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Dichotomous key Kingdom Proyaryota (bacteria) 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 ……)
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Dichotomous key Kingdom Proyaryota (bacteria) 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 remember : • 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.
Examples of Dichotomous keys • 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
Kingdom prokaryota (Kingdom Monera) • 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 )
Reproduction • Reproduce asexually ( binary fission )
3 types of survival ways • Heterotrophs(most) • Autotrophs (some) e.g. blue green algae (cyanobacteria) green sulphur bacteria purple sulphur bacteria • Chemoautotrophs
Kingdom Protoctista • Some: unicellularsome: multicellular • nuclei and other characteristically eukaryotic properties • Size: microscopic form – giant form • Motile ( pseudopodia, cilia, flagella ) • Aquatic • 3 subgroups :algae, protozoans, slime moulds
Algae • Plant-like protoctists • Cellulose cell wall • Non-motile • Undergo photosynthesis • X many plant structures
Protozoa • Animal-like unicellular protoctists • Motile • X cell wall & chlorophyll • Obtain nutrients by engulfing other organisms
Slime 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