THE LIVING WORLD

INTRODUCTION

• The study of the living world is a special endeavor of humans.

• Humans are biological beings and are little different from other living organisms.

 Several animals have curiosity but humans are particularly more curious about natural world and their surroundings, this feature that makes humans singularly different from other living organisms.

• We keep pets, nurture plants, visit zoological and botanical gardens, climb mountain peaks or dive deep into the sea and undertake trekking in the forests to enjoy the serenity of wilderness along with its vast living and non-living resources. All these activities reflect the innate attraction of humans for natural world and their feeling of connectedness to living things.

• In fact, the scientific extension of human curiosity has given birth to the science of biology.

WHAT IS ‘LIVING’?

• When we try to define ‘living’, we conventionally look for distinctive characteristics exhibited by living organisms.

• Growth, reproduction, ability to sense environment and mount a suitable response come to our mind immediately as unique features of living organisms.

• One can add a few more features like metabolism, ability to self-replicate, self-organise, interact and emergence to this list.

Let us try to understand each of these.

1.GROWTH

• Increase in mass and increase in number of individuals are twin characteristics of growth.

• A multicellular organism grows by cell division.

• In plants, this growth by cell division occurs continuously throughout their life span (Indeterminate growth)

• In animals, this growth is seen only up to a certain age (Determinate growth). However, cell division occurs in certain tissues to replace lost cells.

• Unicellular organisms multiply by cell division. One can easily observe this in in vitro cultures by simply counting the number of cells under the microscope.

 In majority of higher animals and plants, growth and reproduction are mutually exclusive events.

• One must remember that increase in body mass is considered as growth but non-living objects also grow if we take increase in body mass as a criterion for growth. e.g. Mountains, boulders and sand mounds do grow. However, this kind of growth exhibited by non-living objects is by accumulation of material on the surface.

 In living organisms, growth is from inside. Growth, therefore, cannot be taken as a defining property

of living organisms.

• Conditions under which it can be observed in all living organisms have to be explained and then we understand that it is a characteristic of living systems. A dead organism does not grow.

2.REPRODUCTION

• In multicellular organisms, reproduction refers to the production of progeny possessing features more or less similar to those of parents. Invariably and implicitly we refer to sexual reproduction.

• Organisms reproduce by asexual means also.

• Fungi multiply and spread easily due to the millions of asexual spores they produce.

• In lower organisms like yeast and hydra, we observe budding.

• In Planaria (flat worms), we observe true regeneration, i.e., a fragmented organism regenerates the lost part of its body and becomes, a new organism.

• The fungi, the filamentous algae, the protonema of mosses, all easily multiply by fragmentation.

 When it comes to unicellular organisms like bacteria, unicellular algae or Amoeba, reproduction is synonymous with growth, i.e., increase in number of cells.

• We have already defined growth as equivalent to increase in cell number or mass.

• Hence, we notice that in single-celled organisms, we are not very clear about the usage of these two terms – growth and reproduction.

 There are many organisms which do not reproduce (mules, sterile worker bees, infertile human couples, etc). Hence, reproduction also cannot be an all-inclusive defining characteristic of living organisms.

• Of course, no non-living object is capable of reproducing or replicating by itself.

3.METABOLISM

• All living organisms are made of chemicals.

• These chemicals, small and big, belonging to various classes, sizes, functions, etc. are constantly being made and changed into some other biomolecules. These conversions are chemical reactions or metabolic reactions.

• There are thousands of metabolic reactions occurring simultaneously inside all living organisms, be they unicellular or multicellular.

• All plants, animals, fungi and microbes exhibit metabolism.

 The sum total of all the chemical reactions occurring in our body is metabolism.

• No non-living object exhibits metabolism.

 Metabolic reactions can be demonstrated outside the body in cell-free systems. An isolated metabolic reaction(s) outside the body of an organism, performed in a test tube is neither living nor non-living.

 Hence, while metabolism is a defining feature of all living organisms without exception, isolated metabolic reactions in vitro are not living things but surely living reactions.

 Hence, cellular organisation of the body is the defining feature of life forms.

4.CONSCIOUSNESS

• Perhaps, the most obvious and technically complicated feature of all living organisms is this ability to sense their surroundings or environment and respond to these environmental stimuli which could be physical, chemical or biological. We sense our environment through our sense organs.

• Plants respond to external factors like light, water, temperature, other organisms, pollutants, etc. All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental cues.

 Photoperiod affects reproduction in seasonal breeders, both plants and animals.

• All organisms handle chemicals entering their bodies.

• All organisms therefore, are ‘aware’ of their surroundings.

 Human being is the only organism who is aware of himself, i.e., has self-consciousness.

Consciousness therefore, becomes the defining property of living organisms.

• When it comes to human beings, it is all the more difficult to define the living state. We observe patients lying in coma in hospitals virtually supported by machines which replace heart and lungs. The patient is otherwise brain-dead. The patient has no self-consciousness.

• Properties of tissues are not present in the constituent cells but arise as a result of interactions among the constituent cells.

• Similarly, properties of cellular organelles are not present in the molecular constituents of the organelle but arise as a result of interactions among the molecular components comprising the organelle.

• These interactions result in emergent properties at a higher level of organization.

• This phenomenon is true in the hierarchy of organizational complexity at all levels.

• Therefore, we can say that living organisms are self-replicating, evolving and self-regulating interactive systems capable of responding to external stimuli.

• Biology is the story of life on earth. Biology is the story of evolution of living organisms on earth.

• All living organisms – present, past and future, are linked to one another by the sharing of the common genetic material, but to varying degrees.

Note: Consciousness, cellular organisation and metabolism are defining properties of living.

DIVERSITY IN THE LIVING WORLD

• The number of species that are known and described ranges between 1.7-1.8 million (1.25 Million animals and 0.5 million plants).

• This refers to biodiversity or the number and types of organisms present on earth.

TAXONOMY:

• Taxonomy: The term Taxonomy used by A.P. de Candolle in his book ‘Theory of elementary de la botanqui’.

• Father of taxonomy: Carolus Linnaeus

 Characterization, identification, classification and nomenclature are the processes that are basic to taxonomy.

• Based on characteristics, all living organisms can be classified into different taxa. This process of classification is taxonomy.

• External (Morphology) and internal structure (Anatomy), along with the structure of cell (Cytology), development process and ecological information of organisms are essential and form the basis of modern taxonomic studies.

SYSTEMATICS:

• The term systematics coined by Carolus Linnaeus. The latter is known as ‘Father of Taxonomy’.

 The word systematics is derived from the Latin word ‘systema’ which means systematic arrangement of organisms. Linnaeus used Systema Naturae as the title of his publication.

• It is the study of diversity and differentiation of organisms based on their phenotypic, genetic and phylogenetic relationships.

 Systematic includes identification, nomenclature, classification and evolutionary relationships between organisms.

.	Difference between Classical Taxonomy and Modern Taxonomy
.	Classical Taxonomy	Modern Taxonomy/ biosytematics
1.	It deals with morphospecies (typological concept.)	It deals with biological species concept.
2.	Called taxonomy by Turril.	Called taxonomy by Turril.
3.	Species is considred to be static.	Species is considered to be dynamic.
4.	Evolutionary relationship are not considered.	Based on evolutionary relationships (Cladistic).
5.	Supported by Aristotle, Theophrastus and Linnaeus.	Supported by Lamark, Huxley and other modern scientist.

New branches of systematics are as follows:

(a)Cytotaxonomy:

 It is based on cytological information like chromosome number, chromosome structure and chromosome behaviour.

• Karyotaxonomy is the most advanced branch of taxonomy.

(b)Numerical Taxonomy (Phenetics or Taximetrics) or Adansonian Taxonomy:

• It was developed by Adanson.

 It is based on all observable characteristic.

 Each character is given equal importance.

 Hundreds of character can be consider at the same time.

 Number and code are assigned to all character and data and then processed using computer

or statistical method.

(c)Chemotaxonomy or Biochemical taxonomy:

 It is based on chemical constituent of plants.

• It involve study of biomolecules particularly secondary metabolites of the cell like betacyanin pigment in beet roots, raphides and cystolith crystals, sequencing of DNA and chemical nature of proteins.

NOMENCLATURE

 It is assigning of names to organisms. There is a need to standardize the naming of living organisms such that a particular organism is known by the same name all over the world. This process is called nomenclature.

• In ancient time organisms are given local names / vernacular names based on their characteristic or uses but local names vary from place to place, even within a country. e.g. Bottle guard is known by different name in different parts of country like – Louki, Dudhi, Ghiya etc.

 Nomenclature or naming is only possible when the organism is described correctly and we know to what organism the name is attached to. This is identification.

• Biologists follow universally accepted principles to provide scientific names to known organisms.

• Rules of standard naming is given by ICN (International code of nomenclature).

ICZN (International Code of Zoological Nomenclature) ICBN (International Code for Botanical Nomenclature-1961) ICVN (International Code of Viral Nomenclature),

ICNB (International Code for Nomenclature of Bacteria),

ICNCP (International Code for Nomenclature of Cultivated Plants)

BINOMIAL NOMENCLATURE

• Initial idea of binomial nomenclature was given by Gespard Bauhim.

• Binomial nomenclature was given by C. Linnaeus.

 Each name has two components – the Generic name (Genus) and the specific epithet (Species). This system of providing a name with two components is called binomial nomenclature (L. bi: two; nomen: name). e.g. Mango – Mangifera indica; Honey bee – Apis indica

• The binomial system became a common and established practice.

• This naming system using a two word format was found convenient.

GUIDELINES FOR NAMING OF ORGANISMS

Let us study some of the universally accepted norms for nomenclature.

i.A scientific name generally has two words in Latin or derived from Latin irrespective of their origin.

ii.First word denotes the genus whereas the second one is for species.

iii.Names are printed in italics or are separately underlined to indicate their Latin origin.

iv.Generic name starts with a capital letter and the specific name with a small letter, e.g. Mangifera indica.

v.The name of the author is written in abbreviated form after the species name and it is printed in Roman,

e.g. Mangifera indica Linn. It indicates that this species was first described by Linnaeus.

vi.Each taxonomic group can have only one correct name.

vii.The name should be short, precise and easy to pronounce.

CLASSIFICATION:

• Nature has vast diversity of living organisms so it is nearly impossible to study all the living organisms, it is necessary to devise some means to make this possible. This process is classification.

• It is the process by which anything is grouped into convenient categories (according to a systematic plan or an order) based on some easily observable characters. e.g. We recognize groups / categories like plant, animals, dog, cat, mammals, wheat etc. on the basis of certain associated characters called as taxa.

• The purpose of biological classification is to organize the vast number of known plants and animals into categories that could be named, remembered and studied.

• The earliest classifications were based on the ‘uses’ of various organisms because in early days, human beings needed to find sources for their basic needs of food (e.g. oil yielding plants – Coconut, Mustard, Sesame), clothing (Cotton) and shelter (e.g. Medicinal plants – Turmeric, Rauwolfia).

• But now systematic is used for knowing more about different kinds of organisms and their diversities, and also the relationships among them.

• Classification is not a single step process but involves hierarchy of steps in which each step represents a rank or category.

TAXONOMIC CATEGORIES

• There are 7 main taxonomic categories (known as obligate or essential or broad categories)

which are essentially used in classification of organism.

• There are many intermediate categories like subkingdom, super phylum or super division, sub division, super class, sub-class, super order, sub order, super family, sub family, Tribe, sub species, variety etc. to facilitate more sound and scientific placement of various taxa.

. Fig.: Taxonomic categories (ascending hierarchy)	. • Kingdom is the highest category.
	. • Species is smallest category / basic unit of classification.
	. • Descending or Ascending arrangement of taxonomic categories known as hierarchy of classification.
	. • Classification of any organism is written in descending order.
	. • No suffix for kingdom, genus and species.

TAXON V/S CATEGORY

 Taxon deals with real objects/living while category deals with ranking / abstract term.

• Taxon belong to any rank while category belongs to one particular rank.

e.g. Bryophyta is a taxon while division is a category. Similarly pea is a taxon while species is a category.

• The number of common character goes on decreasing from species (more common character) to kingdom (less common character). e.g. order being a higher category is the assemblage of families which exhibit a few similar character. And the similar character are less in number as compared to different genera included in family.

Kingdom

Species

Common character increases

• Higher the category, greater is the difficulty of determining relationship to other taxa at the same level so problem the classification become more complex.

A.SPECIES

• Taxonomic studies consider a group of individual organisms with fundamental similarities as a

species.

 Species is a basic unit for understanding taxonomy as well as evolution.

• one species can be distinguished from the other closely related species based on the distinct

morphological differences.

e.g. Mango – Mangifera indica Potato – Solanum tuberosum Brinjal – Solanum melongena Makoi – Solanum nigrum Lion – Panthera leo

Tiger – Panthera tigris

Human – Homo sapiens

indica, tuberosum, melongena, nigrum, leo, tigris, sapiens represent the specific epithets

Species concept:

• Species term and species concept was proposed by John Ray.

• Biological species concept was given by Ernst Mayr. According to Mayr “species is group of organism with similar morphology which can interbreed among themselves and produce fertile offspring”. It is based on reproductive isolation.

B.GENUS

• Genus comprises a group of related species which has more characters in common in comparison to species of other genera.

• Each genus may have one or more than one specific epithets representing different organisms, but having morphological similarities.

• Genus may be monotypic (Single species in a genus e.g. Gregoria fenestrata) and Polytypic (many species in a genus).

.	Tomato – Solanum lycopersicum
Solanum (Genus)	Brinjal – Solanum melongena
.	Potato – Solanum tuberosum
.	Lion – Panthera leo
Panthera	Tiger – Panthera tigris
.	Leopard – Panthera pardus
.	Jaguar – Panthera onca
Felis (Cat) and Canis (Dog)

C.FAMILY (Suffix – aceae)

• Family has a group of related genera with still less number of similarities as compared to genus and species.

• Families are characterised on the basis of both vegetative and reproductive features of plant species.

.	Solanum
Solanaceae (Family)	Petunia
.	Datura
.	Felis (Cats)
Falidae (cat family)	Panthera
Canidae (Dog family)	.

D.ORDER (Suffix – ales)

• Order being a higher category, is the assemblage of families.

.	Convolvulaceae
Polymoniales (Order)	Solanaceae
.	Felidae
Carnivora	Canidae
.	Cercopithecidae (Catarrhini) (Monkey)
.	Hylobatidae (Gibbon)
Primata	Pongidae (Gorilla and Chimpanzee)
.	Hominidae (Human)

E.CLASS (Suffix – ae, – opsida, – phyceae)

• This category includes related orders.

.	Carnivora (order)
Mammalia (Class)	Primata
Dicotyledoneae (Magnoliopsida)	Sapindales
Dicotyledoneae (Magnoliopsida)	Lamiales

F.PHYLUM / DIVISION (Suffix – phyta)

• Phylum (Animals) / Division (Plants) include related classes.

Chordata (Phylum)  Pisces, Amphibia, Reptilia, Aves, Mammalia. Angiosperm (division)  Dicotyledoneae, Monocotyledoneae.

G.KINGDOM

• Highest Taxonomical category

• Plant Kingdom includes different divisions of plants and Kingdom Animalia includes all phylum of animals.

Organisms with their Taxonomic Categories
Common Name	Biological Name	Genus	Family	Order	Class	Phylum/ Division
Human	Homo sapiens	Homo	Hominidae	Primata	Mammalia	Chordata
Housefly	Musca domestica	Musca	Muscidae	Diptera	Insecta	Arthropoda
Mango	Mangifera indica	Mangifera	Anacardiaceae	Sapindales	Dicotyledonae	Angiospermae
Wheat	Triticum aestivum	Triticum	Poaceae	Poales	Monocotyledonae	Angiospermae
Tulsi	Ocimum sanctum	Ocimum	Lamiaceae	Lamiales	Dicotyledonae	Angiospermae
Dog	Canis familiaris	Canis	Canidae	Carnivora	Mammalia	Chordata

BIOLOGICAL CLASSIFICATION:

• Three types of systems of classification have been recognized.

(I) Artificial (II) Natural (III) Phylogenetic

(I)ARTIFICIAL SYSTEMS OF CLASSIFICATION:

• Aristotle: He was the earliest to attempt a more scientific basis for classification of plant and animal.

Organisms

Plants

(On the basis of Morphology)

– Trees

Animals

–Shrubs

–Herbs

Anaima (Invertebrates with no red blood)

Enaima (Vertebrates with red blood)

Ovipara

Vivipara

• Carolus Linnaeus (1707-1778): He proposed an artificial system of classification (Also called sexual system of classification) on the basis of few sexual characters like on the androecium structure (number of stamens), in his book Genera Plantarum. He classified plants into 24 classes. Out of them, 23 were of phanerogams and 24^th class was of cryptogams.

• The earliest systems of classification used only gross superficial morphological characters such as habit, colour, number and shape of leaves, etc.

• They were based mainly on vegetative characters or on the androecium structure (system given by Linnaeus).

 Demerits of artificial system:

(a)They separated the closely related species since they were based on a few characteristics.

(b)The artificial systems gave equal weightage to vegetative and sexual characteristics; this is not acceptable since we know that often the vegetative characters are more easily affected by environment.

(II)NATURAL SYSTEMS OF CLASSIFICATION:

• This system is based on natural affinities among organisms.

• In these systems organisms are classified on the basis of mainly external morphology and internal feature like ultrastructure, anatomy, embryology features, phytochemistry etc.

• Evolutionary evidences are not included.

• These were also proposed by Jussiaeu, de Candolle, Bentham and Hooker.

Bentham and Hooker’s Classification:

• George Bentham and JD Hooker (1862–83) proposed a natural system of classification of angiosperms that was published in ‘Genera Plantarum’ in 3 volumes. It is based on A.P. de Candolle’s system.

 They classified plant kingdom into two subkingdoms–Cryptogamia and Phanerogamia. The phanerogamia classified in to three classes–Dicotyledons, Gymnosperms and Monocotyledons.

Merits:

 (i) It is practically important, most of the herbaria of the world are based on this system.

(ii)They placed Ranales (most primitive) in the beginning of classification that is phylogenetically true.

(iii)They placed monocots after dicots that is similar to phylogenetic systems.

Demerits:

(i)They did not use phylogenetic trends in their classification.

(ii)Gymnosperms placed between dicots and monocots that is not acceptable.

(III)PHYLOGENETIC SYSTEMS OF CLASSIFICATION:

• Evolutionary history of the organism is called Phylogeny (this term was coined by Lamarck). These systems are based on Phylogenetic relationships of organisms.

• Phylogenetic systems are also called Cladistics (Systematic classification based on evolutionary relationships of organisms in order of their assumed divergence from ancestral forms) and the graphic representation of evolutionary relationships is called family tree or Cladogram.

• Engler and Prantl proposed first phylogenetic classification (but it is very little phylogenetic) and published in their book “Die Naturlichen Pflanzenfamilien” in 23 volumes.

• Engler and Prantl divided plant kingdom into two sub kingdom (1) Cryptogamia: invisible sex organs

e.g. Thallophyta, Bryophyta and Pteridophyta.; (2) Phanerogamia: visible sex organs

e.g. Gymnosperm and Angiosperm.

• Later on well-developed phylogenetic systems of classification were created by Hutchinson, Tippo, Takhtajan, Robert Whitaker, Robert thorne and Cronquist.

• Oswald Tippo proposed biggest phylogenetic classification of plant kingdom and it is most accepted for books and study.

• Fossil records are most important evidences in systematics but if fossil record are not available then other branches of taxonomy like Karyotaxonomy, Cytotaxonomy, numerical, Chemotaxonomy etc. play important role to find out phylogeny

• Thallophyta includes those plants in which root, leaf and stem are not differentiated like fungi, Algae and Bryophyta.

• Pteridophyts are considered as vascular cryptogams.

• Thallophyta, Bryophyta and Pteridophyta are zoodiogamous plants (Motile male gamete) while Gymnosperm and Angiosperms are siphonogamous plants (Pollen tube formation).

BIOLOGICAL CLASSIFICATION:

On the basis of number of Kingdom.

1.TWO KINGDOM SYSTEM OF CLASSIFICATION:

• Proposed by C. Linnaeus and he classified all organisms into two kingdoms – Kingdom plantae and kingdom Animalia.

 Kingdom plantae involves autotrophic, fixed organisms while kingdom Animalia includes motile, heterotrophic organisms. Microorganisms involved in both the kingdoms.

Advantage of two Kingdom classification:

• Classification of organisms into plants and animals was easily done and was easy to understand.

Shortcomings of Two-Kingdom System:

(i)This system did not distinguish between the eukaryotes and prokaryotes. e.g. Bacteria and cyanobacteria are included under plants but the formers are prokaryotes.

(ii)Unicellular and multicellular forms have been placed in both the kingdoms though they have different organisation.

(iii)A large number of organisms did not fall into either category. e.g. Viruses are neither plants nor animals and placed at the border line of living and non-living.

(iv)Photosynthetic (green algae) and non-photosynthetic (fungi) organisms were placed together.

Thus two kingdom system of classification used for a long time was found inadequate.

2.THREE KINGDOM SYSTEM:

• Ernst Haeckel proposed it and three kingdoms are Plantae, Animalia and Protista.

• He separated all one celled Eukaryotes (Algae, Slime moulds, Protozoans, Fungi, bacteria) into separate kingdom Protista.

3.FOUR KINGDOM SYSTEM:

• It was proposed by Copeland (1956).

• He established a new kingdom Monera for all acellular prokaryotes containing incipient nucleus like bacteria, blue green algae. The four kingdoms are monera, protista, plantae (metaphyta) and animalia (metazoa).

• Copeland used the term Mycota for monerans. Dougherty used the term Monera.

4.FIVE KINGDOM SYSTEM:

• It was proposed by Whittaker (1969).

• It is a phylogenetic system that is based on following criteria.

(i)Complexity of cell structure: Prokaryotes and eukaryotes.

(ii)Complexity of organisms: i.e., thallus organisation (unicellular or multicellular organisms).

(iii)Mode of nutrition: Autotrophic (holophytic) or heterotrophic [saprophytic and holozoic]. It is major criteria of classification in this system.

(iv)Reproduction

(v)Phylogenetic relationship.

Table: Characteristics of the Five Kingdoms

Character	Five Kingdoms
.	Monera	Protista	Fungi	Plantae	Animalia
Cell type	Prokaryotic	Eukaryotic	Eukaryotic	Eukaryotic	Eukaryotic
Cell Wall	Noncelluloic (Polysaccharide + amino acid)	Present in some	Present (without cellulose) with chitin	Present (cellulose)	Absent
Nuclear membrane	Absent	Present	Present	Present	Present
Body organisation	Cellular	Cellular	Multicellular / loose tissue	tissue / organ	Tissue / organ/ organ system
Mode of nutrition	Autotrophic (chemosynthetic and photosynthetic and Heterotrophic (saprophytic / parasitic)	Autotrophic (Photosynthetic) and Heterotrophic	Heterotrophic (saprophytic / parasitic)	Autotrophic (Photosynthetic)	Heterotrophic (Holozoic/ saprophytic etc.)

Merits:

(i)Fungi are separated from plants or protista and established as kingdom.

(ii)Prokaryotes and eukaryotes are separately recognised in this system.

Demerits:

(i)The position of Viruses is not clear.

(ii)Algae is placed into monera, protista and Plantae.

(iii)Protista is an artificial group.

 Issues and considerations that influenced the classification system:

Issues:

• Besides, gross morphology a need was also felt for including other characteristics like cell structure, nature of wall, mode of nutrition, habitat, methods of reproduction, evolutionary relationships, etc.

• Earlier classification systems plants included bacteria, blue green algae, fungi, mosses, ferns, gymnosperms and the angiosperms because all of these have cell wall.

• Prokaryotic bacteria and BGA were classified with eukaryotic groups.

• Unicellular organism like Chlamydomonas and Spirogyra were placed together under algae which is multicellular.

• Heterotrophic / Saprotrophic group like fungi were classified autotrophic green plants though they also showed a characteristic difference in their walls composition – the fungi had chitin in their walls while the green plants had a cellulosic cell wall.

Consideration:

• Fungi were placed in separate Kingdom because of difference in nutrition and cell wall.

• All prokaryotic organisms were grouped together under Kingdom Monera and the unicellular eukaryotic organisms were placed in Kingdom Protista.

• It has put together organisms which, in earlier classifications, were placed in different kingdoms. e.g. Kingdom Protista has brought together Chlamydomonas, Chlorella (earlier placed in Algae within Plants and both having cell walls) with Paramoecium and Amoeba (which were earlier placed in the animal kingdom which lack cell wall).

• This happened because the criteria for classification changed with time and this kind of changes will also take place in future too depending on the improvement in our understanding of characteristics and evolutionary relationships.

• Though plant and animal kingdoms have been a constant under all different systems, the understanding of what groups/organisms be included under these kingdoms have been changing; the number and nature of other kingdoms have also been understood differently by different scientists over the time.

THREE DOMAIN SYSTEM:

• Carl woese proposed three domains system – Archaea, Bacteria and Eukarya.

• It is based on genetic characters particularly genetic analysis of 16S rRNA.

• 6 Kingdoms are included in three domains (6th Kingdom is Archaebacteria)

• Domain is an intermediate category in classification and represented as super Kingdom.

Living organisms

Archaea Archaebacteria

Domains

Bacteria

Prokaryotes like Bacteria Cyanobacteria

Eukarya

All Eukaryotic forms like Algae, Fungi, Protista, Plants and Animals

TAXONOMICAL AIDS

• Taxonomic studies of various species of plants, animals and other organisms are useful in agriculture, forestry, industry and in general in knowing our bioresources and their diversity.

• These studies would require correct classification and identification of organisms.

• Identification of organisms requires intensive laboratory and field studies.

• The collection of actual specimens of plant and animal species is essential and is the prime source of taxonomic studies.

• These are also fundamental to studies and essential for training in systematics.

• It is used for classification of an organism, and the information gathered is also stored along with the specimens. In some cases the specimen is preserved for future studies.

• Biologists have established certain procedures and techniques to store and preserve the information as well as the specimens. Some of these are explained to help you understand the usage of these aids.

A.HERBARIUM:

 Herbarium is a store house of collected plant specimens that are dried, pressed and preserved on sheets. Further, these sheets are arranged according to a universally accepted system of classification.

• These specimens, along with their descriptions on herbarium sheets, become a store house or repository for future use.

 The herbarium sheets (standard size 16.5 × 11.5 inch.) also carry a label providing information about date and place of collection, English, local and botanical names, family, collector’s name, etc.

• Herbaria also serve as quick referral systems in taxonomical studies.

• One has to carry certain simple tools for collection of specimens or their parts.

• The individual parts of a plants are quite useful in identification.

• In the field, one requires digger for digging roots, scissors for cutting twigs, knife for woody twigs and a pole with a hook for collecting parts of tall trees.

• The collected specimens are carried in a box called vasculum to avoid loss of moisture and distortions by drying and shriveling up.

 Types of herbaria

i.National herbaria have plant specimens of many parts of the world.

ii.Regional herbaria have plant specimens of a region.

iii.Local herbaria have plant specimens of a local area.

B.BOTANICAL GARDENS:

• These specialised gardens have collections of living plants (only) for reference.

 Plant species in these gardens are grown for identification purposes and each plant is labelled indicating its botanical/scientific name and its family.

• The famous botanical gardens are at Kew (England), Indian Botanical Garden, Howrah (India) and at

National Botanical Research Institute, Lucknow (India).

C.MUSEUM:

• Biological museums are generally set up in educational institutes such as schools and colleges.

• Museums have collections of preserved plant and animal specimens for study and reference. Specimens are preserved in the containers or jars in preservative solutions.

• Plant and animal specimens may also be preserved as dry specimens.

• Insects are preserved in insect boxes after collecting, killing and pinning.

• Larger animals like birds and mammals are usually stuffed and preserved.

• Museums often have collections of skeletons of animals too.

• Among plants it store only those plants which cannot be stored in Herbarium like cones of Gymnosperms.

D.ZOOLOGICAL PARKS:

• These are the places where wild animals are kept in protected environments under human care and which enable us to learn about their food habits and behavior.

• All animals in a zoo are provided, as far as possible, the conditions similar to their natural habitats. Children love visiting these parks, commonly called Zoos.

E.KEY:

 Key is another taxonomical aid used for identification of plants and animals based on the similarities and dissimilarities.

 Keys are generally analytical in nature.

 The keys are based on the contrasting characters generally in a pair called couplet.

• It represents the choice made between two opposite options.

• This results in acceptance of only one and rejection of the other.

 Each statement in the key is called a lead.

• Separate taxonomic keys are required for each taxonomic category such as family, genus and species for identification purposes.

Type of keys

• Being analytical in nature these are generally of two types:

(a) Yoked or indented key

• The indented key provides sequence of choices between two or more statements of characters of species. The user has to make correct choice for identification.

(b) Bracketed key (More popular).

• In the bracketed key, the pairs of contrasting statements are used for identification. The number on the right indicates the next choice of paired contrasting statements.

Resonate the Concept

F.FLORA:

• Flora contains the actual account of habitat and distribution and index to the plant species found in a particular area.

G.MANUALS:

• It contains compiled information about area covered, keys and description of families, genus and species.

 They are useful in providing instruction for identification of names of species, occurance and collection of plants found in an area.

H.MONOGRAPHS:

• Monographs contain information on any one taxon like families, genus etc.

I.CATALOGUES:

• Used for identification of organisms and it is list of all species in an area with brief description.

G. PUBLICATIONS:

• It like periodicals and dictionaries are brought out to provide information about new additions and updated information.

ADDITIONAL INFORMATION

• Biology: (Bios: life; logos: to discourse). Science that deals the study of living things.

• Lamarck and Treviranus (1801) were the first to use the term Biology.

• The branch of biology which deals with the study of animals is called zoology (zoon: animal; logos: to discourse). Aristotle is regarded as Father of Zoology. Book – Historia animalia.

• The study of plants is called Botany (botane: plant). Theophrastus (370-287 B.C.) prepared a list of 500 plants and is called “Father of Botany”. Book – Historia plantarum.

• In Chandyogya Upanishad animals were classified into 3 categories i.e. Jivaja (Viviparous), Andaja (Oviparous) Udbhija (Vegetal origin).

• Charaka was the first physician to present the concepts of digestion, metabolism and immunity. According to him, a body functions because it contains three doshas, namely, bile (pitta), phlegm (cough) and wind (vata) and illness is caused when the balance among the three doshas in a human body is disturbed. These are the basis of the indigenous system of medicine in India which is known as Ayurveda.

• Aristotle (384 – 322 BC): Greek; classified animal species and arranged them in hierarchies.

• C. Linneaus: Books – Species plantarum (1753, 5900 plant species) and Systema naturae (1758, 4326 animal species). He also gave term systematics and class.

• Apoplasmic substances are non-living components formed by cell e.g. Cell wall, fibers in connective tissue, matrix of bone etc.

• We can’t create protoplasm because of lack of organisation of biomolecules.

• Silent valley rain forest of Kerala saved from submergence under proposed dam on river Kuntizha.

• Microfossils is used for impression and remains of microorganism as well as microscopic remains of large organisms.

• Theophrastus: On the basis of habit, He classified 480 plants into four group’s – herbs, under shrubs, shrub and trees.

• Tautonyms: Scientific name in which genus and species name are same are called Tautonyms. Tautonyms are valid for animal nomenclature only.

e.g. Rat (Rattus rattus), Cobra (Naja naja)

FATHER IN THE FIELD OF BIOLOGY

Father of Biology – Aristotle

Father of Botany – Theophrastus

Father of Zoology – Aristotle

Father of Taxonomy – Carl Linnaeus

Father of Genetics – G.J. Mendel

Father of Medicine – Hippocrates

Father of Surgery – Susruta

SOME INTERESTING FACTS OF BIOLOGY

ANIMAL WORLD

National bird – Pavo cristatus (Peacock)

Living fossil arthropod – Limulus

Living fossil fish – Latimeria chalumnae

Living fossil reptile – Sphenodon

Smallest Mammal – Shrew

Smallest bird – Humming bird of cuba (5.5 cm)

Smallest bone – Stapes

Smallest virus – Foot mouth virus of cattle (20 micron)

Largest mammal – Blue whale

Largest Invertebrate – Giant squid

Largest cell – Egg of Ostrich

Tallest mammal – Giraffe

Longest cell – Nerve cell (Neuron)

Largest gland – Liver

Largest vein – Inferior vena cava

Largest virus – Pox virus

Fastest mammal – Cheetah (Actiononyx jubatus)

Fastest bird – Spine tailed shift of Japan

PLANT WORLD

National flower of India – Lotus (Nelumbo nucifera) National fruit of India – Mango (Mangifera indica) Joker of plant kingdom – Mycoplasma (PPLO)

Largest flower – Rafflesia arnoldi (1 mt in dia, wt 7 kg)

Largest Botanic Garden of India – Indian Botanic Garden, Sibhpur (Howrah) Kolkata

Largest herbarium of India – Central National Herbarium (CNH), Howrah, WB

IMPORTANT BOOKS

Historia Animalium – Aristotle

Historia Plantarum – Theophrastus

Origin of species – Charles Darwin Philosophic Zoologique – Lamarck Philosophia Botanica – C. Linnaeus Species Plantarum – C. Linnaeus

Systema Naturae – C. Linnaeus

Micrographia – Robert Hooke

Historia naturalis – Pliny and Elder

Historia generalis plantarum – John ray (gave term species, family and genus)

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