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1.Dichotomous key2.Kingdom Proyaryota
(bacteria)3.Kingdom Protoctista
by Hazel 6S (23)
Dichotomous keys
• A device for easy and quick identification of unknown object.
• Construction of a dichotomous key: - Use constant characteristics - Use quantitative
X (e.g. big, small ……) - Precede the descriptive terms with the
name of the anatomical part to which it applies.
When using a key, please When using a key, please reremember member ::
• Always read both choices.• Be sure you understand the meaning of the terms
involved. • When measurements are given, use a calibrated
scale. • Since living things are always variable, do not base
your conclusion on a single observation. Study several specimens to be sure your specimen is typical.
• 1a. Organisms lacking cell nuclei . . . . . Prokaryotae• 1b. Organisms with cell nuclei . . . . . . . . . . . 2
• 2a. Unicellular or tissue-level organisms . . Protista• 2b. Complex, multicellular organisms . . . . . . . . 3
• 3a. Organisms autotrophic . . . . . . . . . . . . . Plantae• 3b. Organisms heterotrophic. . . . . . . . . . . . 4
• 4a. Organisms absorb food . . . . . . . . . . . . . . Fungi• 4b. Organisms ingest food . . . . . . . . . . . . . Animalia
Examples of Dichotomous keys
• Prokaryotic organisms (bacteria)
• Bacteria⁻ Tiny (diameter: 0.5 -1.0um)⁻ Unicellular⁻ Occur in clusters or filaments⁻ Spherical, rod-shaped and helical⁻ Survive even under extreme conditions⁻ Flagella ( motile )
• Prokaryotic organisms (bacteria)
• Bacteria⁻ Tiny (diameter: 0.5 -1.0um)⁻ Unicellular⁻ Occur in clusters or filaments⁻ Spherical, rod-shaped and helical⁻ Survive even under extreme conditions⁻ Flagella ( motile )
Kingdom prokaryota (Kingdom Monera)
ReproductionReproduction
• Reproduce asexually ( binary fission )
Reproduce sexually ( conjugation )
3 types of survival 3 types of survival ways ways – Heterotrophs(most)
– Autotrophs (some) e.g. blue green algae (cyanobacteria)
green sulphur bacteria purple sulphur bacteria
– Chemoautotrophs
Archaebacteria & Eubacteria
Archaebacteria Eubacteria (true bacteria)
Shape Various shape Various shape
Cell wall X Peptidoglycan Peptidoglycan
Cell membrane Branched chain ether linked lipids.
Straight chain ester with lipids.
tRNA X thymine thymine
Interaction with other organisms
• mutualism• commensal
• mutualists• predators• pathogens
Significance in technology and industry
Thermostable enzymes, sewage treatment, antibiotics, organic solvents, production of biogas
Fermented foods, bioremediation, waste processing, agrichemicals, biological pest control, scientific research
Kingdom Subkingdom Major group
Prokaryotae Eubacteria( true bacteria)
Heterotrophic eubacteria
Photosynthetic
Chemosynthetic
Archaebacteria Methanogens
Halophiles
Thermophiles
Kingdom Protoctista• Some: unicellular
some: multicellular• nuclei and other characteristically
eukaryotic properties• Size: microscopic form – giant form• Motile ( pseudopodia, cilia, flagella )• Aquatic• 3 subgroups :
algae, protozoans, slime moulds
AlgaeAlgae • Plant-like protoctists
– Cellulose cell wall– Non-motile– Undergo photosynthesis
• X many plant structuresSubgroup Phylum Distinguishi
ng featurePhotosynthetic pigments
Algae Chlorophyta (green algae )
−Unicellular / multicellular−Cellulose cell wall
Chlorophyll
Phaeophyta(brown algae)
Chlorophyll & fucoxanthin
Bacillariophyta(diatoms)
Cell wall with a kind of silica
Various
ProtozoaProtozoa • Animal-like unicellular protoctists
– Motile– X cell wall & chlorophyll– Obtain nutrients by engulfing other organisms
Subgroup Phylum Distinguishing features
Protozoa Phytoflagellata(plant flagellates)
−Unicellular− X cell wall
− ≥1 flagella−chlorophyll
Zooflagellata(animal flagellates)
− ≥1 flagella−Heterotrophic
Sarcodina(amoebae)
- pseudopodia−Heterotrophic
Ciliophora(ciliates)
−Numerous cilia−2 nuclei−Heterotrophic
Slime mouldsSlime moulds• Fungi-like protoctists
– Body consist of thread-like structures– X photosynthesis– Obtain nutrients through absorption from the
surroundings
• Different structural constituents and composition from fungi
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