungi.
- Importance of fungi in nature and human life.
- Introduction to Plantae and their characteristics.
- Classification of plants based on different criteria.
- Classification and characteristics of major plant groups: Algae, Bryophytes, Pteridophytes, Gymnosperms, and Angiosperms.
- Plant life cycle and alternation of generations.
- Introduction to Animalia and their characteristics.
- Classification of animals based on different criteria.
- Classification and characteristics of major animal phyla.
- Basic animal tissues and organ systems.
- Invertebrates and vertebrates.
- Introduction to viruses, viroids, and lichens.
- Structure and replication of viruses.
- Characteristics and examples of viroids.
- Symbiotic relationship in lichens.
WHAT IS ‘LIVING’?
Living is a unique, complex organization of molecules, expressing through chemical reactions which lead to growth, development, responsiveness, adaptation & reproduction.
PRPPERTIES OF LIVING ORGANISM
- Growth
- Metabolism
- Reproduction
- Consciousness
GROWTH
- All living organisms Grow
- Growth is increase in cell number and increase in cell mass
- Plants : Growth is indefinite
- Animals : Growth is seen up to certain age, cell replacement continue
- Unicellular organism : grow by cell division
- Non Living : Mountains, boulders and sand mounds do grow.
- So Growth can not be considered as defining feature of living
- In majority of higher animals and plants, growth and reproduction are mutually exclusive events.
- In single cell organism , growth and reproduction is mutually inclusive event
REPRODUCTION
- living organisms can reproduce
- Unicellular organism : like bacteria, unicellular algae or Amoeba, reproduction is synonymous with growth, i.e., increases in number of cells.
- There are many organisms which do not reproduce (mules, sterile worker bees, infertile human couples, etc).
- Hence reproduction can not be considered as defining characteristic of living organisms.
MATABOLISM
- Metabolism means conversion of one chemical to another
- All plants, animals, fungi and microbes exhibit metabolism. Metabolic reactions can be demonstrated outside the body in cell-free systems (in vitro)
- Metabolic reaction can occur in living condition (inside cell, tissue, organs) and in non living condition ( in vitro – test tube)
- Metabolic reaction inside cell is a defining feature and hence cellular organization is a defining feature
CONSCIOUSNESS
- It is the response of organism to surrounding
- All organisms therefore, are ‘aware’ of their surroundings
- Consciousness therefore, becomes the defining property of living Organisms.
- Patient lying in coma is living or living? Though patient lying in coma has lost consciousness, still considered as living because metabolic reactions are present
DIVERSITY IN THE LIVING WORLD
- For plants, scientific names are provided in International Code for Botanical Nomenclature (ICBN)
- For animals, scientific names are provided in International Code for Zoological Nomenclature (ICZN) Each scientific name has two components – the Generic name and the specific epithet.
- The system of providing a name with two components is called Binomial nomenclature
- This naming system given by Carolus Linnaeus
PROCESS OF TAXONOMY
It is the process of classification of any organism into suitable taxon.
- Characterisation (description)
- Identification
- Classification
- Nomenclature
SYATEMATIC
- Systematics is systematic arrangement of organisms based upon evolutionary relationship between them
- Systematics = Taxonomy + Evolutionary relationship
- Linnaeus published a book Systema Naturae
CHARACTERIZATION (description)
- Collection of specimens
- Note down details (pentamerous, epipetalous etc)
- Maintain diary
IDENTIFICATION
For identification, compare the specimen with already discovered specimen Specimen or methods that help in identification are called Taxonomic aids.
HERBARIUM
- Herbarium is a store house of collected plant specimens that are dried, pressed and preserved on sheets
- These sheets are arranged according to a universally accepted system of classification
- The herbarium sheets also carry a label providing information about date and place of collection, English, local and botanical names, family, collector’s name.
BOTANICAL GARDEN
Collections of living plants Each plant is labelled Famous botanical gardens are : Royal Botanical gardens are at Kew (England), Indian Botanical Garden, Howrah (India) and at National Botanical Research Institute, Lucknow (India).
MUSEUM
Collection of preserved plants and animal species Insects are preserved in boxes Generally Large animals like mammals, bird are preserved in museum
ZOOLOGICAL PARK
Live animals are kept in human protection in similar natural habitat Ex situ conservation Help study food habits and behaviour
KEY
Taxonomic key help in correct identification Statements are in pair (couplet) Couplet have two contrasting statements (leads) Key is based on similarity and dissimilarity Keys are dichotomous Key is analytical in nature Separate taxonomic keys are required for each taxonomic category such as family, genus and species etc.
CLASSIFICATION
Category and taxon Category : Group of similar organisms Taxon : It is such category to which some feature is attached. It is a Scientific term of category Taxonomic hierarchy: refers to the sequence of categories in increasing or decreasing order.
SPECIES
Group of similar organisms which can interbreed and produce fertile young . Species are immutable (by Linnaeus) Allopatric and sympatric species Keystone species Important for survival of other species A classic keystone species is a predator that prevents a particular herbivorous species from eliminating dominant plant species.
GENUS
Group of similar species For example, potato and brinjal are two different species but both belong to the genus Solanum. Lion (Panthera leo), leopard (P. pardus) and tiger (P. tigris) with several common features, are all species of the genus Panthera.
FAMILY
Group of related genera (Plant : aceae, animal : idea Families are characterised on the basis of both vegetative and reproductive features of plant species. family Solanaceae : Solanum, Petunia and Datura genera Family Felidae : Felis (cats), Panthera, Family Canidae : includes dogs
ORDER
Group of related genera Polynomiales (based on foral character) : Convolvulaceae, Solanaceae families Carnivora : Felidae , Canidae
CLASS
Group of related orders class Mammalia : order Primata (monkey, gorilla and gibbon) . order Carnivora (Tiger, cat, Dog)
PHYLUM AND DIVISION
Ernst Haeckel coined the term Phylum Chordates (presence of notochord) : Mammal, fish, amphibian, reptiles
KINGDOM
All animals belonging to various phyla are assigned to the highest category called Kingdom Animalia.
As we go higher from species to kingdom, the number of common characteristics goes on decreasing.
