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L AB.1
- Biological diversity and its classification
- Plant nomenclature
Phylum: Eubacteriophyta
Class: Eubacteriae
Lab manual :pp. 1-3
Biological diversity:
Definition: Sum total of all living things in a given space.
Our planet has 40 million species of which only about 2 million
species are identified and named to this date.
300,000 species are members of Kingdom Plantae
65,000 species are members of Kingdom Protista
99,000 species are members of Kingdom Fungi
10,500 species are members of Kingdoms Bacteria and Archaea
Without plants, there is no life
They are the only source of food and oxygen for the whole
world, which they produce through the process of
Therefore, the functioning of the planet, and the survival of
mankind and all other living things, depend upon plants.
Owing to the large number of species and their diversity, it is
necessary to classify them, in order to study and manage them
Classification of organisms:
All known living organisms are categorized in six kingdoms based on:
- The structure of the body
- Mode of nutrition
- Mode of reproduction
These six Kingdoms are : Archaea, Bacteria, Protista, Fungi, Plantae and Animalia
The major categories of plant classification in a decending
hierarchical order are:
Kingdom, phylum, class, order, family, genus and species.
There can be additional categories in between.
• Example of classification of onion:
Kingdom: Plantae
Allium cepa
Specific epithet
Scientific naming
Binomial Nomenclature
Rules of Binomial nomenclature:
In 1753, Carl Linnaeus (Swedish
biologist) started using this system of
naming the species and it is continued to
the present day.
The scientific (Latin) name of the species has two parts:
• First part is the genus name.
• The second part is the specific epithet.
Scientific name = Genus name + specific epithet
Scientific names are always written in Latin and follows
the rules of that language.
The two parts together represent the name of the
e.g., Allium cepa or Allium cepa = Onion
The name should be written in italics or underlined.
Rules of Binomial nomenclature
3. No two species can have the same name
4. The specific epithet may be descriptive
5. The name of the genus is always capitalized, specific epithet is not
6. The genus name can be used alone, but the specific epithet cannot stand
7. The name of the author is combined with the binomial to make it more
authentic, especially in scientific publications.
E.g.: Allium cepa L. (Onion)
Kingdom Bacteria
Prokaryotic Cells : Genetic material and other organelles are without
Prokaryotic organisms are separated into two kingdoms: Archaea and Bacteria
They differ in the chemistry, metabolism and RNA molecules of the cells.
◦ Kingdom Archaea : methane bacteria, salt bacteria, sulfolobus bacteria.
◦ Kingdom Bacteria: all the other known bacteria.
Owing to their many similarities, only Kingdom Bacteria is dealt with in the lab
Features of the Kingdom Bacteria
Prokaryotic Cells
Cells are :
- Unicellular
- Colonies or chains
- Filaments
Cell wall material - No cellulose.
Features of the Kingdom Bacteria
 Most bacteria are heterotrophic (saprophytes and parasites).
Food is usually absorbed through the cell wall or membrane.
Some bacteria have symbiotic association with other organisms.
Some are autotrophic
1. Chemosynthetic (obtain their food and energy through chemical reactions).
2. Photoautotrophic (their cells contain chlorophyll, enabling them to make their food by
Asexual reproduction:
1- Binary fission: the division of a single cell into two
or more resembling the original.
2- Formation of spores:
Spore is a unit of sexual or asexual reproduction that
may be adapted for dispersal and for survival, often
for extended periods of time, in unfavorable
New wall growing
inward in a dividing
bacterial cell
Kingdom: Bacteria
Phylum : Eubacteriophyta
Class : Eubacteriae
(True bacteria)
Class : Cyanobacteriae
(The Blue-Green Bacteria)
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class Eubacteriae
Commonly known as true bacteria.
Some true bacteria are autotrophic, some are heterotrophic (saprophytes
and parasites).
Nutrition is by absorption of food in solution through the cell wall.
Some true bacteria are very useful to man (e.g. in composting, diary
industry), while some others are harmful causing various diseases (e.g.
Anthrax, Cholera, Leprosy, Tetanus, Tuberculosis, Typhoid)
Classification of Bacteria is based on several features.
One main feature used to classify bacteria is cell shape
1. Cocci (coccus or spherical shape)
2. Bacilli (rod or cylindrical shape)
3. Spiral or helical
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class: Eubacteriae
Genus: Bacillus
Rod-shaped or cylindrical shaped bacteria
1. Bacillus (rod or cylindrical shape)
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class: Eubacteriae
Genus: Streptococcus
Coccus or spherical (round) cells forming a chain
2. Streptococcus (coccus or spherical shape)
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class: Eubacteriae
Genus: Spirillum
Spiral or helical-shaped cells
3. Spirillum (spiral or helical shape)
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class: Eubacteriae
Genus: Sarcina
Cuboidal cells forming 3-dimensional
4. Sarcina (cuboid shape).
Source: Graphic design by A. Al-Arbash
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class: Eubacteriae
Genus: Rhizobium
 Rhizobium cause the root nodules in
leguminous plants..
 This coccus-shaped bacterium is established
inside the root nodules of legumes
 The relationship between the plant and the
Rhizobium is beneficial (useful) for both
organisms (symbiotic).
 Rhizobium fix atmospheric nitrogen and
provide it to the plant as nitrates and
nitrites that helps the plant to grow better.
 Root nodules provide protection and
nutrients to the bacterial cells.
5. Rhizobium
Plant root
root nodules
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class: Cyanobacteriae
They are known as blue-green bacteria
◦ Cyanobacteria are autotrophic and produce their food by photosynthesis
◦ Pigments in Cyanobacteria:- Chlorophyll a (green color),
- Phycobilins (phycocyanin - blue, phycoerythrin - red) and carotenoids
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class: Cyanobacteriae
 Body forms : unicellular, colonial to filamentous forms.
 Their body is usually covered by a moist, gelatinous sheath.
 Many filamentous forms have the ability to fix atmospheric nitrogen into
nitrogenous compounds like ammonium, nitrate and nitrites, in a structure known
as heterocyst.
 Hence are beneficial to farmers who use them to enhance the growth of their
crop plants.
Kingdom: Bacteria
Phylum: Eubacteriophyta
Class: Cyanobacteriae
Genus: Gloeocapsa
It is unicellular organism, covered with
a gelatinous sheath, that keeps the cell
surface moist and helps the cells to
It forms a false colony produced by
binary fission, within the gelatinous
sheath. Occasionally the sheath breaks
open releasing the unicellular
6. Gloeocapsa (unicellular)
gelatinous sheath
Kingdom: Bacteria
phylum : Eubacteriophyta
Class : Cyanobacteriae
Genus : Merismopedia
 The body consists of a one-cell
gelatinous sheath
thick false colony.
 Ellipsoidal cells are arranged in
Ellipsoidal cells
arranged in columns
 Cells are surrounded by a gelatinous
One cell thick false colony
7. Merismopedia (colonial)
Kingdom: Bacteria
Phylum : Eubacteriophyta
Class : Cyanobacteriae
Genus : Oscillatoria
gelatinous sheath
•Filamentous body structure interrupted with necredia (dead cells)
•The necredia (dead cells) are weak points in the filament where a segment of the filament
(=hormogonium) can break and detach.
•Each filament consists of several vegetative cells arranged in a line and enclosed by a gelatinous
sheath. End cells are rounded.
8. Oscillatoria (filamentous with dead cells)
Kingdom: Bacteria
Phylum : Eubacteriophyta
Class : Cyanobacteriae
Genus : Anabaena
 Filamentous with rounded cells
Akinete is a structure that is formed
under unfavorable conditions . It also aids
in asexual reproduction.
Heterocyst is a thick-walled structure
that helps in fragmentation and nitrogen
Anabaena is used by farmers to enrich
the soil and enhance plant growth
(provide fixed nitrogen).
9. Anabaena (filamentous with heterocysts and akinetes)
Vegetative cells