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Diversity: It refers to the variety and variability among living organisms from all sources
including land, water, and other ecosystems.
Classification
It refers to the identification, naming, and grouping of organisms into a formal
system based on similarities in internal and external structures or evolutionary
history
It helps in organising the diversity of life forms in detail.
Characteristic - A feature that helps identify or describe a person or a thing
There are certain characteristics that are considered more fundamental than others.
These fundamental characteristics make broad divisions in living organisms.
Principles of classification
Nature of cell (Fundamental characteristic): On the basis of the nature of
cell, living organisms are classified as: prokaryotes and eukaryotes
Cellularity: On the basis of cellularity, organisms are classified as: unicellular
and multicellular
Mode of nutrition: On the basis of mode of nutrition, organisms are classified as:
Autotrophs and heterotrophs
Classification and evolution
Primitive organism or lower organism has a simple body structure and ancient
body design
Advanced organism or higher organism has a complex body structure and
organisation
Evolution - The process of gradual and continuous change in primitive or simple
organisms to give rise to advanced organisms
Biodiversity - The variety of life forms present in various ecosystems
Hierarchy of classification
The hierarchical arrangement of various taxonomical categories in descending order
is: Kingdom Phylum (for animals)/ Division (for plants) Class
Order Family Genus Species.Mnemonic to learn this hierarchy: Kids Prefer Cheese Over Fried Green Spinach
Species is the basic unit of classification
Carolus Linnaeus developed the hierarchy of classification. He also brought out
the famous book Systema Naturae
Linnaeus also developed the concept of binomial nomenclature
Binomial nomenclature refers to the naming of species. In this system, the name of a
species is made up of two words: the genus name and the species name. E.g. Rosa
indica
R.H. Whittaker (in 1969) proposed a five-kingdom classification of living organisms
The five kingdoms proposed by Whittaker are: Monera, Protista, Fungi, Plantae,
and Animalia.
1. Kingdom Monera: It includes mainly bacteria, blue-green algae, or
cyanobacteria
Important features of monera:
Absence of well-defined nuclear or membrane-bound organelles- prokaryotic
organisms.
All of them are unicellular
Can be autotrophic or heterotrophic
2. Kingdom Protista: It Includes protozoans such as, Amoeba, Paramecium, diatoms
etc
Important features of protista:
Unicellular, eukaryotic organism
Can be autotrophic or heterotrophic
3. Kingdom Fungi
Commonly known fungi are Yeast, mushroom, Penicillium, Aspergillus, etc.
Important features of fungi:
Multicellular eukaryotic organisms
Always heterotrophic (saprophytes)
Cell wall made of chitin is present
4. Kingdom Plantae
Important features of plantae:
Multicellular eukaryotic organisms Most of the plants contain chlorophyll. Hence, they are autotrophic
Cell wall made of cellulose is present
5. Kingdom Animalia
Important features of animalia:
Multicellular eukaryotic organisms
Chloroplast is absent. Hence, they have heterotrophic mode of nutrition
Cell wall is absent
Kingdom Plantae: It includes five divisions:
1. Division Thallophyta: Includes Spirogyra, Cladophora, Ulva
Characteristic feature of Thallophyta:
Plant body is not differentiated into true root, stem, and leaves
2. Division Bryophyta (also called amphibians of plant kingdom):
Includes mosses, Riccia, Marchantia
Characteristic feature of Bryophyta:
Specialised vascular tissues (such as xylem) for the conduction of water are
absent
Body is differentiated into stem and leaf-like structures
Naked embryo i.e. spores are present.
3. Division Pteridophyta: Includes ferns, Marsilea, Equisetum
Characteristic feature of Pteridophyta
Specialised vascular tissues for the conduction of water are present.
Naked embryo i.e. spores are present
Cryptogams: Plants that do not have well differentiated reproductive organs and produce
naked embryo (spores) are called cryptogams. Thallophyta, Bryophyta and Pteridophyta all
possess naked embryo.
Phanerogams: Plants that have well developed reproductive organs that finally make
seeds are called Phanerogams. Gymnosperms and angiosperms belong to Phanerogams.
4. Division Gymnospermae: Includes Pinus, cedar, fir, Juniper, Cycas, etc
Characteristic feature of Gymnospermae:
Seed bearing, non-flowering plants. Bear naked seeds, not enclosed inside fruits.
5. Division Angiospermae: Includes all flowering plants
Characteristic feature of Angiospermae:
Flowering plants in which seeds are enclosed inside fruits.
Seeds develop inside the ovary, which develops into a fruit
Major groups of Angiosperms
Monocotyledons: Seeds that have one cotyledon. E.g. maize, wheat etc
Dicotyledons: Seeds that have two cotyledons. E.g. Sunflower, gram etc
Kingdom Animalia
Kingdom Animalia can be divided into two major groups on the basis of the presence or
absence of notochord: non-chordata and chordata
Non-chordata can be further divided into the following phyla:
i. Phylum Porifera: Includes sponges such as Spongilla, Euplectella, etc
Characteristic feature of Porifera:
Cellular level of organisation
Mainly found in marine habitats
Posses canal system for circulating water.
ii. Phylum Coelenterata: Includes organisms such as hydra, sea anemone, etc.
Characteristic feature of Coelentrata:
Tissue level of organisation
Body cavity (coelom) is absent
Diploblastic i.e body is made of two layers of cells.
iii. Phylum Platyhelminthes: Includes flatworms, liver flukes and planarians
Characteristic feature of Platyhelminthes:
Bilateral symmetry
Triploblastic i.e. three layers of cells are present
Body cavity is absent
iv. Phylum Nematoda (Aschelminthes): Includes roundworms - Ascaris
Characteristic feature of Nematoda:
Bilaterally symmetrical
Triploblastic Pseudocoelom (false coelom) is present
v. Phylum Annelida: Includes segmented worms such as earthworms and leeches
Characteristic feature of Annelida:
Bilaterlly symmetrical
Triploblastic
Body is segmented
vi. Phylum Arthropoda: Includes crabs, prawns, insects, spiders, scorpions, etc
Characteristic feature of Arthropoda:
Largest group of the animal kingdom.
Bilaterally symmetrical and segmented
Coelomic cavity is blood-filled
Presence of Jointed legs
vii. Phylum Mollusca: Includes snails, octopus, Pila, etc
Characteristic feature of Mollusca:
Bilaterally symmetrical, little segmentation
Coelomic cavity is reduced
Open circulatory system and kidney-like organ for excretion is present.
viii. Phylum Echinodermata: Includes marine animals such as starfishes, sea
urchins, etc
Characteristic feature of Echinodermata:
Spiny skinned organisms
Free living marine organisms
Triploblastic and coelomate
Skeleton is made of calcium carbonate
Chordata can be further divided into sub-phyla Protochordata and Vertebrata
(1) Protochordata: Includes Herdmania and Amphioxus
Characteristic feature of Protochordata
Triploblastic, and have a coelom cavity
Bilaterally symmetrical
Notochord at some stages of life is present. Notochord is a flexible rod-like structure that forms the supporting axis of the body in the
chordates.
(2) Vertebrata: The sub-phylum Vertebrata is further divided into five classes:
i. Class Pisces: Includes all fishes
Characteristic feature of Pisces:
Exclusively aquatic animals
Body is streamlined and covered with scales
They are cold blooded animals
Heart is two chambered
Skeleton is bony or cartilaginous
Oviparous, they lay eggs in water.
ii. Class Amphibia: Includes frogs, toads, and salamanders
Characteristic feature of Amphibia:
Scales are absent
Cold blooded animals
Heart is three chambered
Oviparous, they lay eggs in water
These animals have a dual mode of life (in water and land); respire through gills,
skin, and lungs
iii. Class Reptilia: Includes reptiles such as lizard, snake, turtle, etc
Characteristic feature of Reptilia:
Cold blooded animals
Most of them have three chambered heart (Crocodiles have four chambered
heart)
Skin is covered with scales
These animals are completely terrestrial. They breath through lungs
Lay eggs on land (oviparous)
iv. Class Aves: Includes all birds
Characteristic feature of Aves:
Warm-blooded animals with four chambered heart
They breathe through lungs
Have feathers and forelimbs modified for flight Exclusively egg-laying animals
v. Class Mammalia: Includes kangaroo, rat, dolphin, elephant, horse, human,
tiger, etc
Characteristic feature of Mammalia:
Warm-blooded animals with four chambered heart
Most of them are viviparous except for platypus and Echidna. They both are
oviparous
These animals have milk-producing glands (mammary glands) to nourish their
young ones
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Question 1. What are the advantages of classifying organisms?
Answer : There are many advantages of classifying organisms which are given as below
1. Classifying organisms helps us in recognising the basic arrangement of a hierarchical structure among diverse species.
2. It tells us about the resemblances and relationships between various organisms thus facilitating studies or research of wide variety associated with organisms effortlessly.
3. It helps in understanding the evolution of organisms, as it gives us most of the information permitting a reconstruction of phylogeny of life.
4. It has major role in agriculture, public health and environmental biology. Exact identification of harmful pests, disease vectors makes possible to control diseases much easier.
5. Several ornamental plants have been introduced by horticulturists due to proper identification and nomenclature.
6. It also gives us a fair idea about the vast number of life forms and we are able to understand diversity among living organisms in a much better way.
7. It helps in placement of different organisms in a definite taxonomic group which is the basic requirement of biological sciences.
8. It forms the basis for Taxonomy in biological sciences, which is a science of identifying, grouping, and naming organisms according to their established natural relationship.
9. Classification of organism has facilitated science of genetic engineering to a great extent
Question 2. How would you choose between two characteristics to be used for developing a hierarchy in classification?
Answer : For developing a hierarchy of classification, we choose the fundamental characteristic among several other characteristics. These fundamental characteristics are independent of any other characteristics in their effects on the form and function of the organism. The characteristics in the next level would be dependent on the previous one and would decide the variety in the next level. In this way, we can build up a whole hierarchy of mutually related characteristics to be used for classification. For example, plants differ from animals in many ways such as body design, photosynthesis, the absence of locomotion, chloroplasts, cell wall, etc. But, out of these, only locomotion is considered as the basic or fundamental feature that is used to distinguish between plants and animals. This is because the absence of locomotion in plants gave rise to many structural changes such as the presence of a cell wall for protection, and the presence of chloroplast for photosynthesis (as they cannot move around in search of food like animals). Thus, all these features are a result of locomotion. Therefore, locomotion is considered to be a fundamental characteristic. By choosing the basic or fundamental characteristic, we can make broad divisions in living organisms as the next level of characteristic is dependent on these. This goes on to form a hierarchy of characteristics.
Question 3. Explain the basis for grouping organisms into five kingdoms.
Answer : Robert .H. Whittaker in 1959 proposed a five kingdom classification of living organisms on the basis of Linnaeus’ system of classification encorporating cell structure, mode and source of nutrition and body organisation as main features. The five kingdoms proposed by Whittaker are Monera, Protista, Fungi, Plantae, and Animalia
The basis for grouping organisms into five kingdoms is as follows :
(i) On the basis of the presence or absence of membrane-bound organelles, all living organisms are divided into two broad categories of eukaryotes and prokaryotes. This division lead to the formation of kingdom Monera, which includes all prokaryotes.
(ii) Then, eukaryotes are divided as unicellular and multicellular, on the basis of cellularity. Unicellular eukaryotes form kingdom Protista, and multicellular eukaryotes form kingdom Fungi, Plantae, and Animalia.
(iii) Animals are then separated on the basis of the absence of a cell wall.
(iv) Since fungi and plants both contain a cell wall, they are separated into different kingdoms on the basis of their modes of nutrition. Fungi have saprophytic mode of nutrition, whereas plants have autotrophic mode of nutrition. This results in the formation of the five kingdoms
Question 4. What are the major divisions in the Plantae? What is the basis for these divisions?
Answer : The kingdom Plantae is divided into five main divisions: Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms.
The classification depends on the following criteria:
• Differentiated or Undifferentiated plant body
• Presence /absence of vascular tissues
• With/without seeds
• Naked seeds/ seeds inside fruits
Classification Of Plants |
(i) The first level of classification depends on whether a plant body is well differentiated or not. A group of plants that do not have a well differentiated plant body are known as Thallophyta.
(ii) Plants that have well differentiated body parts are further divided on the basis of the presence or absence of vascular tissues. Plants without specialised vascular tissues are included in division Bryophyta, whereas plants with vascular tissues are known as Tracheophyta.
(iii) Tracheophyta is again sub-divided into two divisions Pteridophyta and Phanerogams on the basis of the absence/presence of seed formation.
(iv) Pteridophyta plants do not produce seeds
(iv) Phanerogams plants have well developed reproductive organs that finally produce seeds.
(v) Phanerogams group is further sub- divided on the basis of whether the seeds are naked or enclosed in fruits. This classifies them into gymnosperms and angiosperms.
Gymnosperms are seed bearing, non-flowering plants, whereas angiosperms are flowering plants in which the seeds are enclosed inside the fruit.
Question 5. How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?
Answer :Criteria for deciding divisions in plants are:
(i) Differentiated/ Undifferentiated plant body
(ii) Presence/ absence of vascular tissues
(iii) With/without seeds
(iv) Naked seeds/ seeds inside fruits
Criteria for deciding subgroups among animals are:
Kingdom Animalia is divided into two major groups on the basis of the presence or absence of a notochord.
Non-chordates do not possess a notochord, while all members of the phylum chordates possess a notochord.
Non-chordate is further divided into subgroups on the basis of the following features:
On the basis of the above features, non-chordates are divided into the following subgroups:
Porifera, Coelenterate, Platyhelminthes, Nematodes, Annelids, Molluscs, Arthropoda, and Echinodermata
All members of the phylum chordate possess a notochord. However, some animals such as Balanoglossus, Amphioxus, Herdmania, etc. have a notochord, which is either absent or does not run the entire length of the animal’s body. Therefore, these animals are kept in a separate sub-phylum called Protochordata, and the rest of the chordates are included in the sub-phylum vertebrata. The members of the sub-phylum vertebrata are advanced chordates. They are divided into five classes: Pisces, Amphibian, Reptilia, Aves, and Mammalia
Question 6. Explain how animals in Vertebrata are classified into further Subgroups ?
Answer : Vertebrata : These animals have a true vertebral column and internal skeleton, allowing a completely different distribution of muscle attachment points to be used for movement. Vertebrates are bilaterally symmetrical, triploblastic, coelomic and segmented, with complex differentiation of body tissues and organs. All chordates possess the following features:
(i) They have a notochord
(ii) They have a dorsal nerve cord
(iii) They are triploblastic
(iv) They have paired gill pouches
(v) They are coelomate.
Vertebrates are grouped into five classes
(i) PISCES (ii) AMPHIBIA (iii) REPTILIA (iv) AVES (v) MAMMALIA
Question 7. How do poriferan animals differ from coelenterate animals?
Answer :
Differences between Poriferan animals and Coelenterate animals |
Porifera | Coelenterate |
They are mostly marine, non-motile and found attached to rocks. They show cellular level of organization Examples - Spongilla, Euplectella etc | They are excusively merine animals that either leave in colonies or have a solitary life span. They show tissues level of organisation Examples - Hydra, Sea Anemone, Corals etc. |
Question 8. How do annelid animals differ from arthropods?
Answer :
Differences between Annelid animals and Arthropods |
Annelid animals | Arthropods animals |
The circulatory system of Annelid animals is closed The body is divided into several identical segments | The Arthropods have an open circulatory system The body is divided into few specialized segments |
Question 9. What are the differences between amphibians and reptiles?
Answer :
Differences between Amphibians and Reptiles |
Amphibians | Reptiles |
They have dual mode of life. Scales are absent. They lay eggs in water. | They are completely terrestrial. The skin is covered with scales. They lay eggs on land. |
Question 10. What are the differences between animals belonging to the Aves group and those in the mammalian group?
Answer :
Differences between Aves group and Mammalian group |
Aves group | Mammalian group |
Most birds have feathers and they possess a beak. They lays eggs, hence are oviparous. | They do not have feathers and beak is also not present. Some of them lay eggs and some give birth to young hence they are both viviparous and oviparous |
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Diversity: It refers to the variety and variability among living organisms from all sources
including land, water, and other ecosystems.Classification It refers to the identification, naming, and grouping of organisms into a formalsystem based on similarities in internal and external structures or evolutionaryhistory It helps in organising the diversity of life forms in detail. Characteristic - A feature that helps identify or describe a person or a thing There are certain characteristics that are considered more fundamental than others.These fundamental characteristics make broad divisions in living organisms.Principles of classification Nature of cell (Fundamental characteristic): On the basis of the nature ofcell, living organisms are classified as: prokaryotes and eukaryotes Cellularity: On the basis of cellularity, organisms are classified as: unicellularand multicellular Mode of nutrition: On the basis of mode of nutrition, organisms are classified as: Autotrophs and heterotrophsClassification and evolution Primitive organism or lower organism has a simple body structure and ancientbody design Advanced organism or higher organism has a complex body structure andorganisation Evolution - The process of gradual and continuous change in primitive or simpleorganisms to give rise to advanced organisms Biodiversity - The variety of life forms present in various ecosystemsHierarchy of classification The hierarchical arrangement of various taxonomical categories in descending orderis: Kingdom Phylum (for animals)/ Division (for plants) Class Order Family Genus Species.Mnemonic to learn this hierarchy: Kids Prefer Cheese Over Fried Green Spinach Species is the basic unit of classification Carolus Linnaeus developed the hierarchy of classification. He also brought outthe famous book Systema Naturae Linnaeus also developed the concept of binomial nomenclature Binomial nomenclature refers to the naming of species. In this system, the name of aspecies is made up of two words: the genus name and the species name. E.g. Rosaindica R.H. Whittaker (in 1969) proposed a five-kingdom classification of living organisms The five kingdoms proposed by Whittaker are: Monera, Protista, Fungi, Plantae,and Animalia.1. Kingdom Monera: It includes mainly bacteria, blue-green algae, orcyanobacteriaImportant features of monera: Absence of well-defined nuclear or membrane-bound organelles- prokaryoticorganisms. All of them are unicellular Can be autotrophic or heterotrophic2. Kingdom Protista: It Includes protozoans such as, Amoeba, Paramecium, diatomsetcImportant features of protista: Unicellular, eukaryotic organism Can be autotrophic or heterotrophic3. Kingdom FungiCommonly known fungi are Yeast, mushroom, Penicillium, Aspergillus, etc.Important features of fungi: Multicellular eukaryotic organisms Always heterotrophic (saprophytes) Cell wall made of chitin is present4. Kingdom PlantaeImportant features of plantae: Multicellular eukaryotic organisms Most of the plants contain chlorophyll. Hence, they are autotrophic Cell wall made of cellulose is present5. Kingdom AnimaliaImportant features of animalia: Multicellular eukaryotic organisms Chloroplast is absent. Hence, they have heterotrophic mode of nutrition Cell wall is absentKingdom Plantae: It includes five divisions:1. Division Thallophyta: Includes Spirogyra, Cladophora, UlvaCharacteristic feature of Thallophyta: Plant body is not differentiated into true root, stem, and leaves2. Division Bryophyta (also called amphibians of plant kingdom):Includes mosses, Riccia, MarchantiaCharacteristic feature of Bryophyta: Specialised vascular tissues (such as xylem) for the conduction of water areabsent Body is differentiated into stem and leaf-like structures Naked embryo i.e. spores are present.3. Division Pteridophyta: Includes ferns, Marsilea, EquisetumCharacteristic feature of Pteridophyta Specialised vascular tissues for the conduction of water are present. Naked embryo i.e. spores are presentCryptogams: Plants that do not have well differentiated reproductive organs and producenaked embryo (spores) are called cryptogams. Thallophyta, Bryophyta and Pteridophyta allpossess naked embryo.Phanerogams: Plants that have well developed reproductive organs that finally makeseeds are called Phanerogams. Gymnosperms and angiosperms belong to Phanerogams.4. Division Gymnospermae: Includes Pinus, cedar, fir, Juniper, Cycas, etcCharacteristic feature of Gymnospermae: Seed bearing, non-flowering plants. Bear naked seeds, not enclosed inside fruits.5. Division Angiospermae: Includes all flowering plantsCharacteristic feature of Angiospermae: Flowering plants in which seeds are enclosed inside fruits. Seeds develop inside the ovary, which develops into a fruit Major groups of Angiosperms Monocotyledons: Seeds that have one cotyledon. E.g. maize, wheat etc Dicotyledons: Seeds that have two cotyledons. E.g. Sunflower, gram etcKingdom AnimaliaKingdom Animalia can be divided into two major groups on the basis of the presence orabsence of notochord: non-chordata and chordata Non-chordata can be further divided into the following phyla:i. Phylum Porifera: Includes sponges such as Spongilla, Euplectella, etcCharacteristic feature of Porifera: Cellular level of organisation Mainly found in marine habitats Posses canal system for circulating water.ii. Phylum Coelenterata: Includes organisms such as hydra, sea anemone, etc.Characteristic feature of Coelentrata: Tissue level of organisation Body cavity (coelom) is absent Diploblastic i.e body is made of two layers of cells.iii. Phylum Platyhelminthes: Includes flatworms, liver flukes and planariansCharacteristic feature of Platyhelminthes: Bilateral symmetry Triploblastic i.e. three layers of cells are present Body cavity is absentiv. Phylum Nematoda (Aschelminthes): Includes roundworms - AscarisCharacteristic feature of Nematoda: Bilaterally symmetrical Triploblastic Pseudocoelom (false coelom) is presentv. Phylum Annelida: Includes segmented worms such as earthworms and leechesCharacteristic feature of Annelida: Bilaterlly symmetrical Triploblastic Body is segmentedvi. Phylum Arthropoda: Includes crabs, prawns, insects, spiders, scorpions, etcCharacteristic feature of Arthropoda: Largest group of the animal kingdom. Bilaterally symmetrical and segmented Coelomic cavity is blood-filled Presence of Jointed legsvii. Phylum Mollusca: Includes snails, octopus, Pila, etcCharacteristic feature of Mollusca: Bilaterally symmetrical, little segmentation Coelomic cavity is reduced Open circulatory system and kidney-like organ for excretion is present.viii. Phylum Echinodermata: Includes marine animals such as starfishes, seaurchins, etcCharacteristic feature of Echinodermata: Spiny skinned organisms Free living marine organisms Triploblastic and coelomate Skeleton is made of calcium carbonate Chordata can be further divided into sub-phyla Protochordata and Vertebrata(1) Protochordata: Includes Herdmania and AmphioxusCharacteristic feature of Protochordata Triploblastic, and have a coelom cavity Bilaterally symmetrical Notochord at some stages of life is present. Notochord is a flexible rod-like structure that forms the supporting axis of the body in thechordates.(2) Vertebrata: The sub-phylum Vertebrata is further divided into five classes:i. Class Pisces: Includes all fishesCharacteristic feature of Pisces: Exclusively aquatic animals Body is streamlined and covered with scales They are cold blooded animals Heart is two chambered Skeleton is bony or cartilaginous Oviparous, they lay eggs in water.ii. Class Amphibia: Includes frogs, toads, and salamandersCharacteristic feature of Amphibia: Scales are absent Cold blooded animals Heart is three chambered Oviparous, they lay eggs in water These animals have a dual mode of life (in water and land); respire through gills,skin, and lungsiii. Class Reptilia: Includes reptiles such as lizard, snake, turtle, etcCharacteristic feature of Reptilia: Cold blooded animals Most of them have three chambered heart (Crocodiles have four chamberedheart) Skin is covered with scales These animals are completely terrestrial. They breath through lungs Lay eggs on land (oviparous)iv. Class Aves: Includes all birdsCharacteristic feature of Aves: Warm-blooded animals with four chambered heart They breathe through lungs Have feathers and forelimbs modified for flight Exclusively egg-laying animalsv. Class Mammalia: Includes kangaroo, rat, dolphin, elephant, horse, human,tiger, etcCharacteristic feature of Mammalia: Warm-blooded animals with four chambered heart Most of them are viviparous except for platypus and Echidna. They both areoviparous These animals have milk-producing glands (mammary glands) to nourish theiryoung ones * * - 1
It refers to the variety and variability among living organisms from all sources
including land, water, and other ecosystems.Classification It refers to the identification, naming, and grouping of organisms into a formalsystem based on similarities in internal and external structures or evolutionaryhistory It helps in organising the diversity of life forms in detail. Characteristic - A feature that helps identify or describe a person or a thing There are certain characteristics that are considered more fundamental than others.These fundamental characteristics make broad divisions in living organisms.Principles of classification Nature of cell (Fundamental characteristic): On the basis of the nature ofcell, living organisms are classified as: prokaryotes and eukaryotes Cellularity: On the basis of cellularity, organisms are classified as: unicellularand multicellular Mode of nutrition: On the basis of mode of nutrition, organisms are classified as: Autotrophs and heterotrophsClassification and evolution Primitive organism or lower organism has a simple body structure and ancientbody design Advanced organism or higher organism has a complex body structure andorganisation Evolution - The process of gradual and continuous change in primitive or simpleorganisms to give rise to advanced organisms Biodiversity - The variety of life forms present in various ecosystemsHierarchy of classification The hierarchical arrangement of various taxonomical categories in descending orderis: Kingdom Phylum (for animals)/ Division (for plants) Class Order Family Genus Species.Mnemonic to learn this hierarchy: Kids Prefer Cheese Over Fried Green Spinach Species is the basic unit of classification Carolus Linnaeus developed the hierarchy of classification. He also brought outthe famous book Systema Naturae Linnaeus also developed the concept of binomial nomenclature Binomial nomenclature refers to the naming of species. In this system, the name of aspecies is made up of two words: the genus name and the species name. E.g. Rosaindica R.H. Whittaker (in 1969) proposed a five-kingdom classification of living organisms The five kingdoms proposed by Whittaker are: Monera, Protista, Fungi, Plantae,and Animalia.1. Kingdom Monera: It includes mainly bacteria, blue-green algae, orcyanobacteriaImportant features of monera: Absence of well-defined nuclear or membrane-bound organelles- prokaryoticorganisms. All of them are unicellular Can be autotrophic or heterotrophic2. Kingdom Protista: It Includes protozoans such as, Amoeba, Paramecium, diatomsetcImportant features of protista: Unicellular, eukaryotic organism Can be autotrophic or heterotrophic3. Kingdom FungiCommonly known fungi are Yeast, mushroom, Penicillium, Aspergillus, etc.Important features of fungi: Multicellular eukaryotic organisms Always heterotrophic (saprophytes) Cell wall made of chitin is present4. Kingdom PlantaeImportant features of plantae: Multicellular eukaryotic organisms Most of the plants contain chlorophyll. Hence, they are autotrophic Cell wall made of cellulose is present5. Kingdom AnimaliaImportant features of animalia: Multicellular eukaryotic organisms Chloroplast is absent. Hence, they have heterotrophic mode of nutrition Cell wall is absentKingdom Plantae: It includes five divisions:1. Division Thallophyta: Includes Spirogyra, Cladophora, UlvaCharacteristic feature of Thallophyta: Plant body is not differentiated into true root, stem, and leaves2. Division Bryophyta (also called amphibians of plant kingdom):Includes mosses, Riccia, MarchantiaCharacteristic feature of Bryophyta: Specialised vascular tissues (such as xylem) for the conduction of water areabsent Body is differentiated into stem and leaf-like structures Naked embryo i.e. spores are present.3. Division Pteridophyta: Includes ferns, Marsilea, EquisetumCharacteristic feature of Pteridophyta Specialised vascular tissues for the conduction of water are present. Naked embryo i.e. spores are presentCryptogams: Plants that do not have well differentiated reproductive organs and producenaked embryo (spores) are called cryptogams. Thallophyta, Bryophyta and Pteridophyta allpossess naked embryo.Phanerogams: Plants that have well developed reproductive organs that finally makeseeds are called Phanerogams. Gymnosperms and angiosperms belong to Phanerogams.4. Division Gymnospermae: Includes Pinus, cedar, fir, Juniper, Cycas, etcCharacteristic feature of Gymnospermae: Seed bearing, non-flowering plants. Bear naked seeds, not enclosed inside fruits.5. Division Angiospermae: Includes all flowering plantsCharacteristic feature of Angiospermae: Flowering plants in which seeds are enclosed inside fruits. Seeds develop inside the ovary, which develops into a fruit Major groups of Angiosperms Monocotyledons: Seeds that have one cotyledon. E.g. maize, wheat etc Dicotyledons: Seeds that have two cotyledons. E.g. Sunflower, gram etcKingdom AnimaliaKingdom Animalia can be divided into two major groups on the basis of the presence orabsence of notochord: non-chordata and chordata Non-chordata can be further divided into the following phyla:i. Phylum Porifera: Includes sponges such as Spongilla, Euplectella, etcCharacteristic feature of Porifera: Cellular level of organisation Mainly found in marine habitats Posses canal system for circulating water.ii. Phylum Coelenterata: Includes organisms such as hydra, sea anemone, etc.Characteristic feature of Coelentrata: Tissue level of organisation Body cavity (coelom) is absent Diploblastic i.e body is made of two layers of cells.iii. Phylum Platyhelminthes: Includes flatworms, liver flukes and planariansCharacteristic feature of Platyhelminthes: Bilateral symmetry Triploblastic i.e. three layers of cells are present Body cavity is absentiv. Phylum Nematoda (Aschelminthes): Includes roundworms - AscarisCharacteristic feature of Nematoda: Bilaterally symmetrical Triploblastic Pseudocoelom (false coelom) is presentv. Phylum Annelida: Includes segmented worms such as earthworms and leechesCharacteristic feature of Annelida: Bilaterlly symmetrical Triploblastic Body is segmentedvi. Phylum Arthropoda: Includes crabs, prawns, insects, spiders, scorpions, etcCharacteristic feature of Arthropoda: Largest group of the animal kingdom. Bilaterally symmetrical and segmented Coelomic cavity is blood-filled Presence of Jointed legsvii. Phylum Mollusca: Includes snails, octopus, Pila, etcCharacteristic feature of Mollusca: Bilaterally symmetrical, little segmentation Coelomic cavity is reduced Open circulatory system and kidney-like organ for excretion is present.viii. Phylum Echinodermata: Includes marine animals such as starfishes, seaurchins, etcCharacteristic feature of Echinodermata: Spiny skinned organisms Free living marine organisms Triploblastic and coelomate Skeleton is made of calcium carbonate Chordata can be further divided into sub-phyla Protochordata and Vertebrata(1) Protochordata: Includes Herdmania and AmphioxusCharacteristic feature of Protochordata Triploblastic, and have a coelom cavity Bilaterally symmetrical Notochord at some stages of life is present. Notochord is a flexible rod-like structure that forms the supporting axis of the body in thechordates.(2) Vertebrata: The sub-phylum Vertebrata is further divided into five classes:i. Class Pisces: Includes all fishesCharacteristic feature of Pisces: Exclusively aquatic animals Body is streamlined and covered with scales They are cold blooded animals Heart is two chambered Skeleton is bony or cartilaginous Oviparous, they lay eggs in water.ii. Class Amphibia: Includes frogs, toads, and salamandersCharacteristic feature of Amphibia: Scales are absent Cold blooded animals Heart is three chambered Oviparous, they lay eggs in water These animals have a dual mode of life (in water and land); respire through gills,skin, and lungsiii. Class Reptilia: Includes reptiles such as lizard, snake, turtle, etcCharacteristic feature of Reptilia: Cold blooded animals Most of them have three chambered heart (Crocodiles have four chamberedheart) Skin is covered with scales These animals are completely terrestrial. They breath through lungs Lay eggs on land (oviparous)iv. Class Aves: Includes all birdsCharacteristic feature of Aves: Warm-blooded animals with four chambered heart They breathe through lungs Have feathers and forelimbs modified for flight Exclusively egg-laying animalsv. Class Mammalia: Includes kangaroo, rat, dolphin, elephant, horse, human,tiger, etcCharacteristic feature of Mammalia: Warm-blooded animals with four chambered heart Most of them are viviparous except for platypus and Echidna. They both areoviparous These animals have milk-producing glands (mammary glands) to nourish theiryoung ones * * - 1