XI CH-2
Systematics of
Living Organisms
2)Kingdom Protista
3) Kingdom Plantae
4) Kingdom Fungi
5)Kingdom Animalia
Salient features of Five
Kingdoms
1)Kingdom Monera :
1)It
contains unicellular organisms with prokaryotic cellular organization. .
2)Monera
includes unicellular prokaryotic organisms. .
3)These
are omnipresent. .
3)They
are found in all types of environment which are not generally inhabited by
other living beings.
4)
Few are photoautotrophs or chemoautotrophs; but majority are heterotrophic in
nature. .
5)These
organisms do not have well defined nucleus. .
6)DNA
exists as a simple double stranded circular single chromosome called as
nucleoid.
7)Smaller
circular molecules of DNA as extra- chromosomal genetic elements called
plasmids are often present. .
8)Cell
wall is made up of peptidoglycan (also called murein) which is a polymer of
sugars and amino acids.
9)Membrane
bound organelles e.g.mitochondria,chloroplast,endoplasmic reticulum are absent.
.
10)Ribosomes
are smaller in size (70S) than in eukaryotic cells. .
11)The
mode of reproduction in monera is asexual or with the help of binary fission or
budding. .
12)Very
rarely, sexual reproduction is by conjugation method. .
13)Morphologicaly,bacteria
are categorised into four groups, the spherical- Coccus, the rod-shaped bacillus,
the comma or kidney shaped- vibrio and
the spiral- spirillum.
14)On
the basis of evolution, bacteria can be classified as Archaebacteria and Eubacteria.
a)Archebacteria
:
1)These
are differentiated from other bacteria on the basis of their different cellular
features. .
2)These bacteria
are mostly found in the extreme environments; hence
termed extremophiles. .
3)They
are found in a
variety of places from volcanic craters to salty lakes and hot springs.
.
4)Their
ability to withstand such hostile environment speaks of their
capacity to survive in very severe conditions.
5)Bacteria
that can withstand high salinities are called halophiles while those that withstand extreme temperature are
known as thermophiles. ..
6)A
very common example is of methanogenic bacteria found in gut of ruminants (cows
and buffaloes).
7)These
bacteria help in production of methane in biogas plants.
b)Eubacteria
:
1)These
are commonly called true bacteria.
2)They
have cell wall of Peptidoglycan .
3)They
are found as autotrophs and heterotrophs.
4)The
autotrophs can be photosynthetic like Chlorobium (Green sulphur
bacteria) and Chromatium or chemosynthetic like sulphur bacteria.
5)These
are mostly multicellular filamentous.
6)They
are living in fresh water.
6)The
body is covered by mucilagenous
sheath.
7)The
genetic material is typical prokaryotic.
8)The
photosynthetic pigments are Chl-a,
Chl-b, carotenes and xanthothylls
9)Filaments
show heterocyst helps in nitrogen
fixation. 10)Heterotrophs are the most abundant.
11)Most
of them are decomposers and
known for breaking down large
molecules in simple molecules or minerals.
12)Eg.
some anaerobes helping in curdling of milk (Lactobacilli), fixation of nitrogen (Az otobacter),
antibiotic production. (Streptomyces),
composting and degrading oil.
13)
Some of them are pathogens i.e. causing disease (typhoid, cholera,
tuberculosis, tetanus).
These
are smallest of the living forms.
They
do not have cell wall.
Many
forms are pathogenic.
They
are found resistant to common. antibiotics due to absence of cell wall.
2) Kingdom Protista :
They
are all the unicellular but eukaryotic organisms. These organisms show link with all eukaryotic Kingdoms like Plantae,
Fungi and Animalia.
a)Plant
like protista :
1)They
are also termed Chrysophytes. .
2)They
are commonly termed phyto-planktons.
3)They
are microscopic and mostly photosynthetic and are major producers in oceans.
4)Most
of them are referred to as diatoms as
the have body wall made up of two soap-box like fitting silica covers. .
5)“Diatomaceous
earth" is nothing but these shells left behind for so many years.
6)Diatomaceous
earth is granular hence finds use in polishing and filtration.
b)Animal
like Protista :-
1)They
are also termed protozoans.
2)They
lack cell wall.
3)They
are heterotrophsThey are believed to be primitive animal forms.
4)
Amoeboid protozoans have pseudopodia as locomotory organs Amoeba is free living
form but Entamoeba is endoparasite and causes amoebic dysentery.
5)Flagellated
protozoans have flagella as locomotory organ.
6)Trypanosoma
is a common flagellated pathogen which causes sleeping sickness.
7)Paramoecium
is a cilliate protozoan having cilia for locomotion.
8)In
Paramoecium, gullet (cavity) opens on the cellsurface.
9)Plasmodium
is a sporozoan protozoa.
10)It
causes malaria. It forms spores in one of its life stage.
c)Dinoflagellates
:-
1)These
are aquatic (mostly marine) .
2)These
are photosynthetic.
3)The cell
wall is made up of cellulosic stiff plates.
4)They
possess a pair of flagella.
5)They
have a wide range photosynthetic pigments, are yellow, green, brown, blue and
red.
6)
It makes even sea appear red ,Gonyaulax is dinoflagellate that is
responsible for famous ‘red tide’.
d)Fungi
like protista :-
1)They
are commonly from the group Myxomycetes.
2)These
are saprophytic organisms found on decaying leaves.
3)Their
cellsaggregate to form a large cell mass called plasmodium (not a malaria
parasite).
4)The
spores produced by plasmodium are very tough and survive even very harsh
conditions
e)Euglenoids
:-
They
lack cell wall but have a tough covering of proteinaceous pellicle.
They
are two flagella, one short and other long. They behave as heterotrophs in absence of light but possess pigments,
similar to that of higher plants, for photosynthesis.
3) Kingdom Plantae:
1)The
kingdom is dominated by autotrophs.
2)It
also includes some semi- autotrophic members, the insectivorous plants like
Venus fly trap, pitcher plant, bladderwort .
3)The
are heterotrophic parasitic members like Cuscuta.
4)The
are multicellular, having eukaryotic cells containing chlorophyll.
5)Cells
have cell wall mostly made up of cellulose.
6)Plants
exhibit alternation of generation i.e., life cycle has two distinct phases.
7)Kingdom
Plantae is divided into two major groups Cryptogamae / Cryptogams
and Phanerogamae / Phanerogams.
4) Kingdom Fungi :
.
1)These are eukaryotic heterotrophs showing extracellular digestion.
.
2)They
are found in warm and humid places. .
3)They
have simple body which may be unicellular or made up of long thread like
structures called hyphae. .
4)
Mushrooms is Large fungi have a compact mass
of cells. .
5)
They are Unicellular organisms have a
protoplast with many
nuclei. e.g. Rhizopus, Saccharomyces (Yeast-unicellular
fungus).
6)Filamentous
fungi consist of a body called mycellium in which hyphae are present. .
7)The
hyphae may be uni or multinucleate. .
8)The
non-septate multinucleate hyphae are called coenocytic hyphae. .
9)The
cell is composed of chitin, a
polysaccharide or fungal cellulose. .
10)The
fungi are hetrotrophic ,saprophytic, some are parasitic or
predators. .
11)They
reproduce sexually as well as asexually.
12)Asexual
reproduction takes place by fragmentation, fission and budding. .
12)Some are symbiotic; live with algae as lichens or as mycorrhiza
in association with roots of higher plants.
13)
Useful
fungi -Mushrooms
are consumed as food, yeast is used in bakery and breweries. Penicillium, a fungus, is
well known for antibiotic production. .
14)Harmful fungi cause diseases in plants and animals. e.g. Puccinia.
classification of fungi - on the basis of theirstructure, mode of spore formation and fruiting bodies as follows-
a)Phycomycetes .
•
i)These are commonly called algal fungi. .
•
Ii)Mycelium is made up of aseptate
coenocytic hyphae.
•
iii)They commonly grow in moist and damp habitats, on decaying
organic matter. .
•
iv)These are aquatic
habitats or as parasites on plants.
•
v)e.g. Mucor, Rhiz opus (bread mould), Albugo (parasitic
fungus on mustard).
b)Ascomycetes
:
•
i)These are called as sac-fungi. .
•
ii)These fungi are mostly multicellular. .
•
iii)Rarely unicellular varieties include yeast. .
•
iv)The hyphae are branched and septate. .
•
v)Sac fungi can be decomposers, parasites or coprophilous (grow on
dung). .
•
vi)Morels and truffles are varieties of sac fungi that are consumed as delicacies.
.
•
vii)useful in genetic and biochemical assays eg.Neurospora .
•
viii)Ex.Aspergillus,Penicillium, Claviceps, Neurospora, Saccharomyces.
c)Basidiomycetes :These are commonly called club fungi. They have branched, septate hyphae. e.g. Agaricus (mushrooms), Ganoderma (bracket fungi),U stilago (smuts), Puccinia (rusts), etc.
d)Deuteromycetes
:
•
These are called imperfect fungi, which are known to reproduce
only asexually.
• e.g. Alternaria, Colletotrichum
5)Kingdom
Animalia :
•
i) Animalia are heterotrophs.
•
ii)Adapted to holozoic nutrition.
•
iii)Most of them have capacity of locomotion.
•
iv)They are multicellular eukaryotes where cells lack chlorophyll
as well as cell wall.
•
v)Growth is determinate with
definite pattern.
Acellular organisms :
1)Viruses :
•
i)Louis Pasteur named Viruses so by considering
the meaning, Venom or poison. .
•
ii)These given the name
'virus' by M. J. Beijernek, .
•
iii)When observation that they were able to migrate in an agar
gel.
•
iv)infectious soluble agent, he called the filtrate as 'contagium
vivum fluidum'.
•
v)It was scientist Stanley who demonstrated that viruses are inert
outside the host cell and can be
crystallised.
• vi)They are made up of proteins.
• ix)They have protein coat (capsid) around nucleic acid strand,
thus considered to be acellular organisms
• x)Viruses lack their own cell machinery. Viruses are inactive outside a host cell; but once they enter their specific host cell, they take charge of cellular machinery of host cell and duplicate themselves.
xi)Viruses thus
can be called infectious nucleoprotein particles.
Types of viruses :
i)Viruses
have either DNA or RNA as their genetic material but never DNA as well as RNA.
ii)As
per genetic material, viruses are grouped as DNA or RNA viruses.
iii) Protein coat called capsid is made up of smaller units, the capsomeres.
iv)Capsomeres are arranged in polyhedral or helical forms.
v)Capsid protects genetic material.
vi)The genetic material in viruses is either single-stranded RNA or
single or double- stranded RNA or double-stranded DNA.
vii)
Bacterial Viruses that infect
bacterial cells are called bacteriophages which normally have double stranded
DNA
vii)
Plants Viruses cause disorders
like leaf curling, yellowing, mosaic formation etc, in plants.
vii)
Animals
Viruses You have heard of
foot and mouth disease in animals . .
vii)
Humans Viruses. swine flu, Small
pox, mumps, herpes to common cold, AIDS, viruses are the causative agents of
many diseases in humans.
2)Viroids :
These infectious RNA strands are called viroids
Potato
spindle tuber disease was found to be caused by single stranded RNA which lacks
protein coat.
T.
O. Diener in 1971 reported that this is low molecular weight RNA and smaller in
size than viruses.
3)Lichens :
i)Lichen is symbiotic
combination of algae and fungi for mutual benefit. .
ii)Algal member, is called phycobiont a, mostly belongs to cyanobacteria
(blue-green algae) or green algae. .
iii)Fungal member is called mycobiont.
.
iv)The
algal component of lichens provides food to fungal part while fungus provides
shelter to alga and also absorbed water and minerals to alga. .
v)The
association is intense and it is difficult to identify them as separate living
beings.
vii)Though
found in extreme environments like snow clad
poles, lichens are
sensitive to pollution. .
vii)They
are not found in polluted regions, hence are considered as pollution
indicators. .
viii)Lichens also
play important role in soil formation by using specific acid
productions.
