DAY ONE

The Living World

Learning & Revision for the Day

u Characteristics of Living Beings u Taxonomy and Systematics u Kingdom–Protista

u General Classification of Living u Tools for Study of Taxonomy u Kingdom–Fungi
Beings u Classification of Living World u Lichens
u Classification and its Needs u Kingdom–Monera u Viruses

Biology is the science, which deals with the study of living organism and their life
processes. Life is a characteristic quality that differentiates non-living objects from the
living forms. Classification is the method of arrangement of these living organisms in
groups, according to their similarities and dissimilarities and finally placing them
within the taxonomic hierarchy, such as species, genus, family, etc. The most
widely accepted method of classification is five kingdom classification given by
RH Whittaker (1969).

Characteristics of Living Beings

Some important characteristic features of living beings, which differentiate living
organisms from non-living organisms are given below
(i) Growth is the characteristic of all living organisms. Increase in biomass and
increase in size of individuals are twin characteristics of growth.
A multicellular organism grows by cell division. In plants, growth occurs by cell
division continuously throughout their lifespan.
(ii) Reproduction is a basic characteristic feature of living organisms. Reproduction
means the production of offsprings possessing features more or less similar to that
of parents.
(iii) Consciusness is the ability of living beings to sense their surroundings or
environment and respond to these environmental stimuli, which could be
physical, chemical or biological.
(iv) Cellular organisation is the defining feature of living forms, as cells are basic
building blocks of the living organisms.
(v) Biological organisation starts with submicroscopic molecular level, where four
types of molecule, i.e. carbohydrates, proteins, lipids and nucleic acids are
organised into cells and cells into organelles of cell.
The cells are organised into tissues. Tissues inturn are organised into organs and
organs are organised into organ systems.
The organism is made up of organ systems. It lives in populations, which form
communities, which are part of ecosystems and ecosystems are part of the
biosphere.
 (vi) Respiration is the process of generation of energy by l
Osmoregulators Animals, whose body fluids are not
breaking of the C—C bonds of complex compound isotonic with the outside environment are called
through oxidation leading to release of energy which is osmoregulators. They must either discharge excess
stored in the form of ATP. water when they live in a hypotonic environment or
All cells require energy and in every kind of organism, continuously intake of water is required when they
ATP is used as a source of energy that is why ATP is live in a hypertonic environment, e.g. all freshwater
called as universal energy carrier. and many marine animals along with humans and
(vii) Evolution refers to changes which occur from time to other terrestrial animals.
time. Infact biology is the study of evolution of living (iii) On the basis of aquatic habitat, animals can be divided
organisms on earth. into two groups
(viii) Homeostasis is the process of maintenance of constant l
Anadromous fishes live and mature in marine water
internal environment. Living things actively maintain and migrate to freshwater for breeding, e.g. Salmon.
their complex structure and their constant internal l
Catadromous fishes live and mature in fresh water
structure through this process. and migrate to ocean for breeding, e.g. American eels
The term ‘Homeostasis’ was coined by American and Anguilla.
physiologist Walter Bradford Cannon in 1929. (iv) On the basis of salinity, animals can be divided into two
(ix) Metabolism is the sum total of all the chemical groups
reactions occurring in our body. l
Stenohaline are fishes which can tolerate only a
Metabolism has two phases, i.e. anabolism and narrow range of salinities.
catabolism. l
Euryhaline are fishes which can tolerate wide range
Metabolism = Anabolism + Catabolism of salinities.

General Classification of Biodiversity

Planet earth exhibits a large variety of living organisms, like
Living Beings plants, animals, fungi, etc. These all constitute our
All living beings have been categorised into different groups ‘Biodiversity’. In it each and every different kind of organism
on the basis of various common features shared by them. represents a species. The number of species that are known
These are as follows and described is in the range between 1.7-1.8 million. These
(i) On the basis of body temperature, living beings can be organisms inhabit distinct geographical locations. Thus, every
divided into two groups distinct geographical location has its own flora (plants) and
fauna (animals).
l
Ectothermic Animals whose body temperature
fluctuates considerably with environment is called
poikilothermic or cold-blooded or ectothermic, Classification and its Need
e.g. amphibians, reptiles, insects, etc. l
It is nearly impossible to study all the living organisms, so
l
Endothermic Some organisms, which are capable of it is necessary to devise some means to make this possible.
maintaining a stable body temperature independent This process is called classification. It is the process by
of the environmental temperature are called which anything is grouped into convenient categories
homeothermic or warm-blooded or endothermic, based on some easily observable characters.
e.g. birds, mammals. l
Classification is the systematic arrangement of organisms
into groups on the basis of their affinities or relationships.
NOTE • Hibernation Winter sleep or dormancy during winter is l
Classification is necessary for organisms due to the
called hibernation.
following reasons
• Aestivation Dormancy during summer or dry weather is
called aestivation.
(i) Convenience of study
(ii) Knowledge of adaptations
(ii) On the basis of osmoregulation, animals are divided
into two groups (iii) Knowledge of sequence of evolution
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Osmoconformers Animals, whose body is (iv) Knowledge of phylogenetic relationships
iso-osmotic with outer environment are called (v) Discovery of new organisms
osmoconformers, e.g. hag fishes (jawless members of l
The modern system of classification began in 1758, when
the class–Agnatha), elasmobranchs, coelocanths Carolus Linnaeus (1707-1778), a Swedish botanist
(Latimeria) and most of the marine invertebrates. published the tenth edition of his book ‘Systema Naturae.’
There are three main systems of classification There are two types of names which can be given during
(i) Artificial classification is based on arbitrary, easily nomenclature
observable, single or a few morphological characters l
Vernacular names are the names given to the organisms in
such as habit, colour, number, form or similar features, the local language of that region. These names are invalid
e.g. Linnaeus system of classification. as they are not recognised universally.
(ii) Natural classification is based on overall similarities or l
Scientific names are given to the organisms by biologists
affinities derived from morphology, anatomy, based on agreed principles and criteria for their
embryology, phytochemistry, ultrastructure and all acceptability all over the world. These are
other fields of study, e.g. Bentham and Hooker’s system. (i) Polynomial Nomenclature Before 1750, this system
(iii) Phylogenetic classification is based on the evolutionary was used, in which, organism’s name consisted of series
descent of a group of organisms. The relationship is of Latin descriptive words. Such names were lengthy
depicted through a phylogram, phylogenetic tree or a and difficult to learn. e.g. Caryophyllum saxatilis, Folis
cladogram, e.g. Engler and Prantl’s system and Takhtajan gramineus, Umbellatis corymbis.
classification. (ii) Trinomial Nomenclature This system is used to
Some Important Books and their Authors describe sub-species, e.g. Homo sapiens sapiens.
(iii) Binomial Nomenclature Swedish naturalist Carolus
Books Authors
Linnaeus established binomial nomenclature, though, it
Philosophica Botanica Carolus Linnaeus was first proposed by Gaspard Bauhin. The
Species Plantarum Carolus Linnaeus nomenclature was used first in his book Species
Systema Naturae Carolus Linnaeus Plantarum (1753), in which, names and description of
5900 plant species were given. Later Linnaeus
Genera Plantarum Bentham and Hooker
published Systema Naturae (1758), in which 4326
Families of Flowering Plants John Hutchinson animal species were described.
According to this system, name of any organism consists
Nomenclature of two parts or epithets, i.e. generic epithet and specific
It is a science of providing distinct and proper names to epithet, e.g. the botanical name of mango is Mangifera
organism, so that they can easily be recognised and indica L. In which, Mangifera is generic epithet, which
differentiated from others. It is done by using rules and represents its genus and indica is specific epithet, which
recommendations of the code, prescribed by different represents its species. L represents the name of the
scientific bodies as mentioned below scientist (Linnaeus), who gave the name of mango.
Various Codes Some rules for binomial nomenclature are
ICBN International Code of Botanical Nomenclature l
Names should be in Greek or Latin language.
ICZN International Code of Zoological Nomenclature
l
Generic name begins with capital letter (Mangifera)
and is placed before species name, while species
ICNB International Code of Nomenclature of Bacteria
name begins with a small letter (indica).
ICNCP International Code of Nomenclature for Cultivated Plant l
The scientific name should be either underlined or
ICTV International Committee for the Taxonomy of Viruses italicised.
The ICBN recognises several kinds or types depending on the l
Name of the authority should be written after specific
way in which a type of specimen is selected. epithet in an abbreviated form.
Types of Specimen l
The most important rule of ICBN is rule of priority.
In case, where two or more names are given, the
Holotype Nomenclature type.
oldest, i.e. the name given first is recognised as valid
Isotype Duplicate of holotype. name and all other names are called synonyms
Paratype Any other specimen described along with holotype. whereas, names with same generic and specific
names are called tautonyms, e.g. Rattus rattus.
Syntype Any one of the two or more specimens cited by
author, when there is no holotype.
Lectotype Specimen selected from original material to serve
Taxonomy and Systematics
as nomenclature type, where there is no holotype. l
Taxonomy is the branch of biology dealing with the
Neotype New nomenclatural type, when the original
identification, nomenclature and classification of living
material is missing. organisms. The term ‘Taxonomy’ was coined by AP de
Candolle. Carolus Linnaeus is known as Father of
Topotype A specimen collected from the same locality from
which the holotype was originally collected.
Taxonomy and Father of Systematic Botany, whereas
Santapau is known as Father of Indian Taxonomy.
l
Systematics is the branch of biology concerned with Category Suffix
reconstructing phylogenies and with naming and
Sub-order incae
classifying species.
Family aceae
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The term ‘Systematics’ was coined by Linnaeus and
G Simpson (1961) distinguished systematics, taxonomy Sub-family oideae
and classification.
Tribe eae
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Julian Huxley (1940) proposed the term ‘New systematics’.
It deals with the study of diversity of organisms and all Suffixes used in the animal kingdom are
their comparative and evolutionary relationship based on (i) Super-family — oidea (ii) Family — idae
comparative anatomy, ecology, physiology and biochemistry. (iii) Sub-family — inae (iv) Tribe — ini
Tribe is an intermediate category between sub-family and
Modern Trends in Taxonomy
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genus.
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Phenetic classification is based on the overall similarity of
organisms evaluated without any regard to phylogeny.
Taxonomic Hierarchy
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A modern method of classification called cladistics, it is l
The system of arranging organism in a definite sequence of
based on evolutionary history.
various taxonomic categories arranged in a proper
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Arranging organisms on the basis of their shared similar or descending or ascending order is called taxonomic
derived characters that differ from ancestral characters hierarchy.
will produce a phylogenetic tree called cladogram. l
It is also called Linnaeus hierarchy as it was first proposed
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The phylogenetic tree is also known as genealogical tree or by Carolus Linnaeus.
dendrogram. l
Linnaeus introduced five categories in the taxonomic
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Karyotaxonomy is based on nucleus and chromosomes. hierarchy viz, Class, Order, Genus, Species and Variety.
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Numerical taxonomy is based on statistical methods. It is l
Later on, three more categories, i.e. Kingdom, Division (in
now easily carried out using computers. Each character is
plants) or Phylum (in animals) and Family were added and
given equal importance and at the same time, hundreds of
Variety was discarded to make a hierarchy of seven obligate
characters can be considered.
categories, viz.
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Experimental taxonomy is based on experimental
determination of genetic inter-relationships. Division (in plants)
Kingdom or Class
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Cytotaxonomy is based on cytological information like Phylum (in animals)
chromosome number, structure and behaviour.
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The chemotaxonomy emphasises on the chemical Species Genus Family Order
constituents of the organisms to resolve confusions and is
used these days to determine evolutionary closeness. Taxonomic hierarchy

Taxonomic Category or Taxon l

The term subspecies is used more commonly by zoologists,
while variety is used commonly by botanists.
l
A taxon is a taxonomic group of any rank. It is a taxonomic
group of real organisms assigned to a category, whereas
taxonomic category represents rank or level in a hierarchy Concept of Species
and does not represents the living organisms. For example, l
Species is the fundamental or smallest unit of
Reptilia is a taxon, but class is a category similarly Poaceae is classification. The term ‘species’ was recognised from
a taxon but family is a category. Genus by John Ray.
l
According to ICBN, the names of different categories must l
Static concept of species or morphological concept of
end in the standard endings (suffixes). species was proposed by Carolus Linnaeus. He considered
Categories and their Suffixes species as a fixed and immutable entity.
l
Dynamic concept of species was proposed by Lamarck,
Category Suffix
who considered species as a mutable and dynamic entity.
Division phyta l
Biological concept of species was proposed by Ernst Mayr.
Sub-division phytina According to this concept, a species is a group of
individuals, who resemble each other in morphological,
Class phyceae or opsida or ae
physiological, biochemical and behavioural characters and
Order ales are capable of interbreeding.
Few important points related to concept of species are l
Insects are preserved in insect boxes, after collecting,
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Taxonomic species are the species having a binomial name. killing and pinning.
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Sibling species are two distinct species, which do not
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Larger animals like birds and mammals are usually
interbreed but are otherwise difficult to separate on the stuffed and preserved.
basis of morphological characters alone. 4. Zoological parks are the places, where wild animals are
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Allopatric species are species having exclusive areas of kept in protected environments under human care.
geographical distribution. Largest zoo of the world is situated in Kruger (South
Africa).
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Sympatric species are species having overlapping areas of
geographical distribution. 5. Taxonomic key is one of the taxonomical aid used for
identification of plants and animals.
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Parapatric species are species with adjacent geographic l
The keys are based on the contrasting characters
ranges meeting in a very narrow zone of overlap.
generally in pair called couplet and represents the
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Allochronic species are species belonging to different time choice made between two opposite options. One is
periods. accepted and other is rejected.
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Synchronic species are species belonging to a same period l
Two types of keys are always used-indented and
or time. bracketed. Each statement in key is called a lead.
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Linnaean species are taxonomic species distinguished on
the basis of morphological grounds. Classification of Living World
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Keystone species play a key role or central role in the The study of all living organisms without placing them at
ecology of a place. appropriate place is not possible, so scientists placed the
organisms into kingdoms. Kingdom is the highest taxonomic
Tools for Study of Taxonomy category.
Taxonomic studies of plants, animals and other organisms are 1. Two Kingdoms Linnaeus divided all organisms into two
useful in agriculture, forestry, industry and in knowing our kingdoms, i.e. plant kingdom and animal kingdom.
bioresources and their diversity. Biologists have established Photosynthetic organisms were included into plant
certain procedures and techniques to store and preserve the kingdom, while non-photosynthetic organisms in animal
information as well as the specimens. These procedures are kingdom. Exceptions
called as taxonomic tools or aids. l
Euglena shows characteristics of both plants and
Following are the main tools for study of taxonomy animals.
1. Herbarium is a store house of collected plant specimens
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Bacteria and cyanobacteria (blue-green algae) have
that are dried, pressed and preserved on sheets. cytological differences from plants and animals.
l
Fungi which are usually classified in plants, are
The biggest herbarium of the world is Royal Botanical
non-photosynthetic. Fungi are non-motile, multiply
Garden at Kew, England, while the biggest herbarium of
like plants and non-photosynthetic like animals.
India is Indian Botanical Garden at Kolkata.
l
Tunicate sponges and corals are non-motile and
2. Botanical garden is essentially a collection of living
fixed like plants.
plants maintained for both pure and applied studies.
Largest Botanical Garden of Asia is Indian Botanical
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Some algae which are photosynthetic are either
Garden, Sibpur. First Botanical Garden is Pisa Botanical motile or produce motile reproductive cells.
Garden, Italy. 2. Three Kingdoms E Haeckel (1866), a German biologist,
The main functions of botanical gardens are suggested a third kingdom–Protista to include
unicellular protozoans and algae.
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To provide records of local flora for monographic
work. 3. Four Kingdoms Copeland (1956) developed four
kingdom system with kingdoms, i.e. Monera, Protista,
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To provide facilities for collections of living plant Plantae and Animalia.
materials for biosystematic studies.
4. Five Kingdoms RH Whittaker (1969), an American
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To supply seeds and materials for botanical taxonomist, divided all the organisms into five
investigation. kingdoms, i.e. Monera, Protista, Fungi, Plantae and
3. Museums have collections of preserved plants and Animalia.
animals for the study and reference. l
The main criterias or characteristics used by him for
l
These are prepared for preservation of algae, fungi, classification were cell structure, body organisation,
mosses, ferns, animals, etc., because they cannot be mode of nutrition, reproduction and
kept in herbaria. phylogenetic relationship.
 l
The major characteristics of all the five kingdoms are tabulated below
Five Kingdom
Characteristics
Monera Protista Fungi Plantae Animalia
Cell type Prokaryotic Eukaryotic Eukaryotic Eukaryotic Eukaryotic
Cell wall Non-cellulosic Present in some Present Present Absent
(polysaccharide + amino acid) (without cellulose) (cellulose)
Nuclear membrane Absent Present Present Present Present
Body organisation Unicellular Unicellular Multicellular/ Tissue/Organ Tissue/
Loose tissue Organ/Organ system
Mode of nutrition Autotrophic (chemosynthetic or Autotrophic Heterotrophic Autotrophic Heterotrophic
photosynthetic) and heterotrophic (photosynthetic) (saprophytic/ (photosynthetic) (holozoic/
(saprophytic/ parasitic) and heterotrophic parasitic) saprophytic, etc.)

5. Six Kingdoms Carl Woese et.al. proposed the six kingdom system, in which monerans are divided into Archaebacteria and
Eubacteria.

Three Domains of Life

Studies of ribosomal RNA (rRNA) show that all living organisms share a common ancestor and there are three major
evolutionary lineages. These are as follows
(i) Archaea (ii) Eubacteria (iii) Eukarya
Each of these lineages is called domain. The domain supersedes.
Distinguishing Features of Domains
Three Domains
Feature
Archaea Eubacteria Eukarya
Membrane bound organelles Absent Absent Present
Membrane lipid structure Branched Unbranched Unbranched
Nuclear envelope Absent Absent Present
Number of different RNA polymerases Several One Several
Peptidoglycan in cell wall Absent Present Absent

Kingdom–Monera
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It includes all prokaryotic organisms, i.e. bacteria, mycoplasma, actinomycetes, spirochaetes, rickettsiae, chlamydiae and
cyanobacteria.
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Members of this kingdom are known as monerans, which lack true nucleus, nuclear membrane, nucleolus, chromatin,
histone proteins and all membrane bound organelles.
l
Genetic material is called nucleoid or genophore or incipient nucleus or prochromosome, which is composed of naked DNA,
RNA and proteins.
l
Plasmids are small extrachromosomal rings of DNA discovered by Hayes and Lederberg (1952). They can replicate
independently without nucleoid. If associated with nucleoid they are called episomes.
l
Ribosomal RNA are of 70S type.
l
Cell wall is made up of peptidoglycan (except archaebacteria and mycoplasma).
l
Reproduction is usually asexual by means of binary fission.
l
Respiratory enzymes are found associated with the plasma membrane.
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Cell division is of amitotic type and lacks spindle formation.
 2. Eubacteria
Classification of Kingdom–Monera
These are typical prokaryotic (i.e. no membrane enclosed
In 1977, Carl Woese and George Fox reported two quite nucleus) cells with a single chromosome (i.e. a closed circle
distinct groups in this kingdom. These groups are of double-stranded DNA, without histone protein) and
archaebacteria and eubacteria. Archaebacteria without mitochondria, chloroplast and any other membrane
(Gr. Archae–primitive; bacteria) includes methanogens, bound cell organelles.
halophiles and thermoacidophiles. Eubacteria (Gr. Eu
—true; bacteria) are true bacteria that includes Bacteria
cyanobacteria, mycoplasma, actinomycetes, rickettsia and
spirochaetes. These are microscopic, relatively simple, unicellular
organism, whose genetic material is not enclosed in nuclear
1. Archaebacteria membrane.
l
It is a primitive group of bacteria. These are oldest of the Size and Shape of Bacteria
living fossils. They inhabit most extreme environments on l
The size of bacteria ranges from 0.1-1.5 µm in diameter and
earth that is why, they are called extremophiles.
2-10 µm in length. Dialister pneumosintes (0.15-0.3 µm
l
Their cell walls lack peptidoglycan which is an important
long) is the smallest bacterium, while Beggiatoa mirabilis
component of the cell wall of eubacteria.
(16-45 µm diameter and upto several centimeter long) is
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The lipids contain phytanyl side chains (branched lipid). the largest bacterium.
Branch chained lipids decrease membrane fluidity and l
On the basis of shape, bacteria can be either coccus (i.e.
increase tolerance to extremes of heat as well as low pH.
spherical or nearly spherical, small and non-flagellated),
l
They possess distinctive ribosomal RNA sequences and bacillus (i.e. rod-shaped, e.g. Escherichia coli and
introns (i.e. non-coding genes) like that of eukaryotes. Lactobacillus), vibrio (i.e. comma-shaped, e.g. Vibrio
l
They are primary producers of deep sea hydrothermal vent cholerae), spiral (i.e. coiled form of bacteria exhibiting
ecosystem and have chemosynthetic mode of nutrition. twist with one or more turns, e.g. Spirillum minus).
The three main groups of Archaebacteria are l
Coccus bacteria can be either Micrococcus (occurs singly,
(a) Methanogens are obligate anaerobic (i.e. free oxygen e.g. Micrococcus agilis, Micrococcus roseus), Diplococcus
will kill them), Gram negative bacteria, which utilise (found in pairs, e.g. Gonococcus, Meningococcus,
CO2 during cellular respiration to produce methane Diplococcus pneumoniae), Streptococcus (i.e. cells remain
(CH4 ) as a waste product. attached to form a chain, e.g. Streptococcus lactis),
Staphylococcus (irregular bunches of cells or grape-like
l
These are found in the musk of swamps and marshes,
clusters, e.g. Staphylococcus aureus) and sarcinae, (cubical
the rumen of cattle (where they live on the hydrogen
packets of 8, 27 or more cells, e.g. Sarcina).
and CO2 produced by other microbes living along
with them), our colon (large intestine), sewage l
Bacilli bacteria arranged in pairs are called diplobacilli,
sludges and the gut of termites. e.g. Bacillus subtilis, bacilli arranged in chain are called
streptobacilli, e.g. Streptobacillus, Azotobacter, Bacillus
l
These are chemoautotrophs, which use hydrogen as a
anthracis, bacilli arranged side-by-side like matchsticks are
source of electrons for reducing carbon dioxide to
called palisade-like, e.g. Corynebacterium diphtheriae, when
food and giving off methane (marsh gas and CH4 ) as a
the cells of a chain have much larger area of contact with
byproduct, e.g. Methanobacterium, Methanobacillus,
each other, it is called trichomes, e.g. Beggiatoa.
Methanosarcina, Methanococcus
Caulobacter is stalked bacterium, Rhodomicrobium is
4H2 +CO2 → CH4 +2H2O budding bacterium, while Rhizobium, Corynebacterium,
(b) Halophiles are found in extremely saline environments Azotobacter and Mycobacterium are called pleomorphic
such as great salt lake in the US and Dead sea. bacteria.
They maintain osmotic balance with their
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surroundings by building up the solute concentration

Structure of Bacterial Cell
within their cells. Structural components of bacteria are as follows
1. Bacterial flagella are made up of a single filament of the
(c) Thermoacidophiles are found in hot and acidic places
protein flagellin, instead of 9 + 2 tubulin containing
such as acidic sulphur springs (i.e. in Yellowstone
microtubules found in eukaryotes.
National Park) and deep-sea-vents (black smockers).
l
It consists of basal body, hook and filament.
l
Some forms of thermoacidophiles (aerobic bacteria)
reduce sulphur to H2S under anaerobic conditions,
l
Basal body is the most complex portion of flagellum
e.g. Sulfolobus, Thermoproteus, etc. having 4 rings (L, P, S and M) in Gram negative and 2
rings (S and M) in Gram positive bacteria.
 l
Hook consists of a single type of protein and Gram Positive and Gram Negative Bacteria
functions to connect the filament to motor portion.
• Bacteria are classified as Gram positive (+ve) and Gram
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Filament is the longest portion of flagellum, which negative (–ve) based on their reaction with Gram’s stain. This
is 20 nm wide and 1-70 nm long and consists of 8 technique of Gram staining was introduced by Hans
vertical rows of flagellin. Christian Gram in 1884.
l
Depending upon the arrangement of flagella, • After staining the bacteria, which retain their original crystal
bacterial cell can be of following types violet stain are called Gram positive bacteria. On the other
hand, bacteria that lose stain and decolourise are called
n
Atrichous Flagella absent, e.g. Lactobacillus, Gram negative bacteria.
Pasteurella.
• The basis of Gram staining is the lipid content of bacteria.
n
Monotrichous Single polar flagellum, e.g. Vibrio Gram negative bacteria have high lipid content due to, which
cholerae and Thiobacillus. the lipids dissolve in organic solvent taking out the stain
n
Amphitrichous Single flagellum at each end of along with itself.
the cell, e.g. Nitrosomonas.
Comparison between Gram Positive and
n
Cephalotrichous Bacteria with many flagella
Gram Negative Bacteria
attached at one end, e.g. Pseudomonas
fluorescence. Characteristic Gram Positive Gram Negative
n
Lophotrichous Bacteria with a group of flagella Gram staining Retain crystal Can be decolourised to
attached at each end, e.g. Spirillum volutans. violet dye and accept counter- stain
stain dark violet or (safranin) and stain red
n
Peritrichous Bacteria with flagella all over the purple
body, e.g. E. coli and Clostridium tetani.
Peptidoglycan layer Thick Thin (single layered)
2. Pili or Fimbriae are extremely minute hair-like (multilayered)
structures found mostly in male bacterial cells.
Teichoic acids Present in many Absent
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Fimbriae are shorter and thinner (3-10 nm diameter)
than flagellum and used for attachment and Outer membrane Absent Present
colonisation. Lipopolysaccharide Virtually none High
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They are composed of protein sub-units called
Flagellar structure Two rings in basal Four rings in basal
pilin. body body
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A special type of pili called sex pili present on male
Toxins produced Primarily exotoxins Primarily endotoxins
bacterium makes conjugation tube during
conjugation. Cell wall disruption High Low (requires
by lysozyme pretreatment
3. Cell wall is the outer tough covering around the cell, to destabilise the outer
which provides specific shape and protection to the membrane)
bacterium. It prevents the cell from swelling and
Susceptibility to High Low
bursting due to the osmotic changes.
anionic detergents
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Glycocalyx is the outer most mucilage layer that
gives sticky character to bacterial cell. Resistance to drying High Low

l
It is composed of a polysaccharide called murein or Examples Staphylococcus, Salmonella,
peptidoglycan. It consists of polysaccharide NAG Streptococcus, Pseudomonas, Vibrio,
and NAM cross linked with short amino acid Pneumococcus, Helicobacter,
Bacillus, Haemophilus and
chains.
Clostridium, Escherichia
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Antibiotics such as penicillin, cephalosporin, etc., Mycobacterium
prevent the cross linking and inhibit the bacterial and Streptomyces
cell wall formation.
4. Cytoplasm is a semi-fluid ground substance enclosed by
l
Lysozyme attacks on the bond between glucosamine
the plasma membrane which is a phospholipid bilayer
and muramic acid and hydrolyses the cell wall. The
but there is no cholesterol or other steroids.
cell wall of Gram positive bacteria is much thicker
and contains less lipids as compared to that of Gram
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Cytoplasm appears granular due to the presence of
negative bacteria. large number (as many as 20,000) of 70 S type
ribosomes, which may occur singly or in clusters
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Lysozyme digests the polysaccharide back bone of
called polyribosome.
murein.
l
Apart from the nucleoid, certain bacterial cells contain 2. Heterotrophic bacteria are unable to manufacture their
extrachromosomal genetic material called plasmids. own organic food and hence, are dependent on external
l
The plasmid DNA replicates independently. It contains source. These bacteria can be distinguished into
genes like fertility factor (F-factor), resistance factor saprophytic bacteria, symbiotic bacteria and parasitic
(R-factor), nitrogen fixing genes (Nif-genes). bacteria.
l
Some plasmids may temporarily become associated with (i) Saprophytic bacteria obtain their nutritional
nucleoid DNA and are known as episomes. requirements from dead organic matter.
l
Plasmid term was coined by Lederberg and Hayes. Each
l
They breakdown the complex organic matter into
plasmid is circular, supercoiled, double-stranded and simple soluble form by secreting exogenous
naked DNA. enzymes.
l
Subsequently, they absorb the simple nutrients and
assimilate them, during which they release energy.
Nutrition in Bacteria These bacteria have a significant role in the
Bacteria exhibit different modes of nutrition. On this basis, ecosystem as they function as decomposers.
broadly two types of bacteria can be recognised; autotrophic l
The aerobic breakdown of organic matter is called
bacteria and heterotrophic bacteria. as decay or decomposition. It is usually complete
1. Autotrophic bacteria are able to synthesise their own and not accompanied by the release of foul gases.
organic food from inorganic substances. They use l
Anaerobic breakdown of organic matter is called
carbon dioxide for obtaining carbon and utilise fermentation. It is usually incomplete and is always
hydrogen sulphide (H2S) or ammonia (NH3 ) or hydrogen accompanied by the release of foul gases. Anaerobic
(H2 ) as the source of hydrogen to reduce carbon. These breakdown of proteins is called putrifaction.
bacteria can be distinguished further into two types,
(ii) Symbiotic bacteria live in a mutually beneficial
i.e. photoautotrophic bacteria and chemosynthetic
association with other organisms. Such bacteria derive
bacteria.
the essential nutrients from their host organisms and
(i) Photoautotrophic bacteria possess photosynthetic in that process help the host through some of their
pigments in membrane bound lamellae (thylakoids) biological activities.
and utilise solar energy. l
The most familiar example of symbiotic bacteria are
l
The bacterial photosynthesis is different from the nitrogen fixing bacteria, found in the root
that of green plants since, here water is not used nodules of leguminous plants.
as a hydrogen donor. l
Bacteria such as Rhizobium and Pseudomonas
l
Hence, oxygen is not released as a byproduct. reside in the root nodules and reduce atmospheric
For this reason, the process is described as nitrogen directly to ammonia. This becomes the
anoxygenic photosynthesis. source of nitrogen for the host plants. The plants in
Light energy return provide bacteria with nutrients and
CO2 + H2S → Sugar + Sulphur + Water
protection.
(ii) Chemosynthetic bacteria manufacture organic l
Nitrogenase enzyme system helps in fixation of
compounds from inorganic raw materials utilising nitrogen. This system is made up of two
energy, liberated from the oxidation of inorganic components, i.e. nitrogenase and nitrogenase
substances. The following are the common types of reductase.
chemosynthetic bacteria l
Blue-green algae (cyanobacteria) fix nitrogen in
(a) Nitrifying bacteria derive energy by oxidising heterocysts under anaerobic conditions.
ammonia into nitrates, e.g. Nitrosomonas and l
Rhizobium bacteria needs leghaemoglobin for
Nitrobacter. fixation of nitrogen. Nif gene is responsible for
NH4+ + 2O2 → NO2 +2H2O+energy synthesis of these enzyme. This gene is found in
(b) Sulphur bacteria derive energy by oxidising plasmids of prokaryotes.
hydrogen sulphide to sulphur, e.g. Thiobacillus l
Because plasmids are not found in eukaryotes, they
and Beggiatoa. cannot fix atmospheric nitrogen.
2H2S+O2 → 2S+2H2O+energy l
The bacteria found in the human alimentary canal,
(c) Iron bacteria derive energy by oxidising ferrous Escherichia coli are non-pathogenic. These
ions into ferric form, e.g. Ferrobacillus and bacteria check the growth of harmful putrefying
Gallionella. bacteria. In addition, these bacteria release
4 FeCO3 +6H2O+O2 → 4Fe (OH)3 vitamin-K and B12 , which are necessary for blood
+4CO2 +energy components.
(iii) Parasitic bacteria occur in the body of animals and 3. Sexual reproduction It takes place by genetic
plants, obtaining their organic food from there. recombination. There are three methods of genetic
Most of these bacteria are pathogenic, causing serious recombination in bacteria.
diseases in the host organisms either by exploiting them (i) Transformation Here, DNA released from one
or by releasing poisonous secretion called toxins which bacterial cell is taken up by another without any
are of two types, i.e. exotoxins and endotoxins. contact between donor and recipient bacterium.
Differences between Exotoxin and Endotoxin l
It was discovered by Griffith in 1928, when he was
working with the bacterium Diplococcus
Exotoxin Endotoxin pneumoniae or Pneumococcus pneumoniae, which
causes pneumonia.
Excreted by Gram Excreted by Gram negative
positive bacteria. bacteria.
l
In 1944, Avery, MacLeod and McCarty succeeded
in isolating and identifying the transforming factor
Also known as protein Also known as and found that it was DNA.
toxins. lipopolysaccharide toxins. l
This was the first direct evidence that DNA is the
Released to outside from Remain in cell wall and genetic material.
a living cell. released on death of cell. (ii) Conjugation In it, transfer of DNA involves direct cell
to cell contact and a conjugative plasmid in donor cell.
Strongly antigenic Poor antigenic
Conjugation was discovered by Lederberg and Tatum
Highly toxic Less toxic (1946) in E. coli.
l
Conjugation occurs between donor cell (F+) and
recipient cell (F− ). Donor cell is having sex pili and
Respiration in Bacteria F-factor, whereas recipient cell is lacking both.
Based on mode of respiration, bacteria may be l
It may involve either only the replication and
(i) Obligate aerobic bacteria They can perform only transfer of the F-plasmid (fertility factor or F-factor)
aerobic respiration, e.g. Bacillus subtilis. from donor (F+) to the recipient (F− ), thus making
the later also a donor or integration of F-plasmid
(ii) Obligate anaerobic bacteria They can perform only
with the chromosome of donor to form episome.
anaerobic respiration, e.g. Clostridium botulinum.
l
Term ‘episome’ is applied to extra-nuclear genetic
(iii) Facultative aerobes These are anaerobic bacteria, but
material, which may remain integrated or free state,
can live in the presence of oxygen, e.g. Chlorobium
e.g. F-factor, temperate phage, etc.
green sulphur bacteria.
l
All plasmids are episomes but all episomes are not
(iv) Facultative anaerobes These are aerobic bacteria, but
plasmids.
can live in the absence of oxygen also, e.g.
l
When F-factor is integrated with main genome or
Pseudomonas.
nuclear DNA, the frequency of recombination
NOTE Anaerobic bacteria do not evolve oxygen during increases by 1000 times. That is why, the donor cell
photosynthesis and they use H 2 S as a source of reducing is called Hfr-donor (High frequency donor) or high
power rather than water. This type of photosynthesis is frequency male.
called anoxygenic photosynthesis. (iii) Transduction Transfer of genetic material between
bacteria is mediated by viruses, e.g. bacteriophage. It
Reproduction in Bacteria was first of all reported in Salmonella typhimurium by
Reproduction in bacteria take place by following three types Zinder and Lederberg (1952). Transduction is of three
types
1. Vegetative reproduction It takes place by binary fission,
in which the bacterial DNA undergoes replication and (a) Generalised transduction, i.e. transducing
under favourable conditions the bacterial cell expands bacteriophage can transfer any gene of the donor
bacterium, e.g. T4 -bacteriophage.
and cytoplasm divides into two parts.
(b) Restricted (specialised) transduction, i.e.
2. Asexual reproduction It takes place by endospore
transducing bacteriophage can carry only a specific
formation.
region of the bacterial DNA to a recipient, e.g.
l
Bacterial population is counted by 2 n(n = number of λ-bacteriophage.
generation). For example, a bacterial cell after 5 (c) Abortive transduction, i.e. DNA fragment from
generations of fission will result into donor bacterium is not integrated in the genome of
2 5 = 2 × 2 × 2 × 2 × 2 = 32 bacterial cells. recipient bacterium and is lost after one or few
generations.
 8. Purple sulphur bacteria are photosynthetic, that use
Some Popular Bacteria energy of sunlight to reduce carbon dioxide to
Some popular bacteria are as follows carbohydrate.
1. Rickettsias are obligate intracellular parasites. This Unlike plants however, they do not use water as a
means that they can only grow and reproduce, within source of electrons. Instead, they use hydrogen sulphide
the living cells of their host including certain arthropods to supply the electrons needed to synthesise NADPH
(ticks, mites, lice and fleas) and mammals. and ATP.
l
Rickettsia prowazekii causes typhus fever, when it is 2H2S+CO2 → (CH2O)+ H2O+2S
transmitted to humans by lice. Rocky mountain l
In this process, they produce elemental sulphur
spotted fever is a rickettsial disease transmitted by
(e.g. Chromatium).
ticks.
l
Photosynthetic bacteria contain special types of
2. Nitrosomonas is a chemoautotroph, which oxidises NH3
chlorophylls called bacterio chlorophylls
(produced from proteins by decay bacteria) to nitrites
incorporated into membranes.
(NO2 ).
l
With this machinery, they can run photosystem-I but
l
This provides the energy to drive their anabolic
not photosystem-II (which explains their inability to
reactions.
use water as a source of electrons).
l
The nitrites are then converted (by other nitrifying
Most photosynthetic bacteria are obligate anaerobes.
bacteria) into nitrates (NO3 − ), which supply the
l

They cannot tolerate free oxygen. Thus, they are

nitrogen needs of plants.
restricted to such habitats as the surface of
3. Neisseria meningitis causes meningococcal meningitis, sediments, at the bottom of shallow ponds and
an extremely serious infection of the meninges that estuaries.
occasionally occurs in very young children and in
military camps. 9. Bacillus sp. organisms differ mainly in the plasmids
that they contain.
l
Neisseria gonorrhoeae causes gonorrhoea, one of the
most common Sexually Transmitted Diseases (STDs).
l
B. anthracis that causes anthrax possess two
plasmids that contain the genes needed to synthesise
4. Escherichia coli is most thoroughly-studied of all capsule, which (like those of Pneumococci) makes it
creatures (possibly excepting ourselves). resistant to phagocytosis and three components of the
5. Salmonella enterica includes two major human toxin, that cause the disease symptoms.
pathogens, they are as follows l
B. thuringiensis toxins and the gene
l
Salmonella enterica var. typhi causes typhoid fever, (also plasmid-encoded) for the toxin are used as
a serious systemic infection occurring only in biocontrol agents against a variety of insect pests.
humans. 10. Clostridium tetani are spore-forming obligate
l
Salmonella enterica var. typhimurium confined to anaerobes. The spores of C. tetani are widespread in the
the intestine, it is a frequent cause of human soil and often get into the body through the wounds.
gastrointestinal upsets but is also found in many l
Puncture wounds (e.g. by splinters or nails) are
other animals (that are often of the source of the particularly dangerous because they provide the
human infection). Also known as Salmonella anaerobic conditions needed for the germination of
typhimurium. spores and growth of bacteria.
6. Vibrio cholerae causes cholera, one of the most l
This interferes with the reciprocal inhibition of
devastating intestinal diseases. antagonistic pairs of skeletal muscles.
l
The bacteria liberate a toxin that causes massive So, the victim suffers from violent muscle spasms.
diarrhoea (10-15 L/day) and loss of salts. 11. Clostridium botulinum Its toxin if eaten with an
7. Yersinia pestis is a Bacillus that causes bubonic plague. uncooked bean or mushroom, can be fatal.
l
It is usually transmitted to human by the bite of an l
The toxin is a protein and is quickly (10 min)
infected flea. denatured at 100°C, so boiling home-canned products
l
As it spreads into the lymph nodes, it causes them to make them safe to eat.
become greatly swollen, hence the name ‘bubonic’ 12. Mycobacterium tuberculosis is the agent of
(bubo–swelling of a lymph node) plague. Tuberculosis (TB).
l
Once in the lungs, however, the bacteria can spread 13. Mycobacterium leprae causes leprosy.
through the air causing the rapidly lethal (2-3 days) l
M. leprae is an obligate intracellular parasite; it has
‘pneumonic’ plague. never been cultured in vitro.
 14. Corynebacterium diphtheriae causes diphtheria. Features Bacteria Cyanobacteria
l
As in tetanus, it is not the growth of the organism (in Accessory Absent Phycocyanin and
the throat), that is dangerous but the toxin it liberates. pigment phycoerythrin are present
l
The toxin is the product of a latent bacteriophage in in dominating form.
the bacterium. Hydrogen During Hydrogen donor is water,
l
The toxin has no such effect on the translation donor photosynthesis, oxygen is evolved. The
hydrogen donor is not process is oxygenic.
machinery of bacteria (or of chloroplasts and
water, as a result
mitochondria).
oxygen is not evolved.
l
Treatment of the toxin with formaldehyde converts it This photosynthesis is
into a harmless toxoid. anoxygenic.
15. Spirochaetes are thin, corkscrew-shaped, flexible Reserve Glycogen Cyanophycean starch.
organisms that range in length from a few to as many as food
500 µm. Two notorious examples are Spore Endogenous Spore formation is not
l
Treponema pallidum, the cause of syphilis, one of the formation endogenous.
most dangerous of the Sexually Transmitted Diseases
(STDs). 18. Mycoplasma are known as the smallest living
organisms. They are so small (0.1 µm) that they can be
l
Borrelia burgdorferi is transmitted to humans through seen only under the electron microscope. Mycoplasmas
the bit of a deer tick causing lyme disease. are obligate parasites.
16. Chlamydiae are also obligate intracellular parasites l
They can live within the cells of other organisms.
(they cannot make their own ATP). l
Mycoplasma Like Organisms (MLOs) or
l
Chlamydia trachomatis infection is usually spread by Pleuropneumonia Like Organisms (PPLOs) were
sexual intercourse making it the most common discovered by Nocard and Roux (1898) in pleural
Sexually Transmitted Disease (STD). fluid of cattle having bovine pleuropneumonia.
l
The eye infection is caused by a strain of l
These are unicellular, prokaryotic, non-motile,
C. trachomatis (and is responsible for its name). highly polymorphic and filterable through bacterial
l
Chlamydia psittaci infects birds, but can also infect filters.
their human contacts causing psittacosis (ornithosis). l
It is resistant to those antibiotics, which act on cell
17. Cyanobacteria (blue-green algae) have many characters walls like penicillin, due to the lack of cell wall.
similar to bacteria. l
Mycoplasmas are inhibited by those antibiotics,
l
They use water as the source of electrons to reduce which act on metabolic pathways such as
CO2 to carbohydrate (because they have tetracycline.
photosystem-II as well as photosystem-I). l
Mycoplasmas do not stain Gram positive because
CO2 +2H2O → CH2O+ H2O+O2
they lack cell walls. These are phylogenetically
l
Cyanobacteria also contain two antenna pigments, related to low GC Gram positive bacteria.
i.e. blue phycocyanin (making them ‘blue-green’) and l
Mycoplasma resemble protoplasts in that they lack
red phycoerythrin (the red sea gets its name from the
cell wall, but they are more resistant to osmotic
periodic blooms of red-coloured cyanobacteria).
lysis and are able to survive conditions, under
l
These two pigments also occur in red algae. which protoplast lyse due to the presence of
Common Differences between Bacteria and sterols. Some mycoplasma require sterols in their
Cyanobacteria (Blue-green Algae) growth media.
Features Bacteria Cyanobacteria l
DNA is linear but coiled. Mesosomes are absent.
Reproduction occurs by fission, elementary bodies
Size Comparatively smaller Comparatively larger
are reproductive units.
Flagella May be present Always absent l
The cells of mycoplasma divide unevenly into very
Nutrition Autotrophic or Usually autotrophic minute bodies (elementary bodies) of 330-450 nm in
heterotrophic size.
Photosynthe Bacteriochlorophyll Chlorophyll-a l
Mycoplasma causes little leaf disease in brinjal,
tic pigments and chlorobium yellow aster, greening stubborn and witches broom in
chlorophyll.
plants.
 (ii) Phylum–Chrysophyta This phyla includes diatoms
Kingdom–Protista and golden algae.
l
It includes all the unicellular eukaryotic organisms, e.g.
(a) Diatoms are the chief producers in the oceans.
flagellates, diatoms, dinoflagellates, slime moulds, sarcodins,
etc. l
Their cell wall is called frustule or shell which
contain silica and hence, it is indestructible.
l
The protists are regarded as ancestors of all multicellular
eukaryotic organisms. l
Their reserve food material is leucosin and oils.
l
Phylogenetically, the kingdom–Protista acts as a connecting l
They grow in size and form auxospores that
link between the prokaryotic kingdom–Monera on one hand develop into diploid diatom.
and the complex multicellular kingdoms of fungi, plants and (b) Golden Algae (Desmids) These are unicellular
animals on the other hand. green algae. Their cell walls have distinct halves.
Sexual reproduction occurs by ‘conjugation’
(similar to Spirogyra). They are usually found in
Classification of Protists freshwater and acts as an indicators of polluted
They are broadly divided into following three groups water.
(iii) Phylum–Euglenophyta Euglenoids live in fresh
Protista
aquatic habitats and damp soils.
l
They are unicellular flagellate protists.
Photosynthetic Fungi-like Animal-like l
Euglenoids have two flagella, usually one long and
protists protists protists
one short.
l
They perform creeping movements by expansion
and contraction of their body. This phenomenon
is called metaboly.
Myxomycota Acrasiomycota l
Reserve food is carbohydrate in the form of
(acellular slime (cellular slime
Phylum Phylum paramylon or paramylum bodies.
moulds) moulds)
Pyrophyta Chrysophyta l
Euglenoids reproduce by longitudinal binary
fission under favourable conditions. The palmella
Phylum stage is found during unfavourable conditions.
Euglenophyta
Phylum Phylum e.g. Euglena, Perenema, Eutreptia, Phacus, etc.
Mastigophora Ciliophora
Phylum
Sarcodina Phylum 2. Fungi-like Protists
Sporozoa These are unicellular, saprophytic organisms.
l
They lack cell wall and chlorophyll.
They move through pseudopodia and exhibit amoeboid
1. Photosynthetic Protists
l

movements.
These are phytoplanktons and their common habitats are lakes l
The somatic structure of Myxomycota are free-living,
and oceans. These protists can be further classified into the
diploid, multinucleate, mobile mass of protoplasm and
following phyla
their thalloid body is called Plasmodium, e.g. Physarum.
(i) Phylum–Pyrophyta (Dinoflagellates) These are unicellular, l
The somatic structure of Acrasiomycota is haploid,
golden-brown photosynthetic protists that are found in
uninucleate cell covered by plasma membrane. They do
both marine and freshwater habitat.
not possess flagellum, e.g. Polysphondylium.
l
Their cell wall is composed of plates made up of
cellulose and pectin. It is called theca or lorica and it
possess a transverse and a longitudinal groove. 3. Animal-like Protists or Protozoans
l
They possess two flagella (heterokontae condition).
l
These are unicellular or acellular eukaryotic animals that
exhibit heterotropic mode of nutrition.
l
Reserve food is starch in freshwater forms and oil in
marine forms.
l
On the basis of locomotory organelles and nuclear
apparatus, protozoans are divided into following phyla
l
They possess eye spot or stigma and trichocyst and
exhibit the phenomenon of bioluminescence. (i) Phylum–Mastigophora includes animal-like
flagellated protists, i.e. zoomastigophores or
l
They are responsible for red tides, e.g. Gonyaulax.
zooflagellates, e.g. Leishmania.
 (ii) Phylum–Sarcodina (or Rhizopoda) includes Types of Mycelium
amoeboid organisms without definite pellicle. Mostly
Type Definition Example
free-living, possess contractile vacuole, locomotion
by pseudopodia, e.g. Amoeba, Entamoeba (parasitic). Coenocytic Aseptate, multinucleate Oomycetes and
mycelium mycelium Zygomycetes
(iii) Phylum–Sporozoa includes organisms that lack
locomotory organs and contractile vacuole as they Primary mycelium Septate and uninucleate Ascomycetes
are endoparasites. Body is surrounded by thick
Secondary mycelium Dikaryotic mycelium Basidiomycetes
pellicle, reproduce by multiple fission or schizogony
(asexually) or spore formation (sexually), e.g.
Plasmodium. Reproduction in Fungi
(iv) Phylum–Ciliophora These are aquatic, actively l
At the reproductive stage, the entire cell protoplast
moving organisms because of the presence of (in unicellular lower fungi) is involved in zoospore
thousands of cilia, e.g. Paramecium, Opalina. formation. The coenocytic thallus is known as holocarpic,
e.g. Synchytrium.
NOTE Ciliates differ from all other protozoans in having two
types of nuclei, i.e. meganucleus and micronucleus.
l
When the mycelium is differentiated into distinct sterile and
fertile portion the thallus is eucarpic, e.g. Phytophthora.
Kingdom–Fungi l
When two types of strain (+ and –) are required for
l
It is a group of eukaryotic, achlorophyllous, performing sexual reproduction, the phenomenon is known as
non-photosynthetic, heterotrophic and thalloid heterothallism.
organisms. l
Blakeslee observed heterothallism in mucorales.
l
The study of fungi is called Mycology. PA Micheli is l
Reproduction in fungi takes place by following methods
known as Father of Mycology, whereas EJ Butler is (i) Asexual reproduction occurs with the help of various
known as Father of Indian Mycology. reproductive structures.
l
KC Mehta, an Indian scientist is famous for studying l
Zoospores are thin-walled, motile spores formed in a
rust disease in wheat. sporangium. Zoospores may be uniflagellates or
l
Fungal cell wall consists of fungal cellulose or chitin, a biflagellates. The flagella are always heterokont type.
polymer of N-acetyl glucosamine (except Oomycetes, l
Conidia or Conidiophores are spores borne on tips of
where cellulose occurs as the main component of cell hyphal structures called conidiophores.
wall). l
Chlamydospores are usually formed during
l
When the septa show a pore in the middle of the cross unfavourable conditions and are thick walled, single
wall, it is known as simple pore (observed in celled spores, which are highly resistant in adverse
Ascomycetes). They look like a large jar (the rim is conditions, e.g. Ustilago, Saprolegnia.
swollen barrel-shaped guarded by cap-like covers). l
Oidia are formed in some mycelial fungi.
l
In dolipore septum (observed in Basidiomycetes) the l
The thallus breaks into its component cells and each cell
cap is like a round bracket or parenthesome. The septal then round up into a structure called oidium (pl. oidia).
pore cap is called parenthesome.
(ii) Sexual reproduction in fungi involves plasmogamy,
l
Reserve food materials found in fungi are glycogen and oil. karyogamy and meiosis. As a result of sexual reproduction,
l
When a single nucleus is present in a cell, the fungal following types of sexual spores are produced
cell is known as monokaryon. When two nuclei are l
Ascospores are usually single celled, produce haploid
present in a cell the fungal cell is known as dikaryon. spores in a sac called an ascus, e.g. Ascomycetes.
l
Most fungi grow as tubular filaments called hyphae. An l
Basidiospores, i.e. haploid spores borne on special
interwoven mass of hyphae is called mycelium. structures called basidia.
l
When cross walls or septa are formed in the mycelium l
Zygospores, i.e. thick-walled diploid spores produced by
dividing it into segments, it is known as septate mycelium. the fusion of entire gametangia.
l
Pseudomycelium is a structure observed in yeast, where l
The site of meiosis in Oomycetes, Zygomycetes is
during budding process, buds are adhered with one zygospore/zygote/oospore, whereas ascus in
another and form a chain-like structure. Ascomycetes and basidium in Basidiomycetes.
 The Major Divisions of Fungi
Common Name Reproductive Cellular App. No. of
(Division) Economic and Health Impact Representative Genera
Structure Characteristics Living sp.
Zygote fungi Produce sexual diploid Cell walls contain Cause soft fruit rot and black Rhizopus (causes black 1050
(Zygomycota) zygospores. chitin; septa are bread mould. bread mould); Pilobolus
absent. (dung fungus).
Sac fungi Sexual spores formed in Cell walls contain Cause moulds on fruit; can Saccharomyces (yeast) : 32,000
(Ascomycota) sac-like ascus. chitin; septa are damage textiles; cause Dutch Ophiostoma (causes
present. elm disease and chestnut blight; Dutch elm disease).
include yeasts and morels. Neurospora
Club fungi Sexual reproduction Cell walls contain Cause smuts and rusts on crop; Amanita (poisonous 22,000
(Basidiomycota) involves production of chitin; septa are include some edible mushroom); Polyporus
haploid basidiospores present. mushrooms. (shelf fungus). Agaricus
on club-shaped basidia.
Imperfect fungi Not observed engaging Cell walls contain Cause athlete’s foot, ringworm, Penicillium (produces 17,000
(Deuteromycota) in sexual reproduction. chitin; septa are histoplasmosis; source of penicillin); Arthrobotrys
present. penicillin. (nematode predator),
Alternaria

Economic Importance of Fungi (v) Mushrooms are used as food for their flavour, protein
(i) Yeast (Saccharomyces cerevisiae) is one of the budding and vitamin contents. Edible part of mushrooms is
yeasts, which ferments sugar to ethanol and carbon basidiocarp, which has a fleshy stalk or stipe and
umbrella cap or pileus. Some edible mushrooms are
dioxide and thus used in
l
Agaricus campestris (common)
l
Making alcoholic beverages like beer and wine.
l
Agaricus bisporus (cultivated)
l
Baker’s yeast is used in baking and commercial
production of some vitamins and in the production of
l
Toadstool is a poisonous mushroom, e.g. Amanita
some human therapeutic proteins by using muscaria (fly mushroom).
recombinant DNA technology. l
Puff-balls are edible in young state,
l
Yeast is also used as Single Cell Protein (SCP). e.g. Lycoperdon, Clavatia.
l
Ashbya gossypii, a filamentous yeast is used in the
l
Stinkhorn produce stinking odour due to the spore
production of vitamin riboflavin. mass, which is attractive for flies, e.g. Phallus
impudicus (dead man’s finger).
(ii) Neurospora is a fungus which belongs to
class–Ascomycetes. It is an excellent research material
for the researchers in genetics, that is why, it is known as Lichens
Drosophila of plant kingdom.
l
These are composite organisms, which are formed by a
fungus mycobiont and an algal partner called photobiont
(iii) Penicillin is obtained from Penicillium notatum and
or phycobiont.
Penicillium chrysogenum.
l
This relation is called symbiosis or mutualism.
(iv) Mucor arrhizus is used for waste water treatment
because it removes heavy metal contamination of water.
l
They may grow on rocks, bark, wood, soil, marine or
freshwater.
l
Fermented foods are prepared from rice and soybean
with the help of Rhizopus and Mucor.
l
The various types of lichens are: crustose, foliose,
fruticose, leprose and filamentous.
l
Citric acid is obtained from molasses with the help of
Mucor.
l
Algal part prepares food for fungi and fungi provide shelter
and absorb mineral nutrients and water for its partner.
l
Fumaric acid is obtained from Rhizopus stolonifer.
l
Lichens can multiply by fragmentation, isidia and soredia.
l
Cortisone is obtained from Rhizopus stolonifer.
Sexual reproduction and asexual spores are formed only
l
Lactic acid is obtained from Rhizopus stolonifer and by the mycobiont.
Rhizopus nodosus. l
They are sensitive to sulphur dioxide and are hence, the
l
Alcohol is obtained from Rhizopus oryzae and Mucor indicator of air pollution. They do not grow in polluted
javanicus. areas.
l
Mycorrhiza is a mutualistic association between a fungus l
Interferon is a glycoprotein having non-specific antiviral
and the root of a higher plant, e.g. pine birch. Mycorrhizal activity produced by host cells after stimulation of
roots occur in superficial layers of soil. pathogenic viruses.
l
Mycorrhiza is of two types, i.e. ectomycorrhiza and l
The multiplication of bacteriophages may be of lytic type
endomycorrhiza. (in virulent phage) or lysogenic type (in temperate phages).
l
Mycorrhiza is an example of symbiosis or mutualism. The l
Virus that infect plants have single-stranded RNA and
fungus obtains shelter and food from root. viruses that infect animals have either single or
double-stranded RNA or double-stranded DNA.
l
It helps the root in absorption of water, dissolution and
absorption of inorganic nutrients locked in organic matter
l
Bacteriophages are usually double-stranded DNA viruses.
(especially nitrogen and phosphorus) and protection from l
Viruses cause disease like mumps, smallpox, herpes,
other fungi. influenza, AIDS, etc., in human.
l
In plants, it causes mosaic formation, leaf rolling and
Viruses curling, yellowing and vein clearing, dwarfing and stunted
l
They did not find a place in classification, since they are growth.
not truely ‘living’. Differences Between Lytic and
l
They are non-cellular organisms that have inert crystalline Lysogenic Phases of Viruses
structure outside the living cell. Character Lytic Phase Lysogenic Phase
l
Once they infect a cell, they take over the machinery of the Integration of Viral genome does not Viral genome gets
host cell to replicate themselves, killing the host. DNA integrate with host integrated with host
l
The name virus was given by DJ Ivanowsky (1892). He DNA. DNA to form prophage
or provirus.
recognised certain microbes as causal organism of the
mosaic disease of tobacco. Hydrolysis of Occurs Does not occur.
host DNA
l
WM Stanley (1935) showed that viruses could be
Replication Prophage replicates Viral genome
crystallised.
once along with replicates many times
l
Viruses are ultramicroscopic, obligatory and intracellular replication of host to form many copies
parasites. Structure of a virus consists of core, capsid and genome to transfer a in same host cell.
envelope. single particle to
daughter cell.
l
Capsid is the outer most protective covering made up of
units called capsomeres.
l
Some highly specialised viruses show an outer covering
Viroids
called envelope. l
These are new infectious agents discovered by TO Diener
l
Virion is a complete virus particle composed of nucleic (1971). They are smaller than viruses and causes potato
acid and surrounded by protein coat. It contains either spindle tuber disease. They are formed of be free RNA,
DNA or RNA as nucleic acid. these lack protein coat that is found in viruses, hence name
as viroid.
l
The nucleic acid is present in the central core.
l
Virusoids discovered by JW Randels and associates are
l
A group of viruses with RNA genome that carry the enzyme small circular RNA, always associated with larger viral
reverse transcriptase and form a DNA copy of their genome RNA and may form part of viral genome.
is called retrovirus.
Phycophages are viruses parasite on algae, whereas
Prions
l

mycophages are parasites on fungi.

Prions discovered by Stanley B Prusiner are infectious
l
Once enter into host genome, the virus’s genetic material is
proteinaceous particles without having nucleic acids. These
copied along with host genetic material.
are formed due to the misfolding of protein particles. They
l
When viral DNA is incorporated into the host chromosome cause a number of diseases like-scrapie in sheep, bovine
as a latent form, this is called provirus in plant and animal spongiform encephalopathy (or mad cow disease),
virus but prophage in bacterial virus. Creutzfeldt-Jacob disease in man, etc.
DAY ONE THE LIVING WORLD 17

DAY PRACTICE SESSION 1

FOUNDATION QUESTIONS EXERCISE

1 In general, growth involves 10 What is the name of the book written by Aristotle?
(a) cell proliferation (a) Systema Naturae (b) Historia Naturae
(b) cell enlargement and secretion of extracellular matrix (c) Historia Animalium (d) Philosophie Zoologique
(c) Both (a) and (b)
11 Species Plantarum was written by
(d) None of the above
(a) Julian Huxley (b) John Ray
2 Growth in living things occur due to synthesis of (c) Carolus Linnaeus (d) Charles Darwin
(a) protoplasmic substances (b) cytoplasmic substances
12 Phenetic classification of organisms is based on
(c) apoplasmic substances (d) Both (a) and (c)
(a) observable characteristics of existing organisms
3 Biological organisation starts with (b) the ancestral lineage of existing organism
(a) submicroscopic molecular level (c) dendrogram based on DNA characteristics
(b) cellular level (d) sexual characteristics
(c) organismic level
13 Type of specimen described along with holotype is
(d) atomic level
(a) isotype (b) paratype
4 Homeostatic mechanisms operate at which level of (c) topotype (d) syntype
hierarchy?
14 Nomenclature is governed by certain universal rules.
(a) Cell level (b) Population level
Which one of the following is contrary to the rules of
(c) Ecosystem level (d) All of these
nomenclature? j
NEET-I 2016
5 Read the statements with respect to homeostasis and (a) The first word in a biological name represents the genus
choose the incorrect statement. name and the second is a specific epithet
(a) It is the process of maintenance of a constant internal (b) The names are written in Latin and are Italicised
environment (c) When written by hand, the names are to be underlined
(b) The term ‘Homeostasis’ was coined by Cannon for the (d) Biological names can be written in any language
first time
(c) Organisms adapt to changes in temperature, salinity, etc. 15 The term ‘Neo systematics’ was introduced by
(d) Most fishes, amphibians, reptiles, plants are (a) Linnaeus (b) John Ray
homeotherms (c) Julian Huxley (d) Georges Cuvier

6 Metabolic reactions can be demonstrated outside the 16 Taxonomy based on number of shared characteristics of
body in cell free systems. An isolated metabolic reaction various organisms is called
outside the body of an organism, performed in a test (a) chemotaxonomy (b) numerical taxonomy
tube is (c) biochemical taxonomy (d) experimental taxonomy
(a) living thing 17 As we go from species to kingdom in a taxonomic
(b) non-living thing hierarchy, the number of common characteristics
(c) Neither living nor non-living thing but a living reaction (a) will decrease
(d) None of the above (b) will increase
7 Reason for diversity in living being is (c) remain same
(d) may increase or decrease
(a) varying environmental conditions
(b) long term evolutionary changes 18 The term ‘Systematics’ refers to
(c) short term evolutionary changes (a) identification and classification of plants and animals
(d) gradual internal changes (b) nomenclature and identification of plants and animals
8 Who proposed phylogenetic system of classification? (c) diversity of kinds of organisms and their relationship
(d) different kinds or organisms and their classification
(a) George Bentham (b) JD Hooker
(c) Engler and Prantl (d) Carolus Linnaeus 19 Genus represents
9 System of classification used by Linnaeus was (a) an individual plant or animal
(b) a collection of plants or animals
(a) natural system (b) artificial system
(c) a group of closely related species of plants or animals
(c) phylogenetic system (d) asexual system
(d) None of the above
20 Which of the following ‘Suffixes’ used for units of 29 Taxonomic key is one of the taxonomic tools in the
classification in plants indicates a taxonomic category of identification and classification of plants and animals. It
‘family’? is used in the preparation of
(a) Ales (b) Onae (a) Monographs (b) Flora
(c) Aceae (d) Ae (c) Both (a) and (b) (d) None of these
21 The taxonomic unit ‘Phylum’ in the classification of 30 Manuals contain information for
animals is equivalent to which hierarchical level in (a) habitat and distribution of animals of a given area
classification of plants? (b) habitat and distribution of all the plants on earth
(a) Class (b) Order (c) identification of names of species found in an area
(c) Division (d) Family (d) habitat and distribution of some useful animals of a
22 The correct sequence of taxa is given area
(a) Class—Order—Family—Tribe—Genus— Species 31 All monerans
(b) Class—Order—Tribe—Family—Genus— Species (a) contain DNA and RNA
(c) Phylum—Order—Class—Tribe—Genus— Species (b) demonstrate a long circular strand of DNA, not found
(d) Phylum—Tribe—Class—Order—Genus— Species enclosed in a nuclear membrane
23 A species inhabiting different geographical areas is (c) are bacteria
known as (d) All of the above
(a) allopatric 32 Which of the followings are found in extreme saline
(b) sympatric conditions? j NEET 2017
(c) biospecies (a) Archaebacteria (b) Eubacteria
(d) sibling species (c) Cyanobacteria (d) Mycobacteria
24 Two plants can be conclusively said to belong to the 33 Thermococcus, Methanococcus and Methanobacterium
same species if they exemplify
(a) can reproduce freely with each other and form seeds (a) archaebacteria that contain protein homologous to
(b) have more than 90% similar genes eukaryotic core histones
(c) look similar and possess identical secondary
(b) archaebacteria that lack any histones resembling those
metabolites
found in eukaryotes, but whose DNA is negatively
(d) have same number of chromosomes
supercoiled
25 What is a keystone species? (c) bacteria whose DNA is relaxed or positively supercoiled
(a) A species, which makes up for only a small proportion but which have a cytoskeleton as well as mitochondria
of the total biomass of a community, yet has a huge (d) bacteria that contain a cytoskeleton and ribosomes
impact on the community’s organisation and survival 34 Archaebacteria differ from eubacteria in
(b) A common species that has plenty of biomass, yet has j
CBSE AIPMT 2014
a fairly low impact on the community’s organisation (a) cell membrane structure (b) mode of nutrition
(c) A rare species that has minimal impact on the biomass (c) cell shape (d) mode of reproduction
and on other species in the community 35 The primitive prokaryotes responsible for the production
(d) A dominant species that constitutes a large proportion of biogas from the dung of ruminant animals, include the
of the biomass and which affect many other species j
NEET-I 2016
26 The label of a herbarium sheet does not carry an (a) thermoacidophiles (b) methanogens
information on j
NEET-II 2016 (c) eubacteria (d) halophiles
(a) date of collection (b) name of collector 36 Some hyperthermophilic organisms that grow in highly
(c) local names (d) height of the plant acidic habitats belong to the two groups called
27 The largest collection of herbarium in India is (a) eubacteria and archaea
(a) Central National Herbarium, Kolkata (b) cyanobacteria and diatoms
(b) Southern Circle Herbarium, Coimbatore (c) protists and mosses
(c) Central Circle Herbarium, Allahabad (d) liverworts and yeasts
(d) Blatter Herbarium, Mumbai 37 Which one of the following statements is incorrect?
28 Botanical gardens and zoological parks have
j
NEET-I 2016
(a) collection of endemic living species only (a) Golden algae are also called desmids
(b) collection of exotic living species only (b) Eubacteria are also called false bacteria
(c) collection of endemic and exotic living species (c) Phycomycetes are also called algal fungi
(d) collection of only local plants and animals (d) Cyanobacteria are also called blue-green algae
38 In eubacteria, a cellular component that resembles 49 In mycoplasma (PPLO), the plasmalemma is rich in
eukaryotic cells is j CBSE AIPMT 2011 (a) cholesterol (b) glycogen
(a) nucleus (b) ribosomes (c) cellulose (d) myosin
(c) cell wall (d) plasma membrane
50 Mycoplasma differ from viruses in that they are sensitive
39 The structures that help some bacteria to attach to rocks to
and/or host tissues are j CBSE AIPMT 2015 (a) penicillin (b) tetracyclines
(a) rhizoids (b) fimbriae (c) sugars (d) amino acids
(c) mesosomes (d) holdfast
51 Outer limiting layer of mycoplasma is
40 Bacteria are (were) considered more as plants than (a) slime layer (b) mucilage layer
animals because of the presence of (c) cell wall (d) cell membrane
(a) small nucleus (b) plasma membrane
52 Which one of the following statements about
(c) cell wall (d) spore formation
mycoplasma is incorrect?
41 Bacterial flagella do not show ATPase activity and 9 + 2 (a) They are also called PPLO
organisation. These are chemically (b) They are pleomorphic
(a) flagellin (b) pilin (c) They are sensitive to penicillin
(c) tubulin (d) bacterin (d) They cause disease in plants
42 Which one of the following statements regarding cilia is 53 Pigment-containing membranous extensions in some
not correct? cyanobacteria are j CBSE AIPMT 2012

(a) The organised beating of cilia is controlled by fluxes of (a) heterocysts (b) basal bodies
Ca 2+ across the membrane (c) pneumatophores (d) chromatophores
(b) Cilia are hair-like cellular appendages 54 Which among the following are the smallest living cells,
(c) Microtubules of cilia are composed of tubulin known without a definite cell wall, pathogenic to plants as
(d) Cilia contain an outer ring of nine doublet microtubules well as animals and can survive without oxygen?
surrounding two single microtubules j
NEET 2017
43 When a bacteriophage in its lytic phase, carries some of (a) Bacillus (b) Pseudomonas
the bacterium’s partially digested chromosome with it to (c) Mycoplasma (d) Nostoc
another host cell, the process is called 55 Chrysophytes, euglenoids, dinoflagellates and slime
(a) transformation (b) general transduction moulds are included in the kingdom j
NEET-I 2016
(c) restricted transduction (d) conjugation (a) Protista (b) Fungi
44 The cyanobacteria are also referred to as (c) Animalia (d) Monera
CBSE AIPMT 2012
j
56 In which group of organisms the cell walls form two thin
(a) protists (b) golden algae overlapping shells which fit together? j
CBSE AIPMT 2015
(c) slime moulds (d) blue-green algae (a) Chrysophytes (b) Euglenoids
45 Oxygen is not produced during photosynthesis by (c) Dinoflagellates (d) Slime moulds
j
NEET 2018 57 Slime moulds in the division–Myxomycota (true slime
(a) Cycas (b) Nostoc moulds) have
(c) Green-sulphur bacteria (d) Chara (a) pseudoplasmodia
46 The fertility or F + factor that plays a role in conjugation (b) spores that develop into free-living amoeboid cells
is a (c) spores that develop into flagellated gametes
(a) retrovirus (b) plasmid (d) feeding stages consisting of solitary individual cells
(c) viroid (d) lysogenic phage 58 What is common about Trypanosoma, Noctiluca,
47 Which statement is correct for the bacterial transduction? Monocystis and Giardia?
(a) transfer of some genes from one bacteria to another (a) These are all unicellular protists
bacteria through virus (b) They have flagella
(c) They produce spores
(b) transfer of genes from one bacteria to another bacteria
by conjugation (d) These are all parasites
(c) bacteria obtained its DNA directly 59 Which of the following organisms are known as chief
(d) bacteria obtained DNA from other external source producers in the oceans?
48 The cells of cyanobacteria and bacteria exhibit similarity (a) Cyanobacteria
in having (b) Diatoms
(c) Dinoflagellates
(a) plastids (b) nuclei
(d) Euglenoids
(c) centrosome (d) naked DNA
60 Which of the following unicellular organisms has a 71 After karyogamy followed by meiosis, spores are produced
macronucleus for trophic function and one or more exogenously in NEET 2018
j

mirconuclei for reproduction? (a) Agaricus (b) Alternaria

(a) Euglena (b) Amoeba (c) Neurospora (d) Saccharomyces
(c) Paramecium (d) Trypanosoma
72 Choose the incorrect statement. j CBSE-AIPMT 2015
61 Which of the following is a dinoflagellate responsible for (a) Penicillium is multicellular and produces antibiotics
red tides? (b) Neurospora is used in the study of biochemical genetics
(a) Anabaena (b) Gonyaulax (c) Morels and truffles are poisonous mushrooms
(c) Mycoplasma (d) Archaebacteria (d) Yeast is unicellular and useful in fermentation
62 Ciliates differ from all other protozoans in 73 Which one of the following is incorrect for fungi?
(a) using pseudopodia for capturing prey j NEET-II 2016

(b) having contractile vacuole for removing excess water

(a) They are eukaryotic
(c) using flagella for locomotion
(b) All fungi possess a purely cellulosic cell wall
(d) having two types of nuclei
(c) They are heterotrophic
63 Which of the following is not correctly matched? (d) They are both unicellular and multicellular
(a) Amoeboid protozoan — Amoeba
74 Virus envelope is known as j CBSE-AIPMT 2010
(b) Flagellated protozoan — Trypanosoma
(c) Sporozoan — Anopheles (a) capsid (b) virion
(d) Ciliated protozoan — Paramecium (c) nucleoprotein (d) core

64 Select the incorrect statement. 75 Viruses that infect bacteria multiply and cause their lysis,
are called
(a) Pseudopodia are locomotory and feeding structures in
sporozoans (a) lysozymes (b) lipolytic
(c) lytic (d) lysogenic
(b) Mushrooms belong to Basidiomycetes
(c) Cell wall is present in members of Fungi and Plantae 76 A naked RNA particle causing the symptoms like that of
(d) Mitochondria are the powerhouse of the cell in all a viral disease is known as
kingdoms except Monera (a) viroid (b) virion
65 The slime moulds and multicellular algae are presently (c) viral (d) None of these
included in the Kingdom–Protista because 77 Which one of the following statements is incorrect for
(a) they appear to be more closely related to unicellular viroids? j
NEET-I 2016
eukaryotes (a) They are smaller than viruses
(b) they lack important characteristics of the fungi and plants (b) They cause infections
(c) kingdom–Protista includes eukaryotic organisms that do (c) Their RNA is of high molecular weight
not clearly belong in the other three kingdoms (d) They lack a protein coat
(d) All of the above 78 Viroids differ from viruses in having j
NEET 2017
66 The highest number of species in the world is (a) DNA molecules with protein coat
represented by j
CBSE-AIPMT 2012 (b) DNA molecules without protein coat
(a) fungi (b) mosses (c) RNA molecules with protein coat
(c) algae (d) lichens (d) RNA molecules without protein coat

67 The imperfect fungi which are decomposers of litter and 79 Which statement is incorrect for viruses?
help in mineral cycling belong to j
CBSE-AIPMT 2015 j
CBSE-AIPMT 2012
(a) Deuteromycetes (b) Basidiomycetes (a) All are parasites
(c) Phycomycetes (d) Ascomycetes (b) All of them have helical symmetry
68 In most of the fungi, the food material is stored in the form of (c) They have ability to synthesise nucleic acids and
(a) starch (b) glucose proteins
(c) sucrose (d) glycogen (d) Antibiotics have no effect on them

69 One of the major components of cell wall of most fungi is 80 Which of the following is not correct about viruses?
j
NEET-I 2016 (a) In addition to proteins, viruses also contain genetic
(a) peptidoglycan (b) cellulose material that could be either DNA or RNA
(c) hemicellulose (d) chitin (b) No virus contains both RNA and DNA
(c) A virus is a nucleoprotein and genetic material is
70 Which of the following would appear as the pioneer
infectious
organisms on bare rocks? j
NEET-II 2016
(d) The protein coat called capsid is made up of small
(a) Liverworts (b) Mosses
subunits called viroids
(c) Green algae (d) Lichens
81 The correct statement is A B C D
(a) generally viruses that infect plants have single-stranded RNA (a) 2 5 4 1
(b) generally viruses that infect animals have either single or (b) 3 2 1 4
double-stranded RNA or double-stranded DNA (c) 1 4 3 2
(c) bacteriophages are double-stranded DNA viruses (d) 3 4 1 2
(d) All of the above 85 Match the following columns.
82 Select incorrect statement. CBSE-AIPMT 2015
j
Column I Column II
(a) The viroids were discovered by DJ lvanowski
A. Dinoflagellate 1. Dictyostelium
(b) WM Stanley showed that viruses could be crystallised
(c) The term ‘Contagium vivum fluidum’ was coined by B. Plasmodium 2. Noctiluca
MW Beijerinck
C. Myxomycota 3. Slime mould
(d) Mosaic disease in tobacco and AIDS in human being are
caused by viruses D. Acrasiomycota 4. Fuligo
83 Study the four statements (I-IV) given below and select the
Codes
two correct ones out of them j NEET-II 2016
A B C D
I. Definition of biological species was given by Ernst Mayr. (a) 3 2 1 4
II. Photoperiod does not affect reproduction in plants. (b) 1 4 3 2
III. Binomial nomenclature system was given by (c) 2 3 4 1
RH Whittaker. (d) 4 3 1 2
IV. In unicellular organisms, reproduction is synonymous Directions (Q. Nos. 86 and 88) In each of the
with growth. following questions a statement of Assertion is given
The two correct statements are followed by the corresponding statements of Reason. Of
(a) II and III (b) III and IV (c) I and IV (d) I and II the statements, mark the correct answer as
(a) If both Assertion and Reason are true and Reason
84 Match the items given in column I with those in column II and
is the correct explanation of Assertion
select the correct option given below. j
NEET 2018
(b) If both Assertion and Reason are true, but Reason
Column I Column II is not the correct explanation of Assertion
(c) If Assertion is true, but Reason is false
A. Herbarium 1. It is a place having a collection of (d) If both Assertion and Reason are false
preserved plants and animals.
86 Assertion Carolus Linnaeus was a Swedish
B. Key 2. A list that enumerates methodically naturalist.
all the species founds in an area Reason Linnaeus is called Father of Taxonomy.
with brief discription aiding
identification. 87 Assertion Cytotaxonomy involves the cytological
information for classification purpose.
C. Museum 3. It is a place where dried and pressed
plant specimens mounted on sheets Reason Chemotaxonomy is based on the
are kept. chemical constituents of plants.
D. Catalogue 4. A booklet containing a list of characters 88 Assertion Macronucleus in Paramecium is
and their alternates which are helpful in polyploid.
identification of various taxa.
Reason Micronucleus in Paramecium is diploid.
22 40 DAYS ~ NEET BIOLOGY DAY ONE

DAY PRACTICE SESSION 2

PROGRESSIVE QUESTIONS EXERCISE

1 Binomial nomenclature is described in the book 12 Golden brown protists belong to
(a) Genera Plantarum (b) Historia Plantarum (a) Chrysophytes (b) Euglenoids
(c) Systema Naturae (d) Flora Japonica (c) Dinoflagellates (d) Diatoms
2 Tribe is an independent category between sub-family and 13 In Mangifera indica L., generic epithet is
(a) family (b) genus (c) class (d) subclass (a) indica (b) Mangifera
3 Clinical death is characterised by stoppage of (c) Linnaeus (d) None of these
(a) breathing (b) pulse
14 ICBN stands for
(c) heartbeat (d) All of these
(a) Indian Congress of Biological Names
4 In the five-kingdom classification Chlamydomonas and (b) International Code of Botanical Nomenclature
Chlorella have been included in (c) International Congress of Biological Names
(a) Protista (b) Algae (d) Indian Code of Botanical Nomenclature
(c) Plantae (d) Monera
15 The type of spores found in Ustilago are
5 Taxon is the
(a) oidia (b) conidia
(a) taxonomic group of any rank (c) zoospores (d) chlamydospores
(b) procedure to assign a scientific name
16 The site of respiration in bacteria is
(c) process of classification
(a) episome (b) mesosome (c) ribosome (d) microsome
(d) process by which any thing is grouped into convenient
categories based on characteristics 17 Protists obtain food as
6 Binomial nomenclature means (a) photosynthesisers, symbionts and holotrophs
(b) photosynthesisers
(a) one name given by two scientists
(c) chemosynthesisers
(b) two names, one scientific, other local
(d) holotrophs
(c) two names, one Latinised, other of a person
(d) one scientific name consisting of a generic and a 18 Genophore bacterial genome or nucleoid is made up of
specific epithet (a) histones and non-histones
7 Most abundant organic compound on earth is (b) RNA and histones
(c) a double-stranded DNA
(a) protein (b) cellulose
(d) a single-stranded DNA
(c) lipids (d) steroids
19 Protists having transverse and longitudinal groove in their
8 How many organisms in the list given below are
theca are
autotrophs?
Lactobacillus, Nostoc, Chara, Nitrosomonas, Nitrobacter, (a) foraminiferans (b) radiolarians
(c) diatoms (d) dinoflagellates
Streptomyces, Saccharomyces, Trypanosoma, Porphyra,
Wolffia 20 The word species was coined by
(a) Four (b) Five (a) Aristotle (b) Linnaeus
(c) Six (d) Three (c) John Ray (d) Engler
9 Which of the following is a slime mould? 21 Chromosomes in a bacterial cell can be 1-3 in number
(a) Rhizopus (b) Physarum (a) can be circular as well as linear within the same cell
(c) Thiobacillus (d) Anabaena (b) are always circular
(c) are always linear
10 The thalloid body of a slime mould (Myxomycetes) is known
as (d) can be either circular, but never both within the same cell
(a) Plasmodium (b) fruiting body 22 Which of the following viral structures are not completely
(c) mycelium (d) protonema coded by the virus’ own nucleic acids?
11 Which of the following is not the locomotory organ of (a) Capsid
Protozoa? (b) Glycoprotein gp 120 of HIV
(c) Viral envelope
(a) Cilia (b) Flagella
(d) Tail sheath of T 4 bacteriophage
(c) Parapodia (d) Pseudopodia
23 Auxospores and hormocysts are formed, respectively by 32 About 98% of the mass of every living organism is
(a) several diatoms and a few cyanobacteria composed of just six elements including carbon,
(b) several cyanobacteria and several diatoms hydrogen, nitrogen, oxygen,
(c) some diatoms and several cyanobacteria (a) phosphorus and sulphur
(d) some cyanobacteria and many diatoms (b) sulphur and magnesium
24 Five kingdom system of classification suggested by (c) magnesium and sodium
RH Whittaker is not based on (d) calcium and phosphorus
(a) presence or absence of a well- defined nucleus 33 Which one of the following statements is not a correct
(b) mode of reproduction statement?
(c) mode of nutrition (a) Herbarium houses dried, pressed and preserved plant
(d) complexity of body organisation specimens
25 Which of the following is not the main criteria for five (b) Botanical gardens have collection of living plants for
kingdom system of classification? reference
(a) Cell structure and thallus organisation (c) A museum has gardens collection of photographs of
(b) Mode of nutrition and reproduction plants and animals
(c) Phylogenetic relationship (d) Key is a taxonomic aid for identification of specimens
(d) Gram staining
34 Neo sytematics aims at
26 Which of the following is not true for a species? (a) the classification of organism based on broad
(a) Members of a species can interbreed morphological characters
(b) Variations occur among members of a species (b) delimiting various taxa of organisms and establishing
(c) Each species is reproductively isolated from every other their relationship
species (c) the classification of organisms based on their
(d) Gene flow does not occur between the populations of a evolutionary history and establishing their phylogeny on
species the totality of various parameters from all fields of
studies
27 Most of the lichens consist of
(d) Identification and arrangement of organisms on the
(a) blue-green algae and Basidiomycetes
basis of their cytological characteristics
(b) blue-green algae and Ascomycetes
(c) red algae and Ascomycetes 35 Which one of the following statements about bacteria is
(d) brown algae and Phycomycetes true?
28 Macro and micronucleus are the characteristic features of (a) Bacteria possess 80S ribosomes, introns and RNA
(a) Paramecium and Vorticella processing
(b) Opalina and Nyctotherus (b) Bacteria possess 70S ribosomes, introns and no RNA
(c) Hydra and Ballantidium processing
(d) Vorticella and Nyctotherus (c) Bacteria possess 70S ribosomes, no introns and no
RNA processing
29 Protistan genome has
(d) Bacteria possess 80S ribosomes, RNA processing and
(a) membrane bound nucleoproteins embedded in
no introns
cytoplasm
(b) free nucleic acid aggregates 36 Match the following columns.
(c) gene containing nucleoproteins condensed together in Column I Column II
loose mass
A. Numerical taxonomy 1. Nuclear and
(d) nucleoprotein in direct contact with cell substance chromosomal studies
30 A gene transfer occurred between two strains of bacteria. It B. Classical taxonomy 2. Number of shared
was observed that cell-cell contact is not required and a characters
filter that removes viruses eliminates transfer. This would C. Practical taxonomy 3. Utility of organism
mean that the transfer occurred by
D. Karyotaxonomy 4. α- taxonomy
(a) conjugation (b) transformation
(c) transposition (d) transduction Codes
31 Which one of the following is not true about lichens? A B C D
(a) Their body is composed of both algal and fungal cells (a) 2 4 3 1
(b) 1 3 2 4
(b) Some form food for reindeers in Arctic regions
(c) 4 2 3 1
(c) Some species can be used as pollution indicators
(d) These grow very fast at the rate of about 2 cm per year (d) 1 2 4 3
37 Match the following columns. Codes
A B C D A B C D
Column I Column II
(a) 2 3 4 1 (b) 4 2 3 1
A. Philosophie Zoologique 1. Carolus Linnaeus (c) 1 3 2 4 (d) 3 2 4 1
B. Historia Plantarum 2. Lamarck
Directions (Q. Nos. 39-40) In each of the following
C. Systema Naturae 3. Theophrastus questions a statement of Assertion is given followed by a
D. Genera Plantarum 4. Bentham and Hooker corresponding statement of Reason just below it. Of the
statements, mark the correct answer as
Codes
(a) If both Assertion and Reason are true and Reason is the
A B C D
correct explanation of Assertion
(a) 3 2 4 1 (b) If both Assertion and Reason are true, but Reason is not
(b) 2 3 1 4 the correct explanation of Assertion
(c) 1 2 3 4 (c) If Assertion is true, but Reason is false
(d) 4 3 2 1 (d) If both Assertion and Reason are false
38 Match the following columns. 39. Assertion Bentham and Hooker’s system of
Column I Column II
classification is based on more number of characters
and natural affinities.
A. Protozoan 1. Gonyaulax Reason Bentham and Hooker’s system of classification
B. Bacillariophyceae 2. Diatoms
is a phylogenetic system.

C. Euglenoid 3. Paramecium 40. Assertion Scientific names are printed in Italics.

Reason The name of author is written in abbreviated
D. Dinoflagellates 4. Euglena form after the specific epithet and is printed in Roman.

ANSWERS
1 (c) 2 (d) 3 (a) 4 (d) 5 (d) 6 (c) 7 (b) 8 (c) 9 (b) 10 (c)
SESSION 1
11 (c) 12 (a) 13 (b) 14 (d) 15 (c) 16 (b) 17 (a) 18 (c) 19 (c) 20 (c)
21 (c) 22 (a) 23 (a) 24 (a) 25 (a) 26 (d) 27 (a) 28 (c) 29 (c) 30 (c)
31 (d) 32 (a) 33 (a) 34 (a) 35 (b) 36 (a) 37 (b) 38 (d) 39 (b) 40 (c)
41 (a) 42 (a) 43 (b) 44 (d) 45 (c) 46 (b) 47 (a) 48 (d) 49 (a) 50 (b)
51 (d) 52 (c) 53 (d) 54 (c) 55 (a) 56 (a) 57 (c) 58 (a) 59 (b) 60 (c)
61 (b) 62 (d) 63 (c) 64 (a) 65 (d) 66 (a) 67 (a) 68 (d) 69 (d) 70 (d)
71 (a) 72 (c) 73 (b) 74 (a) 75 (c) 76 (a) 77 (c) 78 (d) 79 (b) 80 (d)
81 (d) 82 (a) 83 (c) 84 (d) 85 (c) 86 (b) 87 (b) 88 (b)

1 (c) 2 (b) 3 (d) 4 (c) 5 (a) 6 (d) 7 (b) 8 (c) 9 (b) 10 (a)
SESSION 2
11 (c) 12 (c) 13 (b) 14 (b) 15 (d) 16 (b) 17 (a) 18 (c) 19 (d) 20 (c)
21 (b) 22 (c) 23 (a) 24 (c) 25 (d) 26 (d) 27 (b) 28 (a) 29 (a) 30 (d)
31 (d) 32 (a) 33 (c) 34 (c) 35 (c) 36 (a) 37 (b) 38 (d) 39 (c) 40 (b)