Binomial Nomenclature: Binomial nomenclature is a formal system of naming species of living organisms. It was introduced by the Swedish botanist and physician Carl Linnaeus in the 18th century. In this system, each species is assigned a two-part scientific name consisting of the genus and the species. For example, Homo sapiens is the scientific name for humans, with Homo representing the genus and sapiens representing the species. Classification: In biology, classification is the process of organizing living organisms into hierarchical groups based on shared characteristics. The main levels of classification, from broad to specific, are domain, kingdom, phylum, class, order, family, genus, and species. This system helps scientists categorize and study the vast diversity of life on Earth. Evolution: Evolution is the process by which species of living organisms change over time through the gradual accumulation of small genetic variations. This concept, introduced by Charles Darwin in the 19th century, is driven by natural selection, where individuals with advantageous traits are more likely to survive and reproduce, passing those traits to the next generation. Diversity: Biological diversity, often referred to as biodiversity, encompasses the variety of life on Earth, including the diversity of species, ecosystems, and genetic variations within species. It is a crucial aspect of the natural world, contributing to ecosystem stability, resilience, and the overall health of the planet.

1. by THARU.BSc(hons)OCUSL,Dip LDR and
Mang
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2. Just like nature, we encounter
interesting words everywhere!

3. • The arrangement of organisms
into groups based on common
characteristics is called
classification. Taxonomy is the
scientific study of classification,
identification, nomenclature, and
description. This involves placing
groups of organisms in a
hierarchical sequence.

4. • Artificial Classification:
⚬ Grouping is based on a few pre-selected unifying characters.
⚬ Characters are selected for convenience, and organisms are
grouped based on these criteria.
⚬ Evolutionary relationships are ignored.
⚬ Only system used before the 18th century.
⚬ Easy to use and expand by adding more groups.
⚬ Examples: Plants classified as cereals, ornamental plants,
medicinal plants, poisonous plants; Animals classified as two-
legged, four-legged, six-legged, eight-legged, etc.
Natural Classification
Artificial Classification

5. Grouping based on true relationships, representing evolutionary
relationships based on phylogeny.
Developed after the study of evolution.
Based on various characteristics like morphological, anatomical,
cytological, or molecular biological.
Examples: Plants classified into phyla (Bryophyta, Lycophyta,
Pterophyta, Cycadophyta, Coniferophyta, Anthophyta); Animals
classified into Cnidaria, Platyhelminthes, etc.

6. • Early classification systems were artificial and based on
human uses.
• Aristotle was the first to classify organisms scientifically,
dividing them into plants and animals.
• Carolus Linnaeus introduced binomial nomenclature and
classified about 6,000 plants into hierarchical taxa.
• With the discovery of microorganisms, Ernest Haeckel
introduced the kingdom Protista.
• Robert H. Whittaker introduced the five-kingdom system
based on cellular organization and mode of nutrition.
• Carl Woese introduced the three-domain system
(Bacteria, Archaea, Eukarya) based on molecular biology
and evolutionary relationships.

7. • Modern systematics use molecular biology for
taxonomic criteria.
• Criteria include DNA base sequences, mitochondrial
and chloroplast DNA sequences, ribosomal RNA
base sequences, amino acid sequences, and
molecular structure of cellular components.
• Kingdom Protista is considered artificial, and viruses
are separate due to lack of cellular organization.

8. • Taxonomic units at different levels are called
taxa.
• Each taxon has a rank and a name (e.g.,
Panthera at the genus level, Mammalia at the
class level).
• Domains are divided into kingdoms, kingdoms
into phyla, and so on, with many
subcategories.

9. • A species is a group of organisms sharing similar
characteristics that can interbreed and produce
viable and fertile offspring.
• Other definitions include morphological, ecological,
and phylogenetic species concepts.

10. • Proposed by Carolus Linnaeus, it uses a
two-part name: generic name (noun) and
specific epithet (adjective).
• Examples: Homo sapiens (man,
intelligent), Dipterocarpus zeylanicus
(fruit with two wings, endemic to Sri
Lanka), Dipterocarpus grandiflorus (fruit
with two wings, large flowers).
Related species have the same generic name with different specifi c epithets. e.g.
Dipterocarpus zeylanicus and Dipterocarpus grandifl orus Dipterocarpus zeylanicus
means fruit with two wings, and endemic to Sri Lanka. Dipterocarpus grandifl orus
means fruit with two wings and having large fl owers.

11. when scientists name living things, they follow certain rules called "International Codes of
Binomial Nomenclature." These rules are a bit different for plants, animals, bacteria, and
viruses. Here are some important rules:
• Unique Names: No two different species can have the same name.
• Two Parts in a Name: Each species has a special name made up of two parts. One part is
the general name (like a family name), and the other part is the specific name (like a
personal name). Together, they make up the scientific name.
• Latinized Words: The names are made up of Latinized words, written in the Roman script
(like the letters we use).
• Formatting: When writing by hand, the name should be underlined. When printed, it should
be italicized. The first letter of the general name is a capital letter, and the specific name is
in regular letters.
• Author's Name: In scientific writing, the person who gave the name is mentioned with a
capital letter, an abbreviation, or the full word at the end of the name. This part is not in
Latin. For example, "Cocos nucifera L." (L stands for Linnaeus).
• Subspecies or Variety: Sometimes, a third word is used to represent a subspecies or a
variety. For instance, "Panthera parduskotiya" represents a Sri Lankan leopard.

12. Use of Keys: Scientists use keys to group and identify organisms.
These keys don't show how different species are related
evolutionarily.
EXAMPLE 1: SILVERFI SH, BUTTERFL Y, HOUSE FL Y, BEETLE
1. POSSESSES WINGS …………………………………………………. (2)
DO NOT POSSESS WINGS ………………………………………….. SILVERFI SH
2. POSSESS TWO PAIRS OF WINGS …………………………………… (3)
DO NOT POSSESSES TWO PAIRS OF WINGS………………………………HOUSEFL Y
3. POSSESSES A PROBOSCIS ……...………………………………....BUTTERFL Y
DO NOT POSSESS A PROBOSCIS ………………......…….............,.BEETLE
NOT HAVING A RADIALLY SYMMETRICAL BODY …………...…… … ……..(2)
2. POSSESS LEGS……………………....…………………………………(3)
DO NOT POSSESSES LEGS ……………………………………………...(4)
3. WINGS PRESENT………………………………………................. BUTTERFL Y
WINGS ABSENT……...…………………………………................ FROG

13. Domains There are three domains. They are;
a) Domain – Bacteria- consists of one kingdom.
Kingdom - Bacteria
b) Domain –Archaea-consists of one kingdom.
Kingdom - Archaebacteria
c) Domain –Eukarya-consists of four kingdoms