Class XI Chapter - 1 The Living World

Class – XI
Unit - 1
The Living World
AJAY KUMAR GAUTAM
CHAPTER - 1

UNIT-1
• THE LIVING WORLD
• BIOLOGICAL CLASSIFICATION
• PLANT KINGDOM
• ANIMAL KINGDOM
UNIT-2
• MORPHOLOGY OF FLOWERING PLANTS
• ANATOMY FLOWERING PLANTS
• STRUCTURAL ORGANISATION IN
ANIMALS
UNIT-3
• CELL-THE UNIT OF LIFE
• BIOMOLECULES
• CELL CYCLE AND CELL DIVISION

UNIT-4
 TRANSPORT IN PLANTS
 MINERAL NUTRITION
 PHOTOSYNTHESIS IN HIGHER PLANTS
 CELLULAR RESPIRATION
 PLANT GROWTH AND DEVELOPMENT
UNIT-5
 DIGESTION AND ABSORPTION
 BREATHING AND EXCHANGE OF GASES
 BODY FLUIDS AND CIRCULATION
 EXCRETORY PRODUCTS AND THEIR
ELIMINATION
 LOCOMOTION AND MOVEMENT
 NEURAL CONTROL AND COORDINATION
 CHEMICAL COORDINATION AND
INTEGRATION

INTRODUCTION TO BIOLOGY
HISTORY OF BIOLOGY
BRANCHES OF BIOLOGY
SCOPE OF BIOLOGY
WHAT IS LIFE…?
DIVERSITY IN LIVING WORLD

INTRODUCTION TO BIOLOGY:
Biology- The term biology is derived from Greek word “Bios” means “life” and “logos”
means “study of”.
Biology deals with the study of life and living organisms.
Here, we study different aspects of living beings like growth, metabolism,
reproduction, response to stimuli etc.
The word ‘Biology’ was coined by Jean Lamarck and Treviranus in 1802.

HISTORY OF BIOLOGY:
Aristotle, the great Philosopher is known as father of biology.`
He has described about 500 animals in his book “Historia Animalium”.
He is also known as “father of Zoology”.
Theophrastus is known as “father of Botany”.
A.V. Leeuwenhoek discovered lens to see bacteria and other microorganisms. He is regarded as the
“father of Microbiology”.
Robert Hooke discovered the compound microscope and the cell. He is known as “father of
Cytology”.
Carolus Linnaeus introduced naming of animals and plants by Binomial nomenclature. He is
regarded as the “Father of Taxonomy”.
Gregor Johann Mendel is regarded as the “Father of genetics”.

BRANCHES OF BIOLOGY:
There are mainly two branches of biology.
1. Zoology
2. Botany
Zoology: This branch of biology deals with the study of animal life, such as structure,
metabolism, locomotion, life history and evolution. The term Zoology is derived from two
Greek words : Zoon-Animal and logos-study of .
Botany: This branch of biology deals with the study of plant life. It is derived from the Greek
word ‘Botane’ which means plant.

BRANCHES OF ZOOLOGY:
Morphology : Study of external features of the organisms is called as morphology.
Anatomy: Study of internal structure of individual is known as Anatomy.
Histology: It is the study of tissues and tissue system.
Genetics: It is the study of heredity.
Physiology: It is the study of different parts of the organ systems of plants and animal body.
Apiculture: It deals with the culture of honey bee and production of honey bee.
Poultry: It deals with the rearing of chickens for egg and flesh.
Space biology: Study of living organisms in outer space.
Entomology: It is the study of all types of insects.

Osteology: It is the study of bones.
Neurology : Study of structure and function of nerves is known as neurology.
Cardiology: Study of heart, blood and blood vessels in animals.
Dermatology: Study of structure and function of skin is known as dermatology.
Immunology: It deals with the defense mechanism of the body.
Ophthalmology: Study of eye and vision is known as ophthalmology.
Odontology: Study of teeth.
Microbiology: Study of microscopic organisms.
Virology: Study of viruses.
Bacteriology: Study of bacteria.

BRANCHES OF BOTANY:
Agronomy and Crop Science: This is an agricultural science dealing with field crop
production and soil management.
Algology: This is the study of algae.
Palaeobotany: This is the study of plant fossils.
Plant Pathology: This is the study of diseases in plants.
Bryology: This is the study of mosses and liverworts.
Mycology: This is the study of fungi.
Plant Anatomy and Physiology: This is the study of the structure and function of plants.
Plant Cell Biology: This is the study of the structure and function of cells.

SCOPE OF BIOLOGY:
•Biology as a basis of education.
•Helps for scientific study.
•Zoology helps in understanding the evolution
of man.
•It helps in production of drugs.
•It helps in aesthetic value.

The Living World
What is Life…….?
Life is a unique, complex organization of molecules.
It is defined as the property of living organisms that distinguishes from dead or non-
living ones.
Characteristics of living things:
Growth
Reproduction
Metabolism
Response to stimuli (Sensitivity)
Movement

Growth:
Growth is the most important property of living beings.
They in increase in number and mass.
Non-living objects grow in mass by accumulation of material on its surface.
Growth in living being takes place due to internal processes i.e. cell division.
Plants show growth through out their life span while animals growth up to a certain
age.
Reproduction:
All living beings produce their offspring by the process of reproduction.
Reproduction is an important process for continuing the lineage of life process.
It is two types: 1. Sexual Reproduction
2. Asexual Reproduction

Metabolism:
It is the chemical reactions in the body's cells that change food into energy. Our
bodies need this energy to do everything from moving to thinking to growing.
No non-living objects exhibits metabolism.
Response to external stimuli:
Living organisms respond to their surroundings or environment.
Plants respond to the external factors like light, water, temperature, pollutants etc.
Organisms can sense and respond to environment cues.
Movement:
 Movement is defined as the state of changing the position of a body from one
location to another.

Biodiversity:
The diverse form of living organisms present on earth is called biodiversity.
There are millions of plants and animals in the world.
The number of species that are known and described range between 1.7-1.8 million.
Biodiversity refers to every living thing, including plants, bacteria, animals, and
humans.
Brazil is the Earth's biodiversity champion.
Biodiversity provides functioning ecosystems that supply oxygen, clean air and water,
pollination of plants, pest control, wastewater treatment and many ecosystem services.

NEED OF CLASSIFICATION:
 Classification is the act or process of classifying or arranging in groups according to a
specific criteria like structure, property and characteristics.
It is impossible for any person to study all the animals. So Classification is great convenience
to the biologists.
Classification helps in storing information.
It helps to understand diversity better.
It helps in identification of living organisms.
It helps to understand relation between different organisms.

Difference between prokaryotic and eukaryotic
cell:
PROKARYOTIC CELL
1.Nuclear membrane is absent.
2.Membrane limited organelles
such as chloroplast, mitochondria,
Golgi apparatus are absent.
3.Single chromosome containing
circular DNA is present.
EUKARYOTIC CELL
1.Present.
2.Cell organelles are present.
3.More than one chromosome are
present formed of DNA and histone.

THREE DOMAINS OF CLASSIFICATION:
According to this system, all the living organisms are classified into three domains:

Domain Archaea
The Archaea are prokaryotic, with no nuclear membrane.
The Archaean possess unique, ancient evolutionary history for which they are
considered some of the oldest species of organisms on Earth.
 They are found in the extreme, harsh environments where,
it is impossible to survive a normal living beings.
Some examples of archaeal organisms are:
Methanogens – which produce the gas methane.
Halophiles – which live in very salty water.
Thermoacidophiles – which thrive in acidic high-temperature water.

Domain Bacteria:
The bacteria are also prokaryotic.
They consists of cells with DNA, no nuclear membrane, and whose membranes possess
carbohydrates and lipids.
They are found in the same environments favoured by humans.
They were briefly called the eubacteria or "true" bacteria.
Most known pathogenic prokaryotic organisms belong to bacteria .
Some examples of bacteria include:
Cyanobacteria – photosynthesizing bacteria that are related to the chloroplasts of eukaryotic
plants and algae.
Spirochaetes – Gram-negative bacteria that include those causing syphilis and Lyme disease.
Actinobacteria – Gram-positive bacteria including Bifidobacterium animalis which is present
in the human large intestine.

Gram positive bacteria have a thick peptidoglycan layer and no outer lipid membrane
whilst Gram negative bacteria have a thin peptidoglycan layer and have an outer lipid
membrane.

Domain Eukarya:
Eukarya are organisms whose cells contain a membrane-bound nucleus.
They include many large multicellular organisms and all known non-microscopic organisms.
Eukaryotic organisms includes:
Fungi
Saccharomyces – includes true yeasts.
Basidiomycota – includes mushrooms
Plant
Bryophyta – mosses
Magnoliophyta – flowering plants
Animals
Chordata – includes vertebrates

TAXONOMY:
All living organisms can be classified into different taxa. This process of classification is taxonomy.
Taxonomy is the branch of biological science that deals with the identification, nomenclature and
classification of organisms.
Identification: It deals with the structure and function of a particular animal and its position in the animal
and plant kingdom.
Nomenclature: It is the system of giving names to each groups or taxon such that a particular organism is
known by the same name all over the world.
Classification: It is the method of arranging organisms into different groups according to their
resemblances and differences.
 Organisms are classified on the basis of External and internal structure, along with the structure of cell,
development process and ecological information of organisms are essential and form the basis of modern
taxonomic studies.

History of Taxonomy:
Aristotle, classify animals for the first time . He divided animal kingdom into two groups
on the basis of color of blood.
1. Anaima: These animals do not contain red blood.
2. Enaima: These animals contain red blood. This group is again sub-divided into two
groups basing on reproduction.
A. Oviparous: These are egg laying animals like fish, amphibians, reptiles and birds etc.
B. Viviparous: These animals give birth to young ones. Ex- mammals.

Systematics:
It is the branch of science that deals with diversities of organisms and the relation between them.
The word systematics is derived from the Latin word ‘systema’ which means systematic arrangement of organisms.
The word ‘systematics’ was used by Carl Linnaeus for the first time. Systematics takes into account evolutionary relationships
between organisms.
Carolus Linnaeus is regarded as the “Father of Classification” or ‘Father of Systematics’.
He published two famous books such as “Genera Plantarum” and “Species Plantarum”.
Linnaeus published his tenth edition of “Systema Nature” (1758) listing about 4236 species which are still accepted today.
Classification consists of a number of groups or taxons.
Species is the lower most taxon of any classification.

SPECIES CONCEPT:
Species: It is a group of interbreeding population, occurring in nature, having
many characteristics in common and differing from other groups.
Characteristics of Species:
 A species is a population of individual having morphological similarity.
There is free gene flow in a species.
They can interbreed.
Species are reproductively isolated from other species.
It occupies a particular ecological niche.
It helps in evolution by giving rise to new species.

Types of Species:
1. Genetic species: It is defined as the group of genetically identical individuals.
2. Morphological species: According to Linnaeus it can be defined as “a group of individuals that resemble
each other in most of their morphological characters.”
3. Biological species: According to Mayr (1940) “Species is a group of actually interbreeding population
that is reproductively isolated from other such groups.”
A species can be of two types:
1. Polytypic species: A species with two or more sub species is called as polytypic species.
Panthera tigris which has several subspecies; such as—(i) Indian tiger (ii) the Chinese tiger
2. Monotypic species: It is not divided into sub-species.

Taxonomic Hierarchy:
 It is the process of arranging various organisms into successive levels of the biological
classification either in a decreasing or an increasing order.
Each of this level of the hierarchy is called the taxonomic category or taxon.
This system was introduced by Linnaeus which is known as artificial system.
Kingdom is the highest taxon and species is the lowest taxon.
Following are the important taxonomic hierarchies in which different organisms are classified.
Species:
A group of individual organisms with fundamental similarities is considered as a species.
It is the lowest level of taxonomic hierarchy.
For example Mangifera indica(Mango), Solanum tuberosum (potato) and Panthera leo (lion).
Here the words indica, tuberosum and leo are represent three different species.
The scientific name thus, for human being, is written as Homo sapiens and Homo erectus.

Genus:
Genus comprises a group of related species which has more character in common
in comparison to species of other genera.
For example, potato and brinjal are two different species but both belong to the
genus Solanum.
Lion (Panthera leo), leopard (P. pardus) and tiger (P. tigris) with several common
features, are all species of the genus Panthera.
This genus differs from another genus Felis which includes cats.
Family:
 This group includes one or more genera with some similarities and have differences
in many characteristics.
For example the family “Felidae” includes the genus Panthera( Lion, tiger) and the
genus Felis(Cat,, leopard, Golden cat, Fishing Cat).
The related family “Canidae” includes dogs, foxes etc.

Order:
It consists of number of families.
For example families like Felidae, Canidae are included in one order i.e. Carnivora.
Class:
It consists of more than one order.
For example class Mammalia includes nearly 16 living orders such as carnivora, primate
etc.
Phylum:
 It includes one or more classes having some common general characteristics.
For example different classes like Amphibia, Reptilia, Aves and Mammalia are included
under one phylum Chordata.

Kingdom:
All animals belonging to various phyla are assigned to the
highest category called Kingdom Animalia in the classification
system of animals.
It includes all the animals of the world i.e. Kingdom Animalia.
The Kingdom Plantae, on the other hand, is distinct, and
comprises all plants from various divisions.
The taxonomic categories from species to kingdom have been
shown in ascending order starting with species in Figure 1.1.

Common
Name
Biological
Name
Genus Family Order Class Phylum/
Division
Man Homo sapiens Homo Hominidae Primata Mammalia Chordata
Housefly Musca
domestica
Musca Muscidae Diptera Insecta Arthropoda
Mango Mangifera
indica
Mangifera Anacardiaceae Sapindales Dicotyledonae Angiospermae
Wheat Triticum
aestivum
Triticum Poaceae Poales Monocotyledonae Angiospermae

Nomenclature:
There is a need to standardise the naming of living organisms such that a particular organism
is known by the same name all over the world. This process is called nomenclature.
Binomial Nomenclature:
(Bi-two, Nomial-Name, Nomenclature: naming)
Carolus Linnaeus started naming an animal in a scientific way. He named the animal with
two names.
The first name is the generic name and the second name is the name of the species.
The name of the genus starts with a capital letters but the species starts with a small letter.
It is written in italics.
The names mentioned in the 10th edition of “Systema Nature” were first accepted as the
first document on nomenclature by the (ICZN) International Commission on Zoological
Nomenclature,1898.
This type of naming is known as binomial nomenclature.
Example: Panthera tigris

Rules of Nomenclature:
The International Commission on Zoological Nomenclature was established by
International Congress of Zoologists in 1898.
1. The name mentioned in the 10th edition of “Systema Nature” published by C.
Linnaeus are accepted. Any name prior to this is not accepted.
2. No two genera of animals will bear same name.
3. Two species of a genus will not bear similar names.
4. The first letter of genus must begin with a capital letter and the species with a small
letter.
5. The scientific names must be Latin words.
6. The names must be written in italics.
7. When written by hand the genus name and the species name have to be underlined
separately.

Scientific Names of Common Indian animals:
ENGLISH NAME SCIENTIFIC NAME
Rohu Labio rohita
Catla Catla catla
Indian Bull Frog Rana tigerina
Wall Lizard Hemidactylus flaviviridus
Garden Lizard Calotes versicolor
Flying Lizard Draco maculatus
Common cobra Naja naja
King Cobra Naja bungarus
Russell’s viper Viper russelli

ENGLISH NAME SCIENTIFIC NAME
Pigeon Columba livia
Peacock Pavo cristatus
Fowl Gallus domesticus
Crow Corvus splendens
Lion Panthera leo
Tiger Panthera tigris
Dog Canis familiaris
Domestic cat Felis domesticus
House rat Rattus rattus
Elephant Elephas indicus
Cow Bus domesticus
Rhesus Monkey Meccaca mulata
Man Homo sapiens
Crocodile (Magar) Crocodilus porosus

Trinomial Nomenclature:
Sometimes a species is divided into subspecies, due to presence of some differences in
their characters. In this case the name of the sub-species follows the species.
All the rules of nomenclature are applicable for this.
The name of the sub-species will be written after species and it will start with a small
letter.
Thus a scientific name is written with three names i.e., trinomial nomenclature.
Example: The crow is named as Corvus splendens. This species have three sub species.
1. Indian crow: Corvus splendens splendens
2. Burmese crow: Corvus splendens insolens
3. Srilankan crow: Corvus splendens protegatus

Tools for Taxonomic study:
Herbarium and botanical garden may be used as tools
for the study of plant taxonomy.
In the case of animal studies, the classical tools are
Museums, Zoological parks and keys for identification.
Herbarium:
Herbarium is a store house of collected plant
specimens that are dried, pressed and preserved on
sheets.
 Further, these sheets are arranged according to a
universally accepted system of classification. These
specimens, along with their descriptions on herbarium
sheets, become a store house or repository for future
use.
The herbarium sheets also carry a label providing
information about date and place of collection,
English, local and botanical names, family, collector’s
name, etc. Herbaria also serve as quick referral
systems in taxonomical studies.

BotanicalGardens:
These specialised gardens have collections of living plants for reference.
Plant species in these gardens are grown for identification purposes and each plant is
labelled indicating its botanical/scientific name and its family.
The famous botanical gardens are at Kew (England), Indian Botanical Garden, Howrah
(India) and at National Botanical Research Institute, Lucknow (India).
Zoological Parks
These are the places where wild animals are kept in protected environments under
human care and which enable us to learn about their food habits and behaviour.
 All animals in a zoo are provided, as far as possible, the conditions similar to their
natural habitats.
Children love visiting these parks, commonly called Zoos.

Museum:
Biological museums are generally set up in
educational institutes such as schools and colleges.
 Museums have collections of preserved plant and
animal specimens for study and reference.
Specimens are preserved in the containers or jars
in preservative solutions.
Plant and animal specimens may also be
preserved as dry specimens.
Insects are preserved in insect boxes after
collecting, killing and pinning.
 Larger animals like birds and mammals are
usually stuffed and preserved.
 Museums often have collections of skeletons of
animals too.

Taxonomic Key:
A taxonomic key is a device for quickly and easily identifying to which species an unknown plant
belongs. The key consists of a series of choices, based on observed features of the plant specimen
A taxonomic key is a simple tool used to identify a specific object.
A taxonomic key is one of the most useful tools available to scientists trying to identify an unknown
organism.
The keys are based on the contrasting characters generally in a pair called couplet.
It represents the choice made between two opposite options.
 This results in acceptance of only one and rejection of the other.
 Each statement in the key is called lead.
Separate taxonomic keys are required for each taxonomic category such as family, genus and
species for identification purposes.

1. Flora, manuals, monographs and catalogues are some other means of recording
descriptions.
2. They also help in correct identification.
3. Flora is the document of all plant species in a given geographic area. Flora consists
of total number of plant species in an area and gives information about flowering
season, fruiting season and distribution for the given geographic area. It also
provides details on rare and endemic species of that area.
4. Manuals are useful in providing information for identification of names of species
found in an area.
5. Monographs contain information on any one taxon.
6. Catalogue is a small booklet which contains the details, botanical names as well as
full name of author and also name of the publications. Catalogue is used to identify
all species in an area such as :- Flora - It is the plant species present over an area.

Imp Questions:
1. Who is known as father of Botany?
A. Aristotle
B. Theophrastus
C. G. Mendel
D. Robert Hook
2. The study of external features of an organism is called ______________.
A. Anatomy
B. Morphology
C. Histology
D. Ornithology
2. Select correct statement for growth as one of the characteristics of living organisms?
A. Growth by increase in mass is a defining property of prokaryotic organisms only
B. Non-living objects do not show growth by increase in mass of body.
Intrinsic growth is a characteristic of all living organisms.
C. Growth can be extrinsic or intrinsic for multicellular organisms.
D. Intrinsic growth is a characteristics of all living organisms.

Questions:
1. Metabolism reactions involves :
a) Synthesis of biomolecules only.
b) Breakdown of some biomolecules only.
c) All physical changes occurs in object around us.
d) All chemical reactions which occur inside an organism.
2. Growth in living organisms occurs by:
a) Division of cells
b) Increase in mass of living structure
c) Accumulation of material by external agency.
d) Both a and b
3. Which of the following organisms can be found in extreme saline conditions?
(a) Eubacteria
(b) Archaebacteria
(c) Cyanobacteria
(d) Mycobacteria

4. Linnaeus used which kingdom of classification?
(a) Artificial system
(b) Natural system
(c) Phylogenetic system
(d) Asexual system
5. Smallest taxon of classification is _______.
(a) Kingdom
(b) Family
(c) Variety
(d) Species
6.Who wrote the book “Genera Plantarum”?
(a) Bessey
(b) Bentham and Hooker
(c) Linnaeus
(d) Hutchinson

7. Taxon is the ___________
a) Name of a taxonomy journal
b) Name of a branch of taxonomy
c) A rank of classification such as : Phylum, Class, Order, species
d) Group of similarly constituted species.
8. Most acceptable concept of species is_____________.
a) Morphological concept
b) Genetic concept
c) Biological concept
d) All of the above
9.Central national Herbarium is situated at __________.
a) Chennai
b) Kolkata
c) Dehradun
d) Mumbai
10. The international size of herbarium sheet is _____________.
a) 41 * 29 cm
b) 40* 30 inches
c) 51 * 21 cms
d) 39 * 29 cm

Class XI Chapter - 1 The Living World

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Class XI Chapter - 1 The Living World