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

http://sites.google.com/site/scienceprofonline/bugdichotemouskey.gif/bugdichotemouskey-full;init:.gif

• 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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