DOC-20240526-WA0002..pdf living world hints

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Living World

Key Takeaways
Living vs non-living 1
Reproduction
2
Metabolism 3
4
Taxonomy 5
Nomenclature

Systematics 6
Taxonomic categories
7
Taxonomic aids 8
Summary

Living vs Non-living
● Growth is the increase in size, mass or height of an organism. This occurs
by cell division.
● Animals grow only up to a certain age. In the later years, there is only
replacement and repair of worn out cells. Hence their growth is termed
definite.
● Plants, on the other hand, can grow throughout their lifetime. Thus, the
word indefinite is used for growth in case of plants.
o For example: The Great Banyan Tree in AJC Bose Indian Botanical
Garden in West Bengal is 250 years old and is spread across 14,500 m2 .

Living vs Non-living
● In unicellular organisms, growth and reproduction are synonymous.
● In plants and animals, growth and reproduction are two separate
phenomena.
● Living organisms grow due to addition from inside, also called intrinsic
growth. Growth can be extrinsic too as seen in non-living matter by the
accumulation of material on the surface.
o Sand dunes and glaciers are good examples of extrinsic growth.
● Growth is a property of living beings but cannot be considered as a
defining characteristic of living beings.

Asexual reproduction Sexual reproduction
Does not involve the fusion of
gametes
Involves the fusion of gametes
Offspring identical to the
parent
Offspring varies genetically
from the parents
Asexual reproduction is
uniparental
Sexual reproduction is
generally biparental
Types of reproduction
Reproduction
● Production of new individual organisms or offspring by their parents
● Not essential for survival of individual but essential for the survival of a
species

Asexual Reproduction
Spore formation in fungi
● Fungi multiply and spread easily
due to the millions of asexual
spores they produce.
● These are quite resistant
structures and do not damage
easily.
Regeneration in flatworms
● Fragmented parts of
organism regenerate the lost
part of their body and
becomes new organism.
Budding in yeast
● New individuals form from
outgrowths (buds) on the bodies
of mature organisms.
● Examples : Yeast and Hydra
Binary fission in bacteria
● Most common form of
reproduction in prokaryotes and a
few unicellular eukaryotes.
● Example: Bacteria and Amoeba.

Metabolism
 Sum total of all the
chemical reactions
occurring in a
coordinated manner
to support life is
called metabolism.
 Occurs in both
unicellular and
multicellular
organisms.
 Non- living objects do
not perform
metabolic processes.
Catabolism Anabolism
Catabolism
 Molecules are broken down
and energy is released
 E.g. - breakdown of food
during digestion.
Anabolism
 Energy is utilised to
combine smaller
molecules to yield larger,
more complex
molecules.
 E.g. – photosynthesis.
Molecules
Energy
Smaller units
Smaller units
Energy
Molecules

Important Points
 All living beings cannot reproduce
○ Infertile couple : Inability of a couple
to become pregnant and produce an
offspring.
○ Worker bee : Amongst a swarm of
bees, the worker bee is sterile while
only the queen bee is fertile.
○ Mule : Cross between male donkey
and female horse; doesn’t produce
gametes.
 Hence, reproduction is not a
differentiating character between living
and nonliving organisms.
 Chemical reactions performed in a test
tube are neither living nor non-living.
 Metabolic reactions performed outside
can be referred to as living reactions but
not living things.
Reproduction Metabolism

Cellular Organisation
 All living beings are made up of cells.
○ Cells aggregate to form tissues
which in turn aggregate to form
organs.
 Each cell, further, consists of several
organelles.
 Organelles interact with each other for
the proper functioning of the cell. It is a
very organised process.
 Each organelle may be involved in
individual function. The functions
performed by cells are a result of
cumulative activities of all the organelles.
 Thus, cellular organisation is a defining
property of living beings.
Organism
System
Organ
Tissue
Cell

Consciousness
 It is the state of awareness of the surroundings and response to
external stimuli.
 Examples are:
○ Sense organs
○ Photoperiod
 All cells (prokaryotes to eukaryotes) respond to external factors.
○ Example: Folding of leaves in Mimosa pudica (Lajwanti or chhui-
mui) occurs due to external stimulus of touch.
 Consciousness is a defining property of living organisms.
Note
Human beings in coma have no self-consciousness. They are
supported by machines. Some come back to normal life, some don't. It
is difficult to define the living state in such cases, living or non-living or
dead.

Nomenclature
 About 1.7 - 1.8 million species on Earth have been
identified and described.
 Biodiversity is the term used to describe the enormous
variety of life on Earth.
 Identification is the process by which the features or
characteristics of an organism are known, so that one can
identify the organism in any part of the world.
 Identified organisms are named in accordance with a
standard procedure, accepted all across the world. This is
called nomenclature.

Nomenclature
Binomial nomenclature
 Most accepted system
 Given by Carolus Linnaeus
○ Known for two works, namely Species Plantarum (1753) for
plants and Systema Naturae (1758)
○ In Systema Naturae, using the binomial nomenclature system,
Carolus named 4,400 animal species and 7,700 plant species
○ Two terms are used to denote a species of living organism in
this system:
■ Generic name - E.g. - Mangifera
■ Specific epithet - E.g. - indica
o Eg: Mangifera indica (Mango)

Nomenclature
Uses
 Single scientific name to replace multiple vernacular names.
 Description of any organism enables people to arrive at the same name.
 Ensures that a name has not been used for more than one known organism.
Rules of binomial nomenclature
 Biological names are generally in Latin. They are Latinised or derived
from Latin irrespective of their origin.
 The first word in a biological name represents the genus while the
second component denotes the specific epithet.
 Both the words in a biological name, when handwritten, are separately
underlined, or printed in italics to indicate their Latin origin.
 The first word denoting the genus starts with a capital letter while the
specific epithet starts with a small letter.
o E.g. : Mangifera indica

Nomenclature
 There are 2 major codes for naming organisms:
○ International Code for Botanical Nomenclature (ICBN) for
naming plants.
○ International Code of Zoological Nomenclature (ICZN) for
naming animals.
Note
 Animal species having the same name for both genus
and species are known as tautonyms.
 Examples : Eurasian eagle owl (Bubo bubo), European
grass snake (Natrix natrix).

Taxonomy
 Scientists have grouped organisms into convenient categories based on
their characters. This process is called classification of organisms.
 Taxon is a group of one or more populations of an organism or
organisms. It can refer to any category in the hierarchy of classification
system.
 Taxonomy is the branch of study that deals with principles and
procedures of identification, characterisation, classification and
nomenclature of organisms.
 Based on characteristics living organisms can be classified into different
taxa.
 Earliest classifications were based on the ‘uses’ of various organisms
such as,
a. Basic needs of food - small animals like rabbit, deer, carrot, apple.
b. Clothing - hides of animals, leaves from trees.
c. Shelter - coconut leaves, bamboo, etc - to build homes.
 Earliest classification system was not very efficient.

Taxonomy
Basis of modern classification:
External
characteristics
Development
process
Structure of
cell
Ecological
information of
organisms

Steps involved in modern taxonomy
a. Characterization - morphological and all other characters
are described
b. Identification - determining similarities with already
known organisms
c. Classification - placing the organism under a particular
taxa or category
d. Nomenclature - giving a proper scientific name
Taxonomy

Systematics
 Systematics is the study of
evolutionary relationships among
organisms.
 Derived Latin word ‘systema’ which
means the systematic arrangement
of organisms.
 Study of one organism gives
information about the whole group.
 Taxonomy, systematics and
classification are often used
synonymously but technically are
not the same.
Nomenclature (Naming)
Taxonomy
(Description)
Specimen
Classification
(Arrangement)
Morphology
(Terminology of parts)

Taxonomy Systematics
Definition
Process of
classification
Includes taxonomy
and nomenclature
Importance
Identify, name,
describe organisms
Describes
evolutionary
relationships among
organisms
Abiotic
conditions
They are indirectly
related
They are directly
related
Change with
time
Subject to change
with time
Does not change
with time
Taxonomic vs Systematics

 It is also called the
Linnaean hierarchy/
taxonomic hierarchy as
it was first proposed by
Linnaeus.
 A taxon is a group of
organisms and a
category represents the
rank of the taxon.
SPECIES
GENUS
FAMILY
ORDER
CLASS
PHYLUM
KINGDOM
Taxonomic Categories

Kingdom
 It is the highest category of classification in which certain common
fundamental characters are used as the basis of classification.
 For example: Kingdom Animalia comprises organisms that are
multicellular, heterotrophic and eukaryotic.
Monera Protista Fungi Plantae Animalia
R.H Whittaker came up with a 5 kingdom
classification that is widely accepted today.

Phylum
 A phylum is a category below
Kingdom, where classification is
based on common features.
 Organisms in a phylum share the
same set of characteristics which
distinguishes them from another
phylum.
 The same category is called
division in the Kingdom Plantae.
Algae
Division Thallophyta
Kingdom Plantae
Fungi
Sub-division

Class
 This is the category below phylum.
 Category between phylum and class
is subphyla.
 For example :
Kingdom animalia > phylum
chordata > subphylum vertebrata
(has notochord) > Class pisces and
aves.
 Human beings fall under the class
Mammalia.
 This is the category which comes
below class. A group of closely
related orders forms a class.
 For example:
Kingdom animalia > phylum
chordata > subphylum vertebrata
(has notochord) > superclass
tetrapoda (bears limbs) > class
mammalia > order primate or
primates.
 Another example is : Order
Carnivora comprises flesh eating
animals like tiger, cat and dog.
Order

 It is the category below family and forms the first word
of a scientific name.
 Category below family but above genus is a sub-family.
 A group of closely related species forms a genus.
 For example:
Kingdom animalia > phylum chordata > subphylum
vertebrata (has notochord) > superclass tetrapoda
(bears limbs) > class animalia > order primate > family
hominidae > sub family hominidae > genus homo
Genus
Species
 It is the lowest
category of
classification and forms
the second word of a
scientific name.
Family
 This category is below order.
 A group of closely related families forms an order.

Example of taxonomic categorisation Benefits of taxonomy
 Categorisation of organisms for
ease of study.
 Compares similarities and
differences between organisms.
 Shows evolutionary relationships.
 Same name is used for an
organism worldwide
 Knowledge of bioresources and
their diversity
Kingdom Animalia
Phylum Chordata
Sub Phylum Vertebrata
Class Mammalia
Order Primate
Family Hominidae
Genus Homo

Botanical garden
 It is a collection of plant
specimens that are dried, pressed
and preserved on sheets.
 The description on the sheet:
a. Date and place of collection
b. English, local and botanical
names
c. Family name
d. Collector’s name
 It is a repository for future use.
Herbarium
 They are specialised gardens
with collections of living
plants.
 Plant species are also grown
for identification purposes.
 Plant is labelled indicating :
1. Botanical/scientific name
2. Family
Taxonomical Aids

Zoological parks
 Collections of preserved plant
and animal specimens
 Specimens are used for study
and reference.
 Generally, set up in educational
institutes
 Specimens are preserved in
the containers with
preservative solutions.
Museums
 Wild animals are kept in
protected environments under
human care.
 Food habits and behaviours of
the animals are studied.
 The animals are provided with
their natural living conditions.
Taxonomical Aids

Taxonomical Aids
Manual
 Records that provide information of
species found in an area are called
manuals
Monograph
 Complete global record of a
taxon is called a monograph.
Catalogue
 List which methodically
enumerates all species found
in a particular place is called
catalogue. Key
 It is a tool that helps to identify an
unknown organism.
 Keys provide two contrasting
characteristics which are called couplets.
 Each statement in the key is called a lead.
 Separate taxonomic keys are required for
each taxonomic category.

Summary
Types of reproduction
Sexual reproduction Asexual reproduction
Non-identical offspring Identical offspring
Spore formation Budding Binary fission Regeneration
Metabolism
Catabolism Anabolism

Characteristics of living organisms
Reproduction Growth
Metabolism Consciousness
Cellular organisation
5 Kingdom classification
Monera Protista Fungi Plantae Animalia
R.H Whittaker came up with a 5 kingdom
classification that is widely accepted today.
Summary

Steps of modern taxonomy
1.Characterization
4. Nomenclature
2. Identification
3. Classification
Taxonomic categories
SPECIES
GENUS
FAMILY
ORDER
CLASS
PHYLUM
KINGDOM
Summary

TAXONOMICAL AIDS
HERBARIUM
MONOGRAPH
MUSEUM
ZOOLOGICAL PARK
KEYS
MANUAL
CATALOGUE
BOTANICAL GARDEN
Summary

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