Diversity in living organism - Class Notes, Classs 9 , Biology, CBSE - Class 9 PDF Download

 Page 1


CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 1 
 
  
CLASSIFICATION: - Classification of organisms may be defined as a system of 
arrangement of organisms into different groups and sub-groups on the basis of their 
similarities, differences and relationship. 
Classification of organisms is also known as taxonomy. It has the following 
advantages. 
1. Classification makes the study of a wide variety of organisms convenient and 
easy. 
2. It is not possible for man to know about all the organisms but the study of a 
few representatives from each taxonomic group gives a general idea of all life 
forms at a glance. 
3. Classification also reveals the interrelationship among different gr4oups of 
organisms. 
4. Correct identification of an organism and its placement in a definite taxonomic 
group is the basic requirement of various branches of biological sciences.  
Thus, classification of organisms provides a base for the development of other 
biological sciences.  
BASIS OF CLASSIFICATION:- 
Classification can be done on the following basis. 
1. Cells are prokaryotic or eukaryotic. Organisms may be grouped into two 
broad categories on the basis whether they possess prokaryotic cells or 
eukaryotic cells. In case of prokaryotic cells the nuclei and other organelles 
are not clearly demarcated. The eukaryotic cells, on the other hand, have 
membrane-bound organelles, including a nucleus. 
2. Cells occur singly or in clusters. Many organisms are unicellular, i.e. made 
up of only one cell, e.g. Amoeba. Others are multicellular, i.e., cells group 
together to form single organism (e.g., insect). In case of multicellular 
organisms the different groups of cells carry out specialized functions 
3. Organism is photosynthetic or takes food from outside. Green plants 
perform photosynthesis an synthesis their own food. Animals cannot perform 
photosynthesis. They get food from outside.  
4. Organization of different body parts. Grouping of organisms may be done 
on the basis of body organization. For example, plants possess stem, root and 
leaves. Similarly, the animals possess specialized organs to perform different 
function. The characteristic based on body design used for classification of 
plants is quite different when used for classifying animals. 
Systems of classification:-  
 R H whittaker in 1969, suggested five kingdom classification on the basis ofr 
(i) preence or absence of a nucleus (ii) unicells or multicells and (iii) mode of 
nutrition. 
 He proposed five kingdoms: 
1. Monera, 2. Protista, 3.  Fungi, 4.  Plantae and 5.  Animalia. 
Monera: - these organisms do not have a defined nucleus or organelles, nor do any 
of them show multi-cellullar body designs. They show diversity based on many other 
characteristics. Some of organisms of this group are either autotrophic or 
heterotrophic. This group includes bacteria, blue-green algae or cynobacteria and 
mycoplasma. 
Protista:- This group includes many kinds of unicellular eukaryotic organisms. 
Some of these organisms use cilia or flagella for moving around. Their mode of 
nutrition can be autotrophic or heterotrophic. Examples are unicellular algae, 
diatoms and protozoans. 
Page 2


CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 1 
 
  
CLASSIFICATION: - Classification of organisms may be defined as a system of 
arrangement of organisms into different groups and sub-groups on the basis of their 
similarities, differences and relationship. 
Classification of organisms is also known as taxonomy. It has the following 
advantages. 
1. Classification makes the study of a wide variety of organisms convenient and 
easy. 
2. It is not possible for man to know about all the organisms but the study of a 
few representatives from each taxonomic group gives a general idea of all life 
forms at a glance. 
3. Classification also reveals the interrelationship among different gr4oups of 
organisms. 
4. Correct identification of an organism and its placement in a definite taxonomic 
group is the basic requirement of various branches of biological sciences.  
Thus, classification of organisms provides a base for the development of other 
biological sciences.  
BASIS OF CLASSIFICATION:- 
Classification can be done on the following basis. 
1. Cells are prokaryotic or eukaryotic. Organisms may be grouped into two 
broad categories on the basis whether they possess prokaryotic cells or 
eukaryotic cells. In case of prokaryotic cells the nuclei and other organelles 
are not clearly demarcated. The eukaryotic cells, on the other hand, have 
membrane-bound organelles, including a nucleus. 
2. Cells occur singly or in clusters. Many organisms are unicellular, i.e. made 
up of only one cell, e.g. Amoeba. Others are multicellular, i.e., cells group 
together to form single organism (e.g., insect). In case of multicellular 
organisms the different groups of cells carry out specialized functions 
3. Organism is photosynthetic or takes food from outside. Green plants 
perform photosynthesis an synthesis their own food. Animals cannot perform 
photosynthesis. They get food from outside.  
4. Organization of different body parts. Grouping of organisms may be done 
on the basis of body organization. For example, plants possess stem, root and 
leaves. Similarly, the animals possess specialized organs to perform different 
function. The characteristic based on body design used for classification of 
plants is quite different when used for classifying animals. 
Systems of classification:-  
 R H whittaker in 1969, suggested five kingdom classification on the basis ofr 
(i) preence or absence of a nucleus (ii) unicells or multicells and (iii) mode of 
nutrition. 
 He proposed five kingdoms: 
1. Monera, 2. Protista, 3.  Fungi, 4.  Plantae and 5.  Animalia. 
Monera: - these organisms do not have a defined nucleus or organelles, nor do any 
of them show multi-cellullar body designs. They show diversity based on many other 
characteristics. Some of organisms of this group are either autotrophic or 
heterotrophic. This group includes bacteria, blue-green algae or cynobacteria and 
mycoplasma. 
Protista:- This group includes many kinds of unicellular eukaryotic organisms. 
Some of these organisms use cilia or flagella for moving around. Their mode of 
nutrition can be autotrophic or heterotrophic. Examples are unicellular algae, 
diatoms and protozoans. 
CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 2 
 
  
Fungi:- these are heterotrophic eukaryotic organisms. They are saprophytes and 
thrive on decaying organic material. They have cell-walls made of chitin. Examples 
are yeast and mushrooms. 
Plantae:- these are multi-cellular  eukaryotes with cell walls. They are autotrophs 
and used chlorophyll for photosynthesis. All plants are included in this group. 
Animalia:- these includes all multi-cellular organisms. They are heterotrophs. 
NOMENCLATURE:- 
Naming a correct scientific name to an organism or a taxon is called nomenclature. 
It involves the principals governed by set rules formulated by internationals bodies 
so that a particular organism or taxon is known by its specific name throughout the 
world. 
BINOMIAL NOMENCLATURE:- 
According to the binomial system of nomenclature, the scientific name of an 
organism consist of two separate components – first on designates the genus 
(generic name) and the second one designates the species (specific name). For 
example, the scientific binomial name of human species is Homo sapiens, where first 
name Homo is generic and the second name sapiens is a specific. Homo sapiens are 
understood to mean humans all over the world. Since this system of naming 
organisms gives two names to an organism, it is known as a binomial 
nomenclature.  
Various ranks used in classification (Hierarchy of classification). 
In classification, the organisms that closely resemble one another are placed in a 
group. These groups are further placed in large groups on the basis of close 
similarities. The larger groups are again placed in still larger grouping levels or 
ranks in classification are known as categories. Each category has its specific name. 
There are seven major categories: 
1. Species   2. Genus  3. Family  4. Order 
5. Class    6. Phylum (for animals)/division (for plants) 7. 
Kingdom. 
1. Species. Species is the lowest category regarded as basic unit classification. It 
is a group of similar individuals which resembles with each other in 
morphology, breed among themselves but not with others and probably 
descended from a common ancestor. 
2. Genus. A genus is a group of closely resembling species having a common 
ancestry. A;; the species in a genus show similarities in broad features of their 
organization but differ in minor details. 
3. Family. A family represents a larger group of closely related genera. It is 
composed of one or more genera. 
4. Oder. An order is a group of closely related families. 
5. Class. A class is a group of related orders. 
6. Phylum/Division. Phylum (in case of animals) or Division (in case of plants) is 
a group of related classes. 
7. Kingdom. Kingdom is the highest category in biological classification. It is 
group of phyla (in case of animals) or divisions (in case of plants). 
Mainly, the following rules apply to scientific names: 
They were initially framed by Linnzeus. And were revised in 9
th
 and 20
th
 century 
through international code of Botinical Nomenclature (ICBN) and international code 
of Zoological nomenclature (ICZN). They are as followes: 
 
 
Page 3


CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 1 
 
  
CLASSIFICATION: - Classification of organisms may be defined as a system of 
arrangement of organisms into different groups and sub-groups on the basis of their 
similarities, differences and relationship. 
Classification of organisms is also known as taxonomy. It has the following 
advantages. 
1. Classification makes the study of a wide variety of organisms convenient and 
easy. 
2. It is not possible for man to know about all the organisms but the study of a 
few representatives from each taxonomic group gives a general idea of all life 
forms at a glance. 
3. Classification also reveals the interrelationship among different gr4oups of 
organisms. 
4. Correct identification of an organism and its placement in a definite taxonomic 
group is the basic requirement of various branches of biological sciences.  
Thus, classification of organisms provides a base for the development of other 
biological sciences.  
BASIS OF CLASSIFICATION:- 
Classification can be done on the following basis. 
1. Cells are prokaryotic or eukaryotic. Organisms may be grouped into two 
broad categories on the basis whether they possess prokaryotic cells or 
eukaryotic cells. In case of prokaryotic cells the nuclei and other organelles 
are not clearly demarcated. The eukaryotic cells, on the other hand, have 
membrane-bound organelles, including a nucleus. 
2. Cells occur singly or in clusters. Many organisms are unicellular, i.e. made 
up of only one cell, e.g. Amoeba. Others are multicellular, i.e., cells group 
together to form single organism (e.g., insect). In case of multicellular 
organisms the different groups of cells carry out specialized functions 
3. Organism is photosynthetic or takes food from outside. Green plants 
perform photosynthesis an synthesis their own food. Animals cannot perform 
photosynthesis. They get food from outside.  
4. Organization of different body parts. Grouping of organisms may be done 
on the basis of body organization. For example, plants possess stem, root and 
leaves. Similarly, the animals possess specialized organs to perform different 
function. The characteristic based on body design used for classification of 
plants is quite different when used for classifying animals. 
Systems of classification:-  
 R H whittaker in 1969, suggested five kingdom classification on the basis ofr 
(i) preence or absence of a nucleus (ii) unicells or multicells and (iii) mode of 
nutrition. 
 He proposed five kingdoms: 
1. Monera, 2. Protista, 3.  Fungi, 4.  Plantae and 5.  Animalia. 
Monera: - these organisms do not have a defined nucleus or organelles, nor do any 
of them show multi-cellullar body designs. They show diversity based on many other 
characteristics. Some of organisms of this group are either autotrophic or 
heterotrophic. This group includes bacteria, blue-green algae or cynobacteria and 
mycoplasma. 
Protista:- This group includes many kinds of unicellular eukaryotic organisms. 
Some of these organisms use cilia or flagella for moving around. Their mode of 
nutrition can be autotrophic or heterotrophic. Examples are unicellular algae, 
diatoms and protozoans. 
CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 2 
 
  
Fungi:- these are heterotrophic eukaryotic organisms. They are saprophytes and 
thrive on decaying organic material. They have cell-walls made of chitin. Examples 
are yeast and mushrooms. 
Plantae:- these are multi-cellular  eukaryotes with cell walls. They are autotrophs 
and used chlorophyll for photosynthesis. All plants are included in this group. 
Animalia:- these includes all multi-cellular organisms. They are heterotrophs. 
NOMENCLATURE:- 
Naming a correct scientific name to an organism or a taxon is called nomenclature. 
It involves the principals governed by set rules formulated by internationals bodies 
so that a particular organism or taxon is known by its specific name throughout the 
world. 
BINOMIAL NOMENCLATURE:- 
According to the binomial system of nomenclature, the scientific name of an 
organism consist of two separate components – first on designates the genus 
(generic name) and the second one designates the species (specific name). For 
example, the scientific binomial name of human species is Homo sapiens, where first 
name Homo is generic and the second name sapiens is a specific. Homo sapiens are 
understood to mean humans all over the world. Since this system of naming 
organisms gives two names to an organism, it is known as a binomial 
nomenclature.  
Various ranks used in classification (Hierarchy of classification). 
In classification, the organisms that closely resemble one another are placed in a 
group. These groups are further placed in large groups on the basis of close 
similarities. The larger groups are again placed in still larger grouping levels or 
ranks in classification are known as categories. Each category has its specific name. 
There are seven major categories: 
1. Species   2. Genus  3. Family  4. Order 
5. Class    6. Phylum (for animals)/division (for plants) 7. 
Kingdom. 
1. Species. Species is the lowest category regarded as basic unit classification. It 
is a group of similar individuals which resembles with each other in 
morphology, breed among themselves but not with others and probably 
descended from a common ancestor. 
2. Genus. A genus is a group of closely resembling species having a common 
ancestry. A;; the species in a genus show similarities in broad features of their 
organization but differ in minor details. 
3. Family. A family represents a larger group of closely related genera. It is 
composed of one or more genera. 
4. Oder. An order is a group of closely related families. 
5. Class. A class is a group of related orders. 
6. Phylum/Division. Phylum (in case of animals) or Division (in case of plants) is 
a group of related classes. 
7. Kingdom. Kingdom is the highest category in biological classification. It is 
group of phyla (in case of animals) or divisions (in case of plants). 
Mainly, the following rules apply to scientific names: 
They were initially framed by Linnzeus. And were revised in 9
th
 and 20
th
 century 
through international code of Botinical Nomenclature (ICBN) and international code 
of Zoological nomenclature (ICZN). They are as followes: 
 
 
CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 3 
 
  
1. Each organisms has a distinct scientific name having a words, generic and 
scientific. 
2. The generic and specific words should not have less then three letters or more 
than 12(twelve) letters. 
3. The generic name is written first. It is like a noun . Is first letter is  always 
capital. 
4. The specific word is written after the generic name, It starts with small letter. 
5. The name of the discoverer is appended to the two-word scientific name either 
In full or abbreviate form e.g., mangifera indic . L(L stands  for Linnaeus). 
6. Scientific name is printed in italics hand written name is underlined. 
7. When an organism has been given different scientific names by different 
workers the “law of priority” is followed that is old valid name is accepted and 
others rejected.   
KINGDOM PLANTAE:- 
Characteristics features of kingdom plantae. 
i) They are made of eukaryotic cells. 
ii) They are multicellular. 
iii) The cells have wall made of cellulose. 
iv) They store carbohydrates such as starch. 
v) Some cells (except in some parasites) contain chloroplast. 
vi) The organisms feed by photosynthesis. 
                        PLANT KINGDOM 
 
 
 
 
 
 
 
 
 
 
 
 
 
According to the classification proposed by eicher, plant kingdom is divided in to two 
subkingdoms i.e crypotogamae and phanerogamae. 

 CRYTOGAMAE:- These are known as lower plants. The flower/seed are 
absent and hence these are considered to have hidden reproductive organs. It 
is categorized into 3 divisions. 
 
1).THALLOPHYTA:- Thallophytes have a body which is not differentiated into stem, 
root and leaves. This kind of undifferentiated body is called thallus, hence the name 
thallophytes. 
It has the following characteristics. 
(1) The plant body is thalloid i.e., cannot be differentiated into stem, root and 
leaves. 
(2) The vascular system is absent in such plants. 
(3) The reproductive organs are single called and there is no embryo formation. 
 
 
Crypotogama Phanerogama
Thalloph Bryophy
Pteridoph Gymnosper Angiosper
Fungi Algae Monoco Dicot Lichens 
Page 4


CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 1 
 
  
CLASSIFICATION: - Classification of organisms may be defined as a system of 
arrangement of organisms into different groups and sub-groups on the basis of their 
similarities, differences and relationship. 
Classification of organisms is also known as taxonomy. It has the following 
advantages. 
1. Classification makes the study of a wide variety of organisms convenient and 
easy. 
2. It is not possible for man to know about all the organisms but the study of a 
few representatives from each taxonomic group gives a general idea of all life 
forms at a glance. 
3. Classification also reveals the interrelationship among different gr4oups of 
organisms. 
4. Correct identification of an organism and its placement in a definite taxonomic 
group is the basic requirement of various branches of biological sciences.  
Thus, classification of organisms provides a base for the development of other 
biological sciences.  
BASIS OF CLASSIFICATION:- 
Classification can be done on the following basis. 
1. Cells are prokaryotic or eukaryotic. Organisms may be grouped into two 
broad categories on the basis whether they possess prokaryotic cells or 
eukaryotic cells. In case of prokaryotic cells the nuclei and other organelles 
are not clearly demarcated. The eukaryotic cells, on the other hand, have 
membrane-bound organelles, including a nucleus. 
2. Cells occur singly or in clusters. Many organisms are unicellular, i.e. made 
up of only one cell, e.g. Amoeba. Others are multicellular, i.e., cells group 
together to form single organism (e.g., insect). In case of multicellular 
organisms the different groups of cells carry out specialized functions 
3. Organism is photosynthetic or takes food from outside. Green plants 
perform photosynthesis an synthesis their own food. Animals cannot perform 
photosynthesis. They get food from outside.  
4. Organization of different body parts. Grouping of organisms may be done 
on the basis of body organization. For example, plants possess stem, root and 
leaves. Similarly, the animals possess specialized organs to perform different 
function. The characteristic based on body design used for classification of 
plants is quite different when used for classifying animals. 
Systems of classification:-  
 R H whittaker in 1969, suggested five kingdom classification on the basis ofr 
(i) preence or absence of a nucleus (ii) unicells or multicells and (iii) mode of 
nutrition. 
 He proposed five kingdoms: 
1. Monera, 2. Protista, 3.  Fungi, 4.  Plantae and 5.  Animalia. 
Monera: - these organisms do not have a defined nucleus or organelles, nor do any 
of them show multi-cellullar body designs. They show diversity based on many other 
characteristics. Some of organisms of this group are either autotrophic or 
heterotrophic. This group includes bacteria, blue-green algae or cynobacteria and 
mycoplasma. 
Protista:- This group includes many kinds of unicellular eukaryotic organisms. 
Some of these organisms use cilia or flagella for moving around. Their mode of 
nutrition can be autotrophic or heterotrophic. Examples are unicellular algae, 
diatoms and protozoans. 
CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 2 
 
  
Fungi:- these are heterotrophic eukaryotic organisms. They are saprophytes and 
thrive on decaying organic material. They have cell-walls made of chitin. Examples 
are yeast and mushrooms. 
Plantae:- these are multi-cellular  eukaryotes with cell walls. They are autotrophs 
and used chlorophyll for photosynthesis. All plants are included in this group. 
Animalia:- these includes all multi-cellular organisms. They are heterotrophs. 
NOMENCLATURE:- 
Naming a correct scientific name to an organism or a taxon is called nomenclature. 
It involves the principals governed by set rules formulated by internationals bodies 
so that a particular organism or taxon is known by its specific name throughout the 
world. 
BINOMIAL NOMENCLATURE:- 
According to the binomial system of nomenclature, the scientific name of an 
organism consist of two separate components – first on designates the genus 
(generic name) and the second one designates the species (specific name). For 
example, the scientific binomial name of human species is Homo sapiens, where first 
name Homo is generic and the second name sapiens is a specific. Homo sapiens are 
understood to mean humans all over the world. Since this system of naming 
organisms gives two names to an organism, it is known as a binomial 
nomenclature.  
Various ranks used in classification (Hierarchy of classification). 
In classification, the organisms that closely resemble one another are placed in a 
group. These groups are further placed in large groups on the basis of close 
similarities. The larger groups are again placed in still larger grouping levels or 
ranks in classification are known as categories. Each category has its specific name. 
There are seven major categories: 
1. Species   2. Genus  3. Family  4. Order 
5. Class    6. Phylum (for animals)/division (for plants) 7. 
Kingdom. 
1. Species. Species is the lowest category regarded as basic unit classification. It 
is a group of similar individuals which resembles with each other in 
morphology, breed among themselves but not with others and probably 
descended from a common ancestor. 
2. Genus. A genus is a group of closely resembling species having a common 
ancestry. A;; the species in a genus show similarities in broad features of their 
organization but differ in minor details. 
3. Family. A family represents a larger group of closely related genera. It is 
composed of one or more genera. 
4. Oder. An order is a group of closely related families. 
5. Class. A class is a group of related orders. 
6. Phylum/Division. Phylum (in case of animals) or Division (in case of plants) is 
a group of related classes. 
7. Kingdom. Kingdom is the highest category in biological classification. It is 
group of phyla (in case of animals) or divisions (in case of plants). 
Mainly, the following rules apply to scientific names: 
They were initially framed by Linnzeus. And were revised in 9
th
 and 20
th
 century 
through international code of Botinical Nomenclature (ICBN) and international code 
of Zoological nomenclature (ICZN). They are as followes: 
 
 
CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 3 
 
  
1. Each organisms has a distinct scientific name having a words, generic and 
scientific. 
2. The generic and specific words should not have less then three letters or more 
than 12(twelve) letters. 
3. The generic name is written first. It is like a noun . Is first letter is  always 
capital. 
4. The specific word is written after the generic name, It starts with small letter. 
5. The name of the discoverer is appended to the two-word scientific name either 
In full or abbreviate form e.g., mangifera indic . L(L stands  for Linnaeus). 
6. Scientific name is printed in italics hand written name is underlined. 
7. When an organism has been given different scientific names by different 
workers the “law of priority” is followed that is old valid name is accepted and 
others rejected.   
KINGDOM PLANTAE:- 
Characteristics features of kingdom plantae. 
i) They are made of eukaryotic cells. 
ii) They are multicellular. 
iii) The cells have wall made of cellulose. 
iv) They store carbohydrates such as starch. 
v) Some cells (except in some parasites) contain chloroplast. 
vi) The organisms feed by photosynthesis. 
                        PLANT KINGDOM 
 
 
 
 
 
 
 
 
 
 
 
 
 
According to the classification proposed by eicher, plant kingdom is divided in to two 
subkingdoms i.e crypotogamae and phanerogamae. 

 CRYTOGAMAE:- These are known as lower plants. The flower/seed are 
absent and hence these are considered to have hidden reproductive organs. It 
is categorized into 3 divisions. 
 
1).THALLOPHYTA:- Thallophytes have a body which is not differentiated into stem, 
root and leaves. This kind of undifferentiated body is called thallus, hence the name 
thallophytes. 
It has the following characteristics. 
(1) The plant body is thalloid i.e., cannot be differentiated into stem, root and 
leaves. 
(2) The vascular system is absent in such plants. 
(3) The reproductive organs are single called and there is no embryo formation. 
 
 
Crypotogama Phanerogama
Thalloph Bryophy
Pteridoph Gymnosper Angiosper
Fungi Algae Monoco Dicot Lichens 
CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 4 
 
  
Thallophyta is further subdivided into: 
(A) Algae 
(B) Fungi 
(C) Lichens 
(A) ALGAE : They generally include aquatic plants. Some 20,000species of algae 
are known. The main characteristics are as under : 
1. They are generally chorophyllous thallophytes in which vascular tissues are 
absent. 
2. The plant body is thalloid i.e., cannot be differentiated into root, stem and 
leaves. 
3. They are found in fresh water resources as well as in sea water. 
4. They are autotrophic because of the presence of chlorophyll in leaves. The 
reserve food is generally a carbohydrate. 
5. The cell wall is double layered. The outer layer is made of pectin and inner 
layer is made cellulose. 
6. They may be unicellular as well as multicellular. 
7. A few members such as chlamydomonas are motile. 
8. They reproduce by vegetative, asexual as well as sexual methods. The sex 
organs are unicelled and lack a sterile covering around them. 
Example : oedogonium, Chara, Sargassum, Ectocarpus, Chlamydomonas, Ulothrix 
etc. 
(B) FUNGI :  it is a large group of over 90,000 species. They show the following 
characteristics : 
1. They are achlorophyllous and nonvascular plants. 
2. The plant body may be unicelled or vthalloid, made of branched or 
unbranched filamentous structures, the hyphae. 
3. The network of hypae is called mycelium. 
4. The hyphae may be aseptate or sepate and each cell may be uni-or 
multinucleale. 
5. The cell wall is made of chitin or fungal cellulose.  
6. They show heterotrophic mode of nutrition. 
7. The reserved food is in the form of glycogen and oil globules. 
8. They reproduce by asexual or sexual methods. 
9. The sex organs are unicelled and lack a sterile covering around them. The 
higher forms lack distinct sex organs. 
Example : Rhizopus, Yeast, Agaricus (Mushroom) etc. 
(C) LICHENS : They represent a symbiotic association of a fungus and a alga in 
which two organisms are so closely associated with each other as to form a single 
plant. They are show growing long lived plants. The commonly grow on leaves, tree 
trunks, old logs, soils and rocks. Some lichens occur in extreme conditions of cold, 
humidity and drought. 
 In these plants the algal part prepares the food and the fungal part shows 
reproduction. Thus, their association is mutualistic. 
2). BRYOPHYTA:-  Bryophytes are simple terrestrial plants. 
They have over 25,000 species. They show the following characteristics:- 
1. They lice in damp and sandy habitates hence they are called amphibians of 
the plant kingdom. They are aften found to grow during rainy season forming 
green carpets or mats on damp soil, rocks, walls, tree trunks etc. 
2. The vascular tissues are absent. 
3. The roots are absent and instead rhizoids are present. They may be 
unicellular or multicellular. 
Page 5


CLASS 9
th
    DIVERSITY IN LIVING ORGANISMS    BIOLOGY 
  
    Page 1 
 
  
CLASSIFICATION: - Classification of organisms may be defined as a system of 
arrangement of organisms into different groups and sub-groups on the basis of their 
similarities, differences and relationship. 
Classification of organisms is also known as taxonomy. It has the following 
advantages. 
1. Classification makes the study of a wide variety of organisms convenient and 
easy. 
2. It is not possible for man to know about all the organisms but the study of a 
few representatives from each taxonomic group gives a general idea of all life 
forms at a glance. 
3. Classification also reveals the interrelationship among different gr4oups of 
organisms. 
4. Correct identification of an organism and its placement in a definite taxonomic 
group is the basic requirement of various branches of biological sciences.  
Thus, classification of organisms provides a base for the development of other 
biological sciences.  
BASIS OF CLASSIFICATION:- 
Classification can be done on the following basis. 
1. Cells are prokaryotic or eukaryotic. Organisms may be grouped into two 
broad categories on the basis whether they possess prokaryotic cells or 
eukaryotic cells. In case of prokaryotic cells the nuclei and other organelles 
are not clearly demarcated. The eukaryotic cells, on the other hand, have 
membrane-bound organelles, including a nucleus. 
2. Cells occur singly or in clusters. Many organisms are unicellular, i.e. made 
up of only one cell, e.g. Amoeba. Others are multicellular, i.e., cells group 
together to form single organism (e.g., insect). In case of multicellular 
organisms the different groups of cells carry out specialized functions 
3. Organism is photosynthetic or takes food from outside. Green plants 
perform photosynthesis an synthesis their own food. Animals cannot perform 
photosynthesis. They get food from outside.  
4. Organization of different body parts. Grouping of organisms may be done 
on the basis of body organization. For example, plants possess stem, root and 
leaves. Similarly, the animals possess specialized organs to perform different 
function. The characteristic based on body design used for classification of 
plants is quite different when used for classifying animals. 
Systems of classification:-  
 R H whittaker in 1969, suggested five kingdom classification on the basis ofr 
(i) preence or absence of a nucleus (ii) unicells or multicells and (iii) mode of 
nutrition. 
 He proposed five kingdoms: 
1. Monera, 2. Protista, 3.  Fungi, 4.  Plantae and 5.  Animalia. 
Monera: - these organisms do not have a defined nucleus or organelles, nor do any 
of them show multi-cellullar body designs. They show diversity based on many other 
characteristics. Some of organisms of this group are either autotrophic or 
heterotrophic. This group includes bacteria, blue-green algae or cynobacteria and 
mycoplasma. 
Protista:- This group includes many kinds of unicellular eukaryotic organisms. 
Some of these organisms use cilia or flagella for moving around. Their mode of 
nutrition can be autotrophic or heterotrophic. Examples are unicellular algae, 
diatoms and protozoans. 
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Fungi:- these are heterotrophic eukaryotic organisms. They are saprophytes and 
thrive on decaying organic material. They have cell-walls made of chitin. Examples 
are yeast and mushrooms. 
Plantae:- these are multi-cellular  eukaryotes with cell walls. They are autotrophs 
and used chlorophyll for photosynthesis. All plants are included in this group. 
Animalia:- these includes all multi-cellular organisms. They are heterotrophs. 
NOMENCLATURE:- 
Naming a correct scientific name to an organism or a taxon is called nomenclature. 
It involves the principals governed by set rules formulated by internationals bodies 
so that a particular organism or taxon is known by its specific name throughout the 
world. 
BINOMIAL NOMENCLATURE:- 
According to the binomial system of nomenclature, the scientific name of an 
organism consist of two separate components – first on designates the genus 
(generic name) and the second one designates the species (specific name). For 
example, the scientific binomial name of human species is Homo sapiens, where first 
name Homo is generic and the second name sapiens is a specific. Homo sapiens are 
understood to mean humans all over the world. Since this system of naming 
organisms gives two names to an organism, it is known as a binomial 
nomenclature.  
Various ranks used in classification (Hierarchy of classification). 
In classification, the organisms that closely resemble one another are placed in a 
group. These groups are further placed in large groups on the basis of close 
similarities. The larger groups are again placed in still larger grouping levels or 
ranks in classification are known as categories. Each category has its specific name. 
There are seven major categories: 
1. Species   2. Genus  3. Family  4. Order 
5. Class    6. Phylum (for animals)/division (for plants) 7. 
Kingdom. 
1. Species. Species is the lowest category regarded as basic unit classification. It 
is a group of similar individuals which resembles with each other in 
morphology, breed among themselves but not with others and probably 
descended from a common ancestor. 
2. Genus. A genus is a group of closely resembling species having a common 
ancestry. A;; the species in a genus show similarities in broad features of their 
organization but differ in minor details. 
3. Family. A family represents a larger group of closely related genera. It is 
composed of one or more genera. 
4. Oder. An order is a group of closely related families. 
5. Class. A class is a group of related orders. 
6. Phylum/Division. Phylum (in case of animals) or Division (in case of plants) is 
a group of related classes. 
7. Kingdom. Kingdom is the highest category in biological classification. It is 
group of phyla (in case of animals) or divisions (in case of plants). 
Mainly, the following rules apply to scientific names: 
They were initially framed by Linnzeus. And were revised in 9
th
 and 20
th
 century 
through international code of Botinical Nomenclature (ICBN) and international code 
of Zoological nomenclature (ICZN). They are as followes: 
 
 
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1. Each organisms has a distinct scientific name having a words, generic and 
scientific. 
2. The generic and specific words should not have less then three letters or more 
than 12(twelve) letters. 
3. The generic name is written first. It is like a noun . Is first letter is  always 
capital. 
4. The specific word is written after the generic name, It starts with small letter. 
5. The name of the discoverer is appended to the two-word scientific name either 
In full or abbreviate form e.g., mangifera indic . L(L stands  for Linnaeus). 
6. Scientific name is printed in italics hand written name is underlined. 
7. When an organism has been given different scientific names by different 
workers the “law of priority” is followed that is old valid name is accepted and 
others rejected.   
KINGDOM PLANTAE:- 
Characteristics features of kingdom plantae. 
i) They are made of eukaryotic cells. 
ii) They are multicellular. 
iii) The cells have wall made of cellulose. 
iv) They store carbohydrates such as starch. 
v) Some cells (except in some parasites) contain chloroplast. 
vi) The organisms feed by photosynthesis. 
                        PLANT KINGDOM 
 
 
 
 
 
 
 
 
 
 
 
 
 
According to the classification proposed by eicher, plant kingdom is divided in to two 
subkingdoms i.e crypotogamae and phanerogamae. 

 CRYTOGAMAE:- These are known as lower plants. The flower/seed are 
absent and hence these are considered to have hidden reproductive organs. It 
is categorized into 3 divisions. 
 
1).THALLOPHYTA:- Thallophytes have a body which is not differentiated into stem, 
root and leaves. This kind of undifferentiated body is called thallus, hence the name 
thallophytes. 
It has the following characteristics. 
(1) The plant body is thalloid i.e., cannot be differentiated into stem, root and 
leaves. 
(2) The vascular system is absent in such plants. 
(3) The reproductive organs are single called and there is no embryo formation. 
 
 
Crypotogama Phanerogama
Thalloph Bryophy
Pteridoph Gymnosper Angiosper
Fungi Algae Monoco Dicot Lichens 
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Thallophyta is further subdivided into: 
(A) Algae 
(B) Fungi 
(C) Lichens 
(A) ALGAE : They generally include aquatic plants. Some 20,000species of algae 
are known. The main characteristics are as under : 
1. They are generally chorophyllous thallophytes in which vascular tissues are 
absent. 
2. The plant body is thalloid i.e., cannot be differentiated into root, stem and 
leaves. 
3. They are found in fresh water resources as well as in sea water. 
4. They are autotrophic because of the presence of chlorophyll in leaves. The 
reserve food is generally a carbohydrate. 
5. The cell wall is double layered. The outer layer is made of pectin and inner 
layer is made cellulose. 
6. They may be unicellular as well as multicellular. 
7. A few members such as chlamydomonas are motile. 
8. They reproduce by vegetative, asexual as well as sexual methods. The sex 
organs are unicelled and lack a sterile covering around them. 
Example : oedogonium, Chara, Sargassum, Ectocarpus, Chlamydomonas, Ulothrix 
etc. 
(B) FUNGI :  it is a large group of over 90,000 species. They show the following 
characteristics : 
1. They are achlorophyllous and nonvascular plants. 
2. The plant body may be unicelled or vthalloid, made of branched or 
unbranched filamentous structures, the hyphae. 
3. The network of hypae is called mycelium. 
4. The hyphae may be aseptate or sepate and each cell may be uni-or 
multinucleale. 
5. The cell wall is made of chitin or fungal cellulose.  
6. They show heterotrophic mode of nutrition. 
7. The reserved food is in the form of glycogen and oil globules. 
8. They reproduce by asexual or sexual methods. 
9. The sex organs are unicelled and lack a sterile covering around them. The 
higher forms lack distinct sex organs. 
Example : Rhizopus, Yeast, Agaricus (Mushroom) etc. 
(C) LICHENS : They represent a symbiotic association of a fungus and a alga in 
which two organisms are so closely associated with each other as to form a single 
plant. They are show growing long lived plants. The commonly grow on leaves, tree 
trunks, old logs, soils and rocks. Some lichens occur in extreme conditions of cold, 
humidity and drought. 
 In these plants the algal part prepares the food and the fungal part shows 
reproduction. Thus, their association is mutualistic. 
2). BRYOPHYTA:-  Bryophytes are simple terrestrial plants. 
They have over 25,000 species. They show the following characteristics:- 
1. They lice in damp and sandy habitates hence they are called amphibians of 
the plant kingdom. They are aften found to grow during rainy season forming 
green carpets or mats on damp soil, rocks, walls, tree trunks etc. 
2. The vascular tissues are absent. 
3. The roots are absent and instead rhizoids are present. They may be 
unicellular or multicellular. 
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4. The reproduction takes place by vegetative or sexual methods. 
5. The vegetative reproduction is quite common through fragmentation tubes, 
gemmae, buds, adventitions branches etc. 
6. They show distinct alternation of generation. 
Example: Riccia, Marchantia, Funaria (Moss).   
(iii). PTERIODOPHYTA: - These are the oldest vascular plants this includes the 
forms. The important characteristics are. 
1. The plant body is differentiated into roots, stem, and leaves. 
2. The dominant phase or plant body is a sporophyte. 
3. They are seedless vascular plants and hence called vascular cryptogams. 
4. The gymetophyte is small or inconspious. 
5. The sex organs are multicellular. 
6. The fertilization requires water medium results in the formation of zygote. 
7. They show distinct alternation of generation. 
Example : Selaginella, Adiantum, Dryopteris. 
PHANEROGAMAE: - They are seed bearing plants. The plants body is differentiated 
into ture stem, leaves and root. A well developed vascular system is presents in 
phanerogames. Sex organs are multicellular. 
 On the basis of fruit formation, they are classified into two subdivisions. 
(a) Gymnosperme and (b) Angiosperme 
(a). GYMNOSPERME:- the term is made from two Greek words : gymo – means 
naked and sperme means seed. The plants of this group bear naked seeds and are 
usually pereneal, evergreen and woody. It has nearly 650 living species. They chief 
characteristics are:- 
1. They have well developed vascular tissues but lack vessels. The ‘flowers’ 
compose two types of sporophylls i.e., microsporophylls and megas[orohylls. 
2. The pollination is anemophilous and the fertilization does not require water 
medium. There is formation of pollen tube. (Siphonogamous) 
3. The zygote develops into an embryo. 
4. Since the ovules are not covered by a cattel there is no fruit formation. They 
are naked. 
Example : Cycas, Pinus and Emphedra etc. 
(b). ANGIOSPERMAE:- The word is made from two Greek words: anger means 
covered and sperma means seed. The seeds develop inside an organ which is 
modified to become a fruit. These are also called flowering plants. They are most 
abundant and conspicuous plants with about 2,00,000 species. The general 
characteristics are. 
1. They are usually terrestrial plants. The plant body is sporophytic. 
2. The plants may be herbaceous or woody. They may be annual, biennial or 
perennial. 
3. A well developed vascular system is present in them. The xylem has vessels. 
4. The angiosperms are characterized by the presence of the double fertilization 
forming a zygote and the primary endosperm, the nutritive tissue. 
5. During fertilization the nonflagellate male gametes are carried by a pollen tube 
(siphon gamous). 
6. Fertilized ovules ripens into seed thus the ovary is converted into a fruit. 
Example : Brassica campestris (Mustard), Pisum santivum (pea) etc. 
Angiosperms are divided into Monocots and Dicots. 
i. Monocot:- monocots bear seeds which have a single cotyledon or seed leaf . the 
veins on their leave are parallel to each other. Their vascular bundles are arranged 
in a complex manner.