Biological classification

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45 Terms

1
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  1. Q: What were the earliest attempts to classify living organisms based on?

  • Based on instinct and need for human use (food, shelter, clothing).

    • Not scientific criteria.

2
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  1. Q: Who was the earliest to attempt a scientific basis for classification, and what were his criteria?

  • Aristotle.

    • Used simple morphological characters.

    • Classified plants into trees, shrubs, and herbs.

    • Divided animals into those with red blood and those without.

3
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  1. Q: What was the Two Kingdom system of classification, and what were its limitations?

  • Included Plantae and Animalia kingdoms.

    • Did not distinguish between eukaryotes and prokaryotes, unicellular and multicellular organisms, or photosynthetic and non-photosynthetic organisms.

    • Many organisms did not fit into either category.

4
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  1. Q: What additional characteristics were considered for classification beyond gross morphology?

  • Cell structure.

    • Nature of the cell wall.

    • Mode of nutrition.

    • Habitat.

    • Methods of reproduction.

    • Evolutionary relationships.

5
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  1. Q: Who proposed the Five Kingdom Classification, and what were the kingdoms?

  • R.H. Whittaker (1969).

    • Kingdoms: Monera, Protista, Fungi, Plantae, Animalia.

6
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  1. Q: What were the main criteria used by Whittaker for his Five Kingdom Classification?

  • Cell structure.

    • Body organisation.

    • Mode of nutrition.

    • Reproduction.

    • Phylogenetic relationships.

7
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  1. Q: What is the Three-Domain system, and how does it differ from the Five Kingdom system?

  • Divides Kingdom Monera into two domains.

    • Leaves eukaryotic kingdoms in the third domain.

    • Results in a six-kingdom classification.

8
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  1. Q: What were the issues with earlier classification systems that grouped bacteria, fungi, and plants together?

  • Grouped prokaryotic bacteria with eukaryotic organisms.

    • Did not differentiate between unicellular and multicellular organisms.

    • Did not distinguish between heterotrophic fungi and autotrophic plants.

9
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  1. Q: What are the key characteristics of Kingdom Monera?

  • Prokaryotic cells.

    • Non-cellulosic cell wall (polysaccharide + amino acid).

    • No nuclear membrane.

    • Cellular body organisation.

    • Autotrophic (chemosynthetic and photosynthetic) and heterotrophic (saprophytic/parasitic) nutrition.

10
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  1. Q: What are the key characteristics of Kingdom Protista?

  • Eukaryotic cells.

    • Cell wall present in some.

    • Nuclear membrane present.

    • Cellular body organisation.

    • Autotrophic (photosynthetic) and heterotrophic nutrition.

11
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  1. Q: What are the key characteristics of Kingdom Fungi?

  • Eukaryotic cells.

    • Cell wall made of chitin.

    • Nuclear membrane present.

    • Multicellular/loose tissue body organisation.

    • Heterotrophic (saprophytic/parasitic) nutrition.

12
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  1. Q: What are the key characteristics of Kingdom Plantae?

  • Eukaryotic cells.

    • Cell wall made of cellulose.

    • Nuclear membrane present.

    • Tissue/organ body organisation.

    • Autotrophic (photosynthetic) nutrition.

13
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  1. Q: What are the key characteristics of Kingdom Animalia?

  • Eukaryotic cells.

    • No cell wall.

    • Nuclear membrane present.

    • Tissue/organ/organ system body organisation.

    • Heterotrophic (holozoic/saprophytic) nutrition.

14
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  1. Q: What are the four categories of bacteria based on shape?

  • Spherical (Cocci).

    • Rod-shaped (Bacilli).

    • Comma-shaped (Vibrio).

    • Spiral (Spirilla).

15
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  1. Q: What are the metabolic characteristics of bacteria?

  • Some are autotrophic (photosynthetic or chemosynthetic).

    • Most are heterotrophic (depend on other organisms or dead organic matter).

16
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  1. Q: What are Archaebacteria, and where are they found?

  • Special bacteria living in extreme habitats.

    • Found in salty areas (halophiles), hot springs (thermoacidophiles), and marshy areas (methanogens).

17
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  1. Q: What is the role of methanogens in ruminant animals?

  • Present in the gut of ruminants (e.g., cows, buffaloes).

    • Responsible for methane (biogas) production from dung.

18
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  1. Q: What are Eubacteria, and what are their characteristics?

  • "True bacteria."

    • Rigid cell wall, flagella if motile.

    • Cyanobacteria are photosynthetic autotrophs.

19
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  1. Q: What is the ecological role of cyanobacteria?

  • Photosynthetic autotrophs.

    • Fix atmospheric nitrogen in heterocysts.

    • Play a role in nutrient recycling (nitrogen, phosphorous, iron, sulphur).

20
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  1. Q: What are the roles of heterotrophic bacteria in nature?

  • Decomposers.

    • Helpful in making curd, producing antibiotics, and fixing nitrogen in legume roots.

    • Some are pathogens causing diseases like cholera, typhoid, and tetanus.

21
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  1. Q: How do bacteria reproduce?

  • Mainly by fission.

    • Produce spores under unfavourable conditions.

    • Primitive DNA transfer for sexual reproduction.

22
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  1. Q: What are Mycoplasma, and what makes them unique?

  • Lack a cell wall.

    • Smallest living cells.

    • Can survive without oxygen.

    • Many are pathogenic in animals and plants.

23
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  1. Q: What are the characteristics of Kingdom Protista?

  • Single-celled eukaryotes.

    • Primarily aquatic.

    • Reproduce asexually and sexually.

24
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  1. Q: What are Chrysophytes, and what is their ecological role?

  • Include diatoms and golden algae (desmids).

    • Found in freshwater and marine environments.

    • Photosynthetic.

    • Diatomaceous earth is used in polishing and filtration.

25
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  1. Q: What are Dinoflagellates, and what causes red tides?

  • Mostly marine and photosynthetic.

    • Have two flagella.

    • Rapid multiplication of red dinoflagellates (e.g., Gonyaulax) causes red tides.

26
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  1. Q: What are Euglenoids, and how do they behave?

  • Freshwater organisms.

    • Have a protein-rich pellicle instead of a cell wall.

    • Photosynthetic in sunlight, heterotrophic in darkness.

27
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  1. Q: What are Slime Moulds, and how do they reproduce?

  • Saprophytic protists.

    • Form plasmodium under suitable conditions.

    • Produce spores during unfavourable conditions.

28
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  1. Q: What are the four major groups of Protozoans?

  • Amoeboid protozoans (e.g., Amoeba).

    • Flagellated protozoans (e.g., Trypanosoma).

    • Ciliated protozoans (e.g., Paramoecium).

    • Sporozoans (e.g., Plasmodium).

29
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  1. Q: What are the characteristics of Kingdom Fungi?

  • Heterotrophic organisms.

    • Great diversity in morphology and habitat.

    • Cell walls made of chitin and polysaccharides.

30
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  1. Q: What are the modes of reproduction in fungi?

  • Vegetative (fragmentation, fission, budding).

    • Asexual (spores like conidia, sporangiospores, zoospores).

    • Sexual (oospores, ascospores, basidiospores).

31
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  1. Q: What are the three steps in the sexual reproduction of fungi?

  • Plasmogamy (fusion of protoplasms).

    • Karyogamy (fusion of nuclei).

    • Meiosis in zygote resulting in haploid spores.

32
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  1. Q: What are Phycomycetes, and where are they found?

  • Found in aquatic habitats and decaying wood.

    • Asexual reproduction by zoospores or aplanospores.

    • Sexual reproduction by zygospores.

33
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  1. Q: What are Ascomycetes, and what are their characteristics?

  • Known as sac-fungi.

    • Multicellular (e.g., Penicillium) or unicellular (e.g., yeast).

    • Asexual spores called conidia.

    • Sexual spores called ascospores.

34
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  1. Q: What are Basidiomycetes, and what are their characteristics?

  • Include mushrooms, bracket fungi, and puffballs.

    • Reproduce by basidiospores.

    • Examples: Agaricus, Ustilago, Puccinia.

35
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  1. Q: What are Deuteromycetes, and why are they called imperfect fungi?

  • Only asexual or vegetative phases are known.

    • Reproduce by conidia.

    • Examples: Alternaria, Colletotrichum, Trichoderma.

36
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  1. Q: What are the characteristics of Kingdom Plantae?

  • Eukaryotic, chlorophyll-containing organisms.

    • Cell walls made of cellulose.

    • Autotrophic (photosynthetic), with some heterotrophic exceptions.

37
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  1. Q: What is alternation of generations in plants?

  • Life cycle alternates between diploid sporophytic and haploid gametophytic phases.

38
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  1. Q: What are the characteristics of Kingdom Animalia?

  • Heterotrophic, multicellular eukaryotes.

    • Lack cell walls.

    • Holozoic nutrition (ingestion of food).

    • Reproduce sexually.

39
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  1. Q: What are viruses, and why are they not considered truly living?

  • Non-cellular, inert crystalline structure outside living cells.

    • Obligate parasites that replicate using host cell machinery.

    • Lack cell structure.

40
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  1. Q: What are the components of a virus?

  • Genetic material (RNA or DNA).

    • Protein coat (capsid) made of capsomeres.

41
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  1. Q: What are viroids, and how were they discovered?

  • Smaller than viruses, consist of free RNA.

    • Discovered by T.O. Diener in 1971.

    • Cause diseases like potato spindle tuber disease.

42
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  1. Q: What are prions, and what diseases do they cause?

  • Infectious agents made of abnormally folded proteins.

    • Cause diseases like mad cow disease (BSE) and Creutzfeldt-Jakob disease (CJD).

43
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  1. Q: What are lichens, and what is their ecological role?

  • Symbiotic association between algae (phycobiont) and fungi (mycobiont).

    • Algae provide food, fungi provide shelter and nutrients.

    • Lichens are pollution indicators.

44
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  1. Q: What are the main differences between prokaryotic and eukaryotic cells?

  • Prokaryotic: No nucleus, no membrane-bound organelles.

    • Eukaryotic: Nucleus present, membrane-bound organelles present.

45
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  1. Q: What are the main differences between autotrophic and heterotrophic nutrition?

  • Autotrophic: Synthesize own food (photosynthesis or chemosynthesis).

    • Heterotrophic: Depend on other organisms for food.