The Aimers Coaching, Chaibasa

Class: 11
Subject: biology (chapter 1)

What do you mean by living ?

Living as anything that is capable of growth, development,
responsiveness, adaptation, and reproduction is called living.
These distinctive characteristics help biology to define
something as living.
Features of living organism
1. Growth
2. Reproduction
3. Metabolism
4. Cellular organization
5. Consciousness
6.

1. Growth: Increase in mass or size of tissue or organism or

its parts in called growth. Increase in mass and increase in
number of individuals are twin characters of growth. grow is
an irreversible permanent increase in size of the organ or its
part or even of an individual cell.
Growth is of two types:
(i) Intrinsic Growth: Growth from inside of the body of living
organism. This is the defining property of life.
Intrinsic Growth is of two types:

⦁ Indeterminate growth/ unlimited growth: Growth which

occurs continuously throughout thier life span. it occurs
only in plants and not in animals.

⦁ Determinate growth/limited growth: Growth which

occurs only up to certain age. it occurs only in animals.
cell division occurs only in certain tissues to replace lost
cells.
(ii) Extrinsic growth: Growth from outside of the body of the
organism. like accumulation of material on any body surface.
Non- living exhibits this type of growth.
Note: Basically, growth is the increase in mass and size, so
non- living objects also grow (surface accumulation of
material) so growth is not a defining property of living
organisms. In living organisms, growth is from inside
2. Reproduction: It is the production of new progeny having
features similar to those of parents. Reproduction in case of
unicellular orgorganism like bacteria, unicellular algae or
amoeba is increaser in number of cell. Means in unicellular
organism the growth and reproduction are synonyms or
same.
Many organisms do not reproduce (e.g. mules, worker bees,
infertile human couples, etc). Hence,
reproduction can not be a defining property of living
organisms.

Reproduction is of two types:

1. Asexual reproduction :- Asexual reproduction is a mode of
reproduction in which a new offspring is produced by a single
parent. The new individuals produced are genetically and
physically identical to each other,
i.e., they are the clones of their parents. Asexual
reproduction is observed in both multicellular and unicellular
organisms. many methods of asexual reproduction are there

⦁ By Asexual spores: In algae and fungi.

⦁ By Budding: In Yeast and Hydra.

⦁ By Fragmentation: In filamentous Algae, Fungi and

Protonema of moss plants.

⦁ True Regeneration: Fragmented organism regenerate

the lost parts of its body and becomes a new organism
i.e. Planaria
2. Sexual Reproduction: Sexual reproduction is the
production of a new organism from two parents by making
use of their sex cells or gametes. In this process male
gametes fuses with a female gamete to form a new cell
called ‘zygote’. This zygote then grows and develops in to a
new organism in due course of time. Sometimes sex cells or
gametes are also called as germ cells.
Ex-The humans, fish, frogs, cats, dogs etc. all reproduce by
method of sexual reproduction.

3. Metabolism:- The sum total of all the chemical reaction

occurring in our body is metabolism. All organism, both
unicellur as well as multicellular exhibit metabolism. No
nonliving objects show metabolism. It is the defining
property of life.
Ex. All plants, animals, fungi, and microbes exhibit
metabolism.

4. Cellular organization:- Cell is the basic unit of life. All

organisms are composed of cells. Some are composed of
single cell and are called as unicellular organism while other
are composed of many cells, are called multicellular
organism.
Unicellular organism is capable of independent existence and
performing essential functions of life.
A complete structure of a cell, does not ensure independent
living.
Cell is the fundamental structure and functional structural
and functional unit of all living organism. This is the
defining property of life.

5. Consciousness:- It is the ability of organisms to sense

their environment and respond to environmental stimuli
( like light, water, temperature, other organisms,
chemicals, pollutants, etc ). All organisms are ‘aware’ of
their surroundings. So, it is the defining property of
living organisms.
When human is concerned a very well developed
nervous system and supreme level of skill of
communication which is called as self-consciousness.
Human is very fast to respond towards the external
stimuli and even it can think or predict about possible
changes of surrounding so it can prepare itself according to
the surrounding situations.
Diversity in living world:- The living world comprises
millions plants and animals. there is a large variety of them
and other living organisms and is called biodiversity.
Taxonomy:- Taxonomy is the branch of bioloay that deal with
the collection, identification, classification, labeling, and
conservation of organisms. it is a detailed scientific study
of the external and internal personnel of an organism
that finds similarities and differences with others, which
is important for its classification.
Nomenclature:- Nomenclature is the method of providing
an organism a specific identity as two names as Genus and
species. these are names generally adopted from the latin
language.
In the scientific study, the nomenclature is done after
identifying and classifying an organism based on its specific
characteristics which distinguish it from other organism.
Nomenclature is formulated under certain rules by different
scientisits or scientific communities.
These names are based on different codes made by different
committees such as

⦁ International code for botanical nomenclature for plants

⦁ International Code for Zoological Nomenclatures for

Animals
⦁ International Code for Nomenclature of Bacteria
⦁ International Code of Virus Classification Nomenclature
Rules of Nomenclature:-
⦁ The names should contain two words.
⦁ The names should be derived or adopted from the Latin
language.
⦁ The first letter of the generic name should be capital
and the first letter of the species name should be small.
⦁ A space is kept between two names. ex: human-homo
sapiens.
Taxonomy (वग करण):- The word "Taxonomy" is derived
from a Greek word - "taxis", meaning arrangement or
division, and "nomos", meaning method.
Taxonomy is a branch of Biology that refers to the process of
classifying different living species. A taxon is referred to as a
group of organisms classified as a unit.
The Taxonomic Hierarchy :-
A taxon (plural: taxa) is a group of organisms that are
classified as a unit.
Taxonomic hierarchy is the process of arranging various
organisms into successive levels of the biological
classification either in a decreasing or an increasing order
from kingdom to species and vice versa.
Taxonomic Hierarchy Categories:-
1. Species:- A species is defined as a group of individuals,
capable of interacting to produce fertile. It is the basic unit of
taxonomy and helps us understand taxonomy and
development.
Ex- Horse (Equus cabalus) and ass (Equus asinus) are of the
same genera but are two different species because they do
not breed among themselves. The mule is an artificial hybrid
of horse and ass is sterile i.e. it cannot reproduce. Hence the
mule is not a species.
2. Genus (plural; genera):- Two or more species with
common ancestry and similar characteristics are classified
into one species are termed as Genus. Otherwise, a genus is
a group of organisms associated with a common ancestor.
Ex- Lion (Panthera leo), Leopard (Panthera pardas) and Tiger
(Panthera tigris) belong to the same genus Panthera. Genus
Panthera is different from other genera of cats. Domestic cat
and tiger belong to the same family but their genera are
different.
3. Family:- It is the next category higher to the genus. It is a
group of organisms of closely related genera, which resemble
one another in certain characters.
Ex- Domestic cat (Felis domestica) and Lio (Panthera leo)
belong to cat family Felidae because both of them possess a
similar structure and has retractive claws.
4. Order :- It is a higher category than species, genera, and
family. Order is the aggregate of families and shows less
number of similar characters.
Ex- Both the tiger (Panthera tigris) and the wolf (Cannis
lupus) possess jaws with powerful incisors and large sharp
canines. This adaptation is for flesh-eating. Hence tiger and
wolf have the same order Carnivora. Thus Order Carnivora
includes families Felidae and Canidae.
5. Class :- It is the next category higher to the order. It is a
group of organisms of closely related sub-classes or order,
which resemble one another in certain characters. The
similarities in the orders of a class are still less than in the
families of an order.
Ex- Chordates such as rats, dogs, bats, monkeys, camel are
characterized by a hairy exoskeleton, milk glands (mammari
glands) and external ears, belong to the same class
Mammalia. Class Mammalia includes order Carnivora (has
carnivorous animals like lion, tiger, leopards, etc.) and order
Primata (includes man, monkey, Chimpanzee, Gorilla,
Gibbons, etc)

6. Phylum/Division: - Collection of similar classes with

Phylum being used in the case of animals and Division is used
in the case of plants.
Ex- all animals which have a notochord present in embryo
belong to the phylum Chordata. Classes like Pisces (fishes),
Amphibia (frogs and toads), Reptilia (snakes and lizards),
Aves (birds) and Mammalia (mammals) are all grouped into a
single phylum Chordata.

7. Kingdom:- It is the next category higher to the

phylum/division. It is a group of organisms of closely related
phyla, which resemble one another in major characters. All
animals are grouped into Kingdom Animalia and all plants
are grouped into Kingdom Plantae.

Taxonomical aids:
Taxonomic aids are collections of samples or preserved
species that aid in extended investigation for taxonomic
hierarchy identification. The classification of organisms into
distinct categories necessitates extensive field and laboratory
research. This is an important process since taxonomic
categorization aids in the identification of numerous
creatures that are required in various domains such as
agriculture, industry, bio resources, and so on.