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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.
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.
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.
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.
Q: Who proposed the Five Kingdom Classification, and what were the kingdoms?
R.H. Whittaker (1969).
Kingdoms: Monera, Protista, Fungi, Plantae, Animalia.
Q: What were the main criteria used by Whittaker for his Five Kingdom Classification?
Cell structure.
Body organisation.
Mode of nutrition.
Reproduction.
Phylogenetic relationships.
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.
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.
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.
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.
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.
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.
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.
Q: What are the four categories of bacteria based on shape?
Spherical (Cocci).
Rod-shaped (Bacilli).
Comma-shaped (Vibrio).
Spiral (Spirilla).
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).
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).
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.
Q: What are Eubacteria, and what are their characteristics?
"True bacteria."
Rigid cell wall, flagella if motile.
Cyanobacteria are photosynthetic autotrophs.
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).
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.
Q: How do bacteria reproduce?
Mainly by fission.
Produce spores under unfavourable conditions.
Primitive DNA transfer for sexual reproduction.
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.
Q: What are the characteristics of Kingdom Protista?
Single-celled eukaryotes.
Primarily aquatic.
Reproduce asexually and sexually.
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.
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.
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.
Q: What are Slime Moulds, and how do they reproduce?
Saprophytic protists.
Form plasmodium under suitable conditions.
Produce spores during unfavourable conditions.
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).
Q: What are the characteristics of Kingdom Fungi?
Heterotrophic organisms.
Great diversity in morphology and habitat.
Cell walls made of chitin and polysaccharides.
Q: What are the modes of reproduction in fungi?
Vegetative (fragmentation, fission, budding).
Asexual (spores like conidia, sporangiospores, zoospores).
Sexual (oospores, ascospores, basidiospores).
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.
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.
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.
Q: What are Basidiomycetes, and what are their characteristics?
Include mushrooms, bracket fungi, and puffballs.
Reproduce by basidiospores.
Examples: Agaricus, Ustilago, Puccinia.
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.
Q: What are the characteristics of Kingdom Plantae?
Eukaryotic, chlorophyll-containing organisms.
Cell walls made of cellulose.
Autotrophic (photosynthetic), with some heterotrophic exceptions.
Q: What is alternation of generations in plants?
Life cycle alternates between diploid sporophytic and haploid gametophytic phases.
Q: What are the characteristics of Kingdom Animalia?
Heterotrophic, multicellular eukaryotes.
Lack cell walls.
Holozoic nutrition (ingestion of food).
Reproduce sexually.
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.
Q: What are the components of a virus?
Genetic material (RNA or DNA).
Protein coat (capsid) made of capsomeres.
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.
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).
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.
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.
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.
