Plus One Zoology Notes Chapter 1 The Living World is part of Plus One Zoology Notes. Here we have given Kerala Plus One Zoology Notes Chapter 1 The Living World.
|Text Book||NCERT Based|
|Chapter Name||The Living World|
|Category||Kerala Plus One|
Kerala Plus One Zoology Notes Chapter 1 The Living World
The complex organization of molecule that expresses itself through chemical reactions which lead to growth, development, responsiveness, reproduction and other characteristics of life are designated as living beings.
What is Living? (ജീവിക്കുന്നത് എന്താണ്?)
- It is very difficult to define ‘living’. Conventionally various characteristics common to all living beings are to be identified.
- Unique features of living organisms are:
♦ Growth (വളർച്ച)
- The growth of an organism has two characteristics.
- Increase in mass
- Increase in number
- Multicellular organisms grow by cell division.
- In plants, growth by cell division occurs throughout their life span.
- In animals, the growth by cell division occurs only up to a certain age. However, cell division is seen in certain tissues to replace the lost cells.
- The unicellular organism also grows by cell division.
- Nonliving objects are grown by the accumulation of material on the surface.
- In living organisms growth is from inside.
- It is a characteristic of living organisms.
- In living organisms, reproduction means the production of progeny similar to those of parents.
- Organisms reproduce asexually and sexually.
- The production of offspring without the production of gametes is called asexual reproduction.
- The production of offsprings by the fusion of male and female gamete is called sexual reproduction.
|Hydra and Yeast||Budding|
|Filamentous algae, Protonema of mosses, Fungi||Fragmentation|
- In unicellular organisms like bacteria, unicellular algae amoeba, etc. reproduction is synonymous with growth, ie., an increase in a number of cells.
- Many organisms do not reproduce (eg., mute, worker bees, infertile human couples). Hence, reproduction is not a perfect defining characteristic of a living organism.
- The sum total of all the chemical reactions occurring in our body is called Metabolism.
- Isolated metabolic reactions in vitro are not living things but are living reasons.
- Metabolism is a defining feature in all living organisms.
- No nonliving object exhibit metabolism.
♦ Cellular organization
- All organisms are made up of one or more cells.
- They may be unicellular or multicellular.
- Cellular organization of the body is the defining feature of life forms.
- It is the ability to live organisms to sense their surroundings or environment and respond to the environmental stimuli which could be physical, chemical and biological.
- Plants respond to external factors like light, temperature, water pollutants other organisms, etc.
- In both plants and animals, photoperiod (duration of light) affects the reproduction in seasonal breeders.
- A human is the only organism having self-consciousness.
- Consciousness is the defining property of living organisms.
Diversity in the living world
- Biodiversity refers to the number and types of organisms present on the earth.
- They differ in their structure, habitat, mode. of nutrition and physiology.
- The number of species that are known and described ranges between 1.7 1.8 million.
- It is the study of biodiversity and relationship among organisms.
- The word systematics is derived from the Latin word ‘Systema’ which means the systematic arrangement of organisms.
- Linnaeus used Systema Naturae as the title of his publication.
- The scope of systematics later included identification, nomenclature, and classification.
It is the correct description of the organism to know what organism the name is attached to.
Providing a standardized name to the organism. Such that a particular organism is known by the same name all over the world.
The naming of plants is based on the rules provided inICBN. (International Code of Botanical Nomenclature).
Animal names are based on ICZN (International Code for Zoological Nomenclature).
♦ Binomial nomenclature
- It was proposed by Carolus Lin’ Gnaeus.
- It is the system of providing a name with two components, namely
A. Generic name
B. Specific epithet (species name)
- eg., The scientific name of mango is written as Mangifera indica. In this name, Mangifera represents the genus while India is a particular species name.
- Name of the author is written in an ab brievated form after the species name.
eg., Mangifera indaba Linn. It indicates that species was first described by Linnaeus.
♦ Universal Rules of Nomenclature
- Biological names are in Latin and written in italics.
- The first word represents a genus name while the second is species epithet.
- When handwritten, both names are separately underlined or printed in italics to indicate their Latin origin.
- Genus name starts with a capital letter while species name with a small letter.
- It is the process by which anything is grouped into convenient categories. The scientific term for these categories is taxa.
- It is the placing of plants and animals into groups based on relationship.
The branch of biology that deals with identification, nomenclature, and classification of organisms is called taxonomy. Modern taxonomic studies are based on,
- External and internal structure.
- Structure of ceil.
- Development process.
- Ecological information.
- The taxonomic category is a definitive rank or level in the hierarchical system of biological classification.
- There are seven primary categories, they are Species, genus, family, order, class, phylum or division, kingdom.
- A taxon is a category or rank in the taxonomic hierarchy. It is the unit of classification.
- It is the lowest taxon.
- It is a group of individual organisms with fundamental similarities.
Eg., Mangifera indica (Mango)
Solanum tuberosum (Potato)
Panthera leo (Lion)
- India, tuberose, Leo represents specific epithets.
- Mangifera, Solanum, Panthera represents genus name.
- Each genus may have one or more than one specific epithets representing different organisms, but having morphological similarities.
Eg., Solanum includes species like nigrum and melongena
- The scientific name of a human being is written as Homo sapiens.
- It comprises a group of related species which has more characters in common in comparison to the species of another genus.
- Genera are aggregates of closely related species.
Eg. , Lion (Panthera leo),
tiger (Panthera tigris),
Leopard (parades) are all species in the genus Panthera because of the several common features.
- It is a group of related genera with still less number of similarities as compared to genus and species.
- Among animals, the genus Panthera comprising lion, tiger, and leopard are put along with genus felids (cats) in the family Felidae.
- Among plants, three different genera Solarium, Petunia and Datura are placed in the family Solanaceae.
- It is a higher category of related families, which exhibit a few similar characters.
- The animal order Carnivora includes families like Felidae and Canidae.
- It includes related orders having common characters.
- The order Primates (monkey, gorilla, and gibbon) and order Carnivora (tiger, cat, and dog) are placed in the same class Mammalia.
- Classes having the same features in common constitute a Phylum.
- Phylum Chordata includes classes like fishes, amphibians, reptiles, birds, and mammals with common features like,
- Presence of notochord
- Presence of dorsal hollow neural system.
- In the case of plants, classes with a few similar characters are assigned to a higher category called division.
- All animals belonging to various phyla are assigned to the higher category called Kingdom.
- The kingdom Plantae comprises all plants from various divisions.
- As we go higher from species to kingdom, the number of common characteristics goes on decreasing.
♦ Organizations with their Taxonomic Categories
|Common name||Biological name||Genus||Family||Order||Class||Phylum / Division|
- It is the techniques, procedures and stored information that is useful in the identification and classification of organisms.
- The important taxonomic aids are herbarium, botanical gardens, museums, zoological parks, and key.
Important Taxonomic Aids
- Collection of plants that have been dried, pressed preserved on sheets.
- Sheets are arranged according to a universally accepted system of classification.
- It carries a label providing information about the date and place of collection, English, local and botanical names, family, collector’s name.
- These have collections of preserved plants and animals specimens for study and reference.
- Specimens are preserved in containers or jars in preservative solutions.
- Insects are preserved in insect boxes after collecting, killing and pinning.
- Larger animals are usually stuffed and preserved.
- Collections of skeletons of animals are also seen in museums.
♦ Zoological parks
- These are places where wild animals are kept in protected environments under human care.
- It enables to learn about their food habits and behavior.
♦ Botanical gardens
- Collection of living plants maintained for reference.
- Rant specimens are used for identification purposes.
- Each plant is labeled indicating its botanical/scientific name and its family.
- Famous botanical gardens are Botanical garden at Kew (England) National Botanical Research Institute, Lucknow (India). Indian Botanical Garden Howrah (India).
- It is another taxonomical aid used for identification of plants and animals based on similarities and dissimilarities.
- Each statement in the key is called a lead. The keys are based on the contrasting characters generally in a pair called
- Separate taxonomic keys are required for each taxonomic category such as family, genus, and species for identification purposes.
♦ Other taxonomic aids.
Other means of recording descriptions are flora, manuals, monographs, and catalogs.
- They help incorrect identification.
- Flora Actual account of habitat and distribution of plants of the given area.
- Manuals They provide information for identification of names of species found in an area.
- Monograph It contains comprehensive information of any one taxon.
- Catalogs These provide a list of publications. Also means for recording information
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