1. Living World and Classification of Microbes​

Class 8 – Chapter 1: Living World & Classification of Microbes (Maharashtra Board)

Chapter 1: Living World & Classification of Microbes

Class 8 – General Science (Maharashtra Board) • Five Kingdoms • Microbes & their Features

Font: Comic Sans MS Mobile-friendly size Questions in Red, Answers in Green

1) 20 Important Words (with simple meanings in Hindi)

  • Taxonomyजीवों को पहचानने, नाम देने और वर्गों में बाँटने का विज्ञान।
  • Classificationसमानता और भिन्नता के आधार पर समूह बनाना।
  • Speciesएक ही प्रकार के जीव जो आपस में प्रजनन कर सकें।
  • Genusकई नज़दीकी species का समूह।
  • Kingdomसबसे बड़ा वर्गीकरण समूह (जैसे Monera, Protista आदि)।
  • Binomial Nomenclatureवैज्ञानिक नाम लिखने की दो-शब्द वाली पद्धति (Genus + species)।
  • Prokaryoteजिसमें सच्चा nucleus न हो (जैसे bacteria)।
  • Eukaryoteजिसमें सच्चा nucleus और झिल्ली-बद्ध organelles हों।
  • Unicellularएक ही कोशिका से बना जीव।
  • Multicellularकई कोशिकाओं से बना जीव।
  • Autotrophicजो स्वयं भोजन बनाते हैं (जैसे पौधे)।
  • Heterotrophicजो बाहर से भोजन लेते हैं (जैसे जानवर)।
  • Saprophyticसड़ते-गले पदार्थों से पोषण लेना (जैसे fungi)।
  • Producerजो भोजन/ऊर्जा का उत्पादन करें (पौधे)।
  • Consumerजो दूसरों पर पोषण हेतु निर्भर हों (जानवर)।
  • Decomposerजो मृत/कचरे पदार्थों को सड़ा-गलाकर पोषक तत्व वापस मिट्टी में लौटाएँ (fungi)।
  • Phylogenyजीवों का विकास-इतिहास और आपसी संबंध।
  • Chitinकठोर कार्बोहाइड्रेट जिससे fungi की cell wall बनती है।
  • Pseudopodia/Cilia/Flagellaसूक्ष्मजीवों की गति करने वाली बनावटें।
  • Virusडीएनए/आरएनए और प्रोटीन से बना सूक्ष्म कण; केवल जीवित कोशिका में सक्रिय।
Note: Use of Hindi is only for the meanings above, as requested. All other sections are in English.

2) Important Notes (Quick Revision)

  • Need of Classification: ~87 million species (land + sea) are estimated on Earth; grouping makes study easier.
  • History: Linnaeus (1735) – 2 kingdoms; Haeckel (1866) – 3; Chatton (1925) – Prokaryotes & Eukaryotes; Copeland (1938) – 4; Whittaker (1969) – 5 kingdoms.
  • Whittaker’s Criteria: cell type (prokaryotic/eukaryotic), body organization (uni/multi), mode of nutrition (auto/hetero/sapro), life-style (producer/consumer/decomposer), and phylogeny.
  • 5-Kingdom System: Monera, Protista, Fungi, Plantae, Animalia.
  • Monera: unicellular, prokaryotic (bacteria, cyanobacteria/blue-green algae). Binary fission.
  • Protista: unicellular eukaryotes (Amoeba, Paramecium, Euglena, Volvox). Locomotion via pseudopodia/cilia/flagella.
  • Fungi: non-green eukaryotes; mostly saprotrophs; chitinous cell wall; unicellular yeast to multicellular mushrooms.
  • Plantae: cell wall present; chloroplasts; photosynthetic producers.
  • Animalia: no cell wall; ingestive heterotrophs; consumers.
  • Microbial Sizes & Units: $1\\text{ m}=10^{6}\\,\\mu\\text{m}$, $1\\text{ m}=10^{9}\\,\\text{nm}$.
    • Viruses: $\\sim 10$–$100\\,\\text{nm}$
    • Bacteria: $\\sim 1$–$10\\,\\mu\\text{m}$
    • Protozoa: $\\sim 200\\,\\mu\\text{m}$ (approx.)
    • Many unicellular algae/fungi: $\\sim 10$–$100\\,\\mu\\text{m}$
  • Binomial Nomenclature (Linnaeus): two words—Genus (Capitalized) + species (lowercase), both italicized or underlined if handwritten.
  • Bacterial growth (favourable conditions): doubles every 20 min. Formula: $N(t)=N_0\\times 2^{t/20\\ \\text{min}}$.
  • Viruses: DNA or RNA + protein coat; active only inside living cells; cause diseases in plants/animals (e.g., polio, influenza, HIV; Tomato wilt; Tobacco mosaic). Bacteriophage infects bacteria.
  • Institution: National Institute of Virology (NIV), Pune – established 1952 under ICMR; research on viruses.

3) 20 Most Important One-word Answer Type Questions

Q1. Who introduced binomial nomenclature?A1. Carl (Carolus) Linnaeus.
Q2. Smallest among microbes listed?A2. Viruses.
Q3. Kingdom of bacteria?A3. Monera.
Q4. Fungal cell wall is made of?A4. Chitin.
Q5. Nutrition in fungi?A5. Saprophytic (absorption from decaying matter).
Q6. Ecosystem producers?A6. Plants.
Q7. Ecosystem consumers?A7. Animals.
Q8. Ecosystem decomposers?A8. Fungi.
Q9. Locomotion in Amoeba?A9. Pseudopodia.
Q10. Locomotion in Paramecium?A10. Cilia.
Q11. Locomotion in Euglena?A11. Flagellum.
Q12. Unicellular eukaryotes belong to?A12. Protista.
Q13. Blue-green “algae” belong to?A13. Monera (cyanobacteria).
Q14. Two parts of a scientific name?A14. Genus and species (specific epithet).
Q15. Shape of Vibrio?A15. Comma-shaped.
Q16. Bacterial reproduction type?A16. Binary fission.
Q17. Kingdom with no cell wall?A17. Animalia.
Q18. Chloroplast present mainly in?A18. Plantae (also some Protista like Euglena).
Q19. Organisms with true nucleus?A19. Eukaryotes.
Q20. Organisms without true nucleus?A20. Prokaryotes.

4) 20 Most Important Very Short Answer Questions

Q1. Why do we need biological classification?A1. To organise ~87 million species into groups for easier study, comparison and communication.
Q2. List Whittaker’s five criteria.A2. Cell type; body organisation; mode of nutrition; life-style; phylogeny.
Q3. State the rule of binomial nomenclature.A3. Two words—Genus (Capital) + species (lowercase), italicised.
Q4. Write the standard hierarchy of classification.A4. Kingdom → Phylum/Division → Class → Order → Family → Genus → Species.
Q5. Give two examples of fungi.A5. Baker’s yeast, Mushroom (also Penicillium, Aspergillus).
Q6. Define bacteria in one line.A6. Unicellular prokaryotes reproducing by binary fission.
Q7. What is a bacteriophage?A7. A virus that infects bacteria.
Q8. Where do protozoa live?A8. Soil, fresh/salt water; some are parasitic in other organisms.
Q9. What is saprotrophic nutrition?A9. Absorbing nutrients from decaying organic matter (typical of fungi).
Q10. State bacteria doubling time and formula.A10. ~20 min; $N(t)=N_0\\times 2^{t/20\\,\\text{min}}$.
Q11. Why are viruses “at the edge of living”?A11. They show life-like activity only inside host cells; inert outside.
Q12. Name locomotory organelles of Amoeba/Paramecium/Euglena.A12. Pseudopodia / Cilia / Flagellum respectively.
Q13. Describe Monera cell structure.A13. Prokaryotic; no true nucleus or membrane-bound organelles.
Q14. Two pathogenic protozoa with disease.A14. Entamoeba histolytica—amoebiasis; Plasmodium vivax—malaria.
Q15. Role of Lactobacillus in curd.A15. Ferments milk sugar to lactic acid; sets curd; beneficial.
Q16. Name two plant viral diseases.A16. Tomato wilt; Tobacco mosaic disease.
Q17. Which kingdoms are mostly multicellular?A17. Fungi, Plantae, Animalia (many protists are unicellular).
Q18. Producers vs consumers?A18. Producers make food (plants); consumers ingest food (animals).
Q19. What are cyanobacteria?A19. Photosynthetic, prokaryotic “blue-green algae” in Monera.
Q20. Ecological role of fungi?A20. Decomposers—recycle nutrients to the soil.

5) 20 Most Important Short Answer (2–3 lines) Questions

Q1. State the merits of Whittaker’s five-kingdom classification.A1. Separates prokaryotes from eukaryotes; groups organisms by cell type, body plan and nutrition; aligns with evolutionary (phylogenetic) trends; simplifies study.
Q2. Give three key features of Monera.A2. Prokaryotic, unicellular; no true nucleus/organelles; reproduce by binary fission; include bacteria & cyanobacteria.
Q3. Give three key features of Protista.A3. Unicellular eukaryotes; locomotion via pseudopodia, cilia or flagella; nutrition auto/heterotrophic (e.g., Euglena, Amoeba).
Q4. Give three key features of Fungi.A4. Non-green eukaryotes; chitin cell wall; mostly saprotrophic; unicellular yeast to multicellular mushrooms.
Q5. What is fungal cell wall made of and why is it important?A5. Chitin; a tough polysaccharide providing strength and shape, aiding survival on decaying matter.
Q6. Prokaryotic vs Eukaryotic—differentiate briefly.A6. Prokaryotes lack true nucleus/organelles (Monera); eukaryotes have nucleus & membrane-bound organelles (Protista, Fungi, Plantae, Animalia).
Q7. Autotrophic vs Heterotrophic nutrition—explain.A7. Autotrophs (plants, some protists) synthesize food via photosynthesis; heterotrophs (animals, many protists/fungi) obtain food from others.
Q8. Why are decomposers essential?A8. They break down dead matter, releasing nutrients back to soil, closing the nutrient cycle.
Q9. Describe three locomotion types in protists.A9. Pseudopodia—amoeboid streaming; Cilia—short hair-like beats; Flagella—whip-like strokes.
Q10. Outline viral structure and replication.A10. Nucleic acid (DNA/RNA) + protein coat; inside host they make viral proteins and genomes, assemble, and lyse/exit to infect new cells.
Q11. Plantae vs Animalia—two points.A11. Plantae: cell wall, chloroplasts, photosynthetic; Animalia: no cell wall, ingestive heterotrophs.
Q12. What does “phylogenetic relationship” mean here?A12. Evolutionary relationships—progression from prokaryotic to eukaryotic, unicellular to multicellular forms.
Q13. Why are unicellular algae kept in Protista but many algae in Plantae?A13. Unicellular forms fit Protista (simple body plan), whereas many multicellular algae with plant-like traits fit Plantae.
Q14. Sketch the five-kingdom flow in one line.A14. Living organisms → Prokaryotes (Monera) & Eukaryotes → Protista / Fungi / Plantae / Animalia.
Q15. How to prepare and observe pond water mount?A15. Place a drop on slide, cover with cover slip, observe under microscope—look for Amoeba, Paramecium, etc.
Q16. Write two useful unit relations for microscopes.A16. $1\\,\\text{m}=10^{6}\\,\\mu\\text{m}$; $1\\,\\text{m}=10^{9}\\,\\text{nm}$.
Q17. List four bacterial shapes with an example name.A17. Coccus (spherical), Bacillus (rod), Spirillum (spiral), Vibrio (comma-shaped).
Q18. Why use binomial names?A18. Universal, precise, avoids confusion from local/vernacular names.
Q19. Note on NIV Pune.A19. Established 1952 (ICMR); national research centre focused on viruses and viral diseases.
Q20. Write the bacterial doubling idea and a quick example.A20. $N(t)=N_0 2^{t/20}$; e.g., in 1 hour ($t=60$ min), $N= N_0 2^{3}=8N_0$.

6) Textbook Exercises — Perfect Answers

Q1. Use Whittaker method to classify bacteria, protozoa, fungi, algae, prokaryotic and eukaryotic microbes. A1. Monera: Bacteria; cyanobacteria (prokaryotic, unicellular).
Protista: Protozoa (Amoeba, Paramecium), unicellular algae like Chlorella/Chlamydomonas (eukaryotic, unicellular).
Fungi: Yeast, Penicillium, mushrooms (eukaryotic, mostly multicellular, saprotrophic).
Plantae: Multicellular plants & many multicellular algae (cell wall, chloroplasts).
Animalia: Multicellular animals (no cell wall, ingestive).
“Prokaryotic microbes” → Monera; “Eukaryotic microbes” → Protista & some Fungi/Algae.
Q2. Complete the five kingdom method of classification using the given terms. A2. Living organismsProkaryotes (Kingdom Monera) & Eukaryotes → Unicellular (Protista) and Multicellular → with cell wall & photosynthesis (Plantae) / cell wall but no photosynthesis (Fungi) / no cell wall (Animalia).
Q3. Find out my partner (match the columns). A3.
ItemPartner
FungiCandida (also Yeast/Mushroom)
ChlorellaAlgae
ProtozoaAmoeba (also Paramecium)
VirusBacteriophage (also Tomato wilt virus)
BacteriaProkaryotic
Q4. True/False. Explain. A4. (a) Lactobacilli are harmful bacteria — False; they set curd and are useful.
(b) Cell wall of fungi is made up of chitin — True; chitin provides rigidity.
(c) Organ of locomotion in Amoeba is pseudopodia — True; it moves by cytoplasmic streaming.
(e) Tomato wilt is a viral disease — True; caused by plant virus.
Q5. Give answers (short). (a) Merits of Whittaker’s method: clear separation of prokaryotes/eukaryotes; considers nutrition, body organisation & phylogeny; widely accepted and practical.
(b) Characteristics of viruses: acellular; DNA or RNA with protein coat; obligate parasites—replicate only in living cells; cause diseases in plants/animals/bacteria.
(c) Nutrition in fungi: mainly saprotrophic—enzymatically digest dead matter and absorb nutrients; some are parasitic/symbiotic.
(d) Kingdom Monera includes: all prokaryotes—bacteria and cyanobacteria (blue-green algae).
Q6. Who am I? (a) No true nucleus, organelles or plasma membrane — Virus.
(b) I have nucleus and membrane-bound organelles — Eukaryote (Protista/Fungi/Plantae/Animalia).
(c) I live on decaying organic matter — Fungus (saprotroph).
(d) I reproduce mainly by cell division — Protozoan (also bacteria by binary fission).
(e) I can produce my replica — Virus (inside host).
(f) I am green but don’t have organs — Alga (unicellular, e.g., Chlorella).
Q7. Draw neat and labelled diagrams: (a) Types of bacteria (b) Paramecium (c) Bacteriophage. A7. Simple labelled SVG sketches are provided below for classroom reference (students should practice neat hand-drawn versions in notebooks).
Coccus Bacillus Spirillum Vibrio
Nucleus Cilia Pellicle
Protein head (capsid) Tail DNA/RNA inside capsid
Q8. Arrange in ascending order of size: Bacteria, Fungi, Viruses, Algae. A8. Viruses < Bacteria < Fungi < Algae (many unicellular).
Typical ranges: Viruses $\\approx 10$–$100\\,\\text{nm}$; Bacteria $\\approx 1$–$10\\,\\mu\\text{m}$; Fungi/Unicellular algae $\\approx 10$–$100\\,\\mu\\text{m}$ (many algae are larger and multicellular).

Quick Recall

Q. What is the hierarchy for classification of living organisms?A. Kingdom → Phylum/Division → Class → Order → Family → Genus → Species.
Q. Who invented the binomial system of nomenclature?A. Carl (Carolus) Linnaeus.
Q. Which levels are used while writing a scientific name?A. Genus (first) and species (second).

— End of Chapter 1 Notes —

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